[mythtv-users] Audio sync problems with exported Myth recordings - not with manual recordings

Lane Schwartz dowobeha at gmail.com
Mon Dec 13 21:22:19 UTC 2004

My goal is to archive my PVR-250 MPEG2 recordings to DVD. Setup is FC2.

I've hit a big snag - when I export the recordings and cut the
commercials with nuvexport (MPEG2->MPEG2), the audio on the exported
recording is way out of sync. Note that when I play the original files
in Myth or mplayer, the audio sync is just fine.

I tried opening the recording with avidemux, cutting the commercials,
exporting raw audio and video, then manually remuxing them with mplex
(as per instructions in section 21.19 of Mythtv.org docs). I still get
a final mpg with out-of-sync audio.

I should note that I didn't have this problem on my old setup, which
was FC1 using the same PVR-250 on a different box.

I have also tried doing a manual capture. When I manually cut
commercials from the manual capture using avidemux, saved the raw
audio and video, then remuxed then with lvemux, it worked! No audio
sync problems. For reference, I used lvemux because mplex refused to
remux the files in this case.

I had started to suspect that there was something weird with my ivtv
driver. But now I'm back to square one. As far as I can tell, the
possible suspects are ivtv, Myth, avidemux, and lvemux. I've tried
several versions of avidemux and lvemux, on more than 1 machine. That
doesn't seem to make a difference. So I'm down to Myth and ivtv. And
the fact that I can do a manual capture without the problems makes me
think that maybe Myth is involved in the problem.

Anyway.... I'd appreciate any help in debugging this.


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