Just Solve the File Format Problem - User contributions [en]

Just Solve the File Format Problem:Community portal

2025-06-03T11:55:44Z

Johanvanderknijff: Added CAPTCHA issue

: ''please add your signature by typing <nowiki>~~~~</nowiki> if you add or reply

== Open issues ==

Below is a list of "issues" which would ordinarily be in a ticketing system of some kind, but are here on the Wiki instead, because that's how we roll. As things are resolved, they will be moved to the Discussion page. If there's an appeal or an issue, the conversation can continue there - this page will be for open issues.

Use of case in URLS / links. I went through all the electronic format types pages, and tried to normalise all the pages where I could (there was a mix of link structures - I've tried to get them all (apart from animation - I've been at it all day!) so they are [[file extension]] - [[file type name]].
I notice that we have a mix of upper and lower case file extension through out. This means we may have 2 links which should point to the same URL (e.g. [[mix]] and [[MIX]]) is this a known issue with the current layout? --[[User:JaygattusoNLNZ|JaygattusoNLNZ]] ([[User talk:JaygattusoNLNZ|talk]]) 01:32, 20 November 2012 (UTC)
:Since you're linking both the extension and the name, does that mean that there are supposed to be separate articles for each? I don't know if there's really a need for "mainspace" articles by extension, since there are already categories for that purpose; you can browse them through [[:Category:File formats by extension]]. [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 02:12, 20 November 2012 (UTC)
::I just copied the most common model that I found on the formats pages. The problem is, if you don't homogenize the method, the linking/crosslinking doesn't work properly. All instances of .doc (for example) should point to the same resource page / disambiguation page. If someone has linked to only format in one place (e.g. [[MS Word]] (.doc)), and someone else the extension (MS Word - [[doc]]), we can't makes sure they point to the same place. The problem occurs because format names and extensions are used interchangeably. You raise an interesting question about the relationship between the ext and the format name. I would argue they are not equal (1:1), nor (1:many) / (many:1) so it makes sense to protect both aspects as definable things - the extension because that's whats most commonly searched for and referred to by users and 'format name' because its more accurate. How is the [[:Category:File formats by extension]] populated? --[[User:JaygattusoNLNZ|JaygattusoNLNZ]] ([[User talk:JaygattusoNLNZ|talk]]) 18:31, 20 November 2012 (UTC)
:::The categories are inserted when you use the ext template in the infobox. My preference is to have articles by actual format name and use multiple navigation aids (menus, cats, etc.) to get to them. [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 01:38, 21 November 2012 (UTC)

== Article naming convention ==

As mentioned above, there's some dispute over whether to name articles after the full name of a format or its file extension. If using full names, you then get into issues of whether to use the full technical name or a shorter thing that's more popularly used, and in some cases that's even the same as the extension (GIF, for instance). And you also get into tricky issues of capitalization: all-caps like an acronym, all-lowercase like filenames are often done (though this is OS-dependent; some, like MS-DOS, use all-uppercase), or mixed case (proper names capitalized)? And then there's the disambiguation issue of how to name articles on different things that have the same name, which happens sometimes even with long official names, but even more often with short acronyms and file extensions. But there's also yet another issue of which things get separate articles and which are combined, like formats that have had many different versions, etc.

Currently you have things like [[CI]] and [[CT]], recently-created articles that represent two different file types within the data of one type of music tracker. The spec document they link to is the same one, which documents all the file types used in that tracker. Unless there's going to be really a lot to say about each of the specific file types, my own preference would be to have one article called [[CyberTracker]] that discusses all the formats used by the program in question, with subheaders within the article for the different file types, and all the extensions listed in the infobox (and hence in associated categories). If any other indices by extension are built up, they'd also have entries for both CI and CT. For instance, when I documented [[Softdisk Family Tree]], I covered all the various file formats in one article, though there are several versions and multiple files for each. [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 13:39, 21 November 2012 (UTC)
: I realise I'm as guilty of this as anyone, having used both forms at some point (e.g. [[Surprise! Adlib Tracker v2.0]] and [[CI]]). Indeed, the two articles - [[CI]] and [[CT]] - you refer to were created by me. I guess in general I would favour using a descriptive page name rather than simply the file extension - that seems to be something that's being taken care of by infoboxes and categories.

:On the issue of what gets a separate page and what doesn't, I guess that just comes down to individual discretion. There will be instances where a format has undergone a number of minor revisions over time or has a number of minor variants (e.g. the variant forms of Chaos Music Composer's [[CMC]]) where it would make sense to keep them all to a single page, while a major revision would necessitate a multi-page approach (e.g. the shift with Capella from the binary [[CAP]] to the XML-based [[CapXML]] format).

:However, I'm not sure I agree with [[CI]] and [[CT]] having a single [[CyberTracker]] page. While both link to the same spec document and both are used by the same program, they are different formats serving different purposes. I think in general we should try and distinguish between program and file format - [[S3M]] doesn't belong on the [[ScreamTracker]] page, although each should link to the other. [[User:Halftheisland|Halftheisland]] ([[User talk:Halftheisland|talk]]) 14:04, 21 November 2012 (UTC)

:Since the purpose of the wiki is to document file formats, I think it's good that as many formats as possible are listed in the category pages and that you can browse these pages for format extensions. Sometimes it might be better to link multiple extension to the same article (e.g. a specific application), but not always. I think it is difficult to come up with a strict rule for this (but maybe recommendations and, even better, good examples). --[[User:PN|PN]] ([[User talk:PN|talk]]) 15:08, 21 November 2012 (UTC)

::It's a judgment call, certainly. It depends on how the files are typically encountered, distributed, used, etc., and how they're thought of by people who use them; if a bunch of file types related to a particular program are usually found together as part of a larger data set, they most likely belong together in one article (with subsections to describe the function of the particular files), but if they're distinct entities with their own particular treatment (like separate areas of file trading sites for enthusiasts) they should have separate articles, though more descriptive names like "CyberTracker instrument file" might be better than a cryptic and likely ambiguous CI. [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 15:46, 21 November 2012 (UTC)
::And then, somebody has also used a robot to create pages in a separate namespace devoted to file extensions, like [[Ext:cin]]. That's yet another navigational system for getting to information by extension, though those pages oddly don't actually have direct links to the normal pages here about those file formats. [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 15:56, 21 November 2012 (UTC)
::: Yes, that was me with Bender the bot. Still experimenting with it and working on creating a list of all pages in relation to extensions. [[User:Maurice.de.rooij|Maurice.de.rooij]] ([[User talk:Maurice.de.rooij|talk]]) 15:22, 22 November 2012 (UTC)
::What I'd like to avoid is the messy format somebody did to a few index pages like [[Compression]], where each line has separately hyperlinked format names and extensions (not always in a consistent order) where often one or the other is a redlink, or one redirects to the other, or one is just a disambiguation page, making a somewhat confusing hodgepodge. [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 16:22, 21 November 2012 (UTC)
:::I've started rearranging the Compression page to be a little less messy. [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 16:56, 22 November 2012 (UTC)

== So now what? ==
The official month of this project is now over... what are the plans for the site now? It's made a good start at documenting file formats, but has a good long way to go yet. (A project like this can never possibly be "finished", since there are always more file formats coming out of the woodwork, both new ones that are introduced, and old ones that are discovered.) [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 05:10, 1 December 2012 (UTC)
: This is an awesome project and I will stay committed to it. Of course this first month is just a start. Let's roll people! [[User:Maurice.de.rooij|Maurice.de.rooij]] ([[User talk:Maurice.de.rooij|talk]]) 23:22, 3 December 2012 (UTC)

== Anybody else still around? ==
Everybody else seems to have vanished around the middle of December... I'm the only one editing here lately. I hate to put more effort into improving a ghost town... anyone else even reading this? [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 23:16, 2 January 2013 (UTC)

: I will be editing more once I get back to work - still don't have a home internet connection and working from the local library computers / girlfriend's netbook over public wi-fi is a pain. It would be nice to see more contributions from others - you can see how much work is left to do on the music section alone, and I've really only been creating stub entries for most things. [[User:Halftheisland|Halftheisland]] ([[User talk:Halftheisland|talk]]) 13:51, 3 January 2013 (UTC)

:Well, I still stop by on occasion, and I've vowed to use the site as my first stop when I come across a file format I don't recognize, but I never made any substantial additions, so I'm not sure if that gives you any useful information. (My edits were mostly technical or editorial.) [[User:Gphemsley|GPHemsley]] ([[User talk:Gphemsley|talk]]) 00:18, 13 January 2013 (UTC)

:I'll be editing from time-to-time. Currently a bit snowed under with other work, but planning to do more later in the year. Would also like to review the InfoBox(es) at some point, to ensure the information on this site can be reliably linked up to other information sources. [[User:AndyJackson|AndyJackson]] ([[User talk:AndyJackson|talk]]) 12:10, 18 January 2013 (UTC)

:I'm here. Like Andy, my workload is quite high, but I'll be popping in and out. --[[User:Rhetoric X|Rhetoric X]] ([[User talk:Rhetoric X|talk]]) 12:31, 18 January 2013 (UTC)

:I dip in and out when I want a challenge (or can stomach the frustration.) [[User:Foxtrot|Foxtrot]] ([[User talk:Foxtrot|talk]]) 11:47, 11 January 2023 (UTC)

:Hi there! I sometimes add a word here or there. I must say this Wiki is pretty good now. Popular formats are nicely described and niche formats are just niche formats so it's sometimes hard to add anything about them. I think that maybe it would be helpful to start adding images to posts. An image explaining format details or a screenshot of an image editor may be a nice addition. What about algorithms in pseudo-code? --[[User:Tekkno|Tekkno]] ([[User talk:Tekkno|talk]]) 0:28, 7 September 2018 (UTC)

::A description of file formats and pseudo-codes would be helpful (although you do not necessarily need a picture). --[[User:Zzo38|Zzo38]] ([[User talk:Zzo38|talk]]) 05:19, 5 May 2019 (UTC)

== Spam ==

I see the spammers have found the site, as I worried would happen; I run a wiki myself ([http://mpedia.dan.info/ MPedia], about things related to Mensa) and have to constantly play whack-a-mole with them; even adding such annoyances (for legitimate users) as a captcha and e-mail confirmation seem to only slightly slow the spammers down. I don't know the solution. [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 12:59, 18 January 2013 (UTC)

:...but "learn-to-read-Korean-in-15-minutes" is a legitimate addition, going to a comic strip explaining the [[Hangul]] writing system, which is in fact a legitimate article here since "file formats" is interpreted expansively to include human written languages. That link ''sounds'' a bit spammy, but if it was from a spammer, it would go to some page selling a dodgy language-learning tool, not a free-to-read resource! (It can start to get tricky distinguishing spam from legitimate stuff when you've got such a wide range of topics here to begin with! Once there's a huge flood of spam to get rid of, there's some danger of legitimate users getting caught in the net too.) [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 13:03, 18 January 2013 (UTC)

::Yes, it's incumbent on me to make sure we can have people sign up, and be a part of it, without getting spammers. We'll keep exploring. At least bots can't take us on.... I think.... --[[User:Jason Scott|Jason Scott]] ([[User talk:Jason Scott|talk]]) 19:28, 18 January 2013 (UTC)

:::If you've got some tips about how to configure MediaWiki to have open signups but not get the flood of spambots, let me know; that would help me with my own wiki. [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 12:56, 22 January 2013 (UTC)

== Orphaned / Blank Pages ==

I've been making an attempt to clear up some of the orphaned pages, but there are a few I'm not sure of - maybe Dan or someone could sort them out?

* [[Emulation]]
* [[FAQ:File Format]]
* [[File format extensions list]] (seems to be used for the "ext:" pages but hasn't been updated)
* [[Library]]
* [[Original Plan]]
* [[RAD Game Tools]] (should probably have the individual formats moved to appropriate sections)
* [[Statistica]] (clearly belongs in Scientific Data formats, but I'm not sure where)

I've also come across a few pages that should probably be deleted - either because they've been blanked at some point (I know I did this to a few pages) or because they contain data duplicated elsewhere.

* [[AA]]
* [[Compressed executable (.com)]]
* [[SAP]]
* [[Barnes & Noble Fixed-layout Format]]

[[User:Halftheisland|Halftheisland]] ([[User talk:Halftheisland|talk]]) 10:41, 22 January 2013 (UTC)

:OK, I deleted those last three; I'll look at the others. [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 12:58, 22 January 2013 (UTC)
:I put Statistica under "Mathematics" in the science category. [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 13:02, 22 January 2013 (UTC)

Hi Dan, got another one for you - I merged the info from [[ODS files created by Microsoft Office 2007 SP2]] into the main [[OpenDocument Spreadsheet]] page. [[User:Halftheisland|Halftheisland]] ([[User talk:Halftheisland|talk]]) 13:59, 25 February 2013 (UTC)

Added Barnes & Noble to the list (made a bit of a mess and forgot about the rename feature) [[User:Johanvanderknijff|Johanvanderknijff]] ([[User talk:Johanvanderknijff|talk]]) 19:05, 21 April 2016 (UTC)

== Permissions for user pages ==

Is there any way we can get permission to delete sub-pages of our own user pages? I've been using mine to draft articles bit by bit, rather than release half-finished articles into the wild, and it would be nice to be able to remove the drafts once complete [[User:Halftheisland|Halftheisland]] ([[User talk:Halftheisland|talk]]) 12:43, 3 October 2013 (UTC)

:I'm not sure, but as an admin I can delete anything you ask. It might also be possible to use the Move function to move it directly into the intended place. [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 16:45, 3 October 2013 (UTC)

== cd.textfiles.com ==
All the files on http://cd.textfiles.com/ disappeared a few days ago, breaking about a million links on this wiki. Does anyone have any information about that? [[User:Jsummers|Jsummers]] ([[User talk:Jsummers|talk]]) 18:48, 25 January 2015 (UTC)

:As I recall from Jason's Twitter feed, he had some server problems, with most of his sites going down at least temporary, and most of them eventually coming back up, but maybe that one had a harder crash. [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 19:50, 25 January 2015 (UTC)

== Broken image in footer ==
The "Creative Commons 0" image at the bottom of every page (https://www.mediawiki.org/w/skins/common/images/cc-0.png) is broken. Can that be fixed? [[User:Jsummers|Jsummers]] ([[User talk:Jsummers|talk]]) 00:06, 10 July 2015 (UTC)
:Still broken 5 years later... Is this place even maintained? [[User:GoodClover|GoodClover]] ([[User talk:GoodClover|talk]]) 23:23, 12 March 2021 (UTC)
::Ok so it appears it should probably be [https://licensebuttons.net/l/zero/1.0/88x31.png this image], it matches the 88x31px that the HTML claims the image would be if it was there. Who maintains this site so it can be fixed? [[User:GoodClover|GoodClover]] ([[User talk:GoodClover|talk]]) 00:01, 13 March 2021 (UTC)
:::I guess that would be Jason Scott. I'm an admin, but if I have any ability to edit that part of the site I have no idea how. [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 01:31, 13 March 2021 (UTC)

== Wikipedia links ==
At least in my geographical area, Wikipedia has been redirecting "http:" links to "https:". So, all of the <nowiki>[[Wikipedia:...]]</nowiki> links in this wiki are getting redirected. Could/should we change these links to use "https:" directly?

The magic "RFC" links like RFC 822 could also use https:, though the http: links still work. [[User:Jsummers|Jsummers]] ([[User talk:Jsummers|talk]]) 00:10, 10 July 2015 (UTC)

== Google Code ==
We still have around 50 articles that link to Google Code. My understanding is that the next phase of Google Code's shutdown process will happen on 2016-01-25 (two weeks from today). It would be good to update as many of these as possible before then.
* [http://fileformats.archiveteam.org/index.php?title=Special%3ALinkSearch&target=http%3A%2F%2Fcode.google.com&namespace= links to http://code.google.com]
* [http://fileformats.archiveteam.org/index.php?title=Special%3ALinkSearch&target=https%3A%2F%2Fcode.google.com&namespace= links to https://code.google.com]
[[User:Jsummers|Jsummers]] ([[User talk:Jsummers|talk]]) 21:05, 11 January 2016 (UTC)

== Cleanup of top-level categories ==
(Call for objections.) I want to do some cleanup of the [[:Category:Top Level Categories|top-level categories]], and make sure there's at least one category for virtually every article. (See [[Special:UncategorizedPages]].) My plans:
* A new "Meta" category, for articles about the File Formats Wiki (e.g. [[FAQ]], [[Original Plan]], [[Statement of Project]], [[Main Page]], ...).
* Rename the [[:Category:Geek humor|Geek humor]] category to "Humor"
* Remove the [[:Category:Computer facts|Computer facts]] category
* A new "Information" category, for relevant informative articles ([[Ontology]], [[Patents]], ...) that don't have a more suitable top-level category.
* Maybe someday: A category named "Devices", or "Hardware", or even "Things". Most computers and [[Networked devices]] just aren't formats, IMHO. (But I'm not going to delete the infobox from all the "Networked devices" articles. If we can't figure out a way to have infoboxes for nonformats, then I'll leave them be.)
[[User:Jsummers|Jsummers]] ([[User talk:Jsummers|talk]]) 15:56, 1 June 2017 (UTC)

[[Category:Meta]]

== Love It! ==
Hi there, kudos to all you guys who helped create this valuable resource. Wikipedia is such a snob when it comes to detailed technical documentation so this wiki is a lifesaver. I added a few things to:

* [[SWF#Software]]
* [[FLA#Software]]
* [[BSON#Libraries]]

Thanks again!

PS: Can the "thumbs up" icon be changed to something better? Do you want me to design a possible logo?

[[User:Hgupta|Hgupta]] ([[User talk:Hgupta|talk]]) 05:42, 17 August 2017 (UTC)

:Nice work! As for the thumb icon, you'd have to ask Jason Scott, the owner of this site (and the one who put the thumb up). [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 13:02, 17 August 2017 (UTC)

:I support the idea of changing the logo. [[User:Jsummers|Jsummers]] ([[User talk:Jsummers|talk]]) 16:08, 18 August 2017 (UTC)

== What time is it? ==
I'm making this edit at 17:10 UTC, but the timestamp is: [[User:Jsummers|Jsummers]] ([[User talk:Jsummers|talk]]) 17:25, 2 May 2018 (UTC)
:"Does anybody really know what time it is; does anybody really care?" -- Chicago
[posted at 01:20 UTC; let's see when it thinks it is] [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 01:36, 3 May 2018 (UTC)

== Type / Creator codes ==

Curious what everyone's thoughts are on collecting Type/Creator Codes for Macintosh formats. There seems to be a few attempts at doing this around the webs. Is there a way here to gather them all into one area of the wiki? --[[User:Thorsted|Thorsted]] ([[User talk:Thorsted|talk]]) 17:46, 4 May 2019 (UTC)

* [[Wikipedia:Type_code|Type Code : Wikipedia]]
* [[Wikipedia:Creator_code|Creator Code : Wikipedia]]
* [http://www.lacikam.co.il/tcdb/ TCDBx unmaintained]
* [https://vintageapple.org/macprogramming/pdf/The_Programmers_Apple_Mac_Sourcebook_1989.pdf The Programmers Apple Mac Sourcebook]
* [https://www.macdisk.com/macsigen.php Mac Signatures]

:Maybe do it similar to how file extensions are handled, as an item in the infobox that links to a category? [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 19:09, 4 May 2019 (UTC)

::An article for Mac type/creator codes has been on my to-do list for a while, so we could at least do that, and see if there's any interest in listing lots of codes there. Should it be one article, or two? FormatInfo already has a "type code" param that is supposed to be for the Mac code. Maybe we are supposed to make a "Type Code" template to go along with it, so we can do like "<nowiki>|type code={{Type Code|XXXX}}</nowiki>". [[User:Jsummers|Jsummers]] ([[User talk:Jsummers|talk]]) 21:07, 4 May 2019 (UTC)

:::If they were listed in a single article as opposed to a series of categories, I don't see what there would be for a template would do. In that case, the text on the left side of the infobox could link to the list page (although this might be ugly). (It would be convenient if there was something between the complexity of the MediaWiki category system and a list page, but I don't think anything like that exists in a plain Mediawiki installation.) [[User:Effect2|Effect2]] ([[User talk:Effect2|talk]]) 21:30, 4 May 2019 (UTC)

::Even if they went into the infobox, the category system could potentially be left out out, as is currently done with FOURCCs and MIMETypes (the latter links to an external database, but whether anything is there is based on luck more than anything else, as there are so many unregistered mimetypes). These can still be found with the wiki's search feature. [[User:Effect2|Effect2]] ([[User talk:Effect2|talk]]) 21:13, 4 May 2019 (UTC)

:::And there's also the Creator Code, as noted above; that refers to what program created the file, so there might be several associated with one file type code (and several file type codes associated with one creator). Perhaps there needs to be a section of the article listing all the code values associated with a given format and/or program (depending on what's covered by the article). [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 21:44, 4 May 2019 (UTC)

::I like the idea of at least a uniform template for using codes within format descriptions. Since most of the files from the early macintosh days don't have an extension, unless they were cross platform and the Windows extension is used, then the only way to identify the file is from its Type/Creator code. I don't think Apple ever released the full registry, but some estimates are well over 50,000 entries.--[[User:Thorsted|Thorsted]] ([[User talk:Thorsted|talk]]) 03:24, 5 May 2019 (UTC)

== Reverse engineering formats ==
I am trying to reverse engineer some formats. Sometimes successfully, sometimes not. My most recent attempt is:
* http://fileformats.archiveteam.org/wiki/DGI_(Digi-Pic)

Maybe we can do this together instead of everyone here focusing on different things? Also is there a better way to discuss things than writing here?
[[User:Tekkno|Tekkno]] ([[User talk:Tekkno|talk]]) 01:39, 9 May 2019 (UTC)

:You should set up a NNTP for reverse engineering file formats discussions (if there isn't already the appropriaate newsgroup). (I had done some of my own reverse engineering file formats too, but I have not set up a NNTP to discuss them. I do have a NNTP server, so you can suggest newsgroups there if wanted, I suppose) --[[User:Zzo38|Zzo38]] ([[User talk:Zzo38|talk]]) 21:26, 23 August 2021 (UTC)

== CAPTCHA ==

AT is no longer on EFnet: https://archiveteam.org/index.php?title=Archiveteam:IRC#Special_ArchiveTeam_IRC_rules [[User:Arlo James Barnes|Arlo James Barnes]] ([[User talk:Arlo James Barnes|talk]]) 02:57, 8 November 2020 (UTC)

: This is a pretty serious problem. Are there any plans to fix it? -[[User:Jsummers|Jsummers]] ([[User talk:Jsummers|talk]]) 16:22, 12 November 2020 (UTC)

:: <del>Seems like it has been fixed, by removing the CAPTCHA altogether.</del> [2021-12-30 edit: I spoke too soon; still 'efnet'.] Let's all keep a keen eye out for spamdalism. [[User:Arlo James Barnes|Arlo James Barnes]] ([[User talk:Arlo James Barnes|talk]]) 03:33, 23 November 2020 (UTC)

== [[special:interwiki]] ==
don't see it at [[special:specialpages]]? [[User:Arlo James Barnes|Arlo James Barnes]] ([[User talk:Arlo James Barnes|talk]]) 02:57, 8 November 2020 (UTC)

: Perhaps the [https://www.mediawiki.org/wiki/Extension:Interwiki Interwiki extension] is not installed? — [[User:Rjt|rjt]] ([[User talk:Rjt|talk]]) 15:16, 30 December 2023 (UTC)

== List of my idea what maybe should be added on ==
My idea of what things I think that probably should be added on (when someone has the information of it to add):
* TRON character encoding
* TRON Application Databus
* BANCStar
* C67 (music)
(I might add a few others later if I will remember some more later, too) --[[User:Zzo38|Zzo38]] ([[User talk:Zzo38|talk]]) 09:30, 31 July 2021 (UTC)

==Hello==
I’ve joined and made a few edits. Starting with the Linux page by modification of the attribution of Linux to iOS, which is BSD.
Mad a few tweaks to HLP by creating a page for the source file.
As a retro tech enthusiast I think I could help a bit on some of the older files. Especially tape and disk formats; then, and their modern emulation files. As well as format info.
You can take a look at the original writeup I did here [http://wiki.digital-digest.com/index.php?title=History_of_AV]. Thought it has errors and is considerably lacking many formats.

==SSL and SEO==
SSL has been a factor in web site indexing for a while https://security.googleblog.com/2014/08/https-as-ranking-signal_6.html. Anecdotally I am seeing this more profoundly with personal websites. I wonder if Just Solved can be upgraded to HTTPS sometime in the near future. This should help SEO rankings which benefits us all as it attracts more users. It also protects us using the site too. [[User:Ross-spencer|Ross-spencer]] ([[User talk:Ross-spencer|talk]]) 07:34, 3 January 2023 (UTC)

:You'd have to ask Jason about this server-level stuff. [[User:Dan Tobias|Dan Tobias]] ([[User talk:Dan Tobias|talk]]) 16:16, 3 January 2023 (UTC)

:Please do not make TLS mandatory. However, optional TLS is a good idea. --[[User:Zzo38|Zzo38]] ([[User talk:Zzo38|talk]]) 21:13, 5 January 2023 (UTC)

:NB. SSL is listed with further rationale in the TODO: http://fileformats.archiveteam.org/wiki/JustSolve:To_Do [[User:Ross-spencer|Ross-spencer]] ([[User talk:Ross-spencer|talk]]) 09:49, 11 June 2024 (UTC)

== Mediawiki version ==

What are the plans to upgrade this site? Wikimedia is currently at 1.38, Just Solved File Formats is 1.19 with it's dependencies MySQL and PHP somewhat far behind current standards too. [[User:Ross-spencer|Ross-spencer]] ([[User talk:Ross-spencer|talk]]) 07:34, 3 January 2023 (UTC)

: Over the past six weeks, I've sent a few emails to Jason Scott asking how we could get some maintenance for this site. Although he has replied, with some indication that he might be willing to help, I haven't been able to figure out the right thing to say to make that actually happen. At this point, I'm not optimistic that my emails will be sufficient. -[[User:Jsummers|Jsummers]] ([[User talk:Jsummers|talk]]) 14:48, 25 February 2023 (UTC)

:: [[special:version#Installed_software]] is where MW stores the version, for anyone wondering. [[User:Arlo James Barnes|Arlo James Barnes]] ([[User talk:Arlo James Barnes|talk]]) 05:08, 3 January 2025 (UTC)

== About this community portal ==

Hi there! I'm a new editor here ^^ I would like to know a bit more on the status of the project.

Also, I've noticed that both this page and its associated [[{{TALKPAGENAME}}|talk page]] are being used as the community portal. I think we should choose just one of them, consolidate all the discussion there, and redirect the unused page to the one we decide to keep.

For reference, Inkipedia uses the [https://splatoonwiki.org/wiki/Inkipedia_talk:Ink_Pump talk page] as the central community space, with the project page redirecting to it, which works well since the talk page includes an "Add topic" button for easy participation. [[User:It's moon|It's moon]] ([[User talk:It's moon|talk]]) 04:18, 23 May 2025 (UTC)

== File information template ==

On another topic, would y'all be interested in having a template to add to file pages so we can provide license, source and author info? I created [https://deadmau5.miraheze.org/wiki/Template:File this template] on another wiki I edit. [[User:It's moon|It's moon]] ([[User talk:It's moon|talk]]) 04:18, 23 May 2025 (UTC)

== CAPTCHA issue ==

The other day I made some edits to the [[Quattro_Pro]] page. I was able to save most of them, but after another edit that inserted a "references" tag I end with a CAPTCHA: "Your edit includes new external links. To help protect against automated spam, please answer the question that appears below", with the "question" being "Write wiki@textfiles.com to ask for an account". This is a bit puzzling as I already have an account and I'm seeing this while logged in! Does anyone know why this happens (or better, have a fix)? Thanks!

[[User:Johanvanderknijff|Johanvanderknijff]] ([[User talk:Johanvanderknijff|talk]]) 11:55, 3 June 2025 (UTC)

Quattro Pro

2025-06-02T13:46:04Z

Johanvanderknijff: /* Software support */ updated footnotes

{{FormatInfo
|formattype=electronic
|subcat=Document
|subcat2=Spreadsheet
|thiscat=Quattro Pro
|extensions={{ext|wq1}}, {{ext|wq2}}, {{ext|wb1}}, {{ext|wb2}}, {{ext|wb3}}, {{ext|qpw}}, {{ext|snd}}
|pronom={{PRONOM|x-fmt/121}}, {{PRONOM|x-fmt/122}}, others
}}
'''Quattro Pro''' is a spreadsheet program. Originally developed by [[Borland]], current releases are sold by [[Corel]].

== Versions and identifiers ==
{| class="wikitable"
! Format
! Version
! PRONOM
! Refer to
|-
|Quattro Pro Spreadsheet for DOS || 1–4 || {{PRONOM|x-fmt/121}} || [[WQ1]]
|-
|Quattro Pro Spreadsheet for DOS || 5.0, 5.5 || {{PRONOM|x-fmt/122}} || [[WQ2]]
|-
|Quattro Pro Spreadsheet for Windows || 1, 5 || {{PRONOM|fmt/834}} || [[WB1]]
|-
|Quattro Pro Spreadsheet for Windows || 6 || {{PRONOM|fmt/835}} || [[WB2]]
|-
|Quattro Pro Spreadsheet || 7–8 || {{PRONOM|fmt/836}} || [[WB3]]
|-
|Quattro Pro Spreadsheet || 9–12, X3, X4 || {{PRONOM|fmt/837}} || [[QPW]]
|}

== Software support ==

Microsoft Excel dropped support for all Quattro Pro formats 2010. A 2014 test with the (then current) Quattro Pro X7 showed that even though the software was still able to reads all formats, the support of the DOS formats had some limitations<ref>''[https://bitsgalore.org/2014/10/29/quattro-pro-dos-obsolete-format-last Quattro Pro for DOS: an obsolete format at last?]''</ref>. As of 2025, LibreOffice Calc can read Quattro Pro for DOS and Quattro Pro for Windows (version 6.0) files<ref>[https://web.archive.org/web/20250528204810/https://wiki.documentfoundation.org/Feature_Comparison:_LibreOffice_-_Microsoft_Office Feature Comparison: LibreOffice - Microsoft Office]''</ref>. A 2025 update of the earlier 2014 test did reveal some limitations though, which are mainly related to handling of cached formula results, and compatibility issues between some native Quattro Pro functions and their LibreOffice Calc counterparts<ref>''[https://bitsgalore.org/2025/05/28/quattro-pro-for-dos-revisited-an-obsolete-format-no-more Quattro Pro for DOS revisited: an obsolete format no more?]''</ref>.

== Sounds ==

Starting with Quattro Pro 3.0 you could create slide shows which included sounds. The sound files start with <code>STEVE.H</code> and usually have a <code>.SND</code> extension.

== Sample files ==
* {{DexvertSamples|audio/quattroProSound}}
* {{DexvertSamples|document/quattroPro}}

== References ==

* [[Wikipedia: Quattro Pro]]
* [http://www.corel.com/content/pdf/wpx4/corel-wordperfect-office-X4-reviewers-guide.pdf Corel WordPerfect Office Reviewers Guide]
* [http://www.openplanetsfoundation.org/blogs/2014-10-29-quattro-pro-dos-obsolete-format-last Quattro Pro for DOS: an obsolete format at last?]
* [http://openplanetsfoundation.org/blogs/2014-10-29-opening-johans-quattro-pro-files-quattro-pro-6-win-311 Opening Johan's Quattro Pro files in Quattro Pro 6 for Win 3.11]
* [https://books.google.com/books?id=uEkrL23rU98C&pg=PP280&lpg=PP280&dq=%22quattro+pro%22+%22sound%22+%22snd%22&source=bl&ots=UzzKg5NYKG&sig=ACfU3U3_1W1Ut1Qw7wa0-ve5FwptedPydA&hl=en&sa=X&ved=2ahUKEwjHkJvEpovqAhUiTd8KHVC0CVUQ6AEwAHoECCgQAQ#v=onepage&q=%22quattro%20pro%22%20%22sound%22%20%22snd%22&f=false PC Magazine Quattro Pro 3.0 Article mentioning SND files]

[[Category:Borland]]
[[Category:Corel]]

Quattro Pro

2025-06-02T13:33:59Z

Johanvanderknijff: /* References */

{{FormatInfo
|formattype=electronic
|subcat=Document
|subcat2=Spreadsheet
|thiscat=Quattro Pro
|extensions={{ext|wq1}}, {{ext|wq2}}, {{ext|wb1}}, {{ext|wb2}}, {{ext|wb3}}, {{ext|qpw}}, {{ext|snd}}
|pronom={{PRONOM|x-fmt/121}}, {{PRONOM|x-fmt/122}}, others
}}
'''Quattro Pro''' is a spreadsheet program. Originally developed by [[Borland]], current releases are sold by [[Corel]].

== Versions and identifiers ==
{| class="wikitable"
! Format
! Version
! PRONOM
! Refer to
|-
|Quattro Pro Spreadsheet for DOS || 1–4 || {{PRONOM|x-fmt/121}} || [[WQ1]]
|-
|Quattro Pro Spreadsheet for DOS || 5.0, 5.5 || {{PRONOM|x-fmt/122}} || [[WQ2]]
|-
|Quattro Pro Spreadsheet for Windows || 1, 5 || {{PRONOM|fmt/834}} || [[WB1]]
|-
|Quattro Pro Spreadsheet for Windows || 6 || {{PRONOM|fmt/835}} || [[WB2]]
|-
|Quattro Pro Spreadsheet || 7–8 || {{PRONOM|fmt/836}} || [[WB3]]
|-
|Quattro Pro Spreadsheet || 9–12, X3, X4 || {{PRONOM|fmt/837}} || [[QPW]]
|}

== Software support ==

Microsoft Excel dropped support for all Quattro Pro formats 2010. A 2014 test with the (then current) Quattro Pro X7 showed that even though the software was still able to reads all formats, the support of the DOS formats had some limitations<ref name="bitsgalore-qp2014">{{cite web|url=https://bitsgalore.org/2014/10/29/quattro-pro-dos-obsolete-format-last |title=Quattro Pro for DOS: an obsolete format at last?}}</ref>. As of 2025, LibreOffice Calc can read Quattro Pro for DOS and Quattro Pro for Windows (version 6.0) files<ref name="libreoffice-featurecomparison">{{cite web|url=https://web.archive.org/web/20250528204810/https://wiki.documentfoundation.org/Feature_Comparison:_LibreOffice_-_Microsoft_Office |title=Feature Comparison: LibreOffice - Microsoft Office}}</ref>. A 2025 update of the earlier 2014 test did reveal some limitations though, which are mainly related to handling of cached formula results, and compatibility issues between some native Quattro Pro functions and their LibreOffice Calc counterparts<ref name="bitsgalore-qp2025">{{cite web|url=https://bitsgalore.org/2025/05/28/quattro-pro-for-dos-revisited-an-obsolete-format-no-more |title=
Quattro Pro for DOS revisited: an obsolete format no more?}}</ref>.

== Sounds ==

Starting with Quattro Pro 3.0 you could create slide shows which included sounds. The sound files start with <code>STEVE.H</code> and usually have a <code>.SND</code> extension.

== Sample files ==
* {{DexvertSamples|audio/quattroProSound}}
* {{DexvertSamples|document/quattroPro}}

== References ==

* [[Wikipedia: Quattro Pro]]
* [http://www.corel.com/content/pdf/wpx4/corel-wordperfect-office-X4-reviewers-guide.pdf Corel WordPerfect Office Reviewers Guide]
* [http://www.openplanetsfoundation.org/blogs/2014-10-29-quattro-pro-dos-obsolete-format-last Quattro Pro for DOS: an obsolete format at last?]
* [http://openplanetsfoundation.org/blogs/2014-10-29-opening-johans-quattro-pro-files-quattro-pro-6-win-311 Opening Johan's Quattro Pro files in Quattro Pro 6 for Win 3.11]
* [https://books.google.com/books?id=uEkrL23rU98C&pg=PP280&lpg=PP280&dq=%22quattro+pro%22+%22sound%22+%22snd%22&source=bl&ots=UzzKg5NYKG&sig=ACfU3U3_1W1Ut1Qw7wa0-ve5FwptedPydA&hl=en&sa=X&ved=2ahUKEwjHkJvEpovqAhUiTd8KHVC0CVUQ6AEwAHoECCgQAQ#v=onepage&q=%22quattro%20pro%22%20%22sound%22%20%22snd%22&f=false PC Magazine Quattro Pro 3.0 Article mentioning SND files]

[[Category:Borland]]
[[Category:Corel]]

Quattro Pro

2025-06-02T13:33:46Z

Johanvanderknijff: /* References */ added references tag, attempt 2

{{FormatInfo
|formattype=electronic
|subcat=Document
|subcat2=Spreadsheet
|thiscat=Quattro Pro
|extensions={{ext|wq1}}, {{ext|wq2}}, {{ext|wb1}}, {{ext|wb2}}, {{ext|wb3}}, {{ext|qpw}}, {{ext|snd}}
|pronom={{PRONOM|x-fmt/121}}, {{PRONOM|x-fmt/122}}, others
}}
'''Quattro Pro''' is a spreadsheet program. Originally developed by [[Borland]], current releases are sold by [[Corel]].

