Core Audio Format

The Core Audio Format is a container format for storing audio, developed by Apple Inc. It is compatible with Mac OS X 10.4 and higher; Mac OS X 10.3 needs QuickTime 7 to be installed.^[1]

Core Audio Format

Filename extension	.caf
Internet media type	audio/x-caf
Type code	caff
Uniform Type Identifier (UTI)	com.apple.coreaudio-format
Developed by	Apple Inc.
Initial release	2005
Type of format	media container
Container for	digital audio
Website	Apple Core Audio Format Specification 1.0

Core Audio Format is designed to overcome limitations of older digital audio formats, including AIFF and WAV. Just like the QuickTime .mov container, a .caf container can contain many different audio formats, metadata tracks, and much more data. Like the RF64, it is not limited to a 4 GB file size and a single .caf file can theoretically save hundreds of years of recorded audio due to its use of 64-bit file offsets.^[2]

GarageBand, Soundtrack Pro, and Logic Studio use the .caf format for their loop and sound effects library, particularly for surround-sound audio compressed with the Apple Lossless (ALAC) codec. It is also what is used to send Audio Messages over iMessage on iOS and macOS.