If it plays DVD movies, that means it can decode PCM audio and Dolby Digital and probably DTS. However, both DVD-Audio and SACD are a completely different animal, and many DVD players don't have the ability to decode them (a few the former, fewer the latter). Additionally, most machines that can play those formats, output the signal through multiple discrete analog channels (with RCA jacks) to a receiver that has enough inputs to handle them (newer models use HDMI). We have 7 DVD players (including 3 in our computers), and only 2 can handle DVD-Audio, and one can play SACD.
Here's
a wikipedia article on DVD-Audio.