IFF

Latest revision as of 14:39, 23 July 2025

This article is about the generic IFF metaformat. For the IFF image format, see ILBM. For Sun IFF, see Sun TAAC image.

IFF (Interchange File Format) is a general-purpose binary file format introduced by Electronic Arts on the Commodore Amiga computer in 1985. It is sometimes known as IFF 85.

[edit] Format details

An IFF file is composed of elements called "chunks". Each chunk consists of a 4-byte type identifier (represented by four ASCII characters), a 4-byte length, and the chunk's payload data. Some types of chunks contain a sequence of nested chunks. Multi-byte numeric values are big-endian.

IFF defines a number of standard chunks types. Additional types are invented as needed by IFF-based formats.

Of particular significance is chunk type FORM. Most IFF-based files are formatted as a single FORM chunk. A FORM chunk's data contains a four-byte "FORM type" code, indicating the data type, followed by a sequence of nested chunks.

An IFF-based format whose FORM type is xxxx might be referred to as "FORM xxxx". FORM types may also be used as filename extensions.

[edit] Identification

Most IFF files begin with the ASCII characters "FORM". The file type is then indicated by the 4-byte ASCII code beginning at offset 8.

There are also aggregate formats that begin with "LIST" or "CAT ".

[edit] FORM type cross-reference

Selected FORM types, and related articles, are listed below. See also Category:IFF based file formats.

[edit] Variant formats

Some other formats are largely or heavily influenced by the IFF standard, but are not compatible. These include, for example:

• Erlang BEAM compiled modules: Uses 4 byte alignment instead of 2 byte, and the root chunk has a different ID (FOR1 instead of FORM)
• Microsoft's RIFF and RIFX formats are based on IFF (RIFF uses little-endian byte order instead, and the root chunk is called RIFF instead of FORM)
• Apple's AIFF and AIFC formats are similar to IFF/RIFF as well
• Maya IFF
• IFF (The Sims)

[edit] Specifications

• The EA IFF-85 Repository
  • EA IFF 85 - January 14, 1985 (Updated Oct, 1988 Commodore-Amiga, Inc.)
  • A Quick Introduction to IFF
  • IFF Retrospective by Jerry Morrison, 2013
  • 64-bit IFF (abandoned)
• EA IFF 85 (Updated October, 1988 Amiga, Inc.) - From AmigaOS Documentation Wiki
• The original EA spec
  • Another copy at textfiles.com
• IFF.TXT - A concatenation of about a dozen IFF-related documents, from FileFormat.Info

[edit] Sample files

• CTLG: dexvert samples — other/iffCTLG

[edit] Links

• IFF chunk registry, defining all known chunks
• IFF Source Code
• REWiki: .IFF
• IFF File Format Summary, from the Encyclopedia of Graphics File Formats
• 1994 "advanced music formats" discussion that covers some IFF formats
• IBM developerWorks: The Interchange File Format
• IFF file format experiments