== Versions and identifiers ==
{| class="wikitable"
! Format
! Version
! PRONOM
! Refer to
|-
|Quattro Pro Spreadsheet for DOS || 1–4 || {{PRONOM|x-fmt/121}} || [[WQ1]]
|-
|Quattro Pro Spreadsheet for DOS || 5.0, 5.5 || {{PRONOM|x-fmt/122}} || [[WQ2]]
|-
|Quattro Pro Spreadsheet for Windows || 1, 5 || {{PRONOM|fmt/834}} || [[WB1]]
|-
|Quattro Pro Spreadsheet for Windows || 6 || {{PRONOM|fmt/835}} || [[WB2]]
|-
|Quattro Pro Spreadsheet || 7–8 || {{PRONOM|fmt/836}} || [[WB3]]
|-
|Quattro Pro Spreadsheet || 9–12, X3, X4 || {{PRONOM|fmt/837}} || [[QPW]]
|}

== Software support ==

Microsoft Excel dropped support for all Quattro Pro formats 2010. A 2014 test with the (then current) Quattro Pro X7 showed that even though the software was still able to reads all formats, the support of the DOS formats had some limitations<ref name="bitsgalore-qp2014">{{cite web|url=https://bitsgalore.org/2014/10/29/quattro-pro-dos-obsolete-format-last |title=Quattro Pro for DOS: an obsolete format at last?}}</ref>. As of 2025, LibreOffice Calc can read Quattro Pro for DOS and Quattro Pro for Windows (version 6.0) files<ref name="libreoffice-featurecomparison">{{cite web|url=https://web.archive.org/web/20250528204810/https://wiki.documentfoundation.org/Feature_Comparison:_LibreOffice_-_Microsoft_Office |title=Feature Comparison: LibreOffice - Microsoft Office}}</ref>. A 2025 update of the earlier 2014 test did reveal some limitations though, which are mainly related to handling of cached formula results, and compatibility issues between some native Quattro Pro functions and their LibreOffice Calc counterparts<ref name="bitsgalore-qp2025">{{cite web|url=https://bitsgalore.org/2025/05/28/quattro-pro-for-dos-revisited-an-obsolete-format-no-more |title=
Quattro Pro for DOS revisited: an obsolete format no more?}}</ref>.

== Sounds ==

Starting with Quattro Pro 3.0 you could create slide shows which included sounds. The sound files start with <code>STEVE.H</code> and usually have a <code>.SND</code> extension.

== Sample files ==
* {{DexvertSamples|audio/quattroProSound}}
* {{DexvertSamples|document/quattroPro}}

== References ==

<references/>

* [[Wikipedia: Quattro Pro]]
* [http://www.corel.com/content/pdf/wpx4/corel-wordperfect-office-X4-reviewers-guide.pdf Corel WordPerfect Office Reviewers Guide]
* [http://www.openplanetsfoundation.org/blogs/2014-10-29-quattro-pro-dos-obsolete-format-last Quattro Pro for DOS: an obsolete format at last?]
* [http://openplanetsfoundation.org/blogs/2014-10-29-opening-johans-quattro-pro-files-quattro-pro-6-win-311 Opening Johan's Quattro Pro files in Quattro Pro 6 for Win 3.11]
* [https://books.google.com/books?id=uEkrL23rU98C&pg=PP280&lpg=PP280&dq=%22quattro+pro%22+%22sound%22+%22snd%22&source=bl&ots=UzzKg5NYKG&sig=ACfU3U3_1W1Ut1Qw7wa0-ve5FwptedPydA&hl=en&sa=X&ved=2ahUKEwjHkJvEpovqAhUiTd8KHVC0CVUQ6AEwAHoECCgQAQ#v=onepage&q=%22quattro%20pro%22%20%22sound%22%20%22snd%22&f=false PC Magazine Quattro Pro 3.0 Article mentioning SND files]

[[Category:Borland]]
[[Category:Corel]]

Quattro Pro

2025-06-02T13:33:13Z

Johanvanderknijff: /* References */ removed references tag

{{FormatInfo
|formattype=electronic
|subcat=Document
|subcat2=Spreadsheet
|thiscat=Quattro Pro
|extensions={{ext|wq1}}, {{ext|wq2}}, {{ext|wb1}}, {{ext|wb2}}, {{ext|wb3}}, {{ext|qpw}}, {{ext|snd}}
|pronom={{PRONOM|x-fmt/121}}, {{PRONOM|x-fmt/122}}, others
}}
'''Quattro Pro''' is a spreadsheet program. Originally developed by [[Borland]], current releases are sold by [[Corel]].

== Versions and identifiers ==
{| class="wikitable"
! Format
! Version
! PRONOM
! Refer to
|-
|Quattro Pro Spreadsheet for DOS || 1–4 || {{PRONOM|x-fmt/121}} || [[WQ1]]
|-
|Quattro Pro Spreadsheet for DOS || 5.0, 5.5 || {{PRONOM|x-fmt/122}} || [[WQ2]]
|-
|Quattro Pro Spreadsheet for Windows || 1, 5 || {{PRONOM|fmt/834}} || [[WB1]]
|-
|Quattro Pro Spreadsheet for Windows || 6 || {{PRONOM|fmt/835}} || [[WB2]]
|-
|Quattro Pro Spreadsheet || 7–8 || {{PRONOM|fmt/836}} || [[WB3]]
|-
|Quattro Pro Spreadsheet || 9–12, X3, X4 || {{PRONOM|fmt/837}} || [[QPW]]
|}

== Software support ==

Microsoft Excel dropped support for all Quattro Pro formats 2010. A 2014 test with the (then current) Quattro Pro X7 showed that even though the software was still able to reads all formats, the support of the DOS formats had some limitations<ref name="bitsgalore-qp2014">{{cite web|url=https://bitsgalore.org/2014/10/29/quattro-pro-dos-obsolete-format-last |title=Quattro Pro for DOS: an obsolete format at last?}}</ref>. As of 2025, LibreOffice Calc can read Quattro Pro for DOS and Quattro Pro for Windows (version 6.0) files<ref name="libreoffice-featurecomparison">{{cite web|url=https://web.archive.org/web/20250528204810/https://wiki.documentfoundation.org/Feature_Comparison:_LibreOffice_-_Microsoft_Office |title=Feature Comparison: LibreOffice - Microsoft Office}}</ref>. A 2025 update of the earlier 2014 test did reveal some limitations though, which are mainly related to handling of cached formula results, and compatibility issues between some native Quattro Pro functions and their LibreOffice Calc counterparts<ref name="bitsgalore-qp2025">{{cite web|url=https://bitsgalore.org/2025/05/28/quattro-pro-for-dos-revisited-an-obsolete-format-no-more |title=
Quattro Pro for DOS revisited: an obsolete format no more?}}</ref>.

== Sounds ==

Starting with Quattro Pro 3.0 you could create slide shows which included sounds. The sound files start with <code>STEVE.H</code> and usually have a <code>.SND</code> extension.

== Sample files ==
* {{DexvertSamples|audio/quattroProSound}}
* {{DexvertSamples|document/quattroPro}}

== References ==

* [[Wikipedia: Quattro Pro]]
* [http://www.corel.com/content/pdf/wpx4/corel-wordperfect-office-X4-reviewers-guide.pdf Corel WordPerfect Office Reviewers Guide]
* [http://www.openplanetsfoundation.org/blogs/2014-10-29-quattro-pro-dos-obsolete-format-last Quattro Pro for DOS: an obsolete format at last?]
* [http://openplanetsfoundation.org/blogs/2014-10-29-opening-johans-quattro-pro-files-quattro-pro-6-win-311 Opening Johan's Quattro Pro files in Quattro Pro 6 for Win 3.11]
* [https://books.google.com/books?id=uEkrL23rU98C&pg=PP280&lpg=PP280&dq=%22quattro+pro%22+%22sound%22+%22snd%22&source=bl&ots=UzzKg5NYKG&sig=ACfU3U3_1W1Ut1Qw7wa0-ve5FwptedPydA&hl=en&sa=X&ved=2ahUKEwjHkJvEpovqAhUiTd8KHVC0CVUQ6AEwAHoECCgQAQ#v=onepage&q=%22quattro%20pro%22%20%22sound%22%20%22snd%22&f=false PC Magazine Quattro Pro 3.0 Article mentioning SND files]

[[Category:Borland]]
[[Category:Corel]]

Quattro Pro

2025-06-02T13:32:44Z

Johanvanderknijff: /* References */ added tag to see if this works

{{FormatInfo
|formattype=electronic
|subcat=Document
|subcat2=Spreadsheet
|thiscat=Quattro Pro
|extensions={{ext|wq1}}, {{ext|wq2}}, {{ext|wb1}}, {{ext|wb2}}, {{ext|wb3}}, {{ext|qpw}}, {{ext|snd}}
|pronom={{PRONOM|x-fmt/121}}, {{PRONOM|x-fmt/122}}, others
}}
'''Quattro Pro''' is a spreadsheet program. Originally developed by [[Borland]], current releases are sold by [[Corel]].

== Versions and identifiers ==
{| class="wikitable"
! Format
! Version
! PRONOM
! Refer to
|-
|Quattro Pro Spreadsheet for DOS || 1–4 || {{PRONOM|x-fmt/121}} || [[WQ1]]
|-
|Quattro Pro Spreadsheet for DOS || 5.0, 5.5 || {{PRONOM|x-fmt/122}} || [[WQ2]]
|-
|Quattro Pro Spreadsheet for Windows || 1, 5 || {{PRONOM|fmt/834}} || [[WB1]]
|-
|Quattro Pro Spreadsheet for Windows || 6 || {{PRONOM|fmt/835}} || [[WB2]]
|-
|Quattro Pro Spreadsheet || 7–8 || {{PRONOM|fmt/836}} || [[WB3]]
|-
|Quattro Pro Spreadsheet || 9–12, X3, X4 || {{PRONOM|fmt/837}} || [[QPW]]
|}

== Software support ==

Microsoft Excel dropped support for all Quattro Pro formats 2010. A 2014 test with the (then current) Quattro Pro X7 showed that even though the software was still able to reads all formats, the support of the DOS formats had some limitations<ref name="bitsgalore-qp2014">{{cite web|url=https://bitsgalore.org/2014/10/29/quattro-pro-dos-obsolete-format-last |title=Quattro Pro for DOS: an obsolete format at last?}}</ref>. As of 2025, LibreOffice Calc can read Quattro Pro for DOS and Quattro Pro for Windows (version 6.0) files<ref name="libreoffice-featurecomparison">{{cite web|url=https://web.archive.org/web/20250528204810/https://wiki.documentfoundation.org/Feature_Comparison:_LibreOffice_-_Microsoft_Office |title=Feature Comparison: LibreOffice - Microsoft Office}}</ref>. A 2025 update of the earlier 2014 test did reveal some limitations though, which are mainly related to handling of cached formula results, and compatibility issues between some native Quattro Pro functions and their LibreOffice Calc counterparts<ref name="bitsgalore-qp2025">{{cite web|url=https://bitsgalore.org/2025/05/28/quattro-pro-for-dos-revisited-an-obsolete-format-no-more |title=
Quattro Pro for DOS revisited: an obsolete format no more?}}</ref>.

== Sounds ==

Starting with Quattro Pro 3.0 you could create slide shows which included sounds. The sound files start with <code>STEVE.H</code> and usually have a <code>.SND</code> extension.

== Sample files ==
* {{DexvertSamples|audio/quattroProSound}}
* {{DexvertSamples|document/quattroPro}}

== References ==

<references>
* [[Wikipedia: Quattro Pro]]
* [http://www.corel.com/content/pdf/wpx4/corel-wordperfect-office-X4-reviewers-guide.pdf Corel WordPerfect Office Reviewers Guide]
* [http://www.openplanetsfoundation.org/blogs/2014-10-29-quattro-pro-dos-obsolete-format-last Quattro Pro for DOS: an obsolete format at last?]
* [http://openplanetsfoundation.org/blogs/2014-10-29-opening-johans-quattro-pro-files-quattro-pro-6-win-311 Opening Johan's Quattro Pro files in Quattro Pro 6 for Win 3.11]
* [https://books.google.com/books?id=uEkrL23rU98C&pg=PP280&lpg=PP280&dq=%22quattro+pro%22+%22sound%22+%22snd%22&source=bl&ots=UzzKg5NYKG&sig=ACfU3U3_1W1Ut1Qw7wa0-ve5FwptedPydA&hl=en&sa=X&ved=2ahUKEwjHkJvEpovqAhUiTd8KHVC0CVUQ6AEwAHoECCgQAQ#v=onepage&q=%22quattro%20pro%22%20%22sound%22%20%22snd%22&f=false PC Magazine Quattro Pro 3.0 Article mentioning SND files]

[[Category:Borland]]
[[Category:Corel]]

Quattro Pro

2025-06-02T13:31:19Z

Johanvanderknijff: updated to 2025 situation

{{FormatInfo
|formattype=electronic
|subcat=Document
|subcat2=Spreadsheet
|thiscat=Quattro Pro
|extensions={{ext|wq1}}, {{ext|wq2}}, {{ext|wb1}}, {{ext|wb2}}, {{ext|wb3}}, {{ext|qpw}}, {{ext|snd}}
|pronom={{PRONOM|x-fmt/121}}, {{PRONOM|x-fmt/122}}, others
}}
'''Quattro Pro''' is a spreadsheet program. Originally developed by [[Borland]], current releases are sold by [[Corel]].

== Versions and identifiers ==
{| class="wikitable"
! Format
! Version
! PRONOM
! Refer to
|-
|Quattro Pro Spreadsheet for DOS || 1–4 || {{PRONOM|x-fmt/121}} || [[WQ1]]
|-
|Quattro Pro Spreadsheet for DOS || 5.0, 5.5 || {{PRONOM|x-fmt/122}} || [[WQ2]]
|-
|Quattro Pro Spreadsheet for Windows || 1, 5 || {{PRONOM|fmt/834}} || [[WB1]]
|-
|Quattro Pro Spreadsheet for Windows || 6 || {{PRONOM|fmt/835}} || [[WB2]]
|-
|Quattro Pro Spreadsheet || 7–8 || {{PRONOM|fmt/836}} || [[WB3]]
|-
|Quattro Pro Spreadsheet || 9–12, X3, X4 || {{PRONOM|fmt/837}} || [[QPW]]
|}

== Software support ==

Microsoft Excel dropped support for all Quattro Pro formats 2010. A 2014 test with the (then current) Quattro Pro X7 showed that even though the software was still able to reads all formats, the support of the DOS formats had some limitations<ref name="bitsgalore-qp2014">{{cite web|url=https://bitsgalore.org/2014/10/29/quattro-pro-dos-obsolete-format-last |title=Quattro Pro for DOS: an obsolete format at last?}}</ref>. As of 2025, LibreOffice Calc can read Quattro Pro for DOS and Quattro Pro for Windows (version 6.0) files<ref name="libreoffice-featurecomparison">{{cite web|url=https://web.archive.org/web/20250528204810/https://wiki.documentfoundation.org/Feature_Comparison:_LibreOffice_-_Microsoft_Office |title=Feature Comparison: LibreOffice - Microsoft Office}}</ref>. A 2025 update of the earlier 2014 test did reveal some limitations though, which are mainly related to handling of cached formula results, and compatibility issues between some native Quattro Pro functions and their LibreOffice Calc counterparts<ref name="bitsgalore-qp2025">{{cite web|url=https://bitsgalore.org/2025/05/28/quattro-pro-for-dos-revisited-an-obsolete-format-no-more |title=
Quattro Pro for DOS revisited: an obsolete format no more?}}</ref>.

== Sounds ==

Starting with Quattro Pro 3.0 you could create slide shows which included sounds. The sound files start with <code>STEVE.H</code> and usually have a <code>.SND</code> extension.

== Sample files ==
* {{DexvertSamples|audio/quattroProSound}}
* {{DexvertSamples|document/quattroPro}}

== References ==

* [[Wikipedia: Quattro Pro]]
* [http://www.corel.com/content/pdf/wpx4/corel-wordperfect-office-X4-reviewers-guide.pdf Corel WordPerfect Office Reviewers Guide]
* [http://www.openplanetsfoundation.org/blogs/2014-10-29-quattro-pro-dos-obsolete-format-last Quattro Pro for DOS: an obsolete format at last?]
* [http://openplanetsfoundation.org/blogs/2014-10-29-opening-johans-quattro-pro-files-quattro-pro-6-win-311 Opening Johan's Quattro Pro files in Quattro Pro 6 for Win 3.11]
* [https://books.google.com/books?id=uEkrL23rU98C&pg=PP280&lpg=PP280&dq=%22quattro+pro%22+%22sound%22+%22snd%22&source=bl&ots=UzzKg5NYKG&sig=ACfU3U3_1W1Ut1Qw7wa0-ve5FwptedPydA&hl=en&sa=X&ved=2ahUKEwjHkJvEpovqAhUiTd8KHVC0CVUQ6AEwAHoECCgQAQ#v=onepage&q=%22quattro%20pro%22%20%22sound%22%20%22snd%22&f=false PC Magazine Quattro Pro 3.0 Article mentioning SND files]

[[Category:Borland]]
[[Category:Corel]]

PNG

2023-01-17T15:27:48Z

Johanvanderknijff: /* Links */ Updated forensicswiki link to new domain

{{FormatInfo
|formattype=electronic
|subcat=Graphics
|extensions={{ext|png}}
|mimetypes={{mimetype|image/png}}
|locfdd={{LoCFDD|fdd000153}}
|pronom={{PRONOM|fmt/13}}, {{PRONOM|fmt/12}}, {{PRONOM|fmt/11}}
|kaitai struct=png
|wikidata={{wikidata|Q178051}}
|released=1996
}}
'''Portable Network Graphics''' ('''PNG''') was devised starting in a discussion on newsgroup ''comp.graphics'' in 1995, with the first version of its specification released in 1996. The motivation for its creation was to create a free and unencumbered image format in the wake of the patent issue with [[GIF]].

PNG has become a very popular graphic format, but widespread adoption on the Web was slow due to the fact that the first specification came out over a year after the Web had begun to be popular with the general public, meaning that there were many sites and browsers out there not using and supporting the new format; subsequently, browsers began to support it, but often had rendering problems which persisted even in fairly late versions years later; this caused webmasters to be slow to switch from GIF to PNG, though many eventually did so. Since the [[LZW]] patent that affected GIF is expired now, the "free format" motivation for the switch no longer applies.

Unlike GIF, PNG officially supports only still graphics, not animation. However [[APNG]], an unofficial extension of the PNG image format that retains the .png file extention does support animation. Another related format, [[MNG]], officially does support animation.

== Format details ==
A PNG file consists of an 8-byte signature, followed by a sequence of ''chunks''. Each chunk has an 8-byte header containing a 4-byte chunk length, and a 4-byte [[FourCC|chunk type code]]. Each chunk also has a 4-byte trailer containing a checksum.

== Identification ==
A file begins with an 8-byte signature: {{magic|89 50 4E 47 0D 0A 1A 0A}}.

A standard PNG file also has ASCII "{{magic|IHDR}}" at offset 12. You can check for this to distinguish it from [[CgBI]].

== Extensions ==
=== Extensions by chunk type ===
{| class="wikitable"
! Chunk type
! References and remarks
|-
|<code>oFFs</code>, <code>pCAL</code>, <code>sCAL</code>, <code>gIFg</code>, <code>gIFx</code>, <code>gIFt</code>, <code>fRAc</code> || Refer to [http://pmt.sourceforge.net/specs/pngext-1.2.0-pdg-h20.html Extensions to the PNG 1.2 Specification, v1.2.0].
|-
|<code>sTER</code> || Refer to [ftp://ftp.simplesystems.org/pub/libpng/png/documents/pngext-1.3.0-pdg.html Extensions to the PNG 1.2 Specification, v1.3.0].
|-
|<code>dSIG</code> || Refer to [ftp://ftp.simplesystems.org/pub/libpng/png/documents/pngext-1.4.0-pdg.html Extensions to the PNG 1.2 Specification, v1.4.0], and the [http://png-dsig.sourceforge.net/ PNG dSIG website].
|-
|<code>acTL</code>, <code>fcTL</code>, <code>fdAT</code> || Used in [[APNG]] files.
|-
|<code>vpAg</code>, <code>caNv</code>, <code>orNT</code> || Used by [[ImageMagick]].
|-
|<code>CgBI</code> || Refer to [[CgBI]].
|-
|<code>eXIf</code>, <code>exIf</code> || [[Exif]] metadata. Refer to [http://ftp-osl.osuosl.org/pub/libpng/documents/proposals/eXIf/png-proposed-eXIf-chunk-2017-06-15.html PNG Proposed eXIf chunk] [approved 2017-07].
|-
|<code>iDOT</code> || Used by Apple products. Some info at [https://www.hackerfactor.com/blog/index.php?/archives/895-Connecting-the-iDOTs.html].
|}

=== Other extensions ===
* [[XMP]] metadata can be stored in an <code>iTXt</code> chunk with keyword "XML:com.adobe.xmp". Refer to the [[XMP#Specifications|XMP Specification]], Part 3.

== Related Formats ==

* [[APNG]]
* [[MNG]]
* [[JNG]]
* [[CgBI]]
* [[Portable Bitmap Format]]
* [[zlib]]-style [[DEFLATE]] compression: Used to compress image and other data.
* [[CRC-32]]: Used to calculate a checksum of each chunk.
* [[ICC profile]]: The format used by iCCP chunks.

== Specifications ==
* [http://www.w3.org/TR/PNG/ W3C PNG specification] (latest version)
** Specific versions: [http://www.w3.org/TR/REC-png-961001 1996-10-01] · [http://www.w3.org/TR/2003/PR-PNG-20030520/ 2003-05-20] · [http://www.w3.org/TR/2003/REC-PNG-20031110/ 2003-11-10]
* RFC 2083: PNG Specification Version 1.0
* [http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=29581 ISO/IEC 15948:2004] (not free to download)

== Metaformat files ==

* [http://formats.kaitai.io/png/index.html Kaitai Struct Spec]
* {{Synalysis|png}}

== Software ==
''Support for PNG is ubiquitous. Software listed here may have been selected arbitrarily.''
* [http://www.libpng.org/pub/png/libpng.html libpng] and [http://www.zlib.net/ zlib]
* [http://lodev.org/lodepng/ LodePNG]
* [https://libspng.org/ libspng]
* [http://coptr.digipres.org/Bad_Peggy Bad Peggy: scans images for problems]
* [https://www.madebymikal.com/pngtools-0-4/ PNGtools: low-level manipulation of PNG structure]
* [https://encode.su/threads/1725-pngthermal-pseudo-thermal-view-of-PNG-compression-efficiency PNGThermal: indicates compression cost per pixel]
* [[Konvertor]]

== Sample files ==
* [http://www.libpng.org/pub/png/png-sitemap.html#images PNG Images]
* [http://pngimg.com/ pngimg.com]
* https://telparia.com/fileFormatSamples/image/png/

== Links ==
* [http://www.libpng.org/pub/png/png.html PNG website]
* [[Wikipedia:Portable Network Graphics|Portable Network Graphics (Wikipedia)]]
* {{EGFF|png|PNG File Format Summary}}, from the [[Encyclopedia of Graphics File Formats]]
* [https://forensics.wiki/portable_network_graphics_%28png%29/ Forensics Wiki article]
* [http://imgur.com/a/MtQZv#7 PNG format mini-poster]
* [https://mattscodecave.com/posts/plaidctf-2015---corrupt-png.html How to repair a PNG that has suffered DOS->Unix character conversion]
* [http://blog.codinghorror.com/getting-the-most-out-of-png/ Getting the Most Out of PNG (Jeff Atwood)]
* [https://medium.com/@duhroach/how-png-works-f1174e3cc7b7#.n3l0wota6 How PNG Works]
* [https://www.da.vidbuchanan.co.uk/blog/hello-png.html Hello, PNG!]

PNG

2023-01-17T15:23:30Z

Johanvanderknijff: /* Links */ Added link to David Buchanan's blog post

{{FormatInfo
|formattype=electronic
|subcat=Graphics
|extensions={{ext|png}}
|mimetypes={{mimetype|image/png}}
|locfdd={{LoCFDD|fdd000153}}
|pronom={{PRONOM|fmt/13}}, {{PRONOM|fmt/12}}, {{PRONOM|fmt/11}}
|kaitai struct=png
|wikidata={{wikidata|Q178051}}
|released=1996
}}
'''Portable Network Graphics''' ('''PNG''') was devised starting in a discussion on newsgroup ''comp.graphics'' in 1995, with the first version of its specification released in 1996. The motivation for its creation was to create a free and unencumbered image format in the wake of the patent issue with [[GIF]].

PNG has become a very popular graphic format, but widespread adoption on the Web was slow due to the fact that the first specification came out over a year after the Web had begun to be popular with the general public, meaning that there were many sites and browsers out there not using and supporting the new format; subsequently, browsers began to support it, but often had rendering problems which persisted even in fairly late versions years later; this caused webmasters to be slow to switch from GIF to PNG, though many eventually did so. Since the [[LZW]] patent that affected GIF is expired now, the "free format" motivation for the switch no longer applies.

Unlike GIF, PNG officially supports only still graphics, not animation. However [[APNG]], an unofficial extension of the PNG image format that retains the .png file extention does support animation. Another related format, [[MNG]], officially does support animation.

== Format details ==
A PNG file consists of an 8-byte signature, followed by a sequence of ''chunks''. Each chunk has an 8-byte header containing a 4-byte chunk length, and a 4-byte [[FourCC|chunk type code]]. Each chunk also has a 4-byte trailer containing a checksum.

== Identification ==
A file begins with an 8-byte signature: {{magic|89 50 4E 47 0D 0A 1A 0A}}.

A standard PNG file also has ASCII "{{magic|IHDR}}" at offset 12. You can check for this to distinguish it from [[CgBI]].

== Extensions ==
=== Extensions by chunk type ===
{| class="wikitable"
! Chunk type
! References and remarks
|-
|<code>oFFs</code>, <code>pCAL</code>, <code>sCAL</code>, <code>gIFg</code>, <code>gIFx</code>, <code>gIFt</code>, <code>fRAc</code> || Refer to [http://pmt.sourceforge.net/specs/pngext-1.2.0-pdg-h20.html Extensions to the PNG 1.2 Specification, v1.2.0].
|-
|<code>sTER</code> || Refer to [ftp://ftp.simplesystems.org/pub/libpng/png/documents/pngext-1.3.0-pdg.html Extensions to the PNG 1.2 Specification, v1.3.0].
|-
|<code>dSIG</code> || Refer to [ftp://ftp.simplesystems.org/pub/libpng/png/documents/pngext-1.4.0-pdg.html Extensions to the PNG 1.2 Specification, v1.4.0], and the [http://png-dsig.sourceforge.net/ PNG dSIG website].
|-
|<code>acTL</code>, <code>fcTL</code>, <code>fdAT</code> || Used in [[APNG]] files.
|-
|<code>vpAg</code>, <code>caNv</code>, <code>orNT</code> || Used by [[ImageMagick]].
|-
|<code>CgBI</code> || Refer to [[CgBI]].
|-
|<code>eXIf</code>, <code>exIf</code> || [[Exif]] metadata. Refer to [http://ftp-osl.osuosl.org/pub/libpng/documents/proposals/eXIf/png-proposed-eXIf-chunk-2017-06-15.html PNG Proposed eXIf chunk] [approved 2017-07].
|-
|<code>iDOT</code> || Used by Apple products. Some info at [https://www.hackerfactor.com/blog/index.php?/archives/895-Connecting-the-iDOTs.html].
|}

=== Other extensions ===
* [[XMP]] metadata can be stored in an <code>iTXt</code> chunk with keyword "XML:com.adobe.xmp". Refer to the [[XMP#Specifications|XMP Specification]], Part 3.

== Related Formats ==

* [[APNG]]
* [[MNG]]
* [[JNG]]
* [[CgBI]]
* [[Portable Bitmap Format]]
* [[zlib]]-style [[DEFLATE]] compression: Used to compress image and other data.
* [[CRC-32]]: Used to calculate a checksum of each chunk.
* [[ICC profile]]: The format used by iCCP chunks.

== Specifications ==
* [http://www.w3.org/TR/PNG/ W3C PNG specification] (latest version)
** Specific versions: [http://www.w3.org/TR/REC-png-961001 1996-10-01] · [http://www.w3.org/TR/2003/PR-PNG-20030520/ 2003-05-20] · [http://www.w3.org/TR/2003/REC-PNG-20031110/ 2003-11-10]
* RFC 2083: PNG Specification Version 1.0
* [http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=29581 ISO/IEC 15948:2004] (not free to download)

== Metaformat files ==

* [http://formats.kaitai.io/png/index.html Kaitai Struct Spec]
* {{Synalysis|png}}

== Software ==
''Support for PNG is ubiquitous. Software listed here may have been selected arbitrarily.''
* [http://www.libpng.org/pub/png/libpng.html libpng] and [http://www.zlib.net/ zlib]
* [http://lodev.org/lodepng/ LodePNG]
* [https://libspng.org/ libspng]
* [http://coptr.digipres.org/Bad_Peggy Bad Peggy: scans images for problems]
* [https://www.madebymikal.com/pngtools-0-4/ PNGtools: low-level manipulation of PNG structure]
* [https://encode.su/threads/1725-pngthermal-pseudo-thermal-view-of-PNG-compression-efficiency PNGThermal: indicates compression cost per pixel]
* [[Konvertor]]

== Sample files ==
* [http://www.libpng.org/pub/png/png-sitemap.html#images PNG Images]
* [http://pngimg.com/ pngimg.com]
* https://telparia.com/fileFormatSamples/image/png/

== Links ==
* [http://www.libpng.org/pub/png/png.html PNG website]
* [[Wikipedia:Portable Network Graphics|Portable Network Graphics (Wikipedia)]]
* {{EGFF|png|PNG File Format Summary}}, from the [[Encyclopedia of Graphics File Formats]]
* [http://www.forensicswiki.org/wiki/Portable_Network_Graphics_%28PNG%29 Forensics Wiki article]
* [http://imgur.com/a/MtQZv#7 PNG format mini-poster]
* [https://mattscodecave.com/posts/plaidctf-2015---corrupt-png.html How to repair a PNG that has suffered DOS->Unix character conversion]
* [http://blog.codinghorror.com/getting-the-most-out-of-png/ Getting the Most Out of PNG (Jeff Atwood)]
* [https://medium.com/@duhroach/how-png-works-f1174e3cc7b7#.n3l0wota6 How PNG Works]
* [https://www.da.vidbuchanan.co.uk/blog/hello-png.html Hello, PNG!]

PDF

2021-09-07T17:51:23Z

Johanvanderknijff: /* Miscellaneous */ Added link to blog post

{{FormatInfo
|formattype=electronic
|subcat=Document
|extensions={{ext|pdf}}
|mimetypes={{mimetype|application/pdf}}
|locfdd={{LoCFDD|fdd000030}}, others
|pronom={{PRONOM|fmt/276}}, others
|wikidata={{wikidata|Q42332}}
}}
'''Portable Document Format''' ('''PDF''') is a document file format originally from Adobe, based on [[PostScript]]. It has many subsets.

As well as the 'full function' ISO 32000-1:2008 (or PDF 1.7), there are also PDF/X, PDF/A, PDF/E, PDF/VT and PDF/UA, all of which are ISO specifications.

PDF profiles (formalized subsets) include the following:

* PDF/A (optimized for preservation)
** PDF/A-1 (ISO 19005-1:2005)
** PDF/A-2 (ISO 19005-2:2011)
** PDF/A-3 (ISO 19005-3:2012) (extends PDF/A-2 by allowing embedded files of any type)
** PDF/A-4 (ISO 19005-4:2020)
* PDF/E (ISO 24517-1:2008) (for engineering workflows)
* PDF/UA (ISO 14289-1) (making documents accessible through assistive technologies)
* PDF/VT (ISO 16612-2) (support for variable document printing)
* PDF/X (support for prepress graphics exchange)
** PDF/X-1 (ISO 15930-1:2001)
** PDF/X-1a (ISO 15930-4:2003)
** PDF/X-2 (ISO 15930-5:2003)
** PDF/X-3 (ISO 15930-6:2003)
* Tagged PDF
Some scanner documentation references an apparently fictitious "PDF/L" profile (see Gary McGath's [https://madfileformatscience.garymcgath.com/2018/03/21/pdf-l/ "PDF/L?"]).

A PDF 2.0 spec (ISO 32000-2) was published in 2017-07, with some new features as well as clarification of conformance with existing features.

A PDF/raster draft spec was issued in 2017 as a subset of PDF files containing raster images of scanned documents.

== Identifiers ==
{| class="wikitable"
! Format
! PRONOM
! LoCFDD
|-
|PDF || || {{LoCFDD|fdd000030}}
|-
|PDF 1.0 || {{PRONOM|fmt/14}} ||rowspan="4"| {{LoCFDD|fdd000316}}
|-
|PDF 1.1 || {{PRONOM|fmt/15}}
|-
|PDF 1.2 || {{PRONOM|fmt/16}}
|-
|PDF 1.3 || {{PRONOM|fmt/17}}
|-
|PDF 1.4 || {{PRONOM|fmt/18}} || {{LoCFDD|fdd000122}}
|-
|PDF 1.5 || {{PRONOM|fmt/19}} || {{LoCFDD|fdd000123}}
|-
|PDF 1.6 || {{PRONOM|fmt/20}} || {{LoCFDD|fdd000276}}
|-
|PDF 1.7 || {{PRONOM|fmt/276}} || {{LoCFDD|fdd000277}}
|-
|PDF 1.7, Ext. 3 || || {{LoCFDD|fdd000313}}
|-
|PDF 2.0 || {{PRONOM|fmt/1129}}
|-
|PDF/A || || {{LoCFDD|fdd000318}}
|-
|PDF/A-1 || || {{LoCFDD|fdd000125}}
|-
|PDF/A-1a || {{PRONOM|fmt/95}} || {{LoCFDD|fdd000251}}
|-
|PDF/A-1b || {{PRONOM|fmt/354}} || {{LoCFDD|fdd000252}}
|-
|PDF/A-2 || || {{LoCFDD|fdd000319}}
|-
|PDF/A-2a || {{PRONOM|fmt/476}} || {{LoCFDD|fdd000320}}
|-
|PDF/A-2b || {{PRONOM|fmt/477}} || {{LoCFDD|fdd000322}}
|-
|PDF/A-2u || {{PRONOM|fmt/478}} || {{LoCFDD|fdd000321}}
|-
|PDF/A-3a || {{PRONOM|fmt/479}} ||rowspan="3"| {{LoCFDD|fdd000360}}
|-
|PDF/A-3b || {{PRONOM|fmt/480}}
|-
|PDF/A-3u || {{PRONOM|fmt/481}}
|-
|PDF/A-4 || || {{LoCFDD|fdd000532}}
|-
|PDF/X-1 || {{PRONOM|fmt/144}}, {{PRONOM|fmt/145}} ||rowspan="9"| {{LoCFDD|fdd000124}}
|-
|PDF/X-1a || {{PRONOM|fmt/157}}, {{PRONOM|fmt/146}}
|-
|PDF/X-2 || {{PRONOM|fmt/147}}
|-
|PDF/X-3 || {{PRONOM|fmt/158}}, {{PRONOM|fmt/148}}
|-
|PDF/X-4 || {{PRONOM|fmt/488}}
|-
|PDF/X-4p || {{PRONOM|fmt/489}}
|-
|PDF/X-5g || {{PRONOM|fmt/490}}
|-
|PDF/X-5pg || {{PRONOM|fmt/491}}
|-
|PDF/X-5n || {{PRONOM|fmt/492}}
|-
|PDF/UA-1 || || {{LoCFDD|fdd000350}}
|-
|PDF/E-1 || {{PRONOM|fmt/493}}
|-
|PDF, Geospatial || || {{LoCFDD|fdd000315}}
|-
|GeoPDF 2.2 || || {{LoCFDD|fdd000312}}
|}

== Identification ==
The majority of PDF files can be identified by a fixed header e.g. "%PDF-1.4", however, older documents have a number of variations.
* Some can start with "%!PS-Adobe-N.n PDF-M.m" instead, as described [http://blog.didierstevens.com/2010/01/21/quickpost-pdf-header-ps-adobe-n-n-pdf-m-m/ here].
* Since PDF 1.7, the major and minor version numbers have been fixed. i.e. the public version from Adobe after 1.7 was "1.7 Adobe Extension Level 3".
* For the PDF/A families of formats, their conformance is declared via an embedded ([[XMP]]) metadata fragment.
* Some older files from Mac OS may be wrapped up in the [[AppleSingle]]/[[AppleDouble]] formats. This is a general issue, so should perhaps be documented elsewhere. For more information, see:
** http://en.wikipedia.org/wiki/AppleSingle_and_AppleDouble_formats
** http://tools.ietf.org/rfc/rfc1740.txt

== Compression ==
Images in PDF documents may use the following compression schemes:
* [[LZW]]
* Flate ([[zlib]])
* [[Run-length encoding|RunLength]]
* CCITTFax ([[CCITT Group 3]] and [[CCITT Group 4]])
* [[JBIG2]]
* DCT ([[JPEG]])
* [[JPX]] (part of the [[JPEG 2000]] standard)

== Digital Rights Management & Encryption ==
PDF has two types of 'encryption' - it uses an 'user' password to limit the ability to open the document, and a 'creator' password to limit other rights, like printing, copying, etc. The former case, where a password is required to open the file, is the main preservation concern, as our users will not be able to open a PDF encrypted in this way (unless the password can be cracked, which may be problematic both technically and legally). However, the latter case causes problems, because the PDF is encrypted here too, but with a special known user password of "" (an empty string, which is not the same as no password). So, the document is encrypted in both cases, and you can only tell which is which by attempting to decrypt the PDF using the special default password "". Some PDF analysis tools (notably [[JHOVE]]) do not implement the relevant decryption workflow, and so cannot distinguish between the two types of encryption.

