Subtitles and Closed Captions
Many karaoke systems use subtitles imposed over a movie of some kind. Programs like kmid and my Java programs play lyrics on some sort of canvas object. This gives a pretty boring background. Video CDs or MPEG-4 files have a nicer background but have the lyrics hard-coded onto the background video, so there is little chance for manipulation of them. CD+G files keep the lyrics separate from the video, but there doesn’t seem to be any way of playing them directly from Linux. They can be converted to MP3+G, and they can be played by VLC, which loads the MP3 file and picks up the corresponding .cdg file.