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

[Mark Goldberg]

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.