An example of the decryption test workflow can be found here: https://gist.github.com/anjackson/5237071

Some of the most locked-up PDFs anywhere can be found at the [http://ibr.ansi.org/ ANSI IBR Standards Portal], which has made certain standards documents that are incorporated into legislation available for browsing, but only through a convoluted procedure involving downloading a special plug-in and filling out a registration form that must be re-filled-out in every browsing session.

A "Protected PDF" (PPDF) format is [http://www.eweek.com/mobile/microsoft-enterprise-mobility-suite-cozies-up-to-office.html reportedly] used by Microsoft's Azure Rights Management Service for sharing files securely within a workgroup.

== Document redaction ==

Occasionally the attempts of technically-inept users to obscure content in PDF files get in the news. People have sometimes had the mistaken impression that if a section of text is overlayed with a solid-black shape, or set to white-on-white text, or some such thing, before the publicly distributed document is sent out, that would make the redacted sections unavailable; this is not true, as it is in fact easy to find text that has been obscured in such manners, often as simple as dragging a mouse over it to highlight it. This happened in a [http://www.sun-sentinel.com/opinion/fl-op-editorial-judge-elizabeth-scherer-20180823-story.html 2018 Florida case] connected with the school shooting there, where some parts of the school district's report about the shooter were badly redacted and disclosed by a local newspaper, leading to a judge threatening punishment of the paper and prior restraint of future publications of theirs because of this "hacking", raising all sorts of legal and constitutional issues.

== Web linking ==

When linked on the [[Web]], specific pages of a PDF can be referenced by appending <code>#page=N</code> (where N is the desired page number) as a fragment identifier at the end of the [[URL]]. This is a little-known fact.

== Specifications ==
* [http://acroeng.adobe.com/wp/?page_id=321 Adobe PDF References] Contains links to every version of the PDF Reference published by Adobe (starting with PDF 1.0) as well as associated errata, addenda and tech notes.
* Other sources of the above documents:
** [http://www.adobe.com/devnet/pdf/pdf_reference.html PDF Reference and Adobe Extensions to the PDF Specification] Adobe page linking to specification for PDF 1.7 (equivalent to ISO 32000-1:2008) and two Adobe extensions that are expected to be incorporated into ISO 32000-2. These extensions include support for geospatial features and for 3-D content using [[U3D]] and [[Adobe PRC|PRC]] formats.
** [http://www.adobe.com/devnet/pdf/pdf_reference_archive.html Adobe PDF Reference Archives.] Archive of specifications for earlier Adobe versions of PDF, starting with Version 1.3.
* [https://www.iso.org/standard/51502.html ISO 32000-1:2008]: PDF 1.7 (not free to download)
* [https://www.iso.org/standard/63534.html ISO 32000-2:2017]: PDF 2.0 (not free to download)
* [https://pdfraster.org/wp-content/uploads/2017/06/PDFraster10_June-2017.pdf Draft PDF/raster spec 1.0]

== Software ==
* [http://get.adobe.com/reader/ Adobe Reader] views PDF files, either as a standalone program or a browser plugin.
* [http://www.mozilla.org/en-US/products/download.html?product=firefox-19.0&os=win&lang=en-US Firefox 19.0] includes a built-in PDF reader.
* [http://source.mozillaopennews.org/en-US/articles/introducing-tabula/ Tabula: convert tabular data in PDFs to CSV]
* [http://www.mpdf1.com/mpdf/index.php mPDF: convert HTML to PDF]
* [http://en.pdf24.org/ PDF24 creator]
* [http://pdfbox.apache.org/ Apache PDFBox] is an open-source PDF library that includes a PDF/A validator
* [https://pdfium.googlesource.com/pdfium/ pdfium: Open source PDF rendering engine]
* [http://textract.readthedocs.org/en/latest/ Textract: extract text from various document formats including PDF]
* [https://github.com/pramodhkp/pdf2svg/ pdf2svg (in JavaScript)]
* [https://euske.github.io/pdfminer/programming.html Programming with PDFMiner]
* [https://github.com/friesey/preservation-tools/releases/tag/v0.1_alpha_PDFBox_Statistics PDFBox PDF/A Validator]
* [https://pypi.python.org/pypi/PyPDF2/1.24 PyPDF2]
* [https://github.com/sumatrapdfreader Sumatra PDF Reader]
* [https://chrome.google.com/webstore/detail/pdf-viewer/oemmndcbldboiebfnladdacbdfmadadm?hl=en PDF viewer for Chrome]
* [http://verapdf.org/software/ veraPDF library (PDF validator)]
* [http://www.metachris.com/pdfx/ PDFx - Extract metadata and URLs from PDFs, and download all referenced PDFs]
* [https://github.com/ANSSI-FR/caradoc Caradoc: PDF parser and validator]
* [https://github.com/uds-datalab/PDBF PBDF: Create documents that are simultaneously valid PDF, HTML, and VirtualBox OVA.]
* [https://blog.didierstevens.com/programs/pdf-tools/ PDF Tools]
* [https://www.tracker-software.com/product/pdf-xchange-viewer PDF-XChange Viewer]
* [https://www.pdflabs.com/tools/pdftk-the-pdf-toolkit/ The PDF Toolkit PDFTK]

== Online utilities ==
* [http://www.pdf4kindle.com/ PDF to Kindle converter]
* [https://pdftables.com/ PDF to Excel (and some other formats)]

== Sample files ==
* [https://github.com/openplanets/format-corpus/tree/master/pdfCabinetOfHorrors PDF Cabinet of Horrors] - sample PDF files in corrupted or otherwise problematic formats
* [http://acroeng.adobe.com/wp/?page_id=10 Adobe PDF Test Suites] - various PDF test suites on Adobe Acrobat Engineering site
* [http://craphound.com/homeland/Cory_Doctorow_-_Homeland.pdf Homeland by Cory Doctorow]
* [https://www.dan.info/sampledata/msword/testing.pdf Sample document saved from Windows Word 2007]
* [https://github.com/corkami/pocs/blob/master/pdf/quine.pdf Quine PDF; contains its own TeX source]
* [https://www.alchemistowl.org/pocorgtfo/pocorgtfo08.pdf Newsletter designed to work as PDF, ZIP, or shell script]
* [https://github.com/veraPDF/veraPDF-corpus veraPDF corpus]
* [https://github.com/osnr/horrifying-pdf-experiments Horrifying PDF Experiments]
* [https://github.com/mozilla/pdf.js/tree/master/test/pdfs Test PDFs used by Mozilla PDF Reader]
* [https://github.com/pdf-association/pdf20examples PDF 2.0 example files by the PDF Association]
* https://telparia.com/fileFormatSamples/document/pdf/

== See also ==
* [[Ascii85]]
* [[FDF]]
* [[KFP]] Preflight Profile
* [[PostScript]]
* [[WWF]]
* [[XFDF]]

== Links ==

=== Format info ===
* [http://en.wikipedia.org/wiki/Portable_Document_Format Portable Document Format (Wikipedia)]
* [http://www.forensicswiki.org/wiki/PDF Forensics Wiki: PDF]
*[http://acroeng.adobe.com/wp/ Adobe Acrobat Engineering site] - Dedicated Adobe site with lots of technical information, including a history of PDF and Acrobat, conforming viewers and test files.
* [http://www.pdfa.org/2013/04/pdfa-in-a-nutshell-2_0/ PDF/A in a Nutshell 2.0 – online edition]
* [http://www.infinitepartitions.com/cgi-bin/showarticle.cgi?article=art019 Inside the PDF File Format]
* [http://imgur.com/a/PbN8H#7 PDF101 an Adobe document walkthrough]

=== Validation ===
* [http://vimeopro.com/pdfassociation/technical-conference-europe-2013/video/68945979 PDF Validation: Dream or Yawn?] - Presentation on possibilities of an open-source PDF validator
* [http://www.docdroid.net/ciex/5103a198-1.pdf.html The pitfalls of protocol design: Attempting to write a formally verified PDF parser]
* [https://fileformats.wordpress.com/2015/04/22/verapdf/ New open-source file validation project]

=== Jailbreaking ===
* [http://scholrev.org/hackathon/ Jailbreaking the PDF hackathon]
* [http://blogs.ch.cam.ac.uk/pmr/2013/05/28/jailbreaking-the-pdf-a-wonderful-hackathon-and-a-community-leap-forward-for-freedom-1/ Jailbreaking the PDF (discussion)]
* [http://blogs.ch.cam.ac.uk/pmr/2013/05/28/jailbreaking-the-pdf-2-technical-aspects-glyph-processing/ Jailbreaking the PDF (technical aspects: glyph processing)]
* [http://blog.didierstevens.com/2015/04/15/pdf-password-cracking-with-john-the-ripper/ PDF Password Cracking With John The Ripper]

=== Commentary ===
* [http://www.portico.org/digital-preservation/wp-content/uploads/2012/11/TheNetworkIsTheFormat.pdf The Network is the Format: PDF and the Long-term Use of Digital Content] Article by Sheila Morrissey of ITHAKA on the challenges of preserving PDF files based on experience. She illustrates the challenge of defining a "sufficient sub-graph of the network of information about a digital object, for effective future use."
* [http://blogs.loc.gov/digitalpreservation/2014/06/the-pdfs-place-in-a-history-of-paper-knowledge-an-interview-with-lisa-gitelman/ The PDF’s Place in a History of Paper Knowledge: An Interview with Lisa Gitelman]
*[http://wiki.opf-labs.org/display/TR/Portable+Document+Format Portable Document Format on OPF File Format Risk Registry] - Lists various long-term accessibility issues in PDF and how to detect them using Apache Preflight.
* [http://www.openplanetsfoundation.org/system/files/PDFInventoryPreservationRisks_0_2_0.pdf Adobe Portable Document Format - Inventory of long-term preservation risks] - Report by KB/ National Library of the Netherlands.
* [http://fileformats.wordpress.com/2014/06/13/abuses-pdf/ The uses and abuses of PDF]
* [http://duff-johnson.com/2014/04/07/apples-preview-still-not-safe-for-work/ Apple’s Preview: Still not safe for work]
* [http://www.niso.org/publications/isq/2013/v25no3/moore/ Preserving the Grey Literature Explosion: PDF/A and the Digital Archive]
* [http://www.pdfa.org/2014/12/ensuring-long-term-access-pdf-validation-with-jhove/ Ensuring long-term access: PDF validation with JHOVE?]
* [http://www.theguardian.com/higher-education-network/2015/feb/11/researchers-its-time-to-ditch-the-pdf Researchers: it's time to ditch the PDF]
* [http://wiki.dpconline.org/images/5/51/PDF_Assessment_v1.2_external.pdf PDF Format Preservation Assessment (British Library)]
* [http://www.pdfa.org/2015/06/what-will-pdf-2-0-bring/ What will PDF 2.0 bring?]
* [http://www.digitalpreservation.gov/ndsa/working_groups/documents/NDSA_PDF_A3_report_final022014.pdf?loclr=blogsig The Benefits and Risks of the PDF/A-3 file format for archival institutions]
* [https://nicolastreeten.wordpress.com/2015/09/19/becoming-of-age-pdf/ Becoming of Age: PDF (comic)]
* [http://www.pdfa.org/2016/06/what-does-support-pdf-really-mean/ What does "support PDF" really mean?]
* [http://openpreservation.org/blog/2016/12/09/pdfa-as-a-preferred-sustainable-format-for-spreadsheets/ PDF/A as a preferred, sustainable format for spreadsheets?]
* [https://www.filingdb.com/pdf-text-extraction What's so hard about PDF text extraction?]
* [https://www.pdfa.org/perfecting-pdf-lexical-analysis/ Perfecting PDF lexical analysis]

=== Miscellaneous ===
* [http://www.pdfa.org/ PDF/A Competence Center]
* [http://web.archive.org/web/20130515073645/http://libraries.stackexchange.com/questions/964/what-preservation-risks-are-associated-with-the-pdf-file-format What preservation risks are associated with the PDF file format?] - Q&A thread from Libraries and Information Sciences Stack Exchange (archived)
* [http://labs.appligent.com/files/2013/03/recognizing_malformed_pdf_f.pdf Recognizing Corrupt and Malformed PDF Files]
* [https://github.com/davetaz/mh370-data Flight MH370 data was released as a PDF, but somebody extracted it to CSV to make it more useful for data analysis.]
* [https://pdf.yt/ PDFy - free host for publicly viewable PDFs, backed up automatically to Internet Archive]
* [http://www.washingtonpost.com/blogs/the-switch/wp/2014/08/05/uk-judge-says-freedom-of-information-means-choice-of-digital-file-format/ UK judge says ‘freedom of information’ means choice of digital file format]
* [http://blogs.perl.org/users/peter_martini/2014/08/the-chimera-quine-or-the-iso-pdf.html The Chimera Quine; or, the ISO PDF]
* [http://openplanetsfoundation.org/blogs/2014-08-12-coming-preserving-pdf-identify-validate-repair-hamburg PDF info/links for attendees of conference on it]
* [http://anjackson.github.io/keeping-codes/experiments/does-jhove-validate-pdfa-files Does JHOVE validate PDF/A files?]
* [http://raywoodcockslatest.wordpress.com/2014/12/04/pdf-repair/ Methods of Repairing Corrupted or Damaged PDFs]
* [http://stackoverflow.com/questions/17740175/how-do-i-dump-embedded-icc-profile-information-in-pdf-command-line-or-gui-tool/27464166#27464166 How do I dump embedded ICC profile information in PDF? (command line or GUI tools)]
* [http://stackoverflow.com/questions/27938551/how-to-check-pdf-pages-for-resolution-dpi-of-embedded-images/27942530 How to check PDF pages for resolution (DPI) of embedded images?]
* [http://chemxseer.ist.psu.edu/about/digital_library/das08-liu.pdf A Fast Preprocessing Method for Table Boundary Detection: Narrowing Down the Sparse Lines using Solely Coordinate Information]
* [https://github.com/angea/PDF101/tree/master/handcoded/textextract Why text extracting doesn't work for all PDFs]
* [http://stackoverflow.com/questions/29342542/how-can-i-extract-a-javascript-from-a-pdf-file-with-a-command-line-tool/29364036 How can I extract a JavaScript from a PDF file with a command line tool?]
* [http://stackoverflow.com/questions/29331731/postscript-code-to-un-hide-hidden-text-in-pdf/29334742 How to un-hide hidden text in PDF]
* [http://www.pdfa.org/2015/04/infographics-pdfua-and-wcag-2-0/ Infographics: PDF/UA and WCAG 2.0]
* [http://www.prepressure.com/pdf/basics/history The history of PDF] according to prepressure.com, a site for "prepress & print devotees".
* [https://isc.sans.edu/diary/Handling+Special+PDF+Compression+Methods/19597 Handling Special PDF Compression Methods]
* [https://speakerdeck.com/ange/lets-write-a-pdf-file Let's write a PDF file]
* [https://blog.didierstevens.com/2016/06/07/recovering-a-ransomed-pdf/ Recovering a ransomed PDF]
* [https://github.com/digital-preservation/droid/issues/114 PDF version numbers based on deprecated mechanism]
* [https://madfileformatscience.garymcgath.com/2016/09/26/pdf-version/ Figuring out the PDF version is harder than you think]
* [https://www.pdfa.org/slides-and-video-recordings-of-the-pdf-days-europe-2017/ Slides and video recordings of the PDF Days Europe 2017]
* [https://www.pcworld.com/article/2096946/5-cheaper-alternatives-to-acrobat-for-pdf-editing.html 5 cheaper alternatives to Acrobt for PDF editing]
* [https://pdfraster.org/ PDF/raster site]
* [https://www.pdfa.org/hunter-bidens-email-and-the-potential-for-deepfakes-with-pdf/ Hunter Biden’s “email” and the potential for deepfakes with PDF]
* [https://www.bitsgalore.org/2021/09/06/pdf-processing-and-analysis-with-open-source-tools PDF processing and analysis with open-source tools]

[[Category:Page description languages]]
[[Category:Adobe]]

JPEG

2020-07-15T15:34:18Z

Johanvanderknijff: /* External links */

{{FormatInfo
|formattype=electronic
|subcat=Graphics
|thiscat=JPEG
|extensions={{ext|jpg}}, {{ext|jpeg}}, {{ext|jpe}}, {{ext|jif}}
|mimetypes={{mimetype|image/jpeg}}
|locfdd={{LoCFDD|fdd000017}}, others
|pronom={{PRONOM|fmt/41}}, others
|wikidata={{wikidata|Q27996264}}
|released=1992
}}
'''JPEG''' is a popular raster image format well-suited to photographic images. It usually uses lossy [[DCT compression]]. It is named after the Joint Photographic Experts Group, the organization which developed the format. It is sometimes called '''JPEG1''', '''JPEG-1''', or '''JPEG 1992''' to help disambiguate it. (Also see [[JPEG 2000]] and [[JP2]].)

== Terminology ==
''(In which we discuss the tired old question of whether JPEG is a file format, or a compression standard)''

In the original specification (ITU-T Rec. T.81), the term ''JPEG'' refers only to an organization. The serialized form of the compression format it defines is referred to only as the "interchange format".

The followup ITU-T Rec. T.84 document says that ''JPEG'' can also refer to a set of ''standards'', including at least Rec. T.81, Rec. T.83, and Rec. T.84. It also informally uses ''JPEG'' to refer to the Rec. T.81 interchange format.

ITU-T Rec. T.851 refers to the interchange format as ''JPEG-1''.

The interchange format is ''almost'' a full-fledged portable file format, lacking only standard conventions and/or standard metadata elements to tell how to interpret it as an image. The missing pieces can be added in various ways. Some file formats, including [[JFIF]], do so in such a way that the interchange format is used directly as a file format. In practice, the term ''JPEG'' often refers to the family of such file formats, and this usage does not seem unreasonable, especially since there is no other suitable name. The term '''JIF''' (for ''JPEG Interchange Format'') has been tossed around, but it is an ambiguous term that doesn't necessarily refer to a file format, and it's unusable in practice due to similarity to [[GIF]].

It could be that ''JPEG'' is sometimes misused to mean [[JFIF]], but such an accusation might be relying on the incorrect assumption that '''.jpg''' files always use JFIF format.

== Portability ==
In and of itself, JPEG is not really a suitable format for image interchange, for several reasons:
* It essentially only defines a way to store one or more arrays of numbers. It does not say how to interpret those numbers as an image. The decoder will just have to guess.
* It is large and general, and it might be unrealistic to expect every decoder to support all of it.
* It defines no standard metadata elements.

To address these issues, a number of JPEG subformats have been invented. [[JFIF]] is by far the most popular of them, though a significant minority of JPEG files use [[Exif]] instead. The [[SPIFF]] file format was intended as a replacement for JFIF, but never caught on.

In practice, a portable JPEG file is pretty much "whatever the libjpeg software supports". This includes some varieties (such as RGB color) that do not conform to JFIF, and excludes some (such as lossless JPEG) that do.

== Format ==
A JPEG file consists largely of a sequence of tagged segments. Each segment begins with a two-byte "marker". (The term "marker" is often used to refer to the entire segment.) The first byte of a marker is 0xff. The second may have any value except 0x00 or 0xff, and indicates the type of data stored in the segment. Segment types are assigned names; for example, 0xd9 is "SOI", and 0xe1 is "APP1".

Segment types 0x01, and 0xd0 through 0xd9, consist entirely of the two-byte marker. All other markers are followed by a two-byte integer indicating the size of the segment, followed by the payload data contained in the segment.

The image data is the exception to this segmented format. It appears following an "SOS" (0xda) segment, but there is no prefix to indicate its size. Instead, any 0xff bytes in the image data are escaped as 0xff 0x00, so that they won't be mistaken for markers. (Note that some JPEG-like formats, such as [[JPEG-LS]] and [[JPEG 2000 codestream]], use different rules for escaping 0xff bytes.)

=== Application segments ===
There are 16 segment types reserved for application-specific data: 0xe0 ("APP0") through 0xef ("APP15").

An APP segment's data often begins with NUL-terminated text string to identify the type of data contained in it. The actual payload data then begins after the NUL byte. This convention was standardized by ISO/IEC 10918-4:1999 (see ITU-T Rec. T.86), but is not as universal as one might hope. Most APP segments do have a signature of some sort, but because there is no simple matching algorithm that always works, identifying the signature can be difficult.

== Identifiers ==
{| class="wikitable"
! Format
! PRONOM
! LoCFDD
|-
|JPEG || {{PRONOM|fmt/41}} || {{LoCFDD|fdd000017}}
|-
|Baseline JPEG || || {{LoCFDD|fdd000149}}
|-
|Progressive JPEG || || {{LoCFDD|fdd000333}}
|-
|[[Lossless JPEG (original)|Lossless JPEG]] || || {{LoCFDD|fdd000334}}
|-
|Other JPEG || || {{LoCFDD|fdd000150}}
|-
|JFIF 1.00 || {{PRONOM|fmt/42}}
|-
|JFIF 1.01 || {{PRONOM|fmt/43}}
|-
|[[JFIF]] 1.02 || {{PRONOM|fmt/44}} || {{LoCFDD|fdd000018}}
|-
|Exif 2.0 JPEG || {{PRONOM|x-fmt/398}} ||rowspan="3"| {{LoCFDD|fdd000147}}
|-
|Exif 2.1 JPEG || {{PRONOM|x-fmt/390}}
|-
|[[Exif]] 2.2 JPEG || {{PRONOM|x-fmt/391}}
|-
|[[SPIFF]] || {{PRONOM|fmt/112}} || {{LoCFDD|fdd000019}}
|}

== Identification ==
JPEG files begin with bytes <code>ff d8 ff</code>.

However, this does not distinguish them from [[JPEG-LS]]. To do that reliably, one may have to scan the file to look for one of the valid SOF segment types.

== Types of JPEG files ==
The following types are not disjoint. For example, a progressive JPEG may use arithmetic coding.

Some JPEG images do not belong to any of these types. An SOF1 segment is used if no other SOF segment applies.

=== Baseline ===
JPEGs with an SOF0 segment are known as ''Baseline'' JPEGs. They are always lossy, not progressive, use Huffman coding, and have a bit depth of 8. Every application that supports JPEG is supposed to at least support Baseline JPEG.

=== Progressive ===
Progressive JPEG rearranges the image data, so that the the first part of it represents a very low quality version of the entire image, rather than a high quality version of a small part of the image.

A progressive JPEG is identified by the presence of an SOF2, SOF6, SOF10, or SOF14 segment.

=== Non-interleaved ===
Color JPEG images may be either ''interleaved'' or ''non-interleaved''.

In an interleaved JPEG, all the color components (e.g. Y, Cb, Cr) for a pixel are stored close together in the file.

In a non-interleaved JPEG, the image is separated into its color components, and each component is stored separately in the file.

Interleaving is not a simple yes/no option, because a single image may use both interleaved and non-interleaved scans (SOS segments) – in fact, progressive JPEGs usually do just that. Some JPEG decoders do not support non-interleaved images unless they use progressive encoding.

=== Arithmetic coding ===
Even lossy JPEG makes use of a lossless compression algorithm. The lossless algorithm is usually [[Huffman coding]], but [[arithmetic coding]] may be used instead. JPEG's arithmetic coding usually results in a smaller file size, but it is not as widely supported as one might hope, probably because it used to be encumbered by [[patents]].

An arithmetic-coded JPEG is identified by the presence of an SOF9, SOF10, SOF11, SOF13, SOF14, or SOF15 segment.

=== 12-bit ===
Except for Baseline JPEG, all lossy types of JPEG may use a bit depth of either 8 or 12 bits per sample. However, few applications support anything other than 8 bits.

Starting with version 9a, IJG libjpeg also supports bit depths of 9, 10, and 11. These depths are nonstandard, and libjpeg's implementation is nearly unusable in practice, because it only supports a single bit depth, which must be selected at compile time.

=== Lossless JPEG ===
:''Main article: [[Lossless JPEG (original)]]''

JPEG supports true lossless compression, but it is used so rarely that JPEG is commonly thought of as strictly a lossy format.

A lossless JPEG is identified by the presence of an SOF3, SOF7, SOF11, or SOF15 segment.

See also the [[Lossless JPEG|Lossless JPEG disambiguation page]], for other uses of the term.

=== Hierarchical ===
Also called "differential", hierarchical JPEG is vaguely similar to progressive JPEG, but geared toward storing multiple sizes of the same image, such that the decoder can select the size it prefers. Hierarchical JPEGs are, to a close approximation, nonexistent.

A hierarchical JPEG is identified by the presence of an SOF5, SOF6, SOF7, SOF13, SOF14, or SOF15 segment.

== Color format ==
There are five JPEG color types that are reasonably portable:
# Grayscale
# YCbCr
# RGB
# YCCK
# CMYK

To make the compression more effective, RGB images are almost always transformed to YCbCr format when they are written to a JPEG file. However, many applications will still report that such images use "RGB" color. This may be because their authors weren't aware of the transformation, or because they considered it to be an internal part of the compression algorithm as opposed to a different colorspace. Unfortunately, this inconsistent terminology can make it hard to distinguish YCbCr JPEGs from the rare JPEGs that really do use RGB color.

YCCK is a transformed version of CMYK, and the same terminology confusion exists as with YCbCr and RGB.

The JPEG format does not have any clear way to indicate the color type of an image. Decoders usually determine the color type based on several factors:
* The number of color components
* The presence of a JFIF application segment
* The "color transform" field of the APP14 "Adobe" segment, if present
* The component ID numbers ({82, 71, 66} suggests RGB)

== SmartScale ==
Starting with version 7 or 8, the IJG libjpeg software has been adding nonstandard "SmartScale" scaling and color transform features of debatable merit<ref>[http://www.libjpeg-turbo.org/About/SmartScale A Study on the Usefulness of DCT Scaling and SmartScale]</ref><ref>[http://hardwarebug.org/2010/02/01/ijg-swings-again-and-misses/ IJG swings again, and misses]</ref>.

Notably, it is possible to achieve lossless DCT compression by setting the DCT block size to 1, and using RGB color if necessary.

Version 9 introduced a "reversible color transform" feature that can improve the compression of RGB images. Files with this feature contain a JPG8 (0xf8) segment.

== Related Formats ==
* [[JFIF]] is a subformat and extension, and uses APP0 "JFIF" and APP0 "JFXX" segments.
* [[SPIFF]] is a subformat and extension, and uses an APP8 "SPIFF" segment.
* [[JPEG-HDR]] is an extension, and uses APP11 segments.
* [[JPEG XT]] is an extension.
* [[JPEG 360]] is an extension, and/or a metadata format.
* [[JPS]] is an extension, and uses an APP3 "_JPSJPS_" segment.
* [[Multi-Picture Format]] is an extension, and uses an APP2 "MPF" segment.
* The [[Exif]] standard uses an APP1 "Exif" segment.
* [[FlashPix]] data is contained in APP2 "FPXR" segments in Exif-compliant JPEGs. Refer to the [[Exif]] specification.
* [[Photoshop Image Resources]] is contained in an APP13 "Photoshop 3.0" segment.
* [[IPTC-IIM]] metadata often appears in JPEG files, embedded in [[Photoshop Image Resources]].
* [[XMP]] metadata is contained in an APP1 <nowiki>"http://ns.adobe.com/xap/1.0/"</nowiki> segment.
* [[ICC profile]] data is contained in an APP2 "ICC_PROFILE" segment.
* Many other file formats, such as [[TIFF]], [[MNG]]/[[JNG]], and [[PDF]], can contain JPEG-compressed data or encapsulated JPEG files.
* ''(And we heard you like JPEG...)'' JPEG files themselves often contain thumbnail images in the form of embedded JPEG files, via formats such as [[Exif]], [[Photoshop Image Resources]], or [[JFIF]].

Formats that are '''not''' compatible with JPEG include [[JPEG-LS]], [[JPEG 2000]], [[JPEG XR]], and presumably [[JPEG XL]].

== Specifications ==
* [http://www.w3.org/Graphics/JPEG/itu-t81.pdf ITU-T Rec. T.81] (originally CCITT Rec. T.81): The JPEG standard
* [http://www.itu.int/rec/T-REC-T.83/en ITU-T Rec. T.83]: Compliance testing
* [http://www.itu.int/rec/T-REC-T.84/en ITU-T Rec. T.84]: Extensions
* [http://www.itu.int/rec/T-REC-T.86/en ITU-T Rec. T.86]: Registration of JPEG Profiles, etc.
* [http://www.itu.int/rec/T-REC-T.851-200509-I/en ITU-T Rec. T.851]: (JPEG-1)-based still-image coding using an alternative arithmetic coder
* [http://www.itu.int/rec/T-REC-T.872/en ITU-T Rec. T.872]: Application to printing systems
* [http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html#Adobe ExifTool: The APP14 "Adobe" segment]
* ISO/IEC 10918: Digital compression and coding of continuous-tone still images
** [http://www.iso.org/iso/catalogue_detail.htm?csnumber=18902 ISO/IEC 10918-1:1994] - Requirements and guidelines
*** [http://www.iso.org/iso/catalogue_detail.htm?csnumber=41504 ISO/IEC 10918-1:1994/Cor 1:2005] - Patent information update
** [http://www.iso.org/iso/catalogue_detail.htm?csnumber=20689 ISO/IEC 10918-2:1995] - Compliance testing
** [http://www.iso.org/iso/catalogue_detail.htm?csnumber=25037 ISO/IEC 10918-3:1997] - Extensions
*** ISO/IEC 10918-3:1997/Amd 1:1999 - Refer to [[SPIFF]]
** [http://www.iso.org/iso/catalogue_detail.htm?csnumber=25431 ISO/IEC 10918-4:1999] - Registration of JPEG profiles, ...
*** [http://www.iso.org/iso/catalogue_detail.htm?csnumber=59454 ISO/IEC 10918-4:1999/Amd 1:2013] - Application specific marker list
** ISO/IEC 10918-5:2013 - Refer to [[JFIF]]
** [http://www.iso.org/iso/catalogue_detail.htm?csnumber=59634 ISO/IEC 10918-6:2013] - Application to printing systems
** [https://www.iso.org/standard/75845.html ISO/IEC 10918-7:2019] - Reference software
* [https://jpeg.org/jpegsystems/index.html ISO/IEC 19566: JPEG Systems] (a collection of JPEG-related standards)
** [https://www.iso.org/standard/65348.html ISO/IEC 19566-1]: Packaging of information using codestreams and file formats
** [https://www.iso.org/standard/67704.html ISO/IEC 19566-2]: Transport mechanisms and packaging
** [https://www.iso.org/standard/73607.html ISO/IEC 19566-4]: Privacy, security and IPR features
** [https://www.iso.org/standard/73604.html ISO/IEC 19566-5]: JPEG Universal Metadata Box Format (JUMBF)
** ISO/IEC 19566-6 - Refer to [[JPEG 360]]
** [https://www.iso.org/standard/78466.html ISO/IEC 19566-7]: JPEG Linked Media Format
* [https://jpeg.org/downloads/jpeg/wg1n76028-CfP-JPEG-reference-software.pdf Final Call for Proposal for a JPEG Reference Software] (2017-07)

== Sample files ==
* https://telparia.com/fileFormatSamples/image/sm-if09.jpg

== Metaformat files ==
* {{Synalysis|jpeg}}

== Software ==
Nearly all serious graphics applications, including web browsers, support JPEG. This section primarily lists libraries and tools.

* [http://www.ijg.org/ The Independent JPEG Group's software], commonly known as ''libjpeg'' or ''IJG libjpeg''
* [http://libjpeg-turbo.virtualgl.org/ libjpeg-turbo]
* [https://github.com/thorfdbg/libjpeg Thomas Richter's libjpeg]: C++ library that supports all of the JPEG standard
* [https://github.com/mozilla/mozjpeg/ mozjpeg: Improved JPEG encoding library from Mozilla]
** [http://calendar.perfplanet.com/2014/mozjpeg-3-0/ Info on mozjpeg 3.0]
* [https://research.googleblog.com/2017/03/announcing-guetzli-new-open-source-jpeg.html Guetzli] - JPEG encoder optimized for file size
** [https://github.com/google/guetzli Source code at GitHub]
* [http://coptr.digipres.org/Bad_Peggy Bad Peggy: scans images for problems]

== Notes ==
When saving a JPEG image from [[Twitter]] in Google Chrome / Chromium, it will save with the default extension '''.jpg-large'''. This is due to a [https://code.google.com/p/chromium/issues/detail?id=172529 known bug] (and one which shows no signs of being solved any time soon) in the way the browser sanitises Twitter image URLs (the filename is determined to be e.g. Xyzxyzxyz.jpg:large, which is sanitised to Xyzxyzxyz.jpg-large).

== External links ==
* [[Wikipedia:JPEG|JPEG (Wikipedia)]]
* [http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html ExifTool JPEG Tags]
* [http://blog.sucuri.net/2013/07/malware-hidden-inside-jpg-exif-headers.html Malware Hidden Inside JPG EXIF Headers]
* [http://www.theatlantic.com/technology/archive/2013/09/what-is-a-jpeg-the-invisible-object-you-see-every-day/279954/ What Is a JPEG? The Invisible Object You See Every Day]
* [http://l0ss.elliepritts.com/ Project L0SS], a collection of images demonstrating the glitches and artifacts caused by repeatedly recompressing JPEG images
* [http://thenextweb.com/insider/2014/03/05/mozilla-launches-jpeg-encoder-mozjpeg-improve-compression-rates-reduce-network-traffic-page-loads/ Mozilla launches JPEG encoder mozjpeg to reduce webpage loads, results show up to 10% decrease in file size]
* [http://andreasgal.com/2014/07/15/improving-jpeg-image-encoding/ Improving JPEG image encoding]
* [http://arstechnica.com/information-technology/2014/07/we-dont-need-new-image-formats-mozilla-works-to-build-a-better-jpeg/ We don’t need new image formats: Mozilla works to build a better JPEG]
* [http://www.ams.org/samplings/feature-column/fcarc-image-compression Explanation of JPEG compression algorithm]
* [https://github.com/lclevy/libcraw2/blob/master/docs/cr2_lossless.pdf Lossless JPEG decompression]
* [http://xooyoozoo.github.io/yolo-octo-bugfixes/ Online demonstrator]- shows quality differences between similarly-sized images in [[JPEG]], [[JP2]], [[WebP]] and [[BPG]] formats
* [https://github.com/mozilla/mozjpeg/issues/182 Method to improve JPEG compression that was the subject of a now-expired patent]
* [https://medium.freecodecamp.com/how-jpg-works-a4dbd2316f35 How JPG Works]
* [http://frdx.free.fr/JPEG_for_the_horseshoe_crabs.pdf JPEG for the horseshoe crabs]
* [http://cloudinary.com/blog/why_jpeg_is_like_a_photocopier Why JPEG is like a photocopier] - discussion of generation loss in JPEG and other lossy formats (with examples)
* [http://openpreservation.org/blog/2017/04/09/using-exiftool-to-address-tag-out-of-sequence-errors-in-images-and-a-101-level-dive-into-tags/ Using EXIFTool to address “Tag out of sequence” errors in images (and a 101 level dive into tags)]
* [https://openpreservation.org/blog/2019/11/07/jpeg-got-the-blues/ JPEG Got the Blues] - on properly rendering 32-bit (CMYK) JPEGs
* [https://yasoob.me/posts/understanding-and-writing-jpeg-decoder-in-python/ Understanding and Decoding a JPEG Image using Python]

== References ==
<references/>

[[Category:Compression]]
[[Category:JPEG (organization)]]

SKP

2020-03-20T10:50:09Z

Johanvanderknijff: /* Links */ Added "SketchUp in digital archives" report

{{FormatInfo
|formattype=electronic
|subcat=3D and CAD/CAM Models
|extensions={{ext|skp}}
|wikidata={{wikidata|Q79604}}
|released=2000
}}
'''SKP''' is a file format used by SketchUp (once owned by Google after they acquired its original developing company, @Last Software, but later sold to a different company, Trimble) for 3D models. It is proprietary and does not appear to have been documented in any publicly accessible place.

