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. The original version, released in 1985, is sometimes known as IFF 85.

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

Most IFF files begin with the ASCII characters "FORM". There are also aggregate formats that begin with "LIST" or "CAT ".

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
• IBM developerWorks: The Interchange File Format