[mythtv-users] prebuffering pause

George Mari george_mythusers at mari1938.org
Sun Jan 4 04:46:47 UTC 2009


George Mari wrote:
> Mike Kurtz wrote:
>> Have a box set up with a KWorld ATSC115 on SuSE 11.0 with a GeForce 5500. I have XvMC set up properly (substantial drop in CPU usage after I configured it), and sound is working (ALSA:hw:0,0 to avoid pulseaudio). I get full video and audio playback. Ever 5-6 seconds, however, I get a stutter. I look at the console output and I see:
>>
>> NVP: prebuffering pause
>> <repeated>
>> NVP: Prebuffer wait timed out 10 times
>> <repeated>
>> NVP: prebuffering pause
>> WriteAudio: buffer underrun
>> <these two repeated/alternated>
>> this continues for about a minute, then I see
>> NVP:::AddAudioData():pl: Audio buffer overflow, audio data lost!
>> <repeated, interspersed with some prebuffering pauses, then becoming more frequent>
>>
>> I have extra sound buffer on and aggressive sound buffering off. I'm not using CFS. CPU usage is between 40-70, which is high, but I haven't seen it really spiking, just consistent stuttering.
>>
> 
> Are you sure you have extra sound buffering on and agressive sound 
> buffering off?
> 
> Otherwise start experimenting with PCI latency:
> 
> http://www.mythtv.org/wiki/index.php/PCI_Latency
> 

If giving your audio device a high (really high - like 128, or 256) PCI 
latency doesn't improve the problem, you have to experiment. I would try:

1. Turn off XvMC, unless you absolutely need it.
2. Turn off de-interlacing.  Not permanently, remember - you're just 
experimenting.
3. See if anything else is hogging the PCI bus with a high latency.  As 
a matter of fact, please send along the output of lspci -v.  Oh, and 
please don't top-post it - I'll never see it. :-)
4. Is your sound device set to ALSA:default?  It should be, unless 
you're not using ALSA, or have some other, more involved, ALSA 
configuration.


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