More practically, DVDs and blu-rays are files on a filesystem. An audio CD does not have a filesystem, it's a raw stream of pits and lands, which do not corresp

More practically, DVDs and blu-rays are files on a filesystem. An audio CD does not have a filesystem, it's a raw stream of pits and lands, which do not correspond directly to bits, they must be decoded first. The reason why ripping an audio CD is such an "art" is that without a filesystem there's no easy way to tell where the laser actually is on the disc. If it jumps or skips you might not realise.