[mythtv] 720p content constantly going in and out of sync

[Yeasah Pell]

Mark Buechler wrote:
> For a long as I've been using DVB support in MythTV (over a year), 
> I've been seeing a problem with many 720p streams constantly going in 
> and out of sync, ie:
>
> 2006-12-30 18:07:49.845 NVP: Video is 30 frames ahead of audio,
>                         doubling video frame interval to slow down.
> 2006-12-30 18:07:49.879 NVP: Video is 30 frames ahead of audio,
>                         doubling video frame interval to slow down.
> 2006-12-30 18:07: 49.912 NVP: Video is 30 frames ahead of audio,
>                         doubling video frame interval to slow down.
> 2006-12-30 18:07:49.945 NVP: Video is 30 frames ahead of audio,
>                         doubling video frame interval to slow down.
> 2006-12-30 18:07:49.979 NVP: Video is 30 frames ahead of audio,
>                         doubling video frame interval to slow down.
>
> These come very frequently with no more than a couple minutes of 
> perfectly synced video/audio in between. I've seen a few tickets on 
> this as well as a few email threads but with no solution. Has anyone 
> found the cause of this or know how to remedy it? The problem is 
> getting larger for me given more and more of my HD content is showing 
> this problem.
>
> - Mark.

I've seen similar symptoms caused by mixed hard/soft telecine 24fps 
material -- which essentially means the stream changes periodically from 
24fps to 30/60fps or back again. Such recordings generally play ok with 
other players (such as mplayer, which complains when the frame rate 
switches, but manages a reasonably smooth picture), but myth's player 
seems to expect the frame rate to stay constant and behaves somewhat 
badly when it doesn't.

It's possible that adding ivtc explicitly to the filter chain might help 
-- I never tried that, I just play those recordings in mplayer externally.

-y