== Links ==
* [https://help.sketchup.com/ SketchUp site]
* [[Wikipedia:SketchUp|Wikipedia article]]
* [https://forums.sketchup.com/t/is-there-any-documentation-of-the-skp-file-format/62269/5 Discussion over whether format documentation can be found]
* [https://help.sketchup.com/en/sketchup/importing-and-exporting-cad-files SketchUp: Importing and exporting CAD files]
* [https://zenodo.org/record/3718996 SketchUp in digital archives. Software and file format analysis and exploration of the options for digital preservation] - Report by Henk Vanstappen, commissioned by The Flanders Architecture Institute
[[Category:Google]]

ZIP

2020-03-16T15:24:28Z

Johanvanderknijff: /* Links */

:''Not to be confused with [[Zip disk]], an unrelated disk cartridge unit.''
{{FormatInfo
|formattype=electronic
|subcat=Archiving
|extensions={{ext|zip}}
|mimetypes={{mimetype|application/zip}}
|uniform type={{UTI|com.pkware.zip-archive}}
|locfdd={{LoCFDD|fdd000354}}, {{LoCFDD|fdd000355}}, {{LoCFDD|fdd000362}}, {{LoCFDD|fdd000361}}
|pronom={{PRONOM|x-fmt/263}}
|wikidata={{wikidata|Q136218}}
|kaitai struct=zip
|released=1989
}}
'''ZIP''' is one of the most popular file compression formats. It was created in 1989 as the native format of the PKZIP program, which was introduced by Phil Katz in the wake of a lawsuit (which he lost) against him by the makers of the then-popular [[ARC (compression format)|ARC]] program (and file format) for copyright and trademark infringement in an earlier program PKARC which had been file-compatible with ARC. This resulted in Katz creating a new file format, which rapidly overtook ARC in popularity (to a large extent because of BBS sysops, then the primary users of such compression, resenting the lawsuit). Many programs have been released for a variety of operating systems to compress and decompress ZIP files, and native support for the format is built into several popular operating systems.

ZIP implementations vary in their support for features in the specification from PKWARE<ref>http://www.pkware.com/documents/casestudies/APPNOTE.TXT</ref>, particularly features added since version 2 (1993), some of which are protected by patents and require licensing. Many implementations limit the use of compression to the [[DEFLATE]] algorithm, introduced with version 2. Extensions incorporated into the specification that have been widely adopted are: long filenames; large files (using a technique known as ZIP64); and filenames in [[UTF-8]]. In 2011 work began on an interoperable subset of the latest APPNOTE.TXT with the intention of publication as ISO/IEC 21320-1, Document Container File -- Part 1: Core. As of November 2012, a discussion draft is available<ref>http://kikaku.itscj.ipsj.or.jp/sc34/open/1855.pdf</ref>. Designed to promote interoperable implementations, the draft ISO/IEC 21320-1 prohibits compression other than using [[DEFLATE]], segmentation or multiple volumes, and features that are subject to patents.

While .zip is the usual file extension, ZIP-formatted files can be found with many other extensions since a number of other file formats use ZIP compression but store their files in application-specific extensions. See [[:Category:ZIP based file formats]] for a list of such formats.

== See also ==
* [[PKLITE]]
* [[Self-extracting ZIP]]
* [[Zipx]]

== Disambiguation ==
The term "ZIP compression" is sometimes misleadingly used to mean [[DEFLATE]] (which is by far the most common compression scheme used in ZIP files). In such cases, the compressed data format could turn out to be raw [[DEFLATE]], or [[zlib]], or [[gzip]].

== Identification ==
The byte sequence <code>'P' 'K' 0x05 0x06</code> (the "end of central directory signature") appears somewhere in the file, usually beginning exactly 22 bytes from the end of the file. However, it will appear earlier if the file contains a "ZIP file comment" (common in the BBS era, but rare today), or for various other reasons. There seems to be no theoretical limit to how far back you may have to search for the signature, but some software limits it to around 64KB, which is the maximum length of a comment.

Most ZIP files (but not [[self-extracting ZIP]] files) happen to begin with <code>'P' 'K' 0x03 0x04</code>. This is not a global file signature, but is the signature that appears once for every compressed file inside the ZIP file. Some ZIP-based formats are designed such that they necessarily begin in this way. But in general, it is even legal for a ZIP file to contain zero files, and such a ZIP file would not contain this signature at all.

That Phil Katz guy has thus managed to get his initials at the start of a large number of files on many millions of computers and devices, given how many file formats are based on ZIP (even if they use different extensions). He died in 2000, but this memorial to him will live on indefinitely.

== Compression ==
Each file in a ZIP file is compressed using one of a number of compression algorithms. Only compression types 0 (uncompressed) and 8 (DEFLATE) are likely to be seen in modern portable ZIP files. In old ZIP files, types 1 (Shrink) and 6 (Implode) are common.

{| class="wikitable"
! Code
! Compression scheme
! Notes and references
|-
|0 || Uncompressed
|-
|1 || Shrink || [[LZW]]. Used by PKZIP 0.x and 1.x.
|-
|2–5 || Reduce || [[LZ77]] + prediction. Used by PKZIP v0.x. See also [[SCRNCH]].
|-
|6 || Implode || [[LZ77]] + [[Huffman coding|Huffman]]. Used by PKZIP v1.x.
|-
|7 || Tokenized || Never used?
|-
|8 || [[DEFLATE]] || [[LZ77]] + [[Huffman coding|Huffman]]. Used by PKZIP v2.0+.
|-
|9 || Deflate64, a.k.a. Enhanced Deflate || Format version 2.1+.
|-
|10 || [[PKWARE DCL Implode]] (old IBM TERSE) || Format version 2.5+.
|-
|12 || [[Bzip2]] || Format version 4.6+.
|-
|14 || [[LZMA]] (EFS) || Defined in ZIP specification v6.3+.
|-
|16 || IBM z/OS CMPSC
|-
|18 || IBM TERSE (new)
|-
|19 || IBM LZ77 z Architecture (PFS)
|-
|94 || [[MP3]] || Supported by WinZip 21+.
|-
|95 || [[XZ]] || Supported by WinZip 18+.
|-
|96 || [[JPEG]] variant
|-
|97 || [[WavPack]] || Defined in ZIP specification v6.3.2+.
|-
|98 || [[PPMd]] version I, Rev 1 || Defined in ZIP specification v6.3+.
|-
|99 || AES / AE-x encryption marker
|}

== Extensible data fields ==
Each member file of a ZIP file may have one or more ''extensible data fields'' (or ''extra fields''), containing arbitrary data. Each field is tagged with a 16-bit identifier. Extra fields are normally used for platform-specific or filesystem-specific metadata, or to work around limitations of the original ZIP format. They are not normally used for application-specific data.

Most of the extra fields in use are documented in the ZIP "APPNOTE" specification, or by the Info-ZIP software (e.g. the proginfo/extrafld.txt file in the Zip program's source distribution).

=== Known extensible data fields ===
{| class="wikitable"
!ID !! Owner !! Description !! Reference (identification) !! Reference (details)
|-
|0x0001 || PKWARE || Zip64 extended information || APPNOTE || APPNOTE, Info-ZIP
|-
|0x0007 || PKWARE || AV Info || APPNOTE ||
|-
|0x0008 || PKWARE || Reserved for extended language encoding data (PFS) || APPNOTE ||
|-
|0x0009 || PKWARE || OS/2 || APPNOTE || APPNOTE, Info-ZIP
|-
|0x000a || PKWARE || NTFS || APPNOTE || APPNOTE, Info-ZIP
|-
|0x000c || PKWARE || OpenVMS || APPNOTE || APPNOTE, Info-ZIP
|-
|0x000d || PKWARE || UNIX || APPNOTE || APPNOTE, Info-ZIP
|-
|0x000e || PKWARE || Reserved for file stream and fork descriptors || APPNOTE ||
|-
|0x000f || PKWARE || Patch Descriptor || APPNOTE || APPNOTE, Info-ZIP
|-
|0x0014 || PKWARE || PKCS#7 Store for X.509 Certificates || APPNOTE || APPNOTE, Info-ZIP
|-
|0x0015 || PKWARE || X.509 Certificate ID and Signature for individual file || APPNOTE || APPNOTE, Info-ZIP
|-
|0x0016 || PKWARE || X.509 Certificate ID for Central Directory || APPNOTE || APPNOTE, Info-ZIP
|-
|0x0017 || PKWARE || Strong Encryption Header || APPNOTE || APPNOTE
|-
|0x0018 || PKWARE || Record Management Controls || APPNOTE || APPNOTE
|-
|0x0019 || PKWARE || PKCS#7 Encryption Recipient Certificate List || APPNOTE || APPNOTE
|-
|0x0020 || PKWARE || Reserved for Timestamp || APPNOTE ||
|-
|0x0021 || PKWARE || Policy Decryption Key || APPNOTE || APPNOTE
|-
|0x0022 || PKWARE || Smartcrypt Key Provider || APPNOTE || APPNOTE
|-
|0x0023 || PKWARE || Smartcrypt Policy Key Data || APPNOTE || APPNOTE
|-
|rowspan="2"|0x0065 || PKWARE || MVS / IBM S/390 (Z390) attributes - uncompressed || APPNOTE || APPNOTE
|-
|PKWARE || OS/400 / AS/400 (I400) attributes - uncompressed || APPNOTE || APPNOTE
|-
|0x0066 || PKWARE || Reserved for IBM S/390 (Z390), AS/400 (I400) attributes - compressed || APPNOTE ||
|-
|0x07c8 || || Macintosh (Info-ZIP Macintosh, old) || APPNOTE || Info-ZIP
|-
|0x2605 || || ZipIt Macintosh || APPNOTE || APPNOTE, Info-ZIP
|-
|0x2705 || || ZipIt Macintosh 1.3.5+ (w/o full filename) || APPNOTE || APPNOTE, Info-ZIP
|-
|0x2805 || || ZipIt Macintosh 1.3.5+ || APPNOTE || APPNOTE
|-
|0x334d "<code>M3</code>" || || Info-ZIP Macintosh || APPNOTE || Info-ZIP
|-
|0x4154 "<code>TA</code>" || || Tandem NSK || Info-ZIP || Info-ZIP
|-
|0x4341 "<code>AC</code>" || || Acorn/SparkFS || APPNOTE || Info-ZIP
|-
|0x4453 "<code>SE</code>" || || Windows NT security descriptor (binary ACL) || APPNOTE || Info-ZIP
|-
|0x4690 || PKWARE || POSZIP 4690 (reserved) || APPNOTE ||
|-
|0x4704 || || VM/CMS || APPNOTE || Info-ZIP
|-
|0x470f || || MVS || APPNOTE || Info-ZIP
|-
|0x4854 "<code>TH</code>" || || Theos (old) || Info-ZIP || Info-ZIP
|-
|0x4b46 "<code>FK</code>" || || FWKCS MD5 || APPNOTE || APPNOTE, Info-ZIP
|-
|0x4c41 "<code>AL</code>" || || OS/2 access control list (text ACL) || APPNOTE || Info-ZIP
|-
|0x4d49 "<code>IM</code>" || || Info-ZIP OpenVMS || APPNOTE || Info-ZIP
|-
|0x4d63 "<code>cM</code>" || || Macintosh SmartZIP || Info-ZIP || Info-ZIP
|-
|0x4f4c "<code>LO</code>" || || Xceed original location || APPNOTE ||
|-
|0x5350 "<code>PS</code>" || || (Observed in some Psion files.) || ||
|-
|0x5356 "<code>VS</code>" || || AOS/VS (binary ACL) || APPNOTE || Info-ZIP
|-
|0x5455 "<code>UT</code>" || || Extended timestamp || APPNOTE || Info-ZIP
|-
|0x554e "<code>NU</code>" || || Xceed unicode || APPNOTE ||
|-
|0x5855 "<code>UX</code>" || || Info-ZIP UNIX (original, also OS/2, NT, etc.) || APPNOTE || Info-ZIP
|-
|0x6375 "<code>uc</code>" || || Info-ZIP Unicode Comment || APPNOTE || APPNOTE, Info-ZIP
|-
|0x6542 "<code>Be</code>" || || BeOS (BeBox, PowerMac, etc.) || APPNOTE || Info-ZIP
|-
|0x6854 "<code>Th</code>" || || Theos || Info-ZIP || Info-ZIP
|-
|0x7075 "<code>up</code>" || || Info-ZIP Unicode Path || APPNOTE || APPNOTE, Info-ZIP
|-
|0x7441 "<code>At</code>" || || AtheOS || Old Info-ZIP || Old Info-ZIP (e.g. zip v2.32 [ftp://ftp.info-zip.org/pub/infozip/src/zip232.tgz])
|-
|0x756e "<code>nu</code>" || || ASi UNIX || APPNOTE || Info-ZIP
|-
|0x7855 "<code>Ux</code>" || || Info-ZIP Unix (previous new) || APPNOTE || Info-ZIP
|-
|0x7875 "<code>ux</code>" || || Info-ZIP Unix (new) || Info-ZIP || Info-ZIP
|-
|0xa220 || || Microsoft Open Packaging Growth Hint || APPNOTE || APPNOTE
|-
|0xfb4a || || SMS/QDOS || Info-ZIP || Info-ZIP
|-
|0xfd4a || || SMS/QDOS || APPNOTE ||
|}

== Specifications ==
* APPNOTEs - The format documentation from PKWARE is traditionally in a file named APPNOTE.TXT.
** [http://www.pkware.com/documents/casestudies/APPNOTE.TXT APPNOTE from PKWARE] (latest version of formal spec)
** [https://support.pkware.com/display/PKZIP/Application+Note+Archives APPNOTE Archives from PKWARE] (selected versions all the way back to 1.0)
** [ftp://ftp.info-zip.org/pub/infozip/doc/ Documentation from Info-ZIP] (Includes Info-ZIP variants on APPNOTE.TXT dated from 1996 to 2004, specifications used as the basis for various open-source tools)
** [https://www.loc.gov/preservation/digital/formats/digformatspecs/ LoC archive]
** [http://www.textfiles.com/programming/FORMATS/appnote.hac An early version of APPNOTE] (apparently from PKZIP v1.10)
** {{CdTextfiles|simtel/simtel20/MSDOS/ZIP/APPNOTE.ZIP|APPNOTE.ZIP}} - Possibly the first v2.x APPNOTE
** [https://web.archive.org/web/20040819182806/http://www.pkware.com/company/standards/appnote/ APPNOTE v6.1.0], from archive.org
** Bundled with PKZIP software through v1.93 - refer to the [[#Software]] section below.
* [http://www.iana.org/assignments/media-types/application/zip IANA registration for application/zip in July 1993] (corresponds to version 2 of APPNOTE.TXT)
* [http://kikaku.itscj.ipsj.or.jp/sc34/open/1855.pdf November 2012 working draft of ISO/IEC WD 21320-1, Document Container File -- Part 1: Core] Intended as restricted subset of APPNOTE 6.3.3 designed to promote interoperability.
* [http://kikaku.itscj.ipsj.or.jp/sc34/open/1886.pdf February 2013 committee draft of ISO/IEC CD 21320-1, Document Container File -- Part 1: Core] Essentially the same as November 2012 working draft except that it mandates use of the UTF-8 indicator.
* [http://apple2.org.za/gswv/a2zine/GS.WorldView/Resources/The.MacShrinkIt.Project/ARCHIVES.TXT Archive format info, including ZIP] (from 1989, when ZIP was newly released)
* [http://www.textfiles.com/programming/FORMATS/arc_fmts.txt ZIP file header format (among other archive types)]
* [http://rescene.wikidot.com/torrentzip TorrentZip]
* Note that in general there is [https://twitter.com/tef/status/436555938879655937 no official file name encoding for ZIP files], and non ASCII filenames [http://stackoverflow.com/questions/106367/add-non-ascii-file-names-to-zip-in-java are not generally well supported]. The original implementation specified [[CP437|IBM Code Page 437]] for filenames, but as many characters cannot be expressed in that encoding, the filename bytes have often been interpreted using the current system codepage (implementation dependent behaviour). There is a flag to specify [[UTF-8]] as the encoding, but it is not supported in all major clients (e.g. Windows Explorer).
* [http://www.opensource.apple.com/source/zip/zip-6/unzip/unzip/proginfo/extra.fld Info-ZIP's "extra fields" documentation]

== Metaformat files ==

* {{Synalysis|zip}}

== Software ==
* [http://www.info-zip.org Info-ZIP]: [http://www.info-zip.org/Zip.html Zip], [http://www.info-zip.org/UnZip.html UnZip]
* [[7-Zip]]
* [[zlib]] - The zlib library does not support ZIP format, but it is distributed with "minizip" code that supports most ZIP files.
* [http://www.nih.at/libzip/ libzip] - Uses zlib.
* [http://www.libarchive.org libarchive] - Uses zlib.
* [http://zziplib.sourceforge.net zziplib]
** [http://search.cpan.org/~vspader/Archive-ZZip-0.13/ZZip/ZZip.pm Archive::ZZip]: Perl bindings for zziplib
* [https://github.com/richgel999/miniz miniz]
* PKZIP
** For DOS: {{CdTextfiles|swinnund/disk3/FILEUTIL/PKZ080.ZIP|0.80-beta}} · {{CdTextfiles|rbbsv3n1/pool/pkz090.exe|0.90}} · {{CdTextfiles|rbbsv3n1/pool/pkz092.exe|0.92}} · {{CdTextfiles|rbbsv3n1/pool/pkz101.exe|1.01}} · {{CdTextfiles|rbbsv3n1/pool/pkz102.exe|1.02}} · '''{{CdTextfiles|rbbsv3n1/pool/pkz110.exe|1.10}}''' · {{CdTextfiles|somuch/smsharew2/UTIL2/PKZ193A.EXE|1.93-alpha}} · {{CdTextfiles|20mnn/ARCHIVE/PKZ204C.EXE|2.04c}} · {{CdTextfiles|megmonster/ARCHIVE/PKZ204E.EXE|2.04e}} · '''{{CdTextfiles|simtel/simtel20/MSDOS/ZIP/PKZ204G.EXE|2.04g}}''' · {{CdTextfiles|simtel/simtel0101/simtel/arcers/pk250dos.exe|2.50}}
* [[Konvertor]]
* {{Deark}} (for analysis, or converting old compression methods)

== Sample files ==
* https://github.com/corkami/pocs/tree/master/zip
* Examples that use the uncommon "Reduce" compression scheme: {{CdTextfiles|ccbwindows93/CORELDRA/VISA_CRD.ZIP|VISA_CRD.ZIP}}, {{CdTextfiles|librisbritannia/GRAPHICS/CLIPMAC/1608A.ZIP|1608A.ZIP}} → D1-MAC.ZIP

== Links ==
* [[Wikipedia:Zip (file format)|Wikipedia: Zip (file format)]]
* [[Wikipedia:PKZIP|Wikipedia: PKZIP]]
* [http://research.swtch.com/zip Zip files all the way down] (creating an infinitely-regressed ZIP file)
* [http://imgur.com/a/PbN8H#1 ZIP101 an archive walkthrough]
* [http://literarymachin.es/deepzoom-osd-server/ Serve deepzoom images from a zip archive with openseadragon]
* [https://stackoverflow.com/questions/20762094/how-are-zlib-gzip-and-zip-related-what-do-they-have-in-common-and-how-are-they/20765054#20765054 How are zlib, gzip and Zip related? What do they have in common and how are they different?] - Response to StackOverflow question by zlib/gzip co-creator Mark Adler
* [https://www.bitsgalore.org/2020/03/11/does-microsoft-onedrive-export-large-ZIP-files-that-are-corrupt Does Microsoft OneDrive export large ZIP files that are corrupt?] - Discusses an issue where large ZIP files generated by Microsoft OneDrive result in read errors when they are opened with tools like Info-Zip and 7-Zip

== References ==
<references/>

[[Category:Compression]]
[[Category:Metaformats]]
[[Category:ZIP based file formats]]
[[Category:PKWARE]]

ZIP

2020-03-16T15:23:50Z

Johanvanderknijff: /* Links */ Added blog on problematic OneDrive ZIPs

:''Not to be confused with [[Zip disk]], an unrelated disk cartridge unit.''
{{FormatInfo
|formattype=electronic
|subcat=Archiving
|extensions={{ext|zip}}
|mimetypes={{mimetype|application/zip}}
|uniform type={{UTI|com.pkware.zip-archive}}
|locfdd={{LoCFDD|fdd000354}}, {{LoCFDD|fdd000355}}, {{LoCFDD|fdd000362}}, {{LoCFDD|fdd000361}}
|pronom={{PRONOM|x-fmt/263}}
|wikidata={{wikidata|Q136218}}
|kaitai struct=zip
|released=1989
}}
'''ZIP''' is one of the most popular file compression formats. It was created in 1989 as the native format of the PKZIP program, which was introduced by Phil Katz in the wake of a lawsuit (which he lost) against him by the makers of the then-popular [[ARC (compression format)|ARC]] program (and file format) for copyright and trademark infringement in an earlier program PKARC which had been file-compatible with ARC. This resulted in Katz creating a new file format, which rapidly overtook ARC in popularity (to a large extent because of BBS sysops, then the primary users of such compression, resenting the lawsuit). Many programs have been released for a variety of operating systems to compress and decompress ZIP files, and native support for the format is built into several popular operating systems.

ZIP implementations vary in their support for features in the specification from PKWARE<ref>http://www.pkware.com/documents/casestudies/APPNOTE.TXT</ref>, particularly features added since version 2 (1993), some of which are protected by patents and require licensing. Many implementations limit the use of compression to the [[DEFLATE]] algorithm, introduced with version 2. Extensions incorporated into the specification that have been widely adopted are: long filenames; large files (using a technique known as ZIP64); and filenames in [[UTF-8]]. In 2011 work began on an interoperable subset of the latest APPNOTE.TXT with the intention of publication as ISO/IEC 21320-1, Document Container File -- Part 1: Core. As of November 2012, a discussion draft is available<ref>http://kikaku.itscj.ipsj.or.jp/sc34/open/1855.pdf</ref>. Designed to promote interoperable implementations, the draft ISO/IEC 21320-1 prohibits compression other than using [[DEFLATE]], segmentation or multiple volumes, and features that are subject to patents.

While .zip is the usual file extension, ZIP-formatted files can be found with many other extensions since a number of other file formats use ZIP compression but store their files in application-specific extensions. See [[:Category:ZIP based file formats]] for a list of such formats.

== See also ==
* [[PKLITE]]
* [[Self-extracting ZIP]]
* [[Zipx]]

== Disambiguation ==
The term "ZIP compression" is sometimes misleadingly used to mean [[DEFLATE]] (which is by far the most common compression scheme used in ZIP files). In such cases, the compressed data format could turn out to be raw [[DEFLATE]], or [[zlib]], or [[gzip]].

== Identification ==
The byte sequence <code>'P' 'K' 0x05 0x06</code> (the "end of central directory signature") appears somewhere in the file, usually beginning exactly 22 bytes from the end of the file. However, it will appear earlier if the file contains a "ZIP file comment" (common in the BBS era, but rare today), or for various other reasons. There seems to be no theoretical limit to how far back you may have to search for the signature, but some software limits it to around 64KB, which is the maximum length of a comment.

Most ZIP files (but not [[self-extracting ZIP]] files) happen to begin with <code>'P' 'K' 0x03 0x04</code>. This is not a global file signature, but is the signature that appears once for every compressed file inside the ZIP file. Some ZIP-based formats are designed such that they necessarily begin in this way. But in general, it is even legal for a ZIP file to contain zero files, and such a ZIP file would not contain this signature at all.

That Phil Katz guy has thus managed to get his initials at the start of a large number of files on many millions of computers and devices, given how many file formats are based on ZIP (even if they use different extensions). He died in 2000, but this memorial to him will live on indefinitely.

== Compression ==
Each file in a ZIP file is compressed using one of a number of compression algorithms. Only compression types 0 (uncompressed) and 8 (DEFLATE) are likely to be seen in modern portable ZIP files. In old ZIP files, types 1 (Shrink) and 6 (Implode) are common.

{| class="wikitable"
! Code
! Compression scheme
! Notes and references
|-
|0 || Uncompressed
|-
|1 || Shrink || [[LZW]]. Used by PKZIP 0.x and 1.x.
|-
|2–5 || Reduce || [[LZ77]] + prediction. Used by PKZIP v0.x. See also [[SCRNCH]].
|-
|6 || Implode || [[LZ77]] + [[Huffman coding|Huffman]]. Used by PKZIP v1.x.
|-
|7 || Tokenized || Never used?
|-
|8 || [[DEFLATE]] || [[LZ77]] + [[Huffman coding|Huffman]]. Used by PKZIP v2.0+.
|-
|9 || Deflate64, a.k.a. Enhanced Deflate || Format version 2.1+.
|-
|10 || [[PKWARE DCL Implode]] (old IBM TERSE) || Format version 2.5+.
|-
|12 || [[Bzip2]] || Format version 4.6+.
|-
|14 || [[LZMA]] (EFS) || Defined in ZIP specification v6.3+.
|-
|16 || IBM z/OS CMPSC
|-
|18 || IBM TERSE (new)
|-
|19 || IBM LZ77 z Architecture (PFS)
|-
|94 || [[MP3]] || Supported by WinZip 21+.
|-
|95 || [[XZ]] || Supported by WinZip 18+.
|-
|96 || [[JPEG]] variant
|-
|97 || [[WavPack]] || Defined in ZIP specification v6.3.2+.
|-
|98 || [[PPMd]] version I, Rev 1 || Defined in ZIP specification v6.3+.
|-
|99 || AES / AE-x encryption marker
|}

== Extensible data fields ==
Each member file of a ZIP file may have one or more ''extensible data fields'' (or ''extra fields''), containing arbitrary data. Each field is tagged with a 16-bit identifier. Extra fields are normally used for platform-specific or filesystem-specific metadata, or to work around limitations of the original ZIP format. They are not normally used for application-specific data.

Most of the extra fields in use are documented in the ZIP "APPNOTE" specification, or by the Info-ZIP software (e.g. the proginfo/extrafld.txt file in the Zip program's source distribution).

=== Known extensible data fields ===
{| class="wikitable"
!ID !! Owner !! Description !! Reference (identification) !! Reference (details)
|-
|0x0001 || PKWARE || Zip64 extended information || APPNOTE || APPNOTE, Info-ZIP
|-
|0x0007 || PKWARE || AV Info || APPNOTE ||
|-
|0x0008 || PKWARE || Reserved for extended language encoding data (PFS) || APPNOTE ||
|-
|0x0009 || PKWARE || OS/2 || APPNOTE || APPNOTE, Info-ZIP
|-
|0x000a || PKWARE || NTFS || APPNOTE || APPNOTE, Info-ZIP
|-
|0x000c || PKWARE || OpenVMS || APPNOTE || APPNOTE, Info-ZIP
|-
|0x000d || PKWARE || UNIX || APPNOTE || APPNOTE, Info-ZIP
|-
|0x000e || PKWARE || Reserved for file stream and fork descriptors || APPNOTE ||
|-
|0x000f || PKWARE || Patch Descriptor || APPNOTE || APPNOTE, Info-ZIP
|-
|0x0014 || PKWARE || PKCS#7 Store for X.509 Certificates || APPNOTE || APPNOTE, Info-ZIP
|-
|0x0015 || PKWARE || X.509 Certificate ID and Signature for individual file || APPNOTE || APPNOTE, Info-ZIP
|-
|0x0016 || PKWARE || X.509 Certificate ID for Central Directory || APPNOTE || APPNOTE, Info-ZIP
|-
|0x0017 || PKWARE || Strong Encryption Header || APPNOTE || APPNOTE
|-
|0x0018 || PKWARE || Record Management Controls || APPNOTE || APPNOTE
|-
|0x0019 || PKWARE || PKCS#7 Encryption Recipient Certificate List || APPNOTE || APPNOTE
|-
|0x0020 || PKWARE || Reserved for Timestamp || APPNOTE ||
|-
|0x0021 || PKWARE || Policy Decryption Key || APPNOTE || APPNOTE
|-
|0x0022 || PKWARE || Smartcrypt Key Provider || APPNOTE || APPNOTE
|-
|0x0023 || PKWARE || Smartcrypt Policy Key Data || APPNOTE || APPNOTE
|-
|rowspan="2"|0x0065 || PKWARE || MVS / IBM S/390 (Z390) attributes - uncompressed || APPNOTE || APPNOTE
|-
|PKWARE || OS/400 / AS/400 (I400) attributes - uncompressed || APPNOTE || APPNOTE
|-
|0x0066 || PKWARE || Reserved for IBM S/390 (Z390), AS/400 (I400) attributes - compressed || APPNOTE ||
|-
|0x07c8 || || Macintosh (Info-ZIP Macintosh, old) || APPNOTE || Info-ZIP
|-
|0x2605 || || ZipIt Macintosh || APPNOTE || APPNOTE, Info-ZIP
|-
|0x2705 || || ZipIt Macintosh 1.3.5+ (w/o full filename) || APPNOTE || APPNOTE, Info-ZIP
|-
|0x2805 || || ZipIt Macintosh 1.3.5+ || APPNOTE || APPNOTE
|-
|0x334d "<code>M3</code>" || || Info-ZIP Macintosh || APPNOTE || Info-ZIP
|-
|0x4154 "<code>TA</code>" || || Tandem NSK || Info-ZIP || Info-ZIP
|-
|0x4341 "<code>AC</code>" || || Acorn/SparkFS || APPNOTE || Info-ZIP
|-
|0x4453 "<code>SE</code>" || || Windows NT security descriptor (binary ACL) || APPNOTE || Info-ZIP
|-
|0x4690 || PKWARE || POSZIP 4690 (reserved) || APPNOTE ||
|-
|0x4704 || || VM/CMS || APPNOTE || Info-ZIP
|-
|0x470f || || MVS || APPNOTE || Info-ZIP
|-
|0x4854 "<code>TH</code>" || || Theos (old) || Info-ZIP || Info-ZIP
|-
|0x4b46 "<code>FK</code>" || || FWKCS MD5 || APPNOTE || APPNOTE, Info-ZIP
|-
|0x4c41 "<code>AL</code>" || || OS/2 access control list (text ACL) || APPNOTE || Info-ZIP
|-
|0x4d49 "<code>IM</code>" || || Info-ZIP OpenVMS || APPNOTE || Info-ZIP
|-
|0x4d63 "<code>cM</code>" || || Macintosh SmartZIP || Info-ZIP || Info-ZIP
|-
|0x4f4c "<code>LO</code>" || || Xceed original location || APPNOTE ||
|-
|0x5350 "<code>PS</code>" || || (Observed in some Psion files.) || ||
|-
|0x5356 "<code>VS</code>" || || AOS/VS (binary ACL) || APPNOTE || Info-ZIP
|-
|0x5455 "<code>UT</code>" || || Extended timestamp || APPNOTE || Info-ZIP
|-
|0x554e "<code>NU</code>" || || Xceed unicode || APPNOTE ||
|-
|0x5855 "<code>UX</code>" || || Info-ZIP UNIX (original, also OS/2, NT, etc.) || APPNOTE || Info-ZIP
|-
|0x6375 "<code>uc</code>" || || Info-ZIP Unicode Comment || APPNOTE || APPNOTE, Info-ZIP
|-
|0x6542 "<code>Be</code>" || || BeOS (BeBox, PowerMac, etc.) || APPNOTE || Info-ZIP
|-
|0x6854 "<code>Th</code>" || || Theos || Info-ZIP || Info-ZIP
|-
|0x7075 "<code>up</code>" || || Info-ZIP Unicode Path || APPNOTE || APPNOTE, Info-ZIP
|-
|0x7441 "<code>At</code>" || || AtheOS || Old Info-ZIP || Old Info-ZIP (e.g. zip v2.32 [ftp://ftp.info-zip.org/pub/infozip/src/zip232.tgz])
|-
|0x756e "<code>nu</code>" || || ASi UNIX || APPNOTE || Info-ZIP
|-
|0x7855 "<code>Ux</code>" || || Info-ZIP Unix (previous new) || APPNOTE || Info-ZIP
|-
|0x7875 "<code>ux</code>" || || Info-ZIP Unix (new) || Info-ZIP || Info-ZIP
|-
|0xa220 || || Microsoft Open Packaging Growth Hint || APPNOTE || APPNOTE
|-
|0xfb4a || || SMS/QDOS || Info-ZIP || Info-ZIP
|-
|0xfd4a || || SMS/QDOS || APPNOTE ||
|}

== Specifications ==
* APPNOTEs - The format documentation from PKWARE is traditionally in a file named APPNOTE.TXT.
** [http://www.pkware.com/documents/casestudies/APPNOTE.TXT APPNOTE from PKWARE] (latest version of formal spec)
** [https://support.pkware.com/display/PKZIP/Application+Note+Archives APPNOTE Archives from PKWARE] (selected versions all the way back to 1.0)
** [ftp://ftp.info-zip.org/pub/infozip/doc/ Documentation from Info-ZIP] (Includes Info-ZIP variants on APPNOTE.TXT dated from 1996 to 2004, specifications used as the basis for various open-source tools)
** [https://www.loc.gov/preservation/digital/formats/digformatspecs/ LoC archive]
** [http://www.textfiles.com/programming/FORMATS/appnote.hac An early version of APPNOTE] (apparently from PKZIP v1.10)
** {{CdTextfiles|simtel/simtel20/MSDOS/ZIP/APPNOTE.ZIP|APPNOTE.ZIP}} - Possibly the first v2.x APPNOTE
** [https://web.archive.org/web/20040819182806/http://www.pkware.com/company/standards/appnote/ APPNOTE v6.1.0], from archive.org
** Bundled with PKZIP software through v1.93 - refer to the [[#Software]] section below.
* [http://www.iana.org/assignments/media-types/application/zip IANA registration for application/zip in July 1993] (corresponds to version 2 of APPNOTE.TXT)
* [http://kikaku.itscj.ipsj.or.jp/sc34/open/1855.pdf November 2012 working draft of ISO/IEC WD 21320-1, Document Container File -- Part 1: Core] Intended as restricted subset of APPNOTE 6.3.3 designed to promote interoperability.
* [http://kikaku.itscj.ipsj.or.jp/sc34/open/1886.pdf February 2013 committee draft of ISO/IEC CD 21320-1, Document Container File -- Part 1: Core] Essentially the same as November 2012 working draft except that it mandates use of the UTF-8 indicator.
* [http://apple2.org.za/gswv/a2zine/GS.WorldView/Resources/The.MacShrinkIt.Project/ARCHIVES.TXT Archive format info, including ZIP] (from 1989, when ZIP was newly released)
* [http://www.textfiles.com/programming/FORMATS/arc_fmts.txt ZIP file header format (among other archive types)]
* [http://rescene.wikidot.com/torrentzip TorrentZip]
* Note that in general there is [https://twitter.com/tef/status/436555938879655937 no official file name encoding for ZIP files], and non ASCII filenames [http://stackoverflow.com/questions/106367/add-non-ascii-file-names-to-zip-in-java are not generally well supported]. The original implementation specified [[CP437|IBM Code Page 437]] for filenames, but as many characters cannot be expressed in that encoding, the filename bytes have often been interpreted using the current system codepage (implementation dependent behaviour). There is a flag to specify [[UTF-8]] as the encoding, but it is not supported in all major clients (e.g. Windows Explorer).
* [http://www.opensource.apple.com/source/zip/zip-6/unzip/unzip/proginfo/extra.fld Info-ZIP's "extra fields" documentation]

== Metaformat files ==

* {{Synalysis|zip}}

== Software ==
* [http://www.info-zip.org Info-ZIP]: [http://www.info-zip.org/Zip.html Zip], [http://www.info-zip.org/UnZip.html UnZip]
* [[7-Zip]]
* [[zlib]] - The zlib library does not support ZIP format, but it is distributed with "minizip" code that supports most ZIP files.
* [http://www.nih.at/libzip/ libzip] - Uses zlib.
* [http://www.libarchive.org libarchive] - Uses zlib.
* [http://zziplib.sourceforge.net zziplib]
** [http://search.cpan.org/~vspader/Archive-ZZip-0.13/ZZip/ZZip.pm Archive::ZZip]: Perl bindings for zziplib
* [https://github.com/richgel999/miniz miniz]
* PKZIP
** For DOS: {{CdTextfiles|swinnund/disk3/FILEUTIL/PKZ080.ZIP|0.80-beta}} · {{CdTextfiles|rbbsv3n1/pool/pkz090.exe|0.90}} · {{CdTextfiles|rbbsv3n1/pool/pkz092.exe|0.92}} · {{CdTextfiles|rbbsv3n1/pool/pkz101.exe|1.01}} · {{CdTextfiles|rbbsv3n1/pool/pkz102.exe|1.02}} · '''{{CdTextfiles|rbbsv3n1/pool/pkz110.exe|1.10}}''' · {{CdTextfiles|somuch/smsharew2/UTIL2/PKZ193A.EXE|1.93-alpha}} · {{CdTextfiles|20mnn/ARCHIVE/PKZ204C.EXE|2.04c}} · {{CdTextfiles|megmonster/ARCHIVE/PKZ204E.EXE|2.04e}} · '''{{CdTextfiles|simtel/simtel20/MSDOS/ZIP/PKZ204G.EXE|2.04g}}''' · {{CdTextfiles|simtel/simtel0101/simtel/arcers/pk250dos.exe|2.50}}
* [[Konvertor]]
* {{Deark}} (for analysis, or converting old compression methods)

== Sample files ==
* https://github.com/corkami/pocs/tree/master/zip
* Examples that use the uncommon "Reduce" compression scheme: {{CdTextfiles|ccbwindows93/CORELDRA/VISA_CRD.ZIP|VISA_CRD.ZIP}}, {{CdTextfiles|librisbritannia/GRAPHICS/CLIPMAC/1608A.ZIP|1608A.ZIP}} → D1-MAC.ZIP

== Links ==
* [[Wikipedia:Zip (file format)|Wikipedia: Zip (file format)]]
* [[Wikipedia:PKZIP|Wikipedia: PKZIP]]
* [http://research.swtch.com/zip Zip files all the way down] (creating an infinitely-regressed ZIP file)
* [http://imgur.com/a/PbN8H#1 ZIP101 an archive walkthrough]
* [http://literarymachin.es/deepzoom-osd-server/ Serve deepzoom images from a zip archive with openseadragon]
* [https://stackoverflow.com/questions/20762094/how-are-zlib-gzip-and-zip-related-what-do-they-have-in-common-and-how-are-they/20765054#20765054 How are zlib, gzip and Zip related? What do they have in common and how are they different?] - Response to StackOverflow question by zlib/gzip co-creator Mark Adler
* [https://www.bitsgalore.org/2020/03/11/does-microsoft-onedrive-export-large-ZIP-files-that-are-corrupt
Does Microsoft OneDrive export large ZIP files that are corrupt?] - Discusses an issue where large ZIP files generated by Microsoft OneDrive result in read errors when they are opened with tools like Info-Zip and 7-Zip

== References ==
<references/>

[[Category:Compression]]
[[Category:Metaformats]]
[[Category:ZIP based file formats]]
[[Category:PKWARE]]

Access

2019-12-15T13:59:41Z

Johanvanderknijff: /* See Also */

{{FormatInfo
| formattype=electronic
| subcat=Databases
| extensions={{ext|mdb}}
| pronom={{PRONOM|x-fmt/66}}, {{PRONOM|x-fmt/238}}, {{PRONOM|x-fmt/239}}, {{PRONOM|x-fmt/240}}, {{PRONOM|x-fmt/241}}
| released=1992
}}

'''Access''' released by '''Microsoft''' also known as '''Jet DB''' is a standalone database that forms part of the [[Microsoft Office]] Suite of productivity tools. It was first released in 1992.

