u/Ecstatic-Light9805

I've been going through my library of DVDs trying to digitize them with VLC for preservation purposes, but I've been having some strange issues with the dumped video files. Sometimes the audio will have been cut out or desynced, and parts of the film may play faster or slower than they're supposed to. I tried dumping a DVD copy of the Truman Show and for reason around an hour 10 minutes in, the sound just cuts out and the movie plays faster, shortening it by about 8 minutes. Does anybody know what might be causing these problems and how I may be able to fix them?