I don't think the music files are ogg I guess they are dsp files like the ones outside the DAT files maybe the dsp and ogg have something common in their hex which results in the jumbled up audio this obviously is a speculation I have got a open source DAT extractor called dragon unpacker modifying ...

I wanted to replace the music in metal gear solid twin snakes with the original ps1 music on extracting the gc rom the files in the shared/audio/stream and the audio/stream folder are actually dsp files, all the level music and ingame voices(whos there,a surveillance camera,tighten security,mantis r...