A decoded ALAC track is bit-for-bit identical to the original uncompressed sound file. It's proprietary of Apple Inc that widely supported on iTunes, iPhone, iPad, Mac and most iPods. Basically, audios compressed in ALAC is stored in a M4A container. ALAC Converter - How to Convert Audio to Apple Lossless on MacĪLAC, short for Apple Lossless Audio Codec (or simply Apple Lossless), is a data compression method which reduces the size of the audio files with no loss of information for archiving.