I think that there is a problem with "seeking" in general on compressed files. Very few compression algorithms have the property where you can just "land" in a random place in the file and start reading. One problem usually is the ability to "re-sync". A .WAV file can't do this! If you have a huge .WAV file and somehow you get "lost" in the middle of it...there is no way to recover to find the next segment..or at least not that I know of... Some types of linear data structures have "garbage" that you have to read through, but that "garbage" is actually a sync point.