I have an avi file that is quite out of synch in the audio/video. I ran it through virtualdub, added a delay in the audio track, and saved the resulting avi file, which then had no audio/video synch problems.
When I ran it through tmpgenc, using the avi file for both the audio and video input, the resulting mpeg was out of synch. Why did this happen and how do i fix it?

Is it possible to try to manually synch the audio video by introducing a lag in the audio or video when multiplexing an audio file with a video in tmpgenc?

Also using virtualdub, when I try to merge some avi files, the ones that are 29.97 fps merge together with no problem. If the fps is different, then obviously they wont merge. So is there a way to change the fps setting of a file to match that of the other files and if so what will that do to the viewing capabilty of the resulting file (with the changed fps)?