[mythtv] Solving my performance problems...

Isaac Richards ijr at po.cwru.edu
Thu Dec 18 20:17:47 EST 2003


On Thursday 18 December 2003 02:32 pm, Steve Brown wrote:
> Isaac Richards wrote:
> >On Thursday 18 December 2003 08:53 am, Steve Brown wrote:
> >>After more investigation, the stuttering is caused by the sound card
> >>starving. I salted some snd_pcm_delay calls in AddSamples. As the htdv
> >>sample plays, the number of queued sound samples slowly decrease until
> >>the underrun occurs. The up-converted sample seems to maintain about 10k
> >>or so queued samples and does not underrun. Without the patch, it
> >>underruns as well. My 2.8GHz cpu is running about 65% when all this is
> >>going on. I have jitter and experimental av sync on and am using xvmc.
> >
> >Turn on 'extra audio buffering'.
> >
> >Isaac
>
> Not reported accurately.
>
> Jitter, av sync and extra audio buffering were all on.
>
> Any ideas?

Not really.  With extra audio buffering on, that should prevent it from 
underrunning the audio buffer, as it tries to keep at least a tenth of a 
second more audio data than video data..  Could try fiddling with that, make 
it keep more extra, etc..  Line 979 of avformatdecoder.cpp:

    if (lowbuffers && onlyvideo == 0 && lastapts < lastvpts + 100 &&

The 100 there is in ms, so try increasing it a bit.

Isaac


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