CAF File: What is it?
Apple’s CAF, or Core Audio Format, is an advanced file format with several advantages over the better known WAV and AIFF formats. The CAF file format acts as a wrapper for the audio data. Along with the audio data, it can store markers, channel layout, and many metadata types. CAF audio files are used extensively with Apple loops, such as the ones for Garageband and Logic.
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The CAF file format overcomes file size limitations previously associated with other file types. Basic WAV and AIFF files are restricted to 4GB whereas CAF, for practical purposes, is unlimited (hundreds of years of audio). CAF is supposedly safer when recording the audio as well. When a WAV file stops recording it must update the header’s size field. If the recording was interrupted this could be an issue, possibly making the file unusable.
One CAF can hold multichannels. Perhaps, you have used interleaved stereo WAV or AIFF files, but the CAF can store as many channels as required. It can also store the channel layouts.
How much of an advantage does this file format hold over standard WAV or AIFF files? It could come down to the application. For loops or instances where additional data is advantageous, CAF shines. CAF may also offer advantageous features for audio software developers.
Apple OS X Developer Library: CAF File Overview