I've only just looked it up, but it sounds like time compression might not actually remove any of the frames. It removes some of the repeated fields that have to be inserted to bump the 24fps film up to 30fps video. You could save 20 minutes over 2 hours by doing this all the time, but then the film would run 125% quicker and everyone would sound chipmunks

Which leads me to wonder whether the LD->DVDers among us do remove these repeated fields or if they just put 30fps video onto DVD? And if the source has been time compressed, how do you reverse the pulldown?

David