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

[Mark Buechler]

I don't use any type of deinterlace. It does correct itself, after a few
seconds and can remain stable for several seconds before the cycle starts
again.

- Mark.

On 1/19/07, Mark Goldberg <marklgoldberg at gmail.com> wrote:
>
> I'm reposting after joining the list.
>
> >On 1/9/07, Mark Buechler wrote:
> >
> >I get those as well. I'll have a look.
> >
> >Thanks, Mark.
> >
> >On 1/9/07, Stuart Auchterlonie <stuarta[at]squashedfrog.net> wrote:
> >>
> >> 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,
>
>
> I have seen these often, and it seems that if bob deinterlacing is
> used, it cannot
> double the frame interval. It never corrects. In the previous thread,
> overcorrection was discussed. Is the control a proportional control or
> does it correct the same amount no matter how far off it is? If that
> is the case, it can go into a limit cycle oscillation, which I have
> seen if it gets too far off. It bounced between ahead and behind
> continuously. You may need a propotional and a derivitive term to
> insure stability and even an integral term to correct slight long term
> offsets. A slow enough proportional control should be stable though. I
> haven't gone over the code,so forgive me if this is already there.
>
>
> Mark G.
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