Access databases are composed of multiple page types. The length of these pages depends on the version of the Jet Database employed by the specific version of Microsoft Access. The first page of Access 95/97 and Access 2000/2003 databases is always a '''Database Definition Page'''.

== Microsoft Access 95/97 - Jet 3 Database ==

Microsoft Access 95/97 utilizes the Jet3 database engine. The page size of the Jet3 database engine is '''2048''' bytes.

== Microsoft Access 2000/2002 - Jet 4 Database ==

Microsoft Access 2000/2003 utilizes the Jet 4 database engine. The page size of the Jet4 database engine is '''4096''' bytes.

== Internal structure of the format ==

The Jet DB version can be found in the file header by reading the 4 byte little-endian integer at offset 0x13. Jet3 databases have a value of 0. Jet 4 databases have a value of 1.

The version and build number of Microsoft Access used to create the file is stored in the format. These two values are stored within a [http://jabakobob.net/mdb/data-page.html LVAL Data Page] and deeper into that structure a [http://jabakobob.net/mdb/lvprop.html LvProp column] - part of the MSysObjects table. It is possible to extract this information from here alone, the complete MSysObject table definition is always the second page of the database (zero-based index).

The block of data at offset 0x18 running for 126 bytes (Jet 3) and 128+ bytes (Jet 4) represents [[RC4]] encrypted data. It is thought this uses the key: '''0x6b39dac7'''.

== Database Password ==

'''Note:''' ''The information under this section should only be used by owners and custodians of databases where the password has been misplaced or lost and not for any illegal or illegitimate premises.''
 
Among other techniques Jet Databases employ a simple database password. The password field is '''0x42''' bytes into the file. Jet 3 database password fields are '''20 bytes''' in length, Jet 4 are '''40 bytes''' in length.
 
'''Jet 3 Password'''

[[Exclusive Or|XOR-ing]] the byte string running from 0x42 to 0x56 in a non-password protected database with that of a password protected database will reveal the password in plain text.

Studying the Maxsoft tool under [http://fileformats.archiveteam.org/wiki/Access#Password_Tools Password Tools] will help users to understand how Access databases are protected.
 
'''Jet 4 Password'''

The Jet 4 password can be revealed similarly by [[Exclusive Or|XOR-ing]] the byte string running from 0x42 to 0x68. If after the XOR operation if you haven't an ASCII character, that is, you have a value greater than 0xFF you need to XOR that value again with a further key value (byte) at offset 0x54.

Studying the Maxsoft tool under [http://fileformats.archiveteam.org/wiki/Access#Password_Tools Password Tools] will help users to understand how Access databases are protected.

== Jet DB and Access Build Numbers ==

The following table shows that the version of the Jet Database '''format''' remained fairly consistent between versions of Access:

Client Application Jet Engine Used Recommended Jet DB Format
------------------------- --------------- -------------------------
Access 2.0 Jet 2.0 Jet 2.0
Access 95 Jet 3.0 Jet 3.0
Access 97 Jet 3.5 Jet 3.0
Access 2000 Jet 4.0 Jet 4.0
Access 2002 Jet 4.0 Jet 4.0

The controller used to read and write the format by Access versions did change. The version of Access and its build number can help us to understand the version of the DLL used to interact with the format. The version and build number is embedded in the MDB objects (as described as part of its internal structure above) so can be easily extracted. Build numbers and DLL versions are described below ([http://support.microsoft.com/kb/248710 KB Article 248710] and [http://support.microsoft.com/kb/255275 KB Article 255275] and [http://support.microsoft.com/kb/291331 KB Article 291331]):

Version File Version Patches
-------------- ------------ -------
Access 95 7.0 Unknown
Access 97 8.0.3512 n/a
Access 97 SR-1 8.0.4122 n/a
Access 97 SR-2 8.0.5903 SR-1
Access 2000 9.0.2720
Access 2000 9.0.3821 SR-1
Access 2000 9.0.4402 SR-1
Access 2000 9.0.6926 SP-3
Access 2002 10.0.2627.1
Access 2002 10.0.3409.0 SP-1
Access 2002 10.0.4302.0 SP-2
Access 2002 10.0.6501.0 SP-3

Access Version linked with MSJet35.dll ([http://support.microsoft.com/kb/248710 KB Article 248710]):

Version DLL Version
------- -----------
Access 97 3.50.3428.0
Access 97 SR-1 3.50.3907.5
Access 97 SR-2 and Jet35Upd.exe (3rd rel) 3.51.2026.0

The following table from [http://web.archive.org/web/20111115230803/http://support.microsoft.com/kb/178880 KB Article 178880] describes backward compatibility between Jet DB engines and MDB version:

----------------------------------------------
Jet Version 1.0 1.1 2.0 2.5 3.0 3.5
----------------------------------------------
MDB Version
-----------
1.0 Y Y Y Y Y Y
1.1 N Y Y Y Y Y
2.0 N N Y Y Y Y
3.0 N N N N Y Y

'''Note:''' See the [http://web.archive.org/web/20111115230803/http://support.microsoft.com/kb/178880 KB Article] for information on all DLL updates.

== Specifications ==

A formal specification from Microsoft has not been made available. The following links are attempts by third parties to reverse engineer and document the format:

* [https://github.com/brianb/mdbtools/blob/master/HACKING Reverse engineered documentation used by mdbtools on GitHub]

* [http://jabakobob.net/mdb/ Further documentation built on top of mdbtools' work]

== Sample Files ==

* [http://office.microsoft.com/en-ca/templates/results.aspx?qu=access&queryid=64492973-33dd-48c8-a228-6ffdf681fad6&avg=zac Microsoft.com: Sample Database Templates]

* [http://www.utterangel.com/UtterAngel/utterangel.aspx?cat=acc utterangel.com: Sample Access Databases and Applications]

* [https://isda.ncsa.uiuc.edu/NARA/CSR/php/search/formats.php?&cInput=mdb&srg=1&cName=default_extension&fid=866&fd=1&asc=1&num1=1 Conversion Software Registry: Sample Access Databases]

== General Tools ==

* [https://github.com/brianb/mdbtools Brian Bruns GutHub.com mdbtools]
* [https://github.com/exponential-decay/MDBValidator MDBValidator: Tool to read and output the statistics of a Microsoft Access Database]

== Password Tools ==

* [http://planetsourcecode.com/vb/scripts/ShowCode.asp?txtCodeId=73390&lngWId=1 Planet Source Code - Access Database Password Viewer]
* [http://planetsourcecode.com/vb/scripts/ShowCode.asp?txtCodeId=72736&lngWId=1 Planet Source Code - Maxsoft Access Password Viewer]

== References ==

* [[Wikipedia:Microsoft_Access]]
* [https://github.com/brianb/mdbtools/blob/master/HACKING Reverse engineered documentation used by mdbtools on GitHub]
* [http://jabakobob.net/mdb/first-page.html Database definition and encryption key documentation]
* [http://www.everythingaccess.com/tutorials.asp?ID=Jet-MDB-security---under-the-hood EverythingAccess.com Jet MDB Security - Under The Hood]

== See Also ==

* [[Wikipedia:Microsoft_Jet_Database_Engine]]
* [http://allenbrowne.com/ser-53.html Developer resource discussing DLL versions and sample code to retrieve Access version]
* [http://www.techadre.com/content/microsoft-office-version-numbers-xp-2003-2007-2010 Site collating version and build numbers from XP through to 2010]
* [http://en.wikibooks.org/wiki/JET_Database/Manipulation_tools Wikibooks Jet Database/Manipulation tools]
* [http://webcheatsheet.com/SQL/access_specification.php WebCheatSheet.com Microsoft Access Specifications and Limitations]
* [http://www.pcwelt.de/ratgeber/Geknackt-Microsoft-Money-99-504470.html PC Welt Germany discussing vulnerabilities in Microsoft Money 99 which is built on Jet DB 3.0]
* [http://tutorialsto.com/view/printview-3771.html MDB Password View Tutorial]
* [https://groups.google.com/forum/#!topic/pronom/_fz-eP0ge9o PRONOM Google Group Discussion about the distinction between Access versions in the PRONOM registry]
* [http://www.textfiles.com/programming/FORMATS/q88173.txt ODBC Setup for Access and SQL Server]
* [https://medium.com/young-coder/microsoft-access-the-zombie-database-software-that-wont-die-5b09e389c166 Microsoft Access: The Database Software That Won’t Die]

[[Category:Microsoft]]

JPEG

2019-11-08T20:37:19Z

Johanvanderknijff: /* External links */

{{FormatInfo
|formattype=electronic
|subcat=Graphics
|thiscat=JPEG
|extensions={{ext|jpg}}, {{ext|jpeg}}, {{ext|jpe}}, {{ext|jif}}
|mimetypes={{mimetype|image/jpeg}}
|locfdd={{LoCFDD|fdd000017}}, others
|pronom={{PRONOM|fmt/41}}, others
|wikidata={{wikidata|Q27996264}}
|released=1992
}}
'''JPEG''' is a popular raster image format well-suited to photographic images. It usually uses lossy [[DCT compression]]. It is named after the Joint Photographic Experts Group, the organization which developed the format. It is sometimes called '''JPEG1''', '''JPEG-1''', or '''JPEG 1992''' to help disambiguate it. (Also see [[JPEG 2000]] and [[JP2]].)

== Terminology ==
''(In which we discuss the tired old question of whether JPEG is a file format, or a compression standard)''

In the original specification (ITU-T Rec. T.81), the term ''JPEG'' refers only to an organization. The serialized form of the compression format it defines is referred to only as the "interchange format".

The followup ITU-T Rec. T.84 document says that ''JPEG'' can also refer to a set of ''standards'', including at least Rec. T.81, Rec. T.83, and Rec. T.84. It also informally uses ''JPEG'' to refer to the Rec. T.81 interchange format.

ITU-T Rec. T.851 refers to the interchange format as ''JPEG-1''.

The interchange format is ''almost'' a full-fledged portable file format, lacking only standard conventions and/or standard metadata elements to tell how to interpret it as an image. The missing pieces can be added in various ways. Some file formats, including [[JFIF]], do so in such a way that the interchange format is used directly as a file format. In practice, the term ''JPEG'' often refers to the family of such file formats, and this usage does not seem unreasonable, especially since there is no other suitable name. The term '''JIF''' (for ''JPEG Interchange Format'') has been tossed around, but it is an ambiguous term that doesn't necessarily refer to a file format, and it's unusable in practice due to similarity to [[GIF]].

It could be that ''JPEG'' is sometimes misused to mean [[JFIF]], but such an accusation might be relying on the incorrect assumption that '''.jpg''' files always use JFIF format.

== Portability ==
In and of itself, JPEG is not really a suitable format for image interchange, for several reasons:
* It essentially only defines a way to store one or more arrays of numbers. It does not say how to interpret those numbers as an image. The decoder will just have to guess.
* It is large and general, and it might be unrealistic to expect every decoder to support all of it.
* It defines no standard metadata elements.

To address these issues, a number of JPEG subformats have been invented. [[JFIF]] is by far the most popular of them, though a significant minority of JPEG files use [[Exif]] instead. The [[SPIFF]] file format was intended as a replacement for JFIF, but never caught on.

In practice, a portable JPEG file is pretty much "whatever the libjpeg software supports". This includes some varieties (such as RGB color) that do not conform to JFIF, and excludes some (such as lossless JPEG) that do.

== Format ==
A JPEG file consists largely of a sequence of tagged segments. Each segment begins with a two-byte "marker". (The term "marker" is often used to refer to the entire segment.) The first byte of a marker is 0xff. The second may have any value except 0x00 or 0xff, and indicates the type of data stored in the segment. Segment types are assigned names; for example, 0xd9 is "SOI", and 0xe1 is "APP1".

Segment types 0x01, and 0xd0 through 0xd9, consist entirely of the two-byte marker. All other markers are followed by a two-byte integer indicating the size of the segment, followed by the payload data contained in the segment.

The image data is the exception to this segmented format. It appears following an "SOS" (0xda) segment, but there is no prefix to indicate its size. Instead, any 0xff bytes in the image data are escaped as 0xff 0x00, so that they won't be mistaken for markers. (Note that some JPEG-like formats, such as [[JPEG-LS]] and [[JPEG 2000 codestream]], use different rules for escaping 0xff bytes.)

=== Application segments ===
There are 16 segment types reserved for application-specific data: 0xe0 ("APP0") through 0xef ("APP15").

An APP segment's data often begins with NUL-terminated text string to identify the type of data contained in it. The actual payload data then begins after the NUL byte. This convention was standardized by ISO/IEC 10918-4:1999 (see ITU-T Rec. T.86), but is not as universal as one might hope. Most APP segments do have a signature of some sort, but because there is no simple matching algorithm that always works, identifying the signature can be difficult.

== Identifiers ==
{| class="wikitable"
! Format
! PRONOM
! LoCFDD
|-
|JPEG || {{PRONOM|fmt/41}} || {{LoCFDD|fdd000017}}
|-
|Baseline JPEG || || {{LoCFDD|fdd000149}}
|-
|Progressive JPEG || || {{LoCFDD|fdd000333}}
|-
|[[Lossless JPEG (original)|Lossless JPEG]] || || {{LoCFDD|fdd000334}}
|-
|Other JPEG || || {{LoCFDD|fdd000150}}
|-
|JFIF 1.00 || {{PRONOM|fmt/42}}
|-
|JFIF 1.01 || {{PRONOM|fmt/43}}
|-
|[[JFIF]] 1.02 || {{PRONOM|fmt/44}} || {{LoCFDD|fdd000018}}
|-
|Exif 2.0 JPEG || {{PRONOM|x-fmt/398}} ||rowspan="3"| {{LoCFDD|fdd000147}}
|-
|Exif 2.1 JPEG || {{PRONOM|x-fmt/390}}
|-
|[[Exif]] 2.2 JPEG || {{PRONOM|x-fmt/391}}
|-
|[[SPIFF]] || {{PRONOM|fmt/112}} || {{LoCFDD|fdd000019}}
|}

== Identification ==
JPEG files begin with bytes <code>ff d8 ff</code>.

However, this does not distinguish them from [[JPEG-LS]]. To do that reliably, one may have to scan the file to look for one of the valid SOF segment types.

== Types of JPEG files ==
The following types are not disjoint. For example, a progressive JPEG may use arithmetic coding.

Some JPEG images do not belong to any of these types. An SOF1 segment is used if no other SOF segment applies.

=== Baseline ===
JPEGs with an SOF0 segment are known as ''Baseline'' JPEGs. They are always lossy, not progressive, use Huffman coding, and have a bit depth of 8. Every application that supports JPEG is supposed to at least support Baseline JPEG.

=== Progressive ===
Progressive JPEG rearranges the image data, so that the the first part of it represents a very low quality version of the entire image, rather than a high quality version of a small part of the image.

A progressive JPEG is identified by the presence of an SOF2, SOF6, SOF10, or SOF14 segment.

=== Non-interleaved ===
Color JPEG images may be either ''interleaved'' or ''non-interleaved''.

In an interleaved JPEG, all the color components (e.g. Y, Cb, Cr) for a pixel are stored close together in the file.

In a non-interleaved JPEG, the image is separated into its color components, and each component is stored separately in the file.

Interleaving is not a simple yes/no option, because a single image may use both interleaved and non-interleaved scans (SOS segments) – in fact, progressive JPEGs usually do just that. Some JPEG decoders do not support non-interleaved images unless they use progressive encoding.

=== Arithmetic coding ===
Even lossy JPEG makes use of a lossless compression algorithm. The lossless algorithm is usually [[Huffman coding]], but [[arithmetic coding]] may be used instead. JPEG's arithmetic coding usually results in a smaller file size, but it is not as widely supported as one might hope, probably because it used to be encumbered by [[patents]].

An arithmetic-coded JPEG is identified by the presence of an SOF9, SOF10, SOF11, SOF13, SOF14, or SOF15 segment.

=== 12-bit ===
Except for Baseline JPEG, all lossy types of JPEG may use a bit depth of either 8 or 12 bits per sample. However, few applications support anything other than 8 bits.

Starting with version 9a, IJG libjpeg also supports bit depths of 9, 10, and 11. These depths are nonstandard, and libjpeg's implementation is nearly unusable in practice, because it only supports a single bit depth, which must be selected at compile time.

=== Lossless JPEG ===
:''Main article: [[Lossless JPEG (original)]]''

JPEG supports true lossless compression, but it is used so rarely that JPEG is commonly thought of as strictly a lossy format.

A lossless JPEG is identified by the presence of an SOF3, SOF7, SOF11, or SOF15 segment.

See also the [[Lossless JPEG|Lossless JPEG disambiguation page]], for other uses of the term.

=== Hierarchical ===
Also called "differential", hierarchical JPEG is vaguely similar to progressive JPEG, but geared toward storing multiple sizes of the same image, such that the decoder can select the size it prefers. Hierarchical JPEGs are, to a close approximation, nonexistent.

A hierarchical JPEG is identified by the presence of an SOF5, SOF6, SOF7, SOF13, SOF14, or SOF15 segment.

== Color format ==
There are five JPEG color types that are reasonably portable:
# Grayscale
# YCbCr
# RGB
# YCCK
# CMYK

To make the compression more effective, RGB images are almost always transformed to YCbCr format when they are written to a JPEG file. However, many applications will still report that such images use "RGB" color. This may be because their authors weren't aware of the transformation, or because they considered it to be an internal part of the compression algorithm as opposed to a different colorspace. Unfortunately, this inconsistent terminology can make it hard to distinguish YCbCr JPEGs from the rare JPEGs that really do use RGB color.

YCCK is a transformed version of CMYK, and the same terminology confusion exists as with YCbCr and RGB.

The JPEG format does not have any clear way to indicate the color type of an image. Decoders usually determine the color type based on several factors:
* The number of color components
* The presence of a JFIF application segment
* The "color transform" field of the APP14 "Adobe" segment, if present
* The component ID numbers ({82, 71, 66} suggests RGB)

== SmartScale ==
Starting with version 7 or 8, the IJG libjpeg software has been adding nonstandard "SmartScale" scaling and color transform features of debatable merit<ref>[http://www.libjpeg-turbo.org/About/SmartScale A Study on the Usefulness of DCT Scaling and SmartScale]</ref><ref>[http://hardwarebug.org/2010/02/01/ijg-swings-again-and-misses/ IJG swings again, and misses]</ref>.

Notably, it is possible to achieve lossless DCT compression by setting the DCT block size to 1, and using RGB color if necessary.

Version 9 introduced a "reversible color transform" feature that can improve the compression of RGB images. Files with this feature contain a JPG8 (0xf8) segment.

== Related Formats ==
* [[JFIF]] is a subformat and extension, and uses APP0 "JFIF" and APP0 "JFXX" segments.
* [[SPIFF]] is a subformat and extension, and uses an APP8 "SPIFF" segment.
* [[JPEG-HDR]] is an extension, and uses APP11 segments.
* [[JPEG XT]] is an extension.
* [[JPEG 360]] is an extension, and/or a metadata format.
* [[JPS]] is an extension, and uses an APP3 "_JPSJPS_" segment.
* [[Multi-Picture Format]] is an extension, and uses an APP2 "MPF" segment.
* The [[Exif]] standard uses an APP1 "Exif" segment.
* [[FlashPix]] data is contained in APP2 "FPXR" segments in Exif-compliant JPEGs. Refer to the [[Exif]] specification.
* [[Photoshop Image Resources]] is contained in an APP13 "Photoshop 3.0" segment.
* [[IPTC]] metadata often appears in JPEG files, embedded in [[Photoshop Image Resources]].
* [[XMP]] metadata is contained in an APP1 <nowiki>"http://ns.adobe.com/xap/1.0/"</nowiki> segment.
* [[ICC profile]] data is contained in an APP2 "ICC_PROFILE" segment.
* Many other file formats, such as [[TIFF]], [[MNG]]/[[JNG]], and [[PDF]], can contain JPEG-compressed data or encapsulated JPEG files.
* ''(And we heard you like JPEG...)'' JPEG files themselves often contain thumbnail images in the form of embedded JPEG files, via formats such as [[Exif]], [[Photoshop Image Resources]], or [[JFIF]].

Formats that are '''not''' compatible with JPEG include [[JPEG-LS]], [[JPEG 2000]], [[JPEG XR]], and presumably [[JPEG XL]].

== Specifications ==
* [http://www.w3.org/Graphics/JPEG/itu-t81.pdf ITU-T Rec. T.81] (originally CCITT Rec. T.81): The JPEG standard
* [http://www.itu.int/rec/T-REC-T.83/en ITU-T Rec. T.83]: Compliance testing
* [http://www.itu.int/rec/T-REC-T.84/en ITU-T Rec. T.84]: Extensions
* [http://www.itu.int/rec/T-REC-T.86/en ITU-T Rec. T.86]: Registration of JPEG Profiles, etc.
* [http://www.itu.int/rec/T-REC-T.851-200509-I/en ITU-T Rec. T.851]: (JPEG-1)-based still-image coding using an alternative arithmetic coder
* [http://www.itu.int/rec/T-REC-T.872/en ITU-T Rec. T.872]: Application to printing systems
* [http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html#Adobe ExifTool: The APP14 "Adobe" segment]
* ISO/IEC 10918: Digital compression and coding of continuous-tone still images
** [http://www.iso.org/iso/catalogue_detail.htm?csnumber=18902 ISO/IEC 10918-1:1994] - Requirements and guidelines
*** [http://www.iso.org/iso/catalogue_detail.htm?csnumber=41504 ISO/IEC 10918-1:1994/Cor 1:2005] - Patent information update
** [http://www.iso.org/iso/catalogue_detail.htm?csnumber=20689 ISO/IEC 10918-2:1995] - Compliance testing
** [http://www.iso.org/iso/catalogue_detail.htm?csnumber=25037 ISO/IEC 10918-3:1997] - Extensions
*** ISO/IEC 10918-3:1997/Amd 1:1999 - Refer to [[SPIFF]]
** [http://www.iso.org/iso/catalogue_detail.htm?csnumber=25431 ISO/IEC 10918-4:1999] - Registration of JPEG profiles, ...
*** [http://www.iso.org/iso/catalogue_detail.htm?csnumber=59454 ISO/IEC 10918-4:1999/Amd 1:2013] - Application specific marker list
** ISO/IEC 10918-5:2013 - Refer to [[JFIF]]
** [http://www.iso.org/iso/catalogue_detail.htm?csnumber=59634 ISO/IEC 10918-6:2013] - Application to printing systems
* [https://jpeg.org/jpegsystems/index.html ISO/IEC 19566: JPEG Systems] (a collection of JPEG-related standards)
** [https://www.iso.org/standard/65348.html ISO/IEC 19566-1]: Packaging of information using codestreams and file formats
** [https://www.iso.org/standard/67704.html ISO/IEC 19566-2]: Transport mechanisms and packaging
** [https://www.iso.org/standard/73607.html ISO/IEC 19566-4]: Privacy, security and IPR features
** [https://www.iso.org/standard/73604.html ISO/IEC 19566-5]: JPEG Universal Metadata Box Format (JUMBF)
** ISO/IEC 19566-6 = [[JPEG 360]]
* [https://jpeg.org/downloads/jpeg/wg1n76028-CfP-JPEG-reference-software.pdf Final Call for Proposal for a JPEG Reference Software] (2017-07)

== Metaformat files ==
* {{Synalysis|jpeg}}

== Software ==
Nearly all serious graphics applications, including web browsers, support JPEG. This section primarily lists libraries and tools.

* [http://www.ijg.org/ The Independent JPEG Group's software], commonly known as ''libjpeg'' or ''IJG libjpeg''
* [http://libjpeg-turbo.virtualgl.org/ libjpeg-turbo]
* [https://github.com/thorfdbg/libjpeg Thomas Richter's libjpeg]: C++ library that supports all of the JPEG standard
* [https://github.com/mozilla/mozjpeg/ mozjpeg: Improved JPEG encoding library from Mozilla]
** [http://calendar.perfplanet.com/2014/mozjpeg-3-0/ Info on mozjpeg 3.0]
* [https://research.googleblog.com/2017/03/announcing-guetzli-new-open-source-jpeg.html Guetzli] - JPEG encoder optimized for file size
** [https://github.com/google/guetzli Source code at GitHub]
* [http://coptr.digipres.org/Bad_Peggy Bad Peggy: scans images for problems]

== Notes ==
When saving a JPEG image from [[Twitter]] in Google Chrome / Chromium, it will save with the default extension '''.jpg-large'''. This is due to a [https://code.google.com/p/chromium/issues/detail?id=172529 known bug] (and one which shows no signs of being solved any time soon) in the way the browser sanitises Twitter image URLs (the filename is determined to be e.g. Xyzxyzxyz.jpg:large, which is sanitised to Xyzxyzxyz.jpg-large).

== References ==
<references/>

== External links ==
* [[Wikipedia:JPEG|JPEG (Wikipedia)]]
* [http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html ExifTool JPEG Tags]
* [http://blog.sucuri.net/2013/07/malware-hidden-inside-jpg-exif-headers.html Malware Hidden Inside JPG EXIF Headers]
* [http://www.theatlantic.com/technology/archive/2013/09/what-is-a-jpeg-the-invisible-object-you-see-every-day/279954/ What Is a JPEG? The Invisible Object You See Every Day]
* [http://l0ss.elliepritts.com/ Project L0SS], a collection of images demonstrating the glitches and artifacts caused by repeatedly recompressing JPEG images
* [http://thenextweb.com/insider/2014/03/05/mozilla-launches-jpeg-encoder-mozjpeg-improve-compression-rates-reduce-network-traffic-page-loads/ Mozilla launches JPEG encoder mozjpeg to reduce webpage loads, results show up to 10% decrease in file size]
* [http://andreasgal.com/2014/07/15/improving-jpeg-image-encoding/ Improving JPEG image encoding]
* [http://arstechnica.com/information-technology/2014/07/we-dont-need-new-image-formats-mozilla-works-to-build-a-better-jpeg/ We don’t need new image formats: Mozilla works to build a better JPEG]
* [http://www.ams.org/samplings/feature-column/fcarc-image-compression Explanation of JPEG compression algorithm]
* [https://github.com/lclevy/libcraw2/blob/master/docs/cr2_lossless.pdf Lossless JPEG decompression]
* [http://xooyoozoo.github.io/yolo-octo-bugfixes/ Online demonstrator]- shows quality differences between similarly-sized images in [[JPEG]], [[JP2]], [[WebP]] and [[BPG]] formats
* [https://github.com/mozilla/mozjpeg/issues/182 Method to improve JPEG compression that was the subject of a now-expired patent]
* [https://medium.freecodecamp.com/how-jpg-works-a4dbd2316f35 How JPG Works]
* [http://frdx.free.fr/JPEG_for_the_horseshoe_crabs.pdf JPEG for the horseshoe crabs]
* [http://cloudinary.com/blog/why_jpeg_is_like_a_photocopier Why JPEG is like a photocopier] - discussion of generation loss in JPEG and other lossy formats (with examples)
* [http://openpreservation.org/blog/2017/04/09/using-exiftool-to-address-tag-out-of-sequence-errors-in-images-and-a-101-level-dive-into-tags/ Using EXIFTool to address “Tag out of sequence” errors in images (and a 101 level dive into tags)]
* [https://openpreservation.org/blog/2019/11/07/jpeg-got-the-blues/ JPEG Got the Blues] - on properly rendering 32-bit (CMYK) JPEGs

[[Category:Compression]]
[[Category:JPEG (organization)]]

Magnetic tape data storage

2019-09-21T19:52:51Z

Johanvanderknijff: /* Resources */

{{FormatInfo
|formattype=physical
|subcat=Magnetic tape
|thiscat=Magnetic tape data storage
}}
* [[9-track reel-to-reel tape]]
* [[Coleco ADAM Digital Data Pack]] (DDP; similar to normal [[Audio Cassette]] but special high-speed, high-density, preformatted version)
* [[Data tape cartridge]]
* [[DEC tape]]
* [[Digital Audio Tape]]
* [[Digital Data Storage]]
* [[IBM tape]]
* [[Univac tape]]
* [[VidiLoop]] (Chyron, used for broadcast on-screen graphic storage)
* [[ZX Microdrive]] (Sinclair)

Also, [[Audio Cassette#Data formats|Audio Cassettes]] were used for data storage on early personal computers.

== Resources ==

* [[Wikipedia:Magnetic tape data storage|Wikipedia article on magnetic tape data storage]]
* [http://boingboing.net/2013/03/15/lunar-orbiter-image-recovery-p.html Lunar orbiter image recovery project]
* [http://www.wired.com/2014/04/lost-lunar-photos-recovered-by-great-feats-of-hackerdom-developed-at-a-mcdonalds/ The Hackers Who Recovered NASA’s Lost Lunar Photos]
* [http://patrickthomson.tumblr.com/post/2499755681/the-best-debugging-story-ive-ever-heard Debugging story involving tape drives]
* [https://archive.org/details/bitsavers_hptape0797erviceManual_30246672 HP 07975-90470 Operating And Service Manual (Tape drive)]
* [http://www.kotaku.co.uk/2014/10/13/people-used-download-games-radio How People Used to Download Games From the Radio]
* [http://searchdatabackup.techtarget.com/news/4500254525/Tape-update-LTO-7-bit-error-rate-improves-LTFS-use-rises Tape update: LTO-7 bit error rate improves, LTFS use rises]
* [https://www.bitsgalore.org/2019/09/09/recovering-90s-data-tapes-experiences-kb-web-archaeology Recovering '90s Data Tapes - Experiences From the KB Web Archaeology project] - contains detailed information on how to recover data from '90s tape formats
* [https://github.com/KBNLresearch/forensicImagingResources/blob/master/doc/tape-dds.md Workflow for reading DDS tapes]
* [https://github.com/KBNLresearch/forensicImagingResources/blob/master/doc/tape-dlt.md Workflow for reading DLT-IV tapes]
* [https://github.com/KBNLresearch/forensicImagingResources/blob/master/doc/df-resources.md Digital forensics and web archaeology resources] - includes lots of links to resources on tapes, SCSI and tape archive formats
* [https://github.com/KBNLresearch/tapeimgr tapeimgr] - user-friendly tool for recovering data from tapes (Linux-only; wraps around dd and mt)
[[Category:Backup]]

Magnetic tape data storage

2019-09-21T19:52:24Z

Johanvanderknijff: /* Resources */ Added resources from KB Web Archaeology project

{{FormatInfo
|formattype=physical
|subcat=Magnetic tape
|thiscat=Magnetic tape data storage
}}
* [[9-track reel-to-reel tape]]
* [[Coleco ADAM Digital Data Pack]] (DDP; similar to normal [[Audio Cassette]] but special high-speed, high-density, preformatted version)
* [[Data tape cartridge]]
* [[DEC tape]]
* [[Digital Audio Tape]]
* [[Digital Data Storage]]
* [[IBM tape]]
* [[Univac tape]]
* [[VidiLoop]] (Chyron, used for broadcast on-screen graphic storage)
* [[ZX Microdrive]] (Sinclair)

Also, [[Audio Cassette#Data formats|Audio Cassettes]] were used for data storage on early personal computers.

== Resources ==

* [[Wikipedia:Magnetic tape data storage|Wikipedia article on magnetic tape data storage]]
* [http://boingboing.net/2013/03/15/lunar-orbiter-image-recovery-p.html Lunar orbiter image recovery project]
* [http://www.wired.com/2014/04/lost-lunar-photos-recovered-by-great-feats-of-hackerdom-developed-at-a-mcdonalds/ The Hackers Who Recovered NASA’s Lost Lunar Photos]
* [http://patrickthomson.tumblr.com/post/2499755681/the-best-debugging-story-ive-ever-heard Debugging story involving tape drives]
* [https://archive.org/details/bitsavers_hptape0797erviceManual_30246672 HP 07975-90470 Operating And Service Manual (Tape drive)]
* [http://www.kotaku.co.uk/2014/10/13/people-used-download-games-radio How People Used to Download Games From the Radio]
* [http://searchdatabackup.techtarget.com/news/4500254525/Tape-update-LTO-7-bit-error-rate-improves-LTFS-use-rises Tape update: LTO-7 bit error rate improves, LTFS use rises]
* [https://www.bitsgalore.org/2019/09/09/recovering-90s-data-tapes-experiences-kb-web-archaeology Recovering '90s Data Tapes - Experiences From the KB Web Archaeology project] - contains detailed information on how to recover data from '90s tape formats
* [https://github.com/KBNLresearch/forensicImagingResources/blob/master/doc/tape-dds.md Workflow for reading DDS tapes]
* [https://github.com/KBNLresearch/forensicImagingResources/blob/master/doc/tape-dlt.md Workflow for reading DDS tapes]
* [https://github.com/KBNLresearch/forensicImagingResources/blob/master/doc/df-resources.md Digital forensics and web archaeology resources] - includes lots of links to resources on tapes, SCSI and tape archive formats
* [https://github.com/KBNLresearch/tapeimgr tapeimgr] - user-friendly tool for recovering data from tapes (Linux-only; wraps around dd and mt)
[[Category:Backup]]

JP2

2019-08-19T12:24:06Z

Johanvanderknijff: /* Sample files */ Added openjeg-data, updated links to OPF data sets

{{FormatInfo
|formattype=electronic
|subcat=Graphics
|subcat2=JPEG 2000
|extensions={{ext|jp2}}
|mimetypes={{mimetype|image/jp2}}
|pronom={{PRONOM|x-fmt/392}}
|locfdd={{LoCFDD|fdd000143}}, others
}}
[[JP2]] is the baseline image file format defined by the [[JPEG 2000]] standard. It encapsulates a [[JPEG 2000 codestream]].

