[mythtv] prebuffer audio related?
mythmail at richardstraat.homedns.org
Wed Oct 27 15:42:21 UTC 2004
Ed Wildgoose wrote:
>> Recordings play fine with mplayer. This is my video playback command
>> "mplayer -fs -zoom -quiet -ac hwac3, -vo xv %s" but I guess this would
>> use OSS emulation using /dev/dsp. (don't have access right now to check).
> At risk of pointing out the obvious, I was expecting you to test the
> same output device in mplayer as you were using in myth...
> Can you go back, check your myth config, work out exactly which audio
> output device you are using (/dev/dsp or ALSA:blah), then flex the same
> thing in mplayer. If there is any hardware AC3 decoding going on, then
> obviously disable that or else you won't be testing the same thing in
> myth as you do in mplayer!!!
I use /dev/dsp in myth. With mplayer the recordings play fine with oss
emulation and with -oa alsa . Audio is standard PCM from the PVR card.
>> This gives me the feeling the prebuffer pauses have something to do
>> with the "Usleep with busy wait" video timing.
> Perhaps, but this might mainly be because the cpu load is higher. What
> is your CPU load by the way?
> Please debug this a little for yourself and supply all the interesting
> info here
Sorry about that, I had already done and posted some debugging (and
system specs) in a prev tread:
This includes top output (mythfrontend below 30% and X around 25%). If I
disable the extra audio buffering setting the CPU usage goes to 100 %
(with mythfrontend going to 70%, no other processes kicking in) during a
10second period around the the prebuffer pause. With extra audio
buffering on this is reduced to a short skip and I guess the peek in
processor usage goes undetected in top bacause it is so short.
BTW, I have recompiled myth against alsa 1.05 lib after installing that
but that doesn't make a difference.