[mythtv-users] Occasional jerkiness during DVD playback

Brian Wood beww at beww.org
Sat Jun 23 23:20:57 UTC 2007


Juergen Botz wrote:
> Brian Wood wrote:
>>> But when playing DVDs, once in a while, usually on scene changes
>>> where the whole field is different, I get a few seconds of jerky
>>> video and stuttering sound.
>> If you are getting your "20%" CPU load number from top, remember that it
>> is an average, and the peak usage might be well in excess of that.
> 
> Yeah... right after I sent that message I played a DVD and watched
> top carefully and noticed something peculiar...
> 
> The CPU usage seems to follow a kind of reverse sawtooth pattern,
> I.e. it's low for a while (15%-20%) then jumps up to something like
> 60% around the time of the jerkiness.  Then it slowly goes back
> down.
> 
> Looks like a bug, either in in Mythtv or in the XvMC library or
> openchrome driver.
> 
>> How fast is your CPU?
> 
> It's an EPIA SP 13000 board... so the CPU is slow, maybe equivalent
> to a P3 800 at most.  Before I got XvMC working video was frequently
> jerky and the CPU was usually at 70-80%.

That's pretty marginal. I think you're right on the edge, even with XvMC

> 
> There's nothing other than Mythtv using resources on that box right now. 
>   I run mythfrontend directly from xinit.

Well you *do* have something other than MythTV - You have X running,
perhaps you could optimize that a bit. Make sure no other stuff is
running, a lot of distros start daemons that you really don't need.

Also see if you're hitting swap.

BEWW


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