“The Apple Lossless Audio Codec (ALAC) is used to compress the
size of digital audio files without losing any of the original
information, making a decoded ALAC stream ‘bit-for-bit identical to
the original uncompressed audio file’.“Similar to other lossless codecs like FLAC, files are typically
reduced to approximately 50 per cent of their original size. File
formats such as MP3 and AAC are considered to be “lossy”, in that
converting to them results in the loss of some fidelity while
providing much better compression.”