== Identifiers ==
{| class="wikitable"
! Format
! PRONOM
! LoCFDD
|-
|JP2 || {{PRONOM|x-fmt/392}} || {{LoCFDD|fdd000143}}
|-
|JP2, Lossless || || {{LoCFDD|fdd000167}}
|-
|JP2, Lossy || || {{LoCFDD|fdd000168}}
|-
|JP2, Profile 0 || || {{LoCFDD|fdd000195}}
|-
|JP2, Profile 1 || || {{LoCFDD|fdd000197}}
|-
|JP2, Profile 3 || || {{LoCFDD|fdd000212}}
|-
|JP2, Profile 4 || || {{LoCFDD|fdd000214}}
|-
|JP2, BIIF Profile || || {{LoCFDD|fdd000169}}
|-
|JP2, NDNP Profile || || {{LoCFDD|fdd000193}}
|}

== Identification ==
JP2 files begin with bytes <code>00 00 00 0c 6a 50 20 20 0d 0a 87 0a ?? ?? ?? ?? 66 74 79 70 6a 70 32 20</code>.

Note that some Adobe applications (most notably [[Adobe Photoshop]]) produce [[JPX]] (JPEG 2000 Part 2) images that erroneously use the above byte sequence, which makes them (superficially) indistinguishable from JP2 images.

== Specifications ==
* [http://old.jpeg.org/public/15444-1annexi.pdf ISO/IEC 15444-1 Annex I: JP2 file format syntax]
* [http://www.itu.int/rec/T-REC-T.800/en ITU-T Rec. T.800] (not free to download)
* [http://old.jpeg.org/jpeg2000/CDs15444.html JPEG 2000 Committee Drafts] → [http://old.jpeg.org/public/fcd15444-1.pdf fcd15444-1.pdf]
* [http://www.itu.int/rec/T-REC-T.800-201303-P!Amd6/en Updated ICC profile support, bit depth and resolution clarifications] - 2013 amendment to the filespec that extends support of ICC profiles and clarifies use of resolution fields in JP2
* [http://www.itscj.ipsj.or.jp/sc29/open/29view/29n12288t.doc Updated ICC profile support, bit depth and resolution clarifications] - August 2011 draft of above amendment (freely available)
* [http://www.gwg.nga.mil/ntb/baseline/docs/bpj2k01/ISOJ2K_profile.pdf BIIF Profile for JPEG 2000]
* [http://www.loc.gov/ndnp/guidelines/docs/NDNP_JP2HistNewsProfile.pdf JPEG 2000 Profile for the National Digital Newspaper Program] (NDNP Profile)

== Software ==
See also [[JPEG 2000#Software|JPEG 2000]].
* [[Konvertor]]
* [http://jpylyzer.openpreservation.org/ Jpylyzer]: JP2 validator and property extractor
Note also that the [http://jpylyzer.openpreservation.org/userManual.html jpylyzer manual] includes a detailed breakdown of the JP2 format structure.
* [https://gist.github.com/bitsgalore/eeff2b7dd2e44a5f6195 Compute compression ratio for all JP2s in directory tree (shell script)]
* [https://github.com/uoregon-libraries/rais-image-server RAIS Image Server: An IIIF-compliant, 100% open source tile server for JP2 images]

== Sample files ==

* [https://github.com/openpreserve/format-corpus/tree/master/jp2k-test Jp2k test corpus] - annotated set of images, primarily intended to demonstrate specific preservation risks

* [https://github.com/openpreserve/jpylyzer-test-files Jpylyzer test files] - annotated set of images, primarily intended as test dataset in support of jpylyzer development. Includes many (deliberately) corrupted files.

* [https://github.com/openpreserve/format-corpus/tree/master/jp2k-formats JPEG 2000 sample images] - sample files for each format in the JPEG 2000 format family

* [https://github.com/uclouvain/openjpeg-data openjpeg-data] - all files required to run the openjpeg test suite, includes many badly corrupted files

== Related formats ==
* [[GeoJP2]] is an extension of the JP2 format which allows one to include geospatial metadata in georeferenced JP2 images.

== Links ==
* [[Wikipedia:JPEG 2000]]
* [http://blogs.loc.gov/digitalpreservation/2013/01/is-jpeg-2000-a-preservation-risk/ Is JPEG-2000 a Preservation Risk?]
* [http://wiki.opf-labs.org/display/TR/JP2 JP2 entries in OPF File Format Risk Registry] - describes some issues with (older versions of) the format spec and issues with specific implementations
* [http://www.openplanetsfoundation.org/blogs/2014-09-26-six-ways-decode-lossy-jp2 Six ways to decode a lossy JP2]
* [http://wiki.opf-labs.org/display/JP2/Example+JP2+profiles Example JP2 profiles] (types of JP2s used by different institutions)
* [http://xooyoozoo.github.io/yolo-octo-bugfixes/ Online demonstrator]- shows quality differences between similarly-sized images in [[JPEG]], [[JP2]], [[WebP]] and [[BPG]] formats
* [http://wiki.dpconline.org/images/4/4b/JP2_Assessment_v1.2_external.pdf JP2 Format Preservation Assessment (British Library)]
* [https://groups.google.com/forum/#!topic/openjpeg/X0wun3QwIoY Catching and potentially reporting apparent compressed bitstream errors]
* [http://blog.hexagongeospatial.com/jpeg2000-quirks/ JPEG2000 Is Slow … Or Is It?]

[[Category:Box file format]]

CD-i

2019-05-14T14:04:01Z

Johanvanderknijff: /* Software */ Added gametechwiki.com entry on CD-i emulation

{{FormatInfo
|formattype=physical
|subcat=Optical Discs
|subcat2=CD
|released=1991
}}
'''CD-i''' (Compact Disc Interactive) is a multimedia compact disc format, which is defined by the "Green Book" standard.

== Specification ==

* [https://www.lscdweb.com/data/downloadables/2/8/cdi_may94_r2.pdf CD-I Full Functional Specification (1994 version)]

== Software ==

*[http://www.cdiemu.org/ CD-i Emulator]
*[http://emulation.gametechwiki.com/index.php/Philips_CD-i_emulators Philips CD-i emulators]
*[http://www.icdia.co.uk/sw_pc/disctools.html Link to CD-i Filesystem Driver for use on Windows 95/98/Me ]
*[http://www.icdia.co.uk/articles/filesystem.html Article about CD-i Filesystem Driver]
*[http://www.isobuster.com/help/cd-i_and_vcd Explanation of CD-i support in ISOBuster]
*[https://github.com/roysmeding/cditools Python tools for extracting file system data and decoding audio and image tracks from CD-i discs]

== Sample files ==

* [http://www.icdia.co.uk/sw_disc/index.html Two disc image downloads]

== Links ==
* [[Wikipedia:Philips CD-i|Wikipedia article: Philips CD-i]]

* [[Wikipedia:Green Book (CD standard)|Wikipedia article: Green Book (CD standard)]]

* [http://www.icdia.co.uk/ The New International CD-i Association] (probably the most exhaustive website on all things CD-i)

* [http://www.philipscdi.com/ www.philipscdi.com]

*[http://www.consoledatabase.com/faq/philipscdifaq-philips/ Philips CD-i FAQ]

[[Category:Optical Discs]]
[[Category:Philips]]

CD

2019-05-14T13:52:02Z

Johanvanderknijff: /* Imaging/Ripping CDs */ Updated link bc original domain is broken

{{FormatInfo
|formattype=physical
|subcat=Optical Discs
|thiscat=CD
|released=1982
}}
The '''CD''' (Compact Disc) is a popular medium for recorded sound as well as computer data, developed by Philips and Sony. It is a laser-read optical disc. Discs of the same size were later used for the [[DVD]] and [[Blu-ray Disc]] formats, allowing the same player to support all of these formats.

== Types ==
* [[CD-DA]] (Compact Disc Digital Audio or Red Book)
* [[CD-Extra]] (Blue Book)
* [[CD-MIDI]]
* [[CD-ROM]] (Yellow Book)
* [[CD-ROM XA]]
* [[DD-CD]] (Double-density Compact Disc)
* [[Enhanced CD]]
* [[Photo CD]] (Beige Book)
* [[CD-i]] (Green Book)
* [[SACD]] (Super Audio CD or Scarlet Book)
* [[VCD]] (Video CD or White Book)
** [[Super Video CD]]

== Imaging/Ripping CDs ==

* [http://forensicswiki.org/wiki/Category:Disk_Imaging ForensicsWiki:Disk Imaging]
* [https://gist.github.com/bitsgalore/1bea8f015eca21a706e7#file-notescdimaging-md CD imaging notes + sample tool output] by [[User:Johanvanderknijff]]
* Developing a Robust Migration Workflow for Preserving and Curating Hand-held Media [http://anjackson.net/keeping-codes/practice/developing-a-robust-migration-workflow-for-preserving-and-curating-handheld-media.html html], [http://arxiv.org/abs/1309.4932 pdf pre-print].
* [http://wiki.opf-labs.org/display/SPR/Audio+CD+Preservation SPRUCE/OPF Audio CD Preservation]
* [https://www.bitsgalore.org/2015/11/13/preserving-optical-media-from-the-command-line Preserving optical media from the command line]

== Links ==
* [[Wikipedia:Compact disc|Wikipedia article]]
* [http://www.youtube.com/watch?v=ut_40U0t9pU How It's Made: Compact Discs (video)]
* [http://www.digitalmusicnews.com/permalink/2014/03/20/entourage-music-supervisor-throws-out-cds Entourage Music Supervisor Throws Out CDs On The Street]
* [http://www.openplanetsfoundation.org/comment/559 Establishing a Workflow Model for Audio CD Preservation]
* [https://instagram.com/p/1qs52OMeM9/ It turns out that your CD drives really don't like having CDs explode inside them]
* [https://www.gnu.org/software/libcdio/libcdio.html#CD-Formats CD Formats overview] - GNU libcdio documentation
* [http://www.filfre.net/2016/09/a-slow-motion-revolution/ A Slow-Motion Revolution] - History of the CD-ROM (including CD-I)
* [https://www.youtube.com/watch?v=_Tx6TYnPat8 Video: Introducing the amazing Compact Disc (1982)]

[[Category:Philips]]
[[Category:Sony]]

Optical Discs

2019-05-14T13:50:59Z

Johanvanderknijff: /* Links */ Updated link bc original domain is broken

{{FormatInfo
|formattype=physical
|thiscat=Optical Discs
|image=Optical-discs.jpg
|caption=Some CDs and DVDs
}}

An '''optical disc''' is read by a laser. They have been used extensively to store and distribute music, movies, and computer programs and data. CD drives became commonplace in personal computers in the mid-1990s, and burners to create CD-ROMs on personal computers were common by the early 2000s. Later, the higher-capacity DVD format became common both for reading and writing as well, and the even newer BluRay format won a "format war" against rival HD-DVD to get some popularity at present, though physical formats in general are on the wane as a distribution format due to the widespread deployment of the high-bandwidth Internet.

* [[Blu-ray Disc]]
** [[M-Disc]]
** [[UHD Blu-ray]]
* [[CD]] (Compact Disc)
** [[CD-DA]] (Compact Disc Digital Audio or Red Book)
** [[CD-MIDI]]
** [[CD-ROM]] (Yellow Book)
** [[CD-ROM XA]]
** [[DD-CD]] (Double-density Compact Disc)
** [[Enhanced CD]]
** [[Photo CD]] (Beige Book)
*** [[CD-i]] (Green Book)
** [[SACD]] (Super Audio CD or Scarlet Book)
** [[VCD]] (Video CD or White Book)
*** [[Super Video CD]]
* [[DVD]]
** [[DVD-Audio]]
** [[DVD-ROM]]
** [[M-Disc]]
* [[Enhanced Versatile Disc]]
* [[GD-ROM]]
* [[HD-DVD]]
** [[China Blue High-Definition Disc]]
* [[Laserdisc]]
** [[LV-ROM]]
* [[MiniDisc]]
* Nintendo optical discs
** [[Nintendo GameCube Game Disc]]
** [[Nintendo Wii Optical Disc]]
** [[Nintendo Wii U Optical Disc]]
* [[Thomson-CSF system]]
* [[Ultra Density Optical]]
* [[Universal Media Disc]]

== Links ==
* [http://www.thexlab.com/faqs/opticalmedialongevity.html Optical media longevity]
* [http://www.sony.net/SonyInfo/News/Press/201403/14-0310E/index.html "Archival Disc" standard formulated for professional-use next-generation optical discs] (up to 1 TB capacity)
* [http://journal.code4lib.org/articles/9581 An Introduction to Optical Media Preservation] by [https://twitter.com/archivetype @archivetype]
* [http://www.loc.gov/preservation/resources/rfs/softgame.html Library of Congress Recommended Format Specifications: Software/Gaming]
* [http://arxiv.org/ftp/arxiv/papers/1309/1309.4932.pdf Developing a Robust Migration Workflow for Preserving and Curating Hand-held Media]
* [http://www.kurzweilai.net/5d-nanostructured-quartz-glass-optical-memory-could-provide-unlimited-data-storage-for-a-million-years 5D nanostructured quartz glass optical memory could provide ‘unlimited’ data storage for a million years] (but reference link there is already 404 Not Found!)
* [https://www.bitsgalore.org/2015/11/13/preserving-optical-media-from-the-command-line Preserving optical media from the command line]

Unix dump

2019-01-29T17:20:12Z

Johanvanderknijff:

{{FormatInfo
|formattype=electronic
|subcat=Archiving
|extensions={}
|mimetypes={}
|pronom={}
}}
'''dump''' is an archive format that is written by Unix dump, which is a backup program that was popular in the '90s (reference?). Dump files were often written to tape. Dump files can be read using the restore tool. It appears that no specifications exist.

== Variants ==

There are a number of variants to the Unix dump format.

The [https://github.com/file/file/blob/master/magic/Magdir/dump file(1) magic definition of the format] makes a distiction between 'old' and 'new' filesystem variants. Each of these can be big-endian or little endian. In addition a 16-bit subtype of the 'old' variant exists. Finally there is also a ufs2 variant (which again can be big-endian or little endian). In total this results in 7 variants of the format. According to the [http://linux.die.net/man/8/restore restore documentation], the dump file format changed in version 4.4 (of the dump tool?).

== Software ==

* [http://dump.sourceforge.net/ Dump / restore utilities]

== Documentation ==

* [http://linux.die.net/man/8/dump Linux man page for dump]
* [http://linux.die.net/man/8/restore Linux man page for restore]

== Sample files ==

* [https://github.com/bitsgalore/unix-dump-magic Unix dump format] - includes some minimal sample files, created for testing magic patterns

== Restoring the contents of a dump file ==

To restore the contents of a dump file on a Unix system, first the install the "restore" tool. On Debian-based systems:

<code>sudo apt install dump</code>

Then go through the following steps:

<ol>
<li>Create an empty directory, and go to that directory in the command terminal:
<code>mkdir extracted</code>
<code>cd extracted</code>
<li>Run <code>restore</code> in interactive mode on the dump file you want to extract
<code>sudo restore -if ../../tapes-DDS/1/file000002.dd</code></li>
<li>Inspect the contents of the dump file:
<code>restore > ls</code>
Result:
<pre> 5bin/ diag/ kvm/ mdec share/ ucbinclude
5include/ dict/ lddrv/ net spool ucblib
5lib/ etc/ lib/ nserve src xpg2bin/
adm export/ local old/ stand xpg2include/
bin/ games/ local-/ openwin/ sys xpg2lib/
boot hosts/ lost+found/ pub tmp
demo/ include/ man sccs/ ucb/</pre></li>
<li>Use the <code>add</code>command to add directories that are to be extracted to the directory list. To extract everything:
<code>restore > add .</code></li>
<li>Run the <code>extract</code> command:
<code>restore > extract</code>
This results in the following prompt:
<pre> You have not read any volumes yet.
Unless you know which volume your file(s) are on you should start
with the last volume and work towards the first.
Specify next volume # (none if no more volumes):</pre></li>
<li>Now enter <code>1</code>. Response:
<pre>set owner/mode for '.'? [yn]</pre></li>
<li>Enter <code>n</code></li>
<li>When the extraction is finished, exit the interactive restore session:
<code>restore > q</code></li></ol>

== References ==

* [[Wikipedia:Dump_(program)]]
* [http://dump.sourceforge.net/isdumpdeprecated.html Is dump really deprecated?]
* [https://searchdatabackup.techtarget.com/tip/Using-Dump-for-Linux-Unix-data-backup Using Dump for Linux/Unix data backup]
* [https://www.hscripts.com/tutorials/linux-commands/restore.html Restore Linux Commands]
* [https://docs.oracle.com/cd/E19253-01/817-5093/bkuprestoretasks-63510/index.html How to Restore UFS Files Interactively]
* [https://github.com/file/file/blob/master/magic/Magdir/dump file(1) magic for dump file format] (also includes patterns for extraction of header fields)

Unix dump

2019-01-29T17:18:09Z

Johanvanderknijff:

{{FormatInfo
|formattype=electronic
|subcat=Archiving
|extensions={}
|mimetypes={}
|pronom={}
}}
'''dump''' is an archive format that is written by Unix dump, which is a backup program that was popular in the '90s (reference?). Dump files were often written to tape. Dump files can be read using the restore tool. It appears that no specifications exist.

== Variants ==

There are a number of variants to the Unix dump format.

The [https://github.com/file/file/blob/master/magic/Magdir/dump file(1) magic definition of the format] makes a distiction between 'old' and 'new' filesystem variants. Each of these can be big-endian or little endian. In addition a 16-bit subtype of the 'old' variant exists. Finally there is also a ufs2 variant (which again can be big-endian or little endian). In total this results in 7 variants of the format. According to the [http://linux.die.net/man/8/restore restore documentation], the dump file format changed in version 4.4 (of the dump tool?).

== Software ==

* [http://dump.sourceforge.net/ Dump / restore utilities]

== Documentation ==

* [http://linux.die.net/man/8/dump Linux man page for dump]
* [http://linux.die.net/man/8/restore Linux man page for restore]

== Sample files ==

* [https://github.com/bitsgalore/unix-dump-magic Unix dump format] - includes some minimal sample files, created for testing magic patterns

== Restoring the contents of a dump file ==

To restore the contents of a dump file on a Unix system, first the install the "restore" tool. On Debian-based systems:

<code>sudo apt install dump</code>

Then go through the following steps:

<ol>
<li>Create an empty directory, and go to that directory in the command terminal:
<code>mkdir extracted</code>
<code>cd extracted</code>
<li>Run <code>restore</code> in interactive mode on the dump file you want to extract<ref>If you don't run <code>restore</code> as sudo, extraction results in a flood of <code>chown: Operation not permitted</code> messages (the files ''are'' extracted though).</ref>:
<code>sudo restore -if ../../tapes-DDS/1/file000002.dd</code></li>
<li>Inspect the contents of the dump file:
<code>restore > ls</code>
Result:
<pre> 5bin/ diag/ kvm/ mdec share/ ucbinclude
5include/ dict/ lddrv/ net spool ucblib
5lib/ etc/ lib/ nserve src xpg2bin/
adm export/ local old/ stand xpg2include/
bin/ games/ local-/ openwin/ sys xpg2lib/
boot hosts/ lost+found/ pub tmp
demo/ include/ man sccs/ ucb/</pre></li>
<li>Use the <code>add</code>command to add directories that are to be extracted to the directory list. To extract everything:
<code>restore > add .</code></li>
<li>Run the <code>extract</code> command:
<code>restore > extract</code>
This results in the following prompt:
<pre> You have not read any volumes yet.
Unless you know which volume your file(s) are on you should start
with the last volume and work towards the first.
Specify next volume # (none if no more volumes):</pre></li>
<li>Now enter <code>1</code>. Response:
<pre>set owner/mode for '.'? [yn]</pre></li>
<li>Enter <code>n</code> <ref>This needs further investigation, as the implications of this setting are not 100% clear to me.</ref></li>
<li>When the extraction is finished, exit the interactive restore session:
<code>restore > q</code></li></ol>

== References ==

* [[Wikipedia:Dump_(program)]]
* [http://dump.sourceforge.net/isdumpdeprecated.html Is dump really deprecated?]
* [https://searchdatabackup.techtarget.com/tip/Using-Dump-for-Linux-Unix-data-backup Using Dump for Linux/Unix data backup]
* [https://www.hscripts.com/tutorials/linux-commands/restore.html Restore Linux Commands]
* [https://docs.oracle.com/cd/E19253-01/817-5093/bkuprestoretasks-63510/index.html How to Restore UFS Files Interactively]
* [https://github.com/file/file/blob/master/magic/Magdir/dump file(1) magic for dump file format] (also includes patterns for extraction of header fields)

<references />

Unix dump

2019-01-29T17:17:15Z

Johanvanderknijff:

{{FormatInfo
|formattype=electronic
|subcat=Archiving
|extensions={}
|mimetypes={}
|pronom={}
}}
'''dump''' is an archive format that is written by Unix dump, which is a backup program that was popular in the '90s (reference?). Dump files were often written to tape. Dump files can be read using the restore tool. It appears that no specifications exist.

== Variants ==

There are a number of variants to the Unix dump format.

The [https://github.com/file/file/blob/master/magic/Magdir/dump file(1) magic definition of the format] makes a distiction between 'old' and 'new' filesystem variants. Each of these can be big-endian or little endian. In addition a 16-bit subtype of the 'old' variant exists. Finally there is also a ufs2 variant (which again can be big-endian or little endian). In total this results in 7 variants of the format. According to the [http://linux.die.net/man/8/restore restore documentation], the dump file format changed in version 4.4 (of the dump tool?).

== Software ==

* [http://dump.sourceforge.net/ Dump / restore utilities]

== Documentation ==

* [http://linux.die.net/man/8/dump Linux man page for dump]
* [http://linux.die.net/man/8/restore Linux man page for restore]

== Sample files ==

* [https://github.com/bitsgalore/unix-dump-magic Unix dump format] - includes some minimal sample files, created for testing magic patterns

== Restoring the contents of a dump file ==

To restore the contents of a dump file on a Unix system, first the install the "restore" tool. On Debian-based systems:

<code>sudo apt install dump</code>

Then go through the following steps:

<ol>
<li>Create an empty directory, and go to that directory in the command terminal:
<code>mkdir extracted</code>
<code>cd extracted</code>
<li>Run <code>restore</code> in interactive mode on the dump file you want to extract<ref>If you don't run <code>restore</code> as sudo, extraction results in a flood of <code>chown: Operation not permitted</code> messages (the files ''are'' extracted though).</ref>:
<code>sudo restore -if ../../tapes-DDS/1/file000002.dd</code></li>
<li>Inspect the contents of the dump file:
<code>restore > ls</code>
Result:
<pre> 5bin/ diag/ kvm/ mdec share/ ucbinclude
5include/ dict/ lddrv/ net spool ucblib
5lib/ etc/ lib/ nserve src xpg2bin/
adm export/ local old/ stand xpg2include/
bin/ games/ local-/ openwin/ sys xpg2lib/
boot hosts/ lost+found/ pub tmp
demo/ include/ man sccs/ ucb/</pre></li>
<li>Use the <code>add</code>command to add directories that are to be extracted to the directory list. To extract everything:
<code>restore > add .</code></li>
<li>Run the <code>extract</code> command:
<code>restore > extract</code>
This results in the following prompt:
<pre> You have not read any volumes yet.
Unless you know which volume your file(s) are on you should start
with the last volume and work towards the first.
Specify next volume # (none if no more volumes):</pre></li>
<li>Now enter <code>1</code>. Response:
<pre>set owner/mode for '.'? [yn]</pre></li>
<li>Enter <code>n</code> <ref>This needs further investigation, as the implications of this setting are not 100% clear to me.</ref></li>
<li>When the extraction is finished, exit the interactive restore session:
<code>restore > q</code></li></ol>

== References ==

* [[Wikipedia:Dump_(program)]]
* [http://dump.sourceforge.net/isdumpdeprecated.html Is dump really deprecated?]
* [https://searchdatabackup.techtarget.com/tip/Using-Dump-for-Linux-Unix-data-backup Using Dump for Linux/Unix data backup]
* [https://www.hscripts.com/tutorials/linux-commands/restore.html Restore Linux Commands]
* [https://docs.oracle.com/cd/E19253-01/817-5093/bkuprestoretasks-63510/index.html How to Restore UFS Files Interactively]
* [https://github.com/file/file/blob/master/magic/Magdir/dump file(1) magic for dump file format] (also includes patterns for extraction of header fields)

Unix dump

2019-01-25T18:07:49Z

Johanvanderknijff:

Unix dump

2019-01-25T18:04:39Z

Johanvanderknijff:

Unix dump

2019-01-25T18:04:26Z

Johanvanderknijff: Created page with "' {{FormatInfo |formattype=electronic |subcat=Archiving |extensions={} |mimetypes={} |pronom={} }} '''dump''' is an archive format that is written by Unix dump, which is a bac..."

'
{{FormatInfo
|formattype=electronic
|subcat=Archiving
|extensions={}
|mimetypes={}
|pronom={}
}}
'''dump''' is an archive format that is written by Unix dump, which is a backup program that was popular in the '90s (reference?). Dump files were often written to tape. Dump files can be read using the restore tool. It appears that no specifications exist.

== Variants ==

There are a number of variants to the Unix dump format.

The [https://github.com/file/file/blob/master/magic/Magdir/dump file(1) magic definition of the format] makes a distiction between 'old' and 'new' filesystem variants. Each of these can be big-endian or little endian. In addition a 16-bit subtype of the 'old' variant exists. Finally there is also a ufs2 variant (which again can be big-endian or little endian). In total this results in 7 variants of the format. According to the [http://linux.die.net/man/8/restore restore documentation], the dump file format changed in version 4.4 (of the dump tool?).

== Software ==

* [http://dump.sourceforge.net/ Dump / restore utilities]

== Documentation ==

* [http://linux.die.net/man/8/dump Linux man page for dump]
* [http://linux.die.net/man/8/restore Linux man page for restore]

== References ==

* [[Wikipedia:Dump_(program)]]
* [http://dump.sourceforge.net/isdumpdeprecated.html Is dump really deprecated?]
* [https://searchdatabackup.techtarget.com/tip/Using-Dump-for-Linux-Unix-data-backup Using Dump for Linux/Unix data backup]
* [https://www.hscripts.com/tutorials/linux-commands/restore.html Restore Linux Commands]
* [https://docs.oracle.com/cd/E19253-01/817-5093/bkuprestoretasks-63510/index.html How to Restore UFS Files Interactively]
* [https://github.com/file/file/blob/master/magic/Magdir/dump file(1) magic for dump file format] (also includes patterns for extraction of header fields)

NetCDF

2018-10-12T14:10:46Z

Johanvanderknijff: Added link to Uni Michigan format profile

{{FormatInfo
|formattype=electronic
|subcat=Scientific Data formats
|extensions={{ext|nc}}
|mimetypes={{mimetype|application/netcdf}}
|locfdd={{LoCFDD|fdd000330}}, {{LoCFDD|fdd000332}}, {{LoCFDD|fdd000339}}
|pronom={{PRONOM|fmt/282}}, {{PRONOM|fmt/283}}
}}
== General description ==

The Network Common Data Form (netCDF) is a long-lived set of file formats and associated APIs designed by UCAR for multi-dimensional datasets. (Though its name resembles that of [[Common Data Format|CDF]], and their original designs were similar, the two products have greatly diverged.) The various versions are widely used in environmental science, especially atmospheric and oceanographic research. Currently it has two main versions, netCDF-3 and netCDF-4, which are quite different in implementation, and moderately different in API. There are also "subversions" of netCDF-3, notably "netCDF Classic." Tool support for netCDF-3 continues to exceed that for netCDF-4; but the latter, based on [[HDF5]], is generally considered technically superior, so its tool support is increasing rapidly.

Notable features of netCDF include

* incorporation of metadata. netCDF is said to be "self-describing," in that the file format provides for a header describing the structure of the data. In practice, the utility of its metadata depends on the extent to which the data author provides and maintains it.
* platform independence via API: provided the user manipulates netCDF files via supported APIs (which are numerous), the user can effectively ignore issues such as endianness.
* backward compatibility. Software and API capable of manipulating netCDF-4 is also capable of manipulating netCDF-3, though of course advanced features of the later version are not accessible to files written for the earlier version.

According to the FAQ,there are 4 main versions of NetCDF:

* the classic format
* the 64-bit offset format
* the netCDF-4 format
* the netCDF-4 classic model format
Either of the first two may be referred to as NetCDF-3.

NetCDF is described on the [http://www.unidata.ucar.edu/software/netcdf/ Unidata pages] of the UCAR web site. A short document [http://www.esdswg.org/spg/rfc/esds-rfc-011/ESDS-RFC-011v1.00.pdf describing early versions] has been accepted as a standard by NASA.

NetCDF-4 based on [[HDF5]] has been endorsed as a standard by NASA's Earth Observing System Data and Information System (EOSDIS). See [http://earthdata.nasa.gov/our-community/esdswg/standards-process-spg/rfc Endorsed set of EOSDIS approved standards.]

== Other information ==

The format is referenced in the Wikipedia [http://en.wikipedia.org/wiki/NetCDF page on NetCDF].

NetCDF claims full backwards compatibility.

Software and information is made available according to [http://www2.ucar.edu/terms-of-use UCAR Terms of Use], which indicate they are not usable for commercial purposes.

== Software ==
There is a wide range of software available to create and process NetCDF files. The Wikipedia article mentioned above has a starter list.

== Sample files ==

Sample NetCDF files are available on the [http://www.unidata.ucar.edu/software/netcdf/examples/files.html Unidata web site].

== Identification ==

The magic number is CDF\001 .

The file extension is .nc (originally .cdf) and the MIME Type is application/netcdf or
application/x-netcdf.

== References ==

* The User's Guide is: Rew, R. K., G. P. Davis, S. Emmerson, and H. Davies, NetCDF User's Guide for C, An Interface for Data Access, Version 3, April 1997.
* [https://deepblue.lib.umich.edu/bitstream/handle/2027.42/145724/Public-Data-CurationFormat%20Profile-netCDF.pdf Data Curation Format Profile: netCDF] (Research Data Services, University of Michigan Library)

JPEG 2000

2018-10-01T16:31:29Z

Johanvanderknijff: /* Software */

{{FormatInfo
|formattype=electronic
|subcat=Graphics
|thiscat=JPEG 2000
|extensions={{ext|jp2}}, {{ext|jpf}}, {{ext|jpx}}, {{ext|jpm}}, {{ext|mj2}}, others
|mimetypes={{mimetype|image/jp2}}, {{mimetype|image/jpx}}, {{mimetype|image/jpm}}, {{mimetype|video/mj2}}
}}
'''JPEG 2000''' (or '''JPEG2000''') is standard that defines a [[wavelet compression|wavelet-based]] raster image compression format, and a family of associated file formats, protocols, etc. (For the older JPEG-1, see [[JPEG]].)

For details about specific formats, see:
* [[JPEG 2000 codestream]]
* [[JP2]] (base still image format)
* [[JPX]] (extended still image format)
* [[JPM]] (compound image format)
* [[MJ2]] (motion JPEG 2000)

== Disambiguation ==
'''JPEG 2000''' is sometimes incorrectly used as a synonym for '''JP2''', and vice versa. Although JP2 might be the most important part of the JPEG 2000 standard, it is only one small part of it.

In some contexts, '''JPEG 2000''' is used to mean the compressed codestream format, instead of the whole standard.

The terms '''JPEG 2000''' and '''JPEG2000''' (with and without a space) seem to be used interchangeably. The parts of the official specification that are freely available use only '''JPEG 2000''', so that is probably the preferred form. But it must have been settled on late in the standardization process: even some of the committee drafts prefer '''JPEG2000'''.

== Details ==
The JPEG 2000 standard consists of many parts, including:
* Part 1: Core coding system. Defines [[JPEG 2000 codestream]] format and the [[JP2]] file format.
* Part 2: Extensions. Defines [[JPX]].
* Part 3: [[MJ2|Motion JPEG 2000 (MJ2)]]
* Part 6: [[JPM|Compound image file format (JPM)]]
* Part 8: JPSEC
* Part 9: JPIP
* Part 10: JP3D
* Part 11: JPWL
* Part 12: [[ISO Base Media File Format]]

== Format ==
At the highest level, JPEG 2000 files (JP2, JPX, JPM, and MJ2, but not the codestream format) consist of a hierarchical sequence of tagged "boxes" ([[boxes/atoms format]]). It is the same format used by [[QuickTime]] and [[MP4]], but with different terminology.

== Identification ==
Most JPEG 2000-related files (but not the codestream format) begin with bytes <code>00 00 00 0c 6a 50 20 20 0d 0a 87 0a</code>.

This byte sequence represents a box of type "<code>jP  </code>" (JPEG 2000 signature), which contains an arbitrary 4-byte signature (<code>0d 0a 87 0a</code>).

== Brands ==
The JPEG 2000 file formats (except [[JPEG 2000 codestream]]) use a concept called ''brands''. (The term ''profile'' is sometimes used as a synonym for ''brand'', but this can be confusing because ''profile'' is also used to mean any subformat, regardless of whether it has a corresponding brand.)

A brand corresponds to one of the major file formats (JP2, JPX, etc.), or a defined subformat of one of them. Each brand is assigned an identifier consisting of [[FourCC|four ASCII characters]].

Every JPEG 2000 file has a primary brand, indicating the major file format it is based on. The primary brand's identifier usually appears in the file at offset 20.

A file also has a ''compatibility list'', containing any number of brands. The compatibility list usually begins at offset 28.

See [[Boxes/atoms format#Brands]] for more information about brands.

=== Known brands ===
{| class="wikitable"
! Identifier
! Description
! Reference
|-
|"<code>jp2 </code>" || JP2 || JP2 specification
|-
|"<code>jpx </code>" || JPX || JPX specification
|-
|"<code>jpxb</code>" || Baseline JPX || JPX specification
|-
|"<code>jpm </code>" || JPM || JPM specification
|-
|"<code>mjp2</code>" || Motion JPEG 2000 || MJ2 specification
|-
|"<code>mj2s</code>" || Motion JPEG 2000 Simple Profile || MJ2 specification
|}

== Specifications ==
See also the articles about the specific file formats. The most important specifications are not freely available, but the committee drafts are.
* [https://web.archive.org/web/20150711211900/http://old.jpeg.org/jpeg2000/CDs15444.html JPEG 2000 Committee Drafts]
* [http://www.itu.int/rec/T-REC-T.800/en ITU-T Rec. T.800]: JPEG 2000 (Part 1): Core coding system (not free to download)
** [https://web.archive.org/web/20150711211900/http://old.jpeg.org/public/15444-1annexi.pdf Annex I: JP2 file format syntax]
* [http://www.itu.int/rec/T-REC-T.801/en ITU-T Rec. T.801]: JPEG 2000 (Part 2): Extensions (not free to download)
** [https://web.archive.org/web/20150711211900/http://old.jpeg.org/public/15444-2annexm.pdf Annex M: JPX extended file format Syntax]
** [https://web.archive.org/web/20150711211900/http://old.jpeg.org/public/15444-2annexn.pdf Annex N: JPX file format extended metadata definition and syntax]
* [http://www.itu.int/rec/T-REC-T.802/en ITU-T Rec. T.802]: JPEG 2000 (Part 3): Motion JPEG 2000 (not free to download)
* [http://www.itu.int/rec/T-REC-T.803/en ITU-T Rec. T.803]: JPEG 2000 (Part 4): Conformance testing
** [http://www.openjpeg.org/conformance/T.803e.pdf Documentation only]
* [http://www.itu.int/rec/T-REC-T.804/en ITU-T Rec. T.804]: JPEG 2000 (Part 5): Reference software
* [http://www.itu.int/rec/T-REC-T.805/en ITU-T Rec. T.805]: JPEG 2000 (Part 6): Compound image file format
* [http://www.itu.int/rec/T-REC-T.807/en ITU-T Rec. T.807]: JPEG 2000 (Part 8): Secure JPEG 2000
* [http://www.itu.int/rec/T-REC-T.808/en ITU-T Rec. T.808]: JPEG 2000 (Part 9): Interactivity tools, APIs and protocols
* [http://www.itu.int/rec/T-REC-T.809/en ITU-T Rec. T.809]: JPEG 2000 (Part 10): Extensions for three-dimensional data
* [http://www.itu.int/rec/T-REC-T.810/en ITU-T Rec. T.810]: JPEG 2000 (Part 11): Wireless
* [http://www.itu.int/rec/T-REC-T.812/en ITU-T Rec. T.812]: JPEG 2000: An entry level JPEG 2000 encoder
* [http://www.itu.int/rec/T-REC-T.813/en ITU-T Rec. T.813]: JPEG 2000: XML structural representation and reference
* RFC 3745: MIME Type Registrations for JPEG 2000
* ISO/IEC 15444

== Software ==
* [[Konvertor]]
* [http://www.openjpeg.org/ OpenJPEG]
* [http://www.ece.uvic.ca/~frodo/jasper/ JasPer]
* [https://github.com/cureos/csj2k CSJ2K]
* [https://github.com/GrokImageCompression/grok Grok]
* [https://github.com/faceless2/jpeg2000 jpeg2000] (fork of JJ2000, based on Sun JAI adaptation with JAI dependency removed)
* [[XnView]]
* [[Wikipedia:Kakadu (software)|Kakadu]]

== Sample files ==
* [http://www.opf-labs.org/format-corpus/jp2k-formats/ JPEG 2000 sample images]

== Links ==
* [http://www.jpeg.org/jpeg2000/ JPEG 2000 standard]
* [[Wikipedia:JPEG 2000]]
* [http://blogs.loc.gov/digitalpreservation/2013/01/is-jpeg-2000-a-preservation-risk/ Is JPEG-2000 a preservation risk?]
* [http://wiki.dpconline.org/images/7/70/JP2_Assessment_v1.3.pdf File format assessment (British Library)]

JPEG 2000

2018-08-22T16:22:17Z

Johanvanderknijff: /* Specifications */ Replaced links on old.jpeg.org (which is not online anymore) with corresponding WayBack links

{{FormatInfo
|formattype=electronic
|subcat=Graphics
|thiscat=JPEG 2000
|extensions={{ext|jp2}}, {{ext|jpf}}, {{ext|jpx}}, {{ext|jpm}}, {{ext|mj2}}, others
|mimetypes={{mimetype|image/jp2}}, {{mimetype|image/jpx}}, {{mimetype|image/jpm}}, {{mimetype|video/mj2}}
}}
'''JPEG 2000''' (or '''JPEG2000''') is standard that defines a [[wavelet compression|wavelet-based]] raster image compression format, and a family of associated file formats, protocols, etc. (For the older JPEG-1, see [[JPEG]].)

