Apple Lossless (also known as ALAC) is an audio codec developed by Apple Inc. for lossless data compression of digital music. Apple Lossless data is stored within an MP4 container with the filename extension .m4a, this extension is also used by Apple for AAC audio data which is a compressed audio encoder. But , Apple Lossless is not a variant of AAC (which is a lossy format), but rather a distinct lossless format that uses linear prediction similar to other lossless codecs such as FLAC. All current iPods and iPhones, along with iTunes version 4.5 or later, can play Apple Lossless-encoded files.
Apple Lossless uses a relatively simple tagging format, which supports Unicode characters (UTF-8). Any ID tag name can be added, yet the maximum length of each tag value is 255 characters. Multiple artists are supported as is embedded album art. However, Apple has not released any technical documents on Apple lossless, 3rd-party manipulation of Apple Lossless files are solely to the reverse engineering work . Apple Lossless files can be decoded at relatively high speed, in comparison to other lossless codecs. It supports 16 bit and 24 bit rates, as well as multi channel audio, such as 5.1.
As iTunes and iPod users, we prefer this codec, and find it flexible and easy to include meta tags. However there are a limited number of software choices to rip, tag, and play audio files, we use the following: