Ive used dvdsanta to rencode an avi movie to dvd. took about 4 hrs, and into the first 15 min of the film the screen gets blocky and the audio is out of sync for the rest of the film. i then read the guide here using tmpeg and ifoedit, total time for this was around 22 hrs, with the exact same problem. why is this happening and what can i do to fix it?