Audio dubbing MPGs

[PopChronicles]

Hi!!!!

I capture music videos using the DVC80. I connect my VCR using composite. I use Dazzle Moviestar 5 to record the video. The problem is that my VCR isn't stereo so the audio comes out mono and sounds like crap. So after I convert the AVI to MPG, I use TMPGEnc to overwrite the audio layer with a stereo MP3 of the same song.

Example:

I captured Kelis "Milkshake" video. The audio sucks so I extracted the song from her CD into 192 MP3 and replaced the mono audio layer with the new stereo layer MP3.

There is a problem.

I get the MP3 to play in sync with the video, but slowly but surely it tends to get out of sync! By the end of the video, the audio is off by like 1.5 secs! I don't understand. I use the same song version used in the video, so the audio is the same length so why does it slowly fall out of sync. Any input would be appreciated.

Thanks!!!