Apple Lossless

Apple Lossless (also known as Apple Lossless Encoder or ALE) is an audio codec developed by Apple Inc., for lossless encoding of digital music.

The Apple Lossless Encoder was introduced in QuickTime 6.5.1 and thus is a feature of iTunes 4.5 on April 28, 2004.

Apple Lossless data is stored within an MP4 container with the filename extension .m4a. Contrary to popular belief (and possibly also due to the extension itself), Apple Lossless is not a variant of AAC, but a wholly new codec. iPods with a dock connector and recent firmware can play Apple Lossless encoded files.

ALE usually results in files that are 50-75% smaller than uncompressed AIFF or WAV files created from the same audio CD.

Sources and References

 * Wikipedia: Apple Lossless