A dvd format means "mpeg2" audio+video. Your audio stream is usually ac3, or a wav file like pcm. You'll need to convert those avis to mpeg files before you can get them into dvd format, otherwise keep them as VCDs and watch like that. The conversion is heavy on your pc & takes time (& memory). Even then you'll need to re-author the new files into "dvd format"
When going from avi, etc to dvd, make sure to check your dimensions. I noticed a lot of these torrents are smaller (smaller files, of course) but anyone who later wants to burn to dvd later is going to get a degraded image when converting (therefore enlarging...)
DVDshrink only compresses, it doesn't alter. If your sound doesn't play it is becuase the file was authored in a non-standard dvd format. Your PC can roll with the punches & play various formats, but not all dvd players can...Try stripping the audio file out, converting it, then recombining.
That's not as simple as it sounds... :shakeno: