[mythtv] AVSync Problem on entering recorded playback
adeffs.mythtv at gmail.com
Tue Mar 28 21:49:52 UTC 2006
On 3/28/06, Stephen Williams <stephen.gw at gmail.com> wrote:
> On 3/28/06, Stephen Williams <stephen.gw at gmail.com> wrote:
> > I'm only seeing this with recorded content, live TV works fine. Also
> > this is only with SD content, not pushing the box at all (less than
> > 50% CPU usage and no prepuffering pauses).
> > Haven't noticed audio/video slowdown then speed up again. Not sure why
> > you'd be seeing that, the video speed should be constant when using
> > video as timebase unless AV get more than 3 frames out of sync.
> > It's definitely a problem with MythTV directly, from the debugging
> > i've done the AVSync code is clearly failing. Done a bit of code
> > review of that area and there's quite a lot of undocumented 'magic'
> > going on, especially with the audio 'warpfactor' calculation. I'll
> > keep digging and see if it can't be improved.
> > Stephen
> Okay, i've been making some progress on this now. Disabling the
> dropping of frames / doubling of frame times and allowing the AVSync
> code to settle down (takes a few minutes to stabilise) it has become
> apparent that on initial entry to recorded playback it is trying the
> play the video at 30fps (note that this is PAL content at 25fps).
> After pausing / unpausing it then starts to play the content correctly at 25fps.
> Now for the million dollar question, why are we initially defaulting to 30fps?
Did you set it up so that NTSC is your format? I don't remember
exactly where, but in mythtv-setup you can set a default format and
iirc, for each device you can set a format. Make sure yours are set to
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