IFF

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

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

IFF (Interchange File Format) is a file format introduced by Electronic Arts on the Commodore Amiga computer. Its structure is similar to RIFF or PNG, using various self-contained chunks to contain different data. Multi-byte numeric values are big-endian.

Although IFF is most commonly used as an image format (using the file extension .iff), it can actually hold a lot of different data types. Some examples of IFF files are

• ILBM Interleaved bitmap image
• XMI XMidi music files
• 8SVX audio sample data
• SX2 Propellerhead Reason NN-XT patches
• ANIM

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

Identification

IFF files begin with the ASCII characters "FORM".

Resources

• The original EA spec (Another copy at textfiles.com)
• IFF chunk registry, defining all known chunks
• IFF Source Code
• REWiki: .IFF
• IFF File Format Summary
• 1994 "advanced music formats" discussion that covers some IFF formats