For details about specific formats, see:
* [[JPEG 2000 codestream]]
* [[JP2]] (base still image format)
* [[JPX]] (extended still image format)
* [[JPM]] (compound image format)
* [[MJ2]] (motion JPEG 2000)

== Disambiguation ==
'''JPEG 2000''' is sometimes incorrectly used as a synonym for '''JP2''', and vice versa. Although JP2 might be the most important part of the JPEG 2000 standard, it is only one small part of it.

In some contexts, '''JPEG 2000''' is used to mean the compressed codestream format, instead of the whole standard.

The terms '''JPEG 2000''' and '''JPEG2000''' (with and without a space) seem to be used interchangeably. The parts of the official specification that are freely available use only '''JPEG 2000''', so that is probably the preferred form. But it must have been settled on late in the standardization process: even some of the committee drafts prefer '''JPEG2000'''.

== Details ==
The JPEG 2000 standard consists of many parts, including:
* Part 1: Core coding system. Defines [[JPEG 2000 codestream]] format and the [[JP2]] file format.
* Part 2: Extensions. Defines [[JPX]].
* Part 3: [[MJ2|Motion JPEG 2000 (MJ2)]]
* Part 6: [[JPM|Compound image file format (JPM)]]
* Part 8: JPSEC
* Part 9: JPIP
* Part 10: JP3D
* Part 11: JPWL
* Part 12: [[ISO Base Media File Format]]

== Format ==
At the highest level, JPEG 2000 files (JP2, JPX, JPM, and MJ2, but not the codestream format) consist of a hierarchical sequence of tagged "boxes" ([[boxes/atoms format]]). It is the same format used by [[QuickTime]] and [[MP4]], but with different terminology.

== Identification ==
Most JPEG 2000-related files (but not the codestream format) begin with bytes <code>00 00 00 0c 6a 50 20 20 0d 0a 87 0a</code>.

This byte sequence represents a box of type "<code>jP  </code>" (JPEG 2000 signature), which contains an arbitrary 4-byte signature (<code>0d 0a 87 0a</code>).

== Brands ==
The JPEG 2000 file formats (except [[JPEG 2000 codestream]]) use a concept called ''brands''. (The term ''profile'' is sometimes used as a synonym for ''brand'', but this can be confusing because ''profile'' is also used to mean any subformat, regardless of whether it has a corresponding brand.)

A brand corresponds to one of the major file formats (JP2, JPX, etc.), or a defined subformat of one of them. Each brand is assigned an identifier consisting of [[FourCC|four ASCII characters]].

Every JPEG 2000 file has a primary brand, indicating the major file format it is based on. The primary brand's identifier usually appears in the file at offset 20.

A file also has a ''compatibility list'', containing any number of brands. The compatibility list usually begins at offset 28.

See [[Boxes/atoms format#Brands]] for more information about brands.

=== Known brands ===
{| class="wikitable"
! Identifier
! Description
! Reference
|-
|"<code>jp2 </code>" || JP2 || JP2 specification
|-
|"<code>jpx </code>" || JPX || JPX specification
|-
|"<code>jpxb</code>" || Baseline JPX || JPX specification
|-
|"<code>jpm </code>" || JPM || JPM specification
|-
|"<code>mjp2</code>" || Motion JPEG 2000 || MJ2 specification
|-
|"<code>mj2s</code>" || Motion JPEG 2000 Simple Profile || MJ2 specification
|}

== Specifications ==
See also the articles about the specific file formats. The most important specifications are not freely available, but the committee drafts are.
* [https://web.archive.org/web/20150711211900/http://old.jpeg.org/jpeg2000/CDs15444.html JPEG 2000 Committee Drafts]
* [http://www.itu.int/rec/T-REC-T.800/en ITU-T Rec. T.800]: JPEG 2000 (Part 1): Core coding system (not free to download)
** [https://web.archive.org/web/20150711211900/http://old.jpeg.org/public/15444-1annexi.pdf Annex I: JP2 file format syntax]
* [http://www.itu.int/rec/T-REC-T.801/en ITU-T Rec. T.801]: JPEG 2000 (Part 2): Extensions (not free to download)
** [https://web.archive.org/web/20150711211900/http://old.jpeg.org/public/15444-2annexm.pdf Annex M: JPX extended file format Syntax]
** [https://web.archive.org/web/20150711211900/http://old.jpeg.org/public/15444-2annexn.pdf Annex N: JPX file format extended metadata definition and syntax]
* [http://www.itu.int/rec/T-REC-T.802/en ITU-T Rec. T.802]: JPEG 2000 (Part 3): Motion JPEG 2000 (not free to download)
* [http://www.itu.int/rec/T-REC-T.803/en ITU-T Rec. T.803]: JPEG 2000 (Part 4): Conformance testing
** [http://www.openjpeg.org/conformance/T.803e.pdf Documentation only]
* [http://www.itu.int/rec/T-REC-T.804/en ITU-T Rec. T.804]: JPEG 2000 (Part 5): Reference software
* [http://www.itu.int/rec/T-REC-T.805/en ITU-T Rec. T.805]: JPEG 2000 (Part 6): Compound image file format
* [http://www.itu.int/rec/T-REC-T.807/en ITU-T Rec. T.807]: JPEG 2000 (Part 8): Secure JPEG 2000
* [http://www.itu.int/rec/T-REC-T.808/en ITU-T Rec. T.808]: JPEG 2000 (Part 9): Interactivity tools, APIs and protocols
* [http://www.itu.int/rec/T-REC-T.809/en ITU-T Rec. T.809]: JPEG 2000 (Part 10): Extensions for three-dimensional data
* [http://www.itu.int/rec/T-REC-T.810/en ITU-T Rec. T.810]: JPEG 2000 (Part 11): Wireless
* [http://www.itu.int/rec/T-REC-T.812/en ITU-T Rec. T.812]: JPEG 2000: An entry level JPEG 2000 encoder
* [http://www.itu.int/rec/T-REC-T.813/en ITU-T Rec. T.813]: JPEG 2000: XML structural representation and reference
* RFC 3745: MIME Type Registrations for JPEG 2000
* ISO/IEC 15444

== Software ==
* [[Konvertor]]
* [http://www.openjpeg.org/ OpenJPEG]
* [http://www.ece.uvic.ca/~frodo/jasper/ JasPer]
* [https://github.com/cureos/csj2k CSJ2K]
* [https://github.com/GrokImageCompression/grok Grok]
* [[XnView]]
* [[Wikipedia:Kakadu (software)|Kakadu]]

== Sample files ==
* [http://www.opf-labs.org/format-corpus/jp2k-formats/ JPEG 2000 sample images]

== Links ==
* [http://www.jpeg.org/jpeg2000/ JPEG 2000 standard]
* [[Wikipedia:JPEG 2000]]
* [http://blogs.loc.gov/digitalpreservation/2013/01/is-jpeg-2000-a-preservation-risk/ Is JPEG-2000 a preservation risk?]
* [http://wiki.dpconline.org/images/7/70/JP2_Assessment_v1.3.pdf File format assessment (British Library)]

IIQ

2018-01-31T15:33:06Z

Johanvanderknijff:

IIQ

2018-01-30T18:52:16Z

Johanvanderknijff:

{{FormatInfo
|formattype=electronic
|subcat=Cameras and Digital Image Sensors
|extensions={{ext|iiq}}, {{ext|tif}}
|pronom={{PRONOM|fmt/1061}}
}}
'''IIQ Raw''' is a proprietary raw image format developed by [https://en.wikipedia.org/wiki/Phase_One_(company) Phase One]. Structurally, an IIQ Raw image is a valid [[TIFF]] image. The actual raw image content is embedded in a TIFF MakerNote tag. Readers that cannot process the contents of this MakerNote tag will read a IIQ Raw image as a regular TIFF. However, such readers will only be able to read the TIFF-compatible image data (usually a lower-quality preview).

There are two variations on the format: a lossless ''IIQ Large'' format, and an ''IIQ Small'' format, which the [https://help.phaseone.com/en/CO8/Output/File-formats/Capture-One-and-RAW.aspx Phase One website describes as] 'not 100% lossless'.

== Identification ==

Since IIQ Raw is structurally identical to a TIFF, magic-based identification tools like Unix file and Apache Tika identify these files as <code>image/tiff</code>. Exiftool is able to correctly identify the format:

<code>

<File:FileType>IIQ</File:FileType>

<File:MIMEType>image/x-raw</File:MIMEType>

</code>

== Specifications ==

{{FormatInfo
|formattype=electronic
|subcat=Cameras and Digital Image Sensors
|extensions={{ext|iiq}}, {{ext|tif}}
|pronom={{PRONOM|fmt/1061}}
}}
'''IIQ Raw''' is a proprietary raw image format developed by [https://en.wikipedia.org/wiki/Phase_One_(company) Phase One]. Structurally, an IIQ Raw image is a valid [[TIFF]] image. The actual raw image content is embedded in a TIFF MakerNote tag. Readers that cannot process the contents of this MakerNote tag will read a IIQ Raw image as a regular TIFF. However, such readers will only be able to read the TIFF-compatible image data (usually a lower-quality preview).

There are two variations on the format: a lossless ''IIQ Large'' format, and an ''IIQ Small'' format, which the Phase One website describes as 'not 100% lossless'.

== Identification ==

Since IIQ Raw is structurally identical to a TIFF, magic-based identification tools like Unix file and Apache Tika identify these files as <code>image/tiff</code>. Exiftool is able to correctly identify the format:

<code>

<File:FileType>IIQ</File:FileType>
<File:MIMEType>image/x-raw</File:MIMEType>

</code>

== Specifications ==

== Software ==
* [https://en.wikipedia.org/wiki/Capture_One Capture One]
* See also [[Cameras and Digital Image Sensors#Software|Cameras and Digital Image Sensors: Software]]

== Sample files ==

== Links ==
* [https://captureintegration.com/tif-vs-iiq/ .TIF vs .IIQ]
* [https://help.phaseone.com/en/CO8/Output/File-formats/Capture-One-and-RAW.aspx RAW and Output File Formats] (Phase One website)
* [http://u88.n24.queensu.ca/exiftool/forum/index.php?topic=3071.0 Phase One .IIQ raw files] (thread in ExifTool forum)
* [http://www.multipole.org/discourse-server/viewtopic.php?t=26495 IIQ RAW images / generic RAW support] (thread in ImageMagick forum)
* [https://sno.phy.queensu.ca/~phil/exiftool/TagNames/PhaseOne.html Phase One Tags]

Cameras and Digital Image Sensors

2018-01-30T17:33:59Z

Johanvanderknijff: /* Raw image formats */ Added separate item for Phase One IIQ Raw (don't have any info on .cap, .eip and to what extent they are different, so left them as they are)

{{FormatInfo
|formattype=electronic
|thiscat=Cameras and Digital Image Sensors
|locfdd={{LoCFDD|fdd000241}}
|image=Old-camera-1352392502n6P.jpg
}}
Specialized formats (mainly raw image formats) used by digital cameras and scanners

''See also:''
* [[Graphics]]
* [[Scientific Data formats]] - Telescope, microscope, and other formats
* [[Geospatial]]
* [[Health and Medicine]] - Medical imaging

== Raw image formats ==
(Unprocessed data from digital image sensors, usually digital cameras)

* [[Arriflex D-20]]: .ari
* [[BAY]] (Casio)
* [[Camera Image File Format]] (CIFF) as used by Canon: .crw
* [[Canon RAW 2]]: .cr2
* [[CHDK raw]]: (Older-style CHDK RAW files)
* [[DNG]] (Digital Negative): .dng (Adobe)
* [[Epson ERF]]
* [[Fujifilm RAF]]
* [[Hasselblad 3FR]]
* [[HDRiRAW]]
* [[Imacon 3F]]: .fff
* [[Kodak]]: .dcs, .dcr, .drf, .k25, .kdc
* [[Leaf MOS]]
* [[Leica]]: .raw, .rw2, .dng
* [[Logitech]]: .pxn
* [[Lytro]]: .lfp
* [[Mamiya MEF]]
* [[Minolta MDC (Minolta RD-175)]]
* [[Minolta MRW]]
* [[Mitsubishi DJ-1000]]: .dat
* [[Nikon]]: .nef, .nrw, .ndf
* [[Nokia digital pictures]]: .nrw
* [[Olympus ORF]]
* [[Panasonic RAW/RW2]]: .raw, .rw2
* [[Pentax PEF]]
* Phase One [[IIQ]] Raw
* [[Phase One]]: .cap, .eip
* [[Porst]]
* [[Rawzor]]: .rwz
* [[RED digital pictures]]: .r3d
* [[Rollei RDC]]: .rdc
* [[Samsung SRW]]
* [[Sony ARW]]
* [[Sony SRF]]
* [[Sony SR2]] ({{PRONOM|fmt/1126}})
* [[TIFF/EP]] (ISO 12234-2)
* [[X3F]] (Sigma / Foveon)

== Other formats ==

* [[AAE sidecar format]] - Adjustment data
* [[Canon EOS C300 Custom Picture Profile]] (CPF) - Camera settings
* [[Canon XF-AVC]] (video)
* [[DCF]]
* [[DNG camera profile]]
* [[J6I]] - Ricoh Digital Camera image file
* [[PCO B16]] - Image format used by PCO software
* [[PSF (PhotoStudio)]] - Image format used by Canon software
* [[Sony Mavica 411]] - Thumbnail image
* [[ZoomBrowser Ex thumbnail cache]]

== Software ==
Most of the software listed here is based on dcraw.

* [http://www.cybercom.net/~dcoffin/dcraw/ dcraw]
** [http://www.cybercom.net/~dcoffin/dcraw/#others dcraw's list of other raw photo decoders]
* [[Konvertor]]
* [http://libopenraw.freedesktop.org/wiki/ libopenraw]
* [http://www.libraw.org/ LibRaw]
* [http://ufraw.sourceforge.net/ UFRaw]
* [[Netpbm]]: cameratopam
* [[XnView]]
* [http://rawtherapee.com/ RawTherapee]
* [http://rawstudio.org/ Rawstudio]
* [https://www.darktable.org/ darktable]
* [http://rawspeed.org/ RawSpeed]
* [http://www.sno.phy.queensu.ca/~phil/exiftool/ ExifTool]
* [http://www.exiv2.org/ Exiv2]

== Sample files ==
* [http://www.rawsamples.ch/index.php/en/ Raw Samples: sample files from many digital camera formats]
* https://github.com/drewnoakes/metadata-extractor-images

== Links ==
* [[Wikipedia:Raw image format|Wikipedia: Raw image format]]
* [http://lewiscollard.com/cameras/hdr-sucks/ HDR is stupid and it sucks]
* [http://opensource.samsung.com/ Samsung source code (including for their digital cameras)]
* [http://teacherdudebbq.blogspot.co.uk/2012/07/riot-photographers-decalogue.html How to photograph riots]
* [http://imgur.com/gallery/Kl0nI World's first digital camera (1975)]
* [http://www.openraw.org/ OpenRAW] - A mostly-defunct initiative to lobby for the documentation of RAW formats
** [http://www.openraw.org/info/index.html The RAW Problem]
* [http://www.dpconline.org/blog/personal-digital-preservation-richard-wright Personal Digital Preservation: Photographs and Video]

IIQ

2018-01-30T17:30:31Z

Johanvanderknijff:

IIQ

2018-01-30T17:28:58Z

Johanvanderknijff: Created page with "{{FormatInfo |formattype=electronic |subcat=Cameras and Digital Image Sensors |extensions={{ext|iiq}}, {{ext|tif}} |pronom={{PRONOM|fmt/1061}} }} '''IIQ Raw''' is a proprietar..."

Lotus 1-2-3

2017-09-18T12:02:51Z

Johanvanderknijff: Added file extension (.123) for Lotus 97/9.x format

{{FormatInfo
|formattype=electronic
|subcat=Document
|extensions={{ext|wks}}, {{ext|wk1}}, {{ext|wk2}}, {{ext|wk3}}, {{ext|wk4}}, {{ext|123}}
|mimetypes={{mimetype|application/vnd.lotus-1-2-3}}
|pronom={{PRONOM|x-fmt/116}}, {{PRONOM|x-fmt/117}}, {{PRONOM|x-fmt/114}}, {{PRONOM|x-fmt/115}}
|released=1983-01-26
}}
'''Lotus 1-2-3''' was regarded as the "killer app" of the IBM PC in its early days, just as [[VisiCalc]] was for the Apple II platform. Both were spreadsheets which used a similar interface, still familiar to modern spreadsheet users, consisting of a matrix of rows and columns where the columns have letters and the rows have numbers, and a cell can be addressed by an address such as "B2".

After years of dominance of the spreadsheet market for PC/MS-DOS, 1-2-3 failed to successfully move over to the Windows platform, and was eclipsed by [[XLS|Microsoft Excel]]. Making 1-2-3 part of a new "Lotus SmartSuite" didn't help bring it back to prominence. When 1-2-3 was finally officially discontinued in 2013 (by IBM, which now owns Lotus), the general reaction was "What, they still made 1-2-3 until now? I thought it died a long time ago."

The original 1-2-3 files had a .wks extension. Version 2.0 originally used a .wk1 extension, but that was soon changed to .wk2, and from then on the number in the extension corresponded to the program version number. [[Lotus Symphony]] (the '80s version, not the unrelated 2000s version which used a variant of Open Office format) used a similar file format.

== Format specs ==
* [http://www.schnarff.com/file-formats/lotus-1-2-3/WSFF1.TXT Spec introduction]
* [http://www.schnarff.com/file-formats/lotus-1-2-3/WSFF2.TXT Summary of record types]
* [http://www.schnarff.com/file-formats/lotus-1-2-3/WSFF3.TXT Cell format encoding]
* [http://www.schnarff.com/file-formats/lotus-1-2-3/WSFF4.TXT The Formula Compiler]
* [http://www.schnarff.com/file-formats/lotus-1-2-3/WSFF5.TXT 1985 addendum]

== End of support ==
IBM officially ceased its support for Lotus 123 on 30 September 2014 (see the [http://www-01.ibm.com/common/ssi/cgi-bin/ssialias?subtype=ca&infotype=an&appname=iSource&supplier=897&letternum=ENUS913-091 announcement here]). This also applies to its SmartSuite and Organizer products.

== Support by modern spreadsheet software ==
Support of the Lotus 1-2-3 formats has shown a steady decline over recent years. Although older versions of Microsoft Excel were able to read (some of?) these formats, Excel 2010 doesn't support any of them anymore, as shown in [http://office.microsoft.com/en-us/excel-help/file-formats-that-are-supported-in-excel-HP010352464.aspx#BMunsupportedformats this overview of unsupported formats] on Microsoft's website. Meanwhile, OpenOffice only supports the old (.wk1, .wks and .123) versions of the format ([https://wiki.openoffice.org/wiki/Documentation/OOo3_User_Guides/Getting_Started/File_formatslist source here]). No specific info could be found on LibreOffice, but the situation is probably identical to OpenOffice.

== Sample files ==
* [http://www.opf-labs.org/format-corpus/office/spreadsheet/wk1/ Version 2.0 (WK1) samples]
* [http://www.opf-labs.org/format-corpus/office/spreadsheet/wk3/ Version 3.0 (WK3) samples]
* [ftp://ftp.lotus.com/product_information/123weval.zip ZIP file on Lotus FTP site with some WK1 and WK3 files]

== Import/export info ==
* [http://support.microsoft.com/kb/61941 Tips for Importing Lotus 1-2-3 Files to Excel]
* [http://support.sas.com/documentation/cdl/en/acpcref/63184/HTML/default/viewer.htm#a003103772.htm Interfacing with 1-2-3 files in SAS/ACCESS]
* [http://download.cnet.com/Fantastic-Lotus-1-2-3-Converter/3000-2065_4-75758879.html Lotus 1-2-3 converter] (commercial software with free trial)

== See also ==
* [[Lotus 1-2-3 Chart]]

== Other links ==
* [[Wikipedia:Lotus 1-2-3|Wikipedia article]]
* [http://www.zdnet.com/goodbye-lotus-1-2-3-7000015385/ Goodbye, Lotus 1-2-3]
* [ftp://ftp.lotus.com/ Lotus FTP site] (Archived version [https://archive.org/details/2012_11_24_ftp_lotus_com here]) - many resources on Lotus products, including documentation, sample files, software.
* [https://medium.com/backchannel/a-spreadsheet-way-of-knowledge-8de60af7146e A Spreadsheet Way of Knowledge]

[[Category:IBM]]

PDF

2017-09-13T15:29:21Z

Johanvanderknijff: /* Sample files */

{{FormatInfo
|formattype=electronic
|subcat=Document
|extensions={{ext|pdf}}
|mimetypes={{mimetype|application/pdf}}
|locfdd={{LoCFDD|fdd000146}}, others
|pronom={{PRONOM|fmt/276}}, others
}}
'''Portable Document Format''' ('''PDF''') is a document file format originally from Adobe, based on [[PostScript]]. It has many subsets.

As well as the 'full function' ISO 32000-1:2008 (or PDF 1.7), there are also PDF/X, PDF/A, PDF/E, PDF/VT and PDF/UA, all of which are ISO specifications.

PDF profiles (formalized subsets) include the following:

* PDF/A (optimized for preservation)
** PDF/A-1 (ISO 19005-1:2005)
** PDF/A-2 (ISO 19005-2:2011)
** PDF/A-3 (ISO 19005-3:2012) (extends PDF/A-2 by allowing embedded files of any type)
* PDF/E (ISO 24517-1:2008) (for engineering workflows)
* PDF/UA (ISO 14289-1) (making documents accessible through assistive technologies)
* PDF/VT (ISO 16612-2) (support for variable document printing)
* PDF/X (support for prepress graphics exchange)
** PDF/X-1 (ISO 15930-1:2001)
** PDF/X-1a (ISO 15930-4:2003)
** PDF/X-2 (ISO 15930-5:2003)
** PDF/X-3 (ISO 15930-6:2003)
* Tagged PDF

A PDF 2.0 spec is under development with some new features as well as clarification of conformance with existing features.

== Identifiers ==
{| class="wikitable"
! Format
! PRONOM
! LoCFDD
|-
|PDF || || {{LoCFDD|fdd000146}}
|-
|PDF 1.0 || {{PRONOM|fmt/14}} ||rowspan="4"| {{LoCFDD|fdd000316}}
|-
|PDF 1.1 || {{PRONOM|fmt/15}}
|-
|PDF 1.2 || {{PRONOM|fmt/16}}
|-
|PDF 1.3 || {{PRONOM|fmt/17}}
|-
|PDF 1.4 || {{PRONOM|fmt/18}} || {{LoCFDD|fdd000122}}
|-
|PDF 1.5 || {{PRONOM|fmt/19}} || {{LoCFDD|fdd000123}}
|-
|PDF 1.6 || {{PRONOM|fmt/20}} || {{LoCFDD|fdd000276}}
|-
|PDF 1.7 || {{PRONOM|fmt/276}} || {{LoCFDD|fdd000277}}
|-
|PDF 1.7, Ext. 3 || || {{LoCFDD|fdd000313}}
|-
|PDF/A || || {{LoCFDD|fdd000318}}
|-
|PDF/A-1 || || {{LoCFDD|fdd000125}}
|-
|PDF/A-1a || {{PRONOM|fmt/95}} || {{LoCFDD|fdd000251}}
|-
|PDF/A-1b || {{PRONOM|fmt/354}} || {{LoCFDD|fdd000252}}
|-
|PDF/A-2 || || {{LoCFDD|fdd000319}}
|-
|PDF/A-2a || {{PRONOM|fmt/476}} || {{LoCFDD|fdd000320}}
|-
|PDF/A-2b || {{PRONOM|fmt/477}} || {{LoCFDD|fdd000322}}
|-
|PDF/A-2u || {{PRONOM|fmt/478}} || {{LoCFDD|fdd000321}}
|-
|PDF/A-3a || {{PRONOM|fmt/479}} ||rowspan="3"| {{LoCFDD|fdd000360}}
|-
|PDF/A-3b || {{PRONOM|fmt/480}}
|-
|PDF/A-3u || {{PRONOM|fmt/481}}
|-
|PDF/X-1 || {{PRONOM|fmt/144}}, {{PRONOM|fmt/145}} ||rowspan="9"| {{LoCFDD|fdd000124}}
|-
|PDF/X-1a || {{PRONOM|fmt/157}}, {{PRONOM|fmt/146}}
|-
|PDF/X-2 || {{PRONOM|fmt/147}}
|-
|PDF/X-3 || {{PRONOM|fmt/158}}, {{PRONOM|fmt/148}}
|-
|PDF/X-4 || {{PRONOM|fmt/488}}
|-
|PDF/X-4p || {{PRONOM|fmt/489}}
|-
|PDF/X-5g || {{PRONOM|fmt/490}}
|-
|PDF/X-5pg || {{PRONOM|fmt/491}}
|-
|PDF/X-5n || {{PRONOM|fmt/492}}
|-
|PDF/UA-1 || || {{LoCFDD|fdd000350}}
|-
|PDF/E-1 || {{PRONOM|fmt/493}}
|-
|PDF, Geospatial || || {{LoCFDD|fdd000315}}
|-
|GeoPDF 2.2 || || {{LoCFDD|fdd000312}}
|}

== Identification ==
The majority of PDF files can be identified by a fixed header e.g. "%PDF-1.4", however, older documents have a number of variations.
* Some can start with "%!PS-Adobe-N.n PDF-M.m" instead, as described [http://blog.didierstevens.com/2010/01/21/quickpost-pdf-header-ps-adobe-n-n-pdf-m-m/ here].
* Since PDF 1.7, the major and minor version numbers have been fixed. i.e. the public version from Adobe after 1.7 was "1.7 Adobe Extension Level 3".
* For the PDF/A families of formats, their conformance is declared via an embedded ([[XMP]]) metadata fragment.
* Some older files from Mac OS may be wrapped up in the [[AppleSingle]]/[[AppleDouble]] formats. This is a general issue, so should perhaps be documented elsewhere. For more information, see:
** http://en.wikipedia.org/wiki/AppleSingle_and_AppleDouble_formats
** http://tools.ietf.org/rfc/rfc1740.txt

== Compression ==
Images in PDF documents may use the following compression schemes:
* [[LZW]]
* Flate ([[zlib]])
* [[Run-length encoding|RunLength]]
* CCITTFax ([[CCITT Group 3]] and [[CCITT Group 4]])
* [[JBIG2]]
* DCT ([[JPEG]])
* [[JPX]] (part of the [[JPEG 2000]] standard)

== Digital Rights Management & Encryption ==
PDF has two types of 'encryption' - it uses an 'user' password to limit the ability to open the document, and a 'creator' password to limit other rights, like printing, copying, etc. The former case, where a password is required to open the file, is the main preservation concern, as our users will not be able to open a PDF encrypted in this way (unless the password can be cracked, which may be problematic both technically and legally). However, the latter case causes problems, because the PDF is encrypted here too, but with a special known user password of "" (an empty string, which is not the same as no password). So, the document is encrypted in both cases, and you can only tell which is which by attempting to decrypt the PDF using the special default password "". Some PDF analysis tools (notably [[JHOVE]]) do not implement the relevant decryption workflow, and so cannot distinguish between the two types of encryption.

An example of the decryption test workflow can be found here: https://gist.github.com/anjackson/5237071

Some of the most locked-up PDFs anywhere can be found at the [http://ibr.ansi.org/ ANSI IBR Standards Portal], which has made certain standards documents that are incorporated into legislation available for browsing, but only through a convoluted procedure involving downloading a special plug-in and filling out a registration form that must be re-filled-out in every browsing session.

A "Protected PDF" (PPDF) format is [http://www.eweek.com/mobile/microsoft-enterprise-mobility-suite-cozies-up-to-office.html reportedly] used by Microsoft's Azure Rights Management Service for sharing files securely within a workgroup.

== Specifications ==
* [http://acroeng.adobe.com/wp/?page_id=321 Adobe PDF References] Contains links to every version of the PDF Reference published by Adobe (starting with PDF 1.0) as well as associated errata, addenda and tech notes.
* Other sources of the above documents:
** [http://www.adobe.com/devnet/pdf/pdf_reference.html PDF Reference and Adobe Extensions to the PDF Specification] Adobe page linking to specification for PDF 1.7 (equivalent to ISO 32000-1:2008) and two Adobe extensions that are expected to be incorporated into ISO 32000-2. These extensions include support for geospatial features and for 3-D content using [[U3D]] and [[Adobe PRC|PRC]] formats.
** [http://www.adobe.com/devnet/pdf/pdf_reference_archive.html Adobe PDF Reference Archives.] Archive of specifications for earlier Adobe versions of PDF, starting with Version 1.3.

== Software ==
* [http://get.adobe.com/reader/ Adobe Reader] views PDF files, either as a standalone program or a browser plugin.
* [http://www.mozilla.org/en-US/products/download.html?product=firefox-19.0&os=win&lang=en-US Firefox 19.0] includes a built-in PDF reader.
* [http://source.mozillaopennews.org/en-US/articles/introducing-tabula/ Tabula: convert tabular data in PDFs to CSV]
* [http://www.mpdf1.com/mpdf/index.php mPDF: convert HTML to PDF]
* [http://en.pdf24.org/ PDF24 creator]
* [http://pdfbox.apache.org/ Apache PDFBox] is an open-source PDF library that includes a PDF/A validator
* [https://pdfium.googlesource.com/pdfium/ pdfium: Open source PDF rendering engine]
* [http://textract.readthedocs.org/en/latest/ Textract: extract text from various document formats including PDF]
* [https://github.com/pramodhkp/pdf2svg/ pdf2svg (in JavaScript)]
* [https://euske.github.io/pdfminer/programming.html Programming with PDFMiner]
* [https://github.com/friesey/preservation-tools/releases/tag/v0.1_alpha_PDFBox_Statistics PDFBox PDF/A Validator]
* [https://pypi.python.org/pypi/PyPDF2/1.24 PyPDF2]
* [https://github.com/sumatrapdfreader Sumatra PDF Reader]
* [https://chrome.google.com/webstore/detail/pdf-viewer/oemmndcbldboiebfnladdacbdfmadadm?hl=en PDF viewer for Chrome]
* [http://verapdf.org/software/ veraPDF library (PDF validator)]
* [http://www.metachris.com/pdfx/ PDFx - Extract metadata and URLs from PDFs, and download all referenced PDFs]
* [https://github.com/ANSSI-FR/caradoc Caradoc: PDF parser and validator]
* [https://github.com/uds-datalab/PDBF PBDF: Create documents that are simultaneously valid PDF, HTML, and VirtualBox OVA.]
* [https://blog.didierstevens.com/programs/pdf-tools/ PDF Tools]

== Online utilities ==
* [http://www.pdf4kindle.com/ PDF to Kindle converter]
* [https://pdftables.com/ PDF to Excel (and some other formats)]

== Sample files ==
* [https://github.com/openplanets/format-corpus/tree/master/pdfCabinetOfHorrors PDF Cabinet of Horrors] - sample PDF files in corrupted or otherwise problematic formats
* [http://acroeng.adobe.com/wp/?page_id=10 Adobe PDF Test Suites] - various PDF test suites on Adobe Acrobat Engineering site
* [http://craphound.com/homeland/Cory_Doctorow_-_Homeland.pdf Homeland by Cory Doctorow]
* [http://www.dan.info/sampledata/msword/testing.pdf Sample document saved from Windows Word 2007]
* [https://github.com/corkami/pocs/blob/master/pdf/quine.pdf Quine PDF; contains its own TeX source]
* [https://www.alchemistowl.org/pocorgtfo/pocorgtfo08.pdf Newsletter designed to work as PDF, ZIP, or shell script]
* [https://github.com/veraPDF/veraPDF-corpus veraPDF corpus]
* [https://github.com/osnr/horrifying-pdf-experiments Horrifying PDF Experiments]
* [https://github.com/mozilla/pdf.js/tree/master/test/pdfs Test PDFs used by Mozilla PDF Reader]
* [https://github.com/pdf-association/pdf20examples PDF 2.0 example files by the PDF Association]

== See also ==
* [[Ascii85]]
* [[FDF]]
* [[PostScript]]
* [[WWF]]
* [[XFDF]]

== Links ==

=== Format info ===
* [http://en.wikipedia.org/wiki/Portable_Document_Format Portable Document Format (Wikipedia)]
* [http://www.forensicswiki.org/wiki/PDF Forensics Wiki: PDF]
*[http://acroeng.adobe.com/wp/ Adobe Acrobat Engineering site] - Dedicated Adobe site with lots of technical information, including a history of PDF and Acrobat, conforming viewers and test files.
* [http://www.pdfa.org/2013/04/pdfa-in-a-nutshell-2_0/ PDF/A in a Nutshell 2.0 – online edition]
* [http://www.infinitepartitions.com/cgi-bin/showarticle.cgi?article=art019 Inside the PDF File Format]
* [http://imgur.com/a/PbN8H#7 PDF101 an Adobe document walkthrough]

=== Validation ===
* [http://vimeopro.com/pdfassociation/technical-conference-europe-2013/video/68945979 PDF Validation: Dream or Yawn?] - Presentation on possibilities of an open-source PDF validator
* [http://www.docdroid.net/ciex/5103a198-1.pdf.html The pitfalls of protocol design: Attempting to write a formally verified PDF parser]
* [https://fileformats.wordpress.com/2015/04/22/verapdf/ New open-source file validation project]

=== Jailbreaking ===
* [http://scholrev.org/hackathon/ Jailbreaking the PDF hackathon]
* [http://blogs.ch.cam.ac.uk/pmr/2013/05/28/jailbreaking-the-pdf-a-wonderful-hackathon-and-a-community-leap-forward-for-freedom-1/ Jailbreaking the PDF (discussion)]
* [http://blogs.ch.cam.ac.uk/pmr/2013/05/28/jailbreaking-the-pdf-2-technical-aspects-glyph-processing/ Jailbreaking the PDF (technical aspects: glyph processing)]
* [http://blog.didierstevens.com/2015/04/15/pdf-password-cracking-with-john-the-ripper/ PDF Password Cracking With John The Ripper]

=== Commentary ===
* [http://www.portico.org/digital-preservation/wp-content/uploads/2012/11/TheNetworkIsTheFormat.pdf The Network is the Format: PDF and the Long-term Use of Digital Content] Article by Sheila Morrissey of ITHAKA on the challenges of preserving PDF files based on experience. She illustrates the challenge of defining a "sufficient sub-graph of the network of information about a digital object, for effective future use."
* [http://blogs.loc.gov/digitalpreservation/2014/06/the-pdfs-place-in-a-history-of-paper-knowledge-an-interview-with-lisa-gitelman/ The PDF’s Place in a History of Paper Knowledge: An Interview with Lisa Gitelman]
*[http://wiki.opf-labs.org/display/TR/Portable+Document+Format Portable Document Format on OPF File Format Risk Registry] - Lists various long-term accessibility issues in PDF and how to detect them using Apache Preflight.
* [http://www.openplanetsfoundation.org/system/files/PDFInventoryPreservationRisks_0_2_0.pdf Adobe Portable Document Format - Inventory of long-term preservation risks] - Report by KB/ National Library of the Netherlands.
* [http://fileformats.wordpress.com/2014/06/13/abuses-pdf/ The uses and abuses of PDF]
* [http://duff-johnson.com/2014/04/07/apples-preview-still-not-safe-for-work/ Apple’s Preview: Still not safe for work]
* [http://www.niso.org/publications/isq/2013/v25no3/moore/ Preserving the Grey Literature Explosion: PDF/A and the Digital Archive]
* [http://www.pdfa.org/2014/12/ensuring-long-term-access-pdf-validation-with-jhove/ Ensuring long-term access: PDF validation with JHOVE?]
* [http://www.theguardian.com/higher-education-network/2015/feb/11/researchers-its-time-to-ditch-the-pdf Researchers: it's time to ditch the PDF]
* [http://wiki.dpconline.org/images/5/51/PDF_Assessment_v1.2_external.pdf PDF Format Preservation Assessment (British Library)]
* [http://www.pdfa.org/2015/06/what-will-pdf-2-0-bring/ What will PDF 2.0 bring?]
* [http://www.digitalpreservation.gov/ndsa/working_groups/documents/NDSA_PDF_A3_report_final022014.pdf?loclr=blogsig The Benefits and Risks of the PDF/A-3 file format for archival institutions]
* [https://nicolastreeten.wordpress.com/2015/09/19/becoming-of-age-pdf/ Becoming of Age: PDF (comic)]
* [http://www.pdfa.org/2016/06/what-does-support-pdf-really-mean/ What does "support PDF" really mean?]
* [http://openpreservation.org/blog/2016/12/09/pdfa-as-a-preferred-sustainable-format-for-spreadsheets/ PDF/A as a preferred, sustainable format for spreadsheets?]

