IFF

File Format
Name	IFF
Ontology	Electronic File Formats Metaformats IFF
Extension(s)	.iff, many others
LoCFDD	fdd000115
PRONOM	x-fmt/157
Released	1985

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.

FORM type	Refer to
8SVX	8-Bit Sampled Voice
ACBM	ILBM#ACBM
AIFC	AIFC
AIFF	AIFF
ANIM	ANIM
DEEP	IFF-DEEP
FAXX	FAXX
ILBM	ILBM
LWLO, LWOB, LWO2	LightWave Object
PBM	ILBM#PBM
TDDD	TDDD, Imagine Object File

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