weird mythtv behavior (playback)

[usingloser]

I finally got my myth box all setup and working perfectly (almost :S ). The quality on both the video and audio is perfect. Anyway, on my first couple of recordings (recorded to rtjpeg then transcoded to mpeg4 with comercial flagging) I noticed a really weird playback bug. The audio was smooth and clear, and the video sync'ed with it perfectly save for the fact sometimes the audio keeps playing, but its like there isn't video for it. So when it comes to one of these points, the video jumps ahead, but slows way down so that the audio can catch up, and then they resync. Its not a processing power issue, i have a P4 2.7 gighz and 512 meg ram, and not doing anything else on the server when I am watching playback.
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gentoo 4tw