=== Miscellaneous ===
* [http://www.pdfa.org/ PDF/A Competence Center]
* [http://web.archive.org/web/20130515073645/http://libraries.stackexchange.com/questions/964/what-preservation-risks-are-associated-with-the-pdf-file-format What preservation risks are associated with the PDF file format?] - Q&A thread from Libraries and Information Sciences Stack Exchange (archived)
* [http://labs.appligent.com/files/2013/03/recognizing_malformed_pdf_f.pdf Recognizing Corrupt and Malformed PDF Files]
* [https://github.com/davetaz/mh370-data Flight MH370 data was released as a PDF, but somebody extracted it to CSV to make it more useful for data analysis.]
* [https://pdf.yt/ PDFy - free host for publicly viewable PDFs, backed up automatically to Internet Archive]
* [http://www.washingtonpost.com/blogs/the-switch/wp/2014/08/05/uk-judge-says-freedom-of-information-means-choice-of-digital-file-format/ UK judge says ‘freedom of information’ means choice of digital file format]
* [http://blogs.perl.org/users/peter_martini/2014/08/the-chimera-quine-or-the-iso-pdf.html The Chimera Quine; or, the ISO PDF]
* [http://openplanetsfoundation.org/blogs/2014-08-12-coming-preserving-pdf-identify-validate-repair-hamburg PDF info/links for attendees of conference on it]
* [http://anjackson.github.io/keeping-codes/experiments/does-jhove-validate-pdfa-files Does JHOVE validate PDF/A files?]
* [http://raywoodcockslatest.wordpress.com/2014/12/04/pdf-repair/ Methods of Repairing Corrupted or Damaged PDFs]
* [http://stackoverflow.com/questions/17740175/how-do-i-dump-embedded-icc-profile-information-in-pdf-command-line-or-gui-tool/27464166#27464166 How do I dump embedded ICC profile information in PDF? (command line or GUI tools)]
* [http://stackoverflow.com/questions/27938551/how-to-check-pdf-pages-for-resolution-dpi-of-embedded-images/27942530 How to check PDF pages for resolution (DPI) of embedded images?]
* [http://chemxseer.ist.psu.edu/about/digital_library/das08-liu.pdf A Fast Preprocessing Method for Table Boundary Detection: Narrowing Down the Sparse Lines using Solely Coordinate Information]
* [https://github.com/angea/PDF101/tree/master/handcoded/textextract Why text extracting doesn't work for all PDFs]
* [http://stackoverflow.com/questions/29342542/how-can-i-extract-a-javascript-from-a-pdf-file-with-a-command-line-tool/29364036 How can I extract a JavaScript from a PDF file with a command line tool?]
* [http://stackoverflow.com/questions/29331731/postscript-code-to-un-hide-hidden-text-in-pdf/29334742 How to un-hide hidden text in PDF]
* [http://www.pdfa.org/2015/04/infographics-pdfua-and-wcag-2-0/ Infographics: PDF/UA and WCAG 2.0]
* [http://www.prepressure.com/pdf/basics/history The history of PDF] according to prepressure.com, a site for "prepress & print devotees".
* [https://isc.sans.edu/diary/Handling+Special+PDF+Compression+Methods/19597 Handling Special PDF Compression Methods]
* [https://speakerdeck.com/ange/lets-write-a-pdf-file Let's write a PDF file]
* [https://blog.didierstevens.com/2016/06/07/recovering-a-ransomed-pdf/ Recovering a ransomed PDF]
* [https://github.com/digital-preservation/droid/issues/114 PDF version numbers based on deprecated mechanism]
* [https://madfileformatscience.garymcgath.com/2016/09/26/pdf-version/ Figuring out the PDF version is harder than you think]
* [https://www.pdfa.org/slides-and-video-recordings-of-the-pdf-days-europe-2017/ Slides and video recordings of the PDF Days Europe 2017]

[[Category:Page description languages]]
[[Category:Adobe]]

ISO 9660

2017-09-06T15:52:12Z

Johanvanderknijff: /* Reading */

{{FormatInfo
|formattype=electronic
|subcat=Filesystem
|extensions={{ext|iso}}
|mimetypes={{mimetype|application/x-iso9660-image}}
|kaitai struct=iso_9660
}}
'''ISO 9660''' is a read-only [[filesystem]] often used on [[CD-ROM|CD-ROMs]]. It is also common to encounter files containing an [[ISO image|image]] of an ISO 9660 filesystem.

== Details ==
The standard limits filenames to the DOS 8.3 style. Several extensions – [[TRANS.TBL]], [[Rock Ridge]], and [[Joliet]] – were developed to remove this restriction.

The filenames also have a VMS-style version number, so sometimes they are shown with a ";1" suffix.

The size of a file is limited to 4GB (2GB in some implementations). This is irrelevant with respect to CD-ROMs, because of their small capacity, but it is a reason to avoid using ISO 9660 on [[DVD-ROM|DVD-ROMs]] and other media. (An extension called "multiple extents" makes larger files possible, but support for it is limited.)

== Identification ==
Usually, the ASCII string "<code>CD001</code>" appears at offset 32769.

The first 32768 bytes are not used. Be aware that hybrid filesystems are possible. Just because something is a valid ISO 9660 filesystem doesn't mean it can't also be a valid filesystem of some other type.

== See also ==
* [[ISO image]]
* [[Universal Disk Format]] (UDF) - The successor to ISO 9660

== Software ==
=== Reading ===
* [[7-Zip]], [http://unix.stackexchange.com/questions/70738/what-is-the-fastest-way-to-extract-an-iso see here for an example]
* [http://linux.die.net/man/1/isoinfo isoinfo] can perform basic operations and some validation.
* Operating systems often include drivers for ISO 9660. On Linux, an ISO 9660 image file can be mounted using a loopback driver (<code>mount -t iso9660 -o loop ...</code>).
* [https://github.com/KBNLresearch/isolyzer isolyzer] is a tool that verifies if the file size of an ISO image is consistent with the information in its filesystem-level headers. This can be useful for detecting incomplete (e.g. truncated) ISO images. Apart from ISO 9660, isolyzer also supports UDF, HFS and HFS+, as well as hybrids of all of these filesystems.

=== Writing ===
* [http://www.cdrkit.org/ cdrkit] → genisoimage
* Countless CD burning applications

== Links ==
* [[Wikipedia:ISO 9660|Wikipedia: ISO 9660]]
* [[Wikipedia:TRANS.TBL|Wikipedia: TRANS.TBL]]
* [[Wikipedia:Rock Ridge|Wikipedia: Rock Ridge]]
* [[Wikipedia:Joliet_(file_system)|Wikipedia: Joliet]]

ISO 9660

2017-09-06T15:51:26Z

Johanvanderknijff: /* Reading */

{{FormatInfo
|formattype=electronic
|subcat=Filesystem
|extensions={{ext|iso}}
|mimetypes={{mimetype|application/x-iso9660-image}}
|kaitai struct=iso_9660
}}
'''ISO 9660''' is a read-only [[filesystem]] often used on [[CD-ROM|CD-ROMs]]. It is also common to encounter files containing an [[ISO image|image]] of an ISO 9660 filesystem.

== Details ==
The standard limits filenames to the DOS 8.3 style. Several extensions – [[TRANS.TBL]], [[Rock Ridge]], and [[Joliet]] – were developed to remove this restriction.

The filenames also have a VMS-style version number, so sometimes they are shown with a ";1" suffix.

The size of a file is limited to 4GB (2GB in some implementations). This is irrelevant with respect to CD-ROMs, because of their small capacity, but it is a reason to avoid using ISO 9660 on [[DVD-ROM|DVD-ROMs]] and other media. (An extension called "multiple extents" makes larger files possible, but support for it is limited.)

== Identification ==
Usually, the ASCII string "<code>CD001</code>" appears at offset 32769.

The first 32768 bytes are not used. Be aware that hybrid filesystems are possible. Just because something is a valid ISO 9660 filesystem doesn't mean it can't also be a valid filesystem of some other type.

== See also ==
* [[ISO image]]
* [[Universal Disk Format]] (UDF) - The successor to ISO 9660

== Software ==
=== Reading ===
* [[7-Zip]], [http://unix.stackexchange.com/questions/70738/what-is-the-fastest-way-to-extract-an-iso see here for an example]
* [http://linux.die.net/man/1/isoinfo isoinfo] can perform basic operations and some validation.
Operating systems often include drivers for ISO 9660. On Linux, an ISO 9660 image file can be mounted using a loopback driver (<code>mount -t iso9660 -o loop ...</code>).
* [https://github.com/KBNLresearch/isolyzer isolyzer] is a tool that verifies if the file size of an ISO image is consistent with the information in its filesystem-level headers. This can be useful for detecting incomplete (e.g. truncated) ISO images. Apart from ISO 9660, isolyzer also supports UDF, HFS and HFS+, as well as hybrids of all of these filesystems.

=== Writing ===
* [http://www.cdrkit.org/ cdrkit] → genisoimage
* Countless CD burning applications

== Links ==
* [[Wikipedia:ISO 9660|Wikipedia: ISO 9660]]
* [[Wikipedia:TRANS.TBL|Wikipedia: TRANS.TBL]]
* [[Wikipedia:Rock Ridge|Wikipedia: Rock Ridge]]
* [[Wikipedia:Joliet_(file_system)|Wikipedia: Joliet]]

Universal Disk Format

2017-09-06T15:50:33Z

Johanvanderknijff: Added isolyzer link

{{FormatInfo
|formattype=electronic
|subcat=Filesystem
}}
:''"UDF" redirects here. For another UDF format, see [[Softdisk Publishing UDF files]].''

'''Universal Disk Format''' ('''UDF''') is a filesystem often used on [[DVD-ROM|DVD-ROMs]] (and other optical disc formats, such as [[Blu-ray Disc]]s), but which is suitable for general purposes. Informally, it is the successor to [[ISO 9660]].

It uses [[Endianness|little-endian]] byte order format, as people sometimes find out [https://twitter.com/bitsgalore/status/878226563778699265 the hard way].

== See also ==
* [[ISO image]]
* [[ISO 9660]]

== Software ==
* [http://sourceforge.net/projects/linux-udf/ udftools]
Operating systems often include drivers for UDF. On Linux, a UDF image file can be mounted using a loopback driver (<code>mount -r -t udf -o loop ...</code>).
* [https://github.com/KBNLresearch/isolyzer isolyzer] is a tool that verifies if the file size of an ISO image is consistent with the information in its filesystem-level headers. This can be useful for detecting incomplete (e.g. truncated) ISO images. Supported filesystems include UDF (as well as ISO 9660, HFS, HFS+, and hybrids of all of these filesystems).

== Links ==
* [[Wikipedia:Universal Disk Format|Wikipedia article]]
* [http://www.blu-raydisc.com/Assets/Downloadablefile/3_filesystem-15265.pdf Documentation of Blu-ray Disc filesystem]

ISO 9660

2017-09-06T15:47:56Z

Johanvanderknijff: Updated description and URL for Isolyzer

{{FormatInfo
|formattype=electronic
|subcat=Filesystem
|extensions={{ext|iso}}
|mimetypes={{mimetype|application/x-iso9660-image}}
|kaitai struct=iso_9660
}}
'''ISO 9660''' is a read-only [[filesystem]] often used on [[CD-ROM|CD-ROMs]]. It is also common to encounter files containing an [[ISO image|image]] of an ISO 9660 filesystem.

== Details ==
The standard limits filenames to the DOS 8.3 style. Several extensions – [[TRANS.TBL]], [[Rock Ridge]], and [[Joliet]] – were developed to remove this restriction.

The filenames also have a VMS-style version number, so sometimes they are shown with a ";1" suffix.

The size of a file is limited to 4GB (2GB in some implementations). This is irrelevant with respect to CD-ROMs, because of their small capacity, but it is a reason to avoid using ISO 9660 on [[DVD-ROM|DVD-ROMs]] and other media. (An extension called "multiple extents" makes larger files possible, but support for it is limited.)

== Identification ==
Usually, the ASCII string "<code>CD001</code>" appears at offset 32769.

The first 32768 bytes are not used. Be aware that hybrid filesystems are possible. Just because something is a valid ISO 9660 filesystem doesn't mean it can't also be a valid filesystem of some other type.

== See also ==
* [[ISO image]]
* [[Universal Disk Format]] (UDF) - The successor to ISO 9660

== Software ==
=== Reading ===
* [[7-Zip]], [http://unix.stackexchange.com/questions/70738/what-is-the-fastest-way-to-extract-an-iso see here for an example]
* [http://linux.die.net/man/1/isoinfo isoinfo] can perform basic operations and some validation.
Operating systems often include drivers for ISO 9660. On Linux, an ISO 9660 image file can be mounted using a loopback driver (<code>mount -t iso9660 -o loop ...</code>).
* [https://github.com/KBNLresearch/isolyzer] is a tool that verifies if the file size of an ISO image is consistent with the information in its filesystem-level headers. This can be useful for detecting incomplete (e.g. truncated) ISO images. Apart from ISO 9660, isolyzer also supports UDF, HFS and HFS+, as well as hybrids of all of these filesystems.

=== Writing ===
* [http://www.cdrkit.org/ cdrkit] → genisoimage
* Countless CD burning applications

== Links ==
* [[Wikipedia:ISO 9660|Wikipedia: ISO 9660]]
* [[Wikipedia:TRANS.TBL|Wikipedia: TRANS.TBL]]
* [[Wikipedia:Rock Ridge|Wikipedia: Rock Ridge]]
* [[Wikipedia:Joliet_(file_system)|Wikipedia: Joliet]]

ISO 9660

2017-01-17T14:09:51Z

Johanvanderknijff: /* Reading */ Added Isolyzer reference

{{FormatInfo
|formattype=electronic
|subcat=Filesystem
|extensions={{ext|iso}}
|mimetypes={{mimetype|application/x-iso9660-image}}
}}
'''ISO 9660''' is a read-only [[filesystem]] often used on [[CD-ROM|CD-ROMs]]. It is also common to encounter files containing an [[ISO image|image]] of an ISO 9660 filesystem.

== Details ==
The standard limits filenames to the DOS 8.3 style. Several extensions – [[TRANS.TBL]], [[Rock Ridge]], and [[Joliet]] – were developed to remove this restriction.

The filenames also have a VMS-style version number, so sometimes they are shown with a ";1" suffix.

The size of a file is limited to 4GB (2GB in some implementations). This is irrelevant with respect to CD-ROMs, because of their small capacity, but it is a reason to avoid using ISO 9660 on [[DVD-ROM|DVD-ROMs]] and other media. (An extension called "multiple extents" makes larger files possible, but support for it is limited.)

== Identification ==
Usually, the ASCII string "<code>CD001</code>" appears at offset 32769.

The first 32768 bytes are not used. Be aware that hybrid filesystems are possible. Just because something is a valid ISO 9660 filesystem doesn't mean it can't also be a valid filesystem of some other type.

== See also ==
* [[ISO image]]
* [[Universal Disk Format]] (UDF) - The successor to ISO 9660

== Software ==
=== Reading ===
* [[7-Zip]], [http://unix.stackexchange.com/questions/70738/what-is-the-fastest-way-to-extract-an-iso see here for an example]
* [http://linux.die.net/man/1/isoinfo isoinfo] can perform basic operations and some validation.
Operating systems often include drivers for ISO 9660. On Linux, an ISO 9660 image file can be mounted using a loopback driver (<code>mount -t iso9660 -o loop ...</code>).
* [https://github.com/KBNLresearch/verifyISOSize isolyzer] is a tool that verifies if the file size of an ISO image is consistent with the information in its Primary Volume Descriptor. For hybrid images that contain both an ISO 9660 file system and an Apple partition, the expected file size is calculated using the information in the partition table (zero block) or the master directory block. This can be useful for detecting incomplete (e.g. truncated) ISO images.

=== Writing ===
* [http://www.cdrkit.org/ cdrkit] → genisoimage
* Countless CD burning applications

== Links ==
* [[Wikipedia:ISO 9660|Wikipedia: ISO 9660]]
* [[Wikipedia:TRANS.TBL|Wikipedia: TRANS.TBL]]
* [[Wikipedia:Rock Ridge|Wikipedia: Rock Ridge]]
* [[Wikipedia:Joliet_(file_system)|Wikipedia: Joliet]]

WebP

2016-11-06T14:20:07Z

Johanvanderknijff: /* Links */

{{FormatInfo
|formattype=electronic
|subcat=Graphics
|extensions={{ext|webp}}
|mimetypes={{mimetype|image/webp}} (unregistered)
|pronom={{PRONOM|fmt/566}}, {{PRONOM|fmt/567}}, {{PRONOM|fmt/568}}
|released=2010
}}
'''WebP''' is an image file format developed by Google, primarily intended for use on web pages.

It can use either lossy or lossless compression. Its lossy compression is based on portions of the [[VP8]] video compression format.

It uses the [[RIFF]] container format.

== Identification ==
Files begin with bytes <code>'R' 'I' 'F' 'F' ?? ?? ?? ?? 'W' 'E' 'B' 'P'</code>.

== Software ==
* [[Konvertor]]
* libwebp: [https://developers.google.com/speed/webp/download download] · [http://www.webmproject.org/code/#webp-repositories development]
* [https://www.google.com/chrome/ Google Chrome] can display WebP images

== Links ==
* [https://developers.google.com/speed/webp/ Google's WebP page]
* [[Wikipedia:WebP|Wikipedia article]]
* [http://xooyoozoo.github.io/yolo-octo-bugfixes/ Online demonstrator] - shows quality differences between similarly-sized images in [[JPEG]], [[JP2]], [[WebP]] and [[BPG]] formats
* [https://medium.com/@duhroach/how-webp-works-lossly-mode-33bd2b1d0670 How WebP works (lossly mode)]

[[Category:RIFF based file formats]]
[[Category:Google]]

PNG

2016-11-06T14:17:06Z

Johanvanderknijff: /* Links */

{{FormatInfo
|formattype=electronic
|subcat=Graphics
|extensions={{ext|png}}
|mimetypes={{mimetype|image/png}}
|locfdd={{LoCFDD|fdd000153}}
|pronom={{PRONOM|fmt/13}}, {{PRONOM|fmt/12}}, {{PRONOM|fmt/11}}
|released=1996
}}
'''Portable Network Graphics''' ('''PNG''') was devised starting in a discussion on newsgroup ''comp.graphics'' in 1995, with the first version of its specification released in 1996. The motivation for its creation was to create a free and unencumbered image format in the wake of the patent issue with [[GIF]].

PNG has become a very popular graphic format, but widespread adoption on the Web was slow due to the fact that the first specification came out over a year after the Web had begun to be popular with the general public, meaning that there were many sites and browsers out there not using and supporting the new format; subsequently, browsers began to support it, but often had rendering problems which persisted even in fairly late versions years later; this caused webmasters to be slow to switch from GIF to PNG, though some are doing so now. Since the [[LZW]] patent that affected GIF is expired now, the "free format" motivation for the switch no longer applies.

Unlike GIF, PNG officially supports only still graphics, not animation. However [[APNG]], an unofficial extension of the PNG image format that retains the .png file extention does support animation. Another related format, [[MNG]], officially does support animation.

== Format ==

A PNG file consists of an 8-byte signature (hex <code>89 50 4E 47 0D 0A 1A 0A</code>), followed by a sequence of "chunks". Each chunk has an 8-byte header, 4 bytes of which indicate the chunk length, and 4 bytes of which are a [[FourCC|chunk type code]] indicating the type of data stored in the chunk. Each chunk also has a 4-byte trailer which stores a checksum.

== Extensions ==
{| class="wikitable"
! Chunk type
! References
|-
|oFFs, pCAL, sCAL, gIFg, gIFx, gIFt, fRAc || Refer to [http://pmt.sourceforge.net/specs/pngext-1.2.0-pdg-h20.html Extensions to the PNG 1.2 Specification, v1.2.0].
|-
|sTER || Refer to [ftp://ftp.simplesystems.org/pub/libpng/png/documents/pngext-1.3.0-pdg.html Extensions to the PNG 1.2 Specification, v1.3.0].
|-
|dSIG || Refer to [ftp://ftp.simplesystems.org/pub/libpng/png/documents/pngext-1.4.0-pdg.html Extensions to the PNG 1.2 Specification, v1.4.0], and the [http://png-dsig.sourceforge.net/ PNG dSIG website].
|-
|acTL, fcTL, fdAT || Used in [[APNG]] files.
|-
|vpAg || Used by [[ImageMagick]].
|-
|CgBI || Refer to [[CgBI]].
|}

== Related Formats ==

* [[zlib]]-style [[DEFLATE]] compression: Used to compress image and other data.
* [[CRC-32]]: Used to calculate a checksum of each chunk.
* [[ICC profile]]: The format used by iCCP chunks.
* [[MNG]]
* [[APNG]]
* [[CgBI]]
* [[Portable Bitmap Format]]

== Specifications ==
* [http://www.w3.org/TR/PNG/ W3C PNG specification] (latest version)
** Specific versions: [http://www.w3.org/TR/REC-png-961001 1996-10-01] · [http://www.w3.org/TR/2003/PR-PNG-20030520/ 2003-05-20] · [http://www.w3.org/TR/2003/REC-PNG-20031110/ 2003-11-10]
* RFC 2083: PNG Specification Version 1.0
* [http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=29581 ISO/IEC 15948:2004] (not free to download)

== Metaformat files ==

* [https://www.synalysis.net/Grammars/png.grammar Synalysis grammar file] (for Hexinator / Synalize It!; [[Synalysis grammar file|more details]])

== Software ==
* [http://www.libpng.org/pub/png/libpng.html libpng] and [http://www.zlib.net/ zlib]
* [http://coptr.digipres.org/Bad_Peggy Bad Peggy: scans images for problems]
* [[Konvertor]]

== Sample files ==
* [http://www.libpng.org/pub/png/png-sitemap.html#images PNG Images]

== Links ==
* [http://www.libpng.org/pub/png/png.html PNG website]
* [[Wikipedia:Portable Network Graphics|Portable Network Graphics (Wikipedia)]]
* {{EGFF|png|PNG File Format Summary}}, from the [[Encyclopedia of Graphics File Formats]]
* [http://www.forensicswiki.org/wiki/Portable_Network_Graphics_%28PNG%29 Forensics Wiki article]
* [http://imgur.com/a/MtQZv#7 PNG format mini-poster]
* [https://mattscodecave.com/posts/plaidctf-2015---corrupt-png How to repair a PNG that has suffered DOS->Unix character conversion]
* [http://blog.codinghorror.com/getting-the-most-out-of-png/ Getting the Most Out of PNG (Jeff Atwood)]
* [https://medium.com/@duhroach/how-png-works-f1174e3cc7b7#.n3l0wota6 How PNG Works]

JSON

2016-10-27T09:50:13Z

Johanvanderknijff: /* Other links */

{{FormatInfo
|formattype=electronic
|subcat=Serialization
|extensions={{ext|json}}
|mimetypes={{mimetype|application/json}}
}}
'''JSON''' (JavaScript Object Notation) is widely used by web applications, mobile apps, and other programs to communicate between different systems (such as between a client and server). While it is named after [[JavaScript]], there are libraries for many other programming and scripting languages to let them use this format as well. The geospatial format [[GeoJSON]] is based on JSON, as is the remote-procedure-call protocol [[JSON-RPC]] and the [[JSON-LD]] linked-data format. The IBM standard of [[JSONx]] is an [[XML]] implementation of JSON. [[I-JSON]] is a restricted profile of JSON for Internet use.

== Format ==

JSON is a very simply-defined format for representing data in text-based form using a few simple types, including two "compound types" which can be nested:

* '''number''': A decimal number, optionally including a decimal point or exponential notation. Leading zeroes are not allowed unless the only number before the decimal point is a single zero, or the number is equal to zero. (Other formats and programming languages may call these ''int'', ''float'', ''double'', ''long'', etc.)

* '''string''': A string of ([[Unicode]]) characters surrounded by double quotes ("). The only characters not allowed directly (without escaping) are double quotes, backslashes, or control characters; a backslash can be used to precede a quote or backslash used as a character within the string, as well as \b for backspace, \f for formfeed, \n for newline, \r for carriage return, \t for tab, and \u followed by 4 hexadecimal digits for encoding any Unicode character in the 0000-FFFF range. (Other formats and programming languages may call these ''string'' or ''array of char'').

* ''true'', ''false'', or ''nil'' are permitted as typeless values. (Other formats and programming languages may put these into boolean or pointer types.)

* '''object''': An associative array consisting of names and values, where the name and value are separated by a colon (:), the name/value pairs are separated by commas, and the whole object is surrounded by curly braces {}. The name is a (double-quoted) string, and the value can be any of the data types in JSON including another object. There is no inherent ordering to the values of an object. (Other formats and programming languages may call these ''associative arrays'', ''hashes'', or ''dictionaries''.)

* '''array''': An ordered collection of values, which can each be any of the JSON data types, and are separated by commas and surrounded by square brackets []. (Other formats and programming languages may call these ''arrays'' or ''lists''.)

== JSONP ==

'''JSONP''' is a variant of JSON, "padded" with additional [[JavaScript]] code to permit the entire data set to be a valid piece of JS code able to be imported via a <code><script></code> statement for execution. Generally the extra code will be a function call encompassing the JSON data as its parameter, but sometimes it will be a variable assignment or other code. This gets around security restrictions in browser implementations of JavaScript which limit use of external data loaded from other sites (script statements can reference outside URLs), making it both very powerful and very dangerous if misused.

== JSON Pointer ==

JSON Pointer (described in RFC 6901) is a syntax for referencing a specific value within a JSON document.

== See also ==
* [[CoffeeScript-Object-Notation]]
* [[Cursive Script Object Notation]]
* [[GeoJSON]]
* [[Hjson]]
* [[I-JSON]]
* [[JSON API]]
* [[JSON-LD]]
* [[JSON-RPC]]
* [[JSON Table Schema]]
* [[JSONx]]

== Specs and schemas ==

* [http://www.json.org/ Official website] (includes spec and links to libraries in many languages)
* [http://json-schema.org/ JSON Schema]
* [http://www.ecma-international.org/publications/standards/Ecma-404.htm ECMA-404]
* RFC 4627

== Sample data ==

* [http://parltrack.euwiki.org/dumps/ Data from European Parliament in JSON form] (Source: [http://parltrack.euwiki.org/ ParlTrack])

== Utilities ==

* [http://pro.jsonlint.com/ Linter/Validator]
* [http://www.pal-blog.de/entwicklung/perl/2013/quick-json-pretty-reformatter-json-tidy.html Quick JSON pretty reformatter / JSON-tidy]
* [https://github.com/ChimeraCoder/gojson gojson: A simple command-line tool for manipulating JSON for use in developing Go code] (generates [[Go]] structures from JSON)
* [http://golang.org/pkg/encoding/json/ Go package to encode/decode JSON]
* [http://stedolan.github.io/jq/ jq: command line JSON processor]
* [http://papaparse.com/ PapaParse: in-browser conversions between CSV and JSON]
* [http://textract.readthedocs.org/en/latest/ Textract: extract text from various document formats including JSON]

== Other links ==

* [[Wikipedia:JSON|Wikipedia: JSON]]
* [[Wikipedia:JSONP|Wikipedia: JSONP]]
* [http://www.infoq.com/news/2013/04/JSON-Validation?utm_medium=referral&utm_source=t.co JSON Validation Roundup]
* [http://stackoverflow.com/questions/2669690/why-does-google-prepend-while1-to-their-json-responses Why does Google prepend while(1); to their JSON responses?]
* [http://www.w3.org/TR/csv2json/ Generating JSON from tabular data on the Web (W3C)]
* [http://seriot.ch/parsing_json.html Parsing JSON is a Minefield] - in test with 30 JSON parsers no two parsers showed the same behaviour

JSON

2016-10-27T09:48:58Z

Johanvanderknijff: /* Other links */

CD

2016-10-10T11:10:17Z

Johanvanderknijff: /* Imaging/Ripping CDs */

{{FormatInfo
|formattype=physical
|subcat=Optical Discs
|thiscat=CD
|released=1982
}}
The '''CD''' (Compact Disc) is a popular medium for recorded sound as well as computer data. It is a laser-read optical disc. Discs of the same size were later used for the [[DVD]] and [[Blu-ray Disc]] formats, allowing the same player to support all of these formats.

== Types ==
* [[CD-DA]] (Compact Disc Digital Audio or Red Book)
* [[CD-MIDI]]
* [[CD-ROM]] (Yellow Book)
* [[DD-CD]] (Double-density Compact Disc)
* [[Enhanced CD]]
* [[Photo CD]] (Beige Book)
* [[CD-i]] (Green Book)
* [[SACD]] (Super Audio CD or Scarlet Book)
* [[VCD]] (Video CD or White Book)
** [[Super Video CD]]

== Imaging/Ripping CDs ==

* [http://forensicswiki.org/wiki/Category:Disk_Imaging ForensicsWiki:Disk Imaging]
* [https://gist.github.com/bitsgalore/1bea8f015eca21a706e7#file-notescdimaging-md CD imaging notes + sample tool output] by [[User:Johanvanderknijff]]
* Developing a Robust Migration Workflow for Preserving and Curating Hand-held Media [http://anjackson.net/keeping-codes/practice/developing-a-robust-migration-workflow-for-preserving-and-curating-handheld-media.html html], [http://arxiv.org/abs/1309.4932 pdf pre-print].
* [http://wiki.opf-labs.org/display/SPR/Audio+CD+Preservation SPRUCE/OPF Audio CD Preservation]
* [http://blog.kbresearch.nl/2015/11/13/preserving-optical-media-from-the-command-line/ Preserving optical media from the command line]

== Links ==
* [[Wikipedia:Compact disc|Wikipedia article]]
* [http://www.youtube.com/watch?v=ut_40U0t9pU How It's Made: Compact Discs (video)]
* [http://www.digitalmusicnews.com/permalink/2014/03/20/entourage-music-supervisor-throws-out-cds Entourage Music Supervisor Throws Out CDs On The Street]
* [http://www.openplanetsfoundation.org/comment/559 Establishing a Workflow Model for Audio CD Preservation]
* [https://instagram.com/p/1qs52OMeM9/ It turns out that your CD drives really don't like having CDs explode inside them]
* [https://www.gnu.org/software/libcdio/libcdio.html#CD-Formats CD Formats overview] - GNU libcdio documentation
* [http://www.filfre.net/2016/09/a-slow-motion-revolution/ A Slow-Motion Revolution] - History of the CD-ROM (including CD-I)

CD

2016-10-10T11:06:58Z

Johanvanderknijff: /* Links */

{{FormatInfo
|formattype=physical
|subcat=Optical Discs
|thiscat=CD
|released=1982
}}
The '''CD''' (Compact Disc) is a popular medium for recorded sound as well as computer data. It is a laser-read optical disc. Discs of the same size were later used for the [[DVD]] and [[Blu-ray Disc]] formats, allowing the same player to support all of these formats.

== Types ==
* [[CD-DA]] (Compact Disc Digital Audio or Red Book)
* [[CD-MIDI]]
* [[CD-ROM]] (Yellow Book)
* [[DD-CD]] (Double-density Compact Disc)
* [[Enhanced CD]]
* [[Photo CD]] (Beige Book)
* [[CD-i]] (Green Book)
* [[SACD]] (Super Audio CD or Scarlet Book)
* [[VCD]] (Video CD or White Book)
** [[Super Video CD]]

== Imaging/Ripping CDs ==

* [http://forensicswiki.org/wiki/Category:Disk_Imaging ForensicsWiki:Disk Imaging]
* [https://gist.github.com/bitsgalore/1bea8f015eca21a706e7#file-notescdimaging-md CD imaging notes + sample tool output] by [[User:Johanvanderknijff]]
* Developing a Robust Migration Workflow for Preserving and Curating Hand-held Media [http://anjackson.net/keeping-codes/practice/developing-a-robust-migration-workflow-for-preserving-and-curating-handheld-media.html html], [http://arxiv.org/abs/1309.4932 pdf pre-print].
* [http://wiki.opf-labs.org/display/SPR/Audio+CD+Preservation SPRUCE/OPF Audio CD Preservation]

== Links ==
* [[Wikipedia:Compact disc|Wikipedia article]]
* [http://www.youtube.com/watch?v=ut_40U0t9pU How It's Made: Compact Discs (video)]
* [http://www.digitalmusicnews.com/permalink/2014/03/20/entourage-music-supervisor-throws-out-cds Entourage Music Supervisor Throws Out CDs On The Street]
* [http://www.openplanetsfoundation.org/comment/559 Establishing a Workflow Model for Audio CD Preservation]
* [https://instagram.com/p/1qs52OMeM9/ It turns out that your CD drives really don't like having CDs explode inside them]
* [https://www.gnu.org/software/libcdio/libcdio.html#CD-Formats CD Formats overview] - GNU libcdio documentation
* [http://www.filfre.net/2016/09/a-slow-motion-revolution/ A Slow-Motion Revolution] - History of the CD-ROM (including CD-I)

PostScript Printer Description

2016-10-08T17:58:01Z

Johanvanderknijff: Added link to sample files

{{FormatInfo
|formattype=electronic
|subcat=Page description languages
|extensions={{ext|ppd}}
}}
'''[[PostScript]] Printer Description''' ('''PPD''') files describe the capabilities of a printer (paper size, etc).

I mean, sure, the Internet Printing Protocol also describes this, but apparently printers need to describe themselves in both formats.

You can find these files bundled with CUPS, and also extract them from your printer.

PPD files probably begin {{magic|*PPD-Adobe:}}.

== Links ==

* https://wiki.linuxfoundation.org/en/OpenPrinting/Database/PPDDocumentation

== Sample files ==

* http://www.openprinting.org/download/PPD/

CD

2016-09-15T11:24:38Z

Johanvanderknijff: /* Links */

{{FormatInfo
|formattype=physical
|subcat=Optical Discs
|thiscat=CD
|released=1982
}}
The '''CD''' (Compact Disc) is a popular medium for recorded sound as well as computer data. It is a laser-read optical disc. Discs of the same size were later used for the [[DVD]] and [[Blu-ray Disc]] formats, allowing the same player to support all of these formats.

== Types ==
* [[CD-DA]] (Compact Disc Digital Audio or Red Book)
* [[CD-MIDI]]
* [[CD-ROM]] (Yellow Book)
* [[DD-CD]] (Double-density Compact Disc)
* [[Enhanced CD]]
* [[Photo CD]] (Beige Book)
* [[CD-i]] (Green Book)
* [[SACD]] (Super Audio CD or Scarlet Book)
* [[VCD]] (Video CD or White Book)
** [[Super Video CD]]

== Imaging/Ripping CDs ==

* [http://forensicswiki.org/wiki/Category:Disk_Imaging ForensicsWiki:Disk Imaging]
* [https://gist.github.com/bitsgalore/1bea8f015eca21a706e7#file-notescdimaging-md CD imaging notes + sample tool output] by [[User:Johanvanderknijff]]
* Developing a Robust Migration Workflow for Preserving and Curating Hand-held Media [http://anjackson.net/keeping-codes/practice/developing-a-robust-migration-workflow-for-preserving-and-curating-handheld-media.html html], [http://arxiv.org/abs/1309.4932 pdf pre-print].
* [http://wiki.opf-labs.org/display/SPR/Audio+CD+Preservation SPRUCE/OPF Audio CD Preservation]

== Links ==
* [[Wikipedia:Compact disc|Wikipedia article]]
* [http://www.youtube.com/watch?v=ut_40U0t9pU How It's Made: Compact Discs (video)]
* [http://www.digitalmusicnews.com/permalink/2014/03/20/entourage-music-supervisor-throws-out-cds Entourage Music Supervisor Throws Out CDs On The Street]
* [http://www.openplanetsfoundation.org/comment/559 Establishing a Workflow Model for Audio CD Preservation]
* [https://instagram.com/p/1qs52OMeM9/ It turns out that your CD drives really don't like having CDs explode inside them]
* [https://www.gnu.org/software/libcdio/libcdio.html#CD-Formats CD Formats overview] - GNU libcdio documentation