IFF

Revision as of 16:50, 29 November 2016

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

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.

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.

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 ".

FORM type cross-reference

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

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

Specifications

• The original EA spec (Another copy at textfiles.com)

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