[mythtv] live TV stuttering

[Dan Morphis]

FWIW, I see this with a standard bttv framegrabber card.  IIRC, it 
started to happen after the latest ffmpeg sync.  Like Hamish, I don't 
see anything on the console

-dan

Hamish Moffatt wrote:

> I'm having a problem with live TV where Myth will start "stuttering".
> It'll start within a second or two of changing to a channel, else it
> will be ok. The audio and picture will pause then resume, over and over.
> 
> I can always fix it by quitting back to the menu and going straight back
> to live TV (which goes to the same channel). I can usually fix it by
> switching to another channel and back again.
> 
> When the stuttering occurs, there are no messages output to either the
> mythfrontend terminal or the backend log (I have -v all).
> 
> 
> One channel seems to cause it the most here. (Nine, for Australian
> readers.) I'm running DVB-T. I get varying bit rate reports in the log
> for this station;
> 
> Audiostream: Layer: 1  BRate: 320 kb/s  Freq: 0.0 kHz
> Videostream: ASPECT: 16:9  Size = 720x576  FRate: 25 fps  BRate: 10.00 Mbit/s
> 
> Videostream: ASPECT: 16:9  Size = 720x576  FRate: 25 fps  BRate: 10.00 Mbit/s
> Audiostream: Layer: 1  BRate: 256 kb/s  Freq: 44.1 kHz
> 
> Audiostream: Layer: 1  BRate: 128 kb/s  Freq: 48.0 kHz
> Videostream: ASPECT: 16:9  Size = 720x576  FRate: 25 fps  BRate: 10.00 Mbit/s
> 
> Audiostream: Layer: 1  BRate: 352 kb/s  Freq: 32.0 kHz
> Videostream: ASPECT: 16:9  Size = 720x576  FRate: 25 fps  BRate: 10.00 Mbit/s
> 
> I have other stations using higher bit rates (eg 15 Mbit/sec video).
> There are other stations using both layer 1 and layer 2 audio. And
> others using both the same picture size and a slightly different one. So
> I can't find a pattern there.
> 
> I've tried tweaking my PCI bus latency settings while it's occurring but
> it didn't help (using powertweak). I have an Athlon XP 2600+, plenty of 
> RAM, fast disk etc.
> 
> I'm using linux 2.6.4 with OSS. I've seen it occur with 2.4.24.
> I think it occurs much more often with ALSA. Pausing the live TV for a
> few seconds then resuming does not help.
> 
> One time when it started occurring I switched to another channel, and it
> didn't go away. Then the frontend starting print messages about audio
> buffer overruns and prebuffering pauses. I haven't had that happen a
> second time though.
> 
> I would welcome suggestions on how to debug this.... It's been present
> for a few months here now. I've just checked it with absolute latest CVS.
> 
> thanks,
> Hamish
> 
> 
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