Help with a Burnt movie's Audio

Ok i’ve made backup copys of some dvds and also some ive downloaded… And alot of the movies when i put them into a home dvd player the audio is really messed up… makes a sort of a weird sound and plays throughout the whole movie… sounds really bad and you cant hear the dvd’s audio… When i put it into my computer it works fine. I’ve tried many dvd players and they all do the same . SO i was wondering if you can help me please .