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

Stuart Auchterlonie stuarta at squashedfrog.net
Tue Jan 9 17:11:30 UTC 2007


On Sat, Dec 30, 2006 at 06:12:47PM -0500, 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.
> 

In an earlier thread from 2nd Dec entitled 
"Dynamic Ringbuffer and prebuffering pauses."
I was discussing what if found in this area.

If you have the problem I did, then you should see some messages
before these like "Audio is xx.xxx behind, dropping ... to catch up."

What is happening is the A/V sync is out, and NVP attempts to
compensate, but "overshoots" such that the A/V sync is out the other
way. So the resyncing code needs looking at, and Bruce put forward
some useful suggestions in that previous thread.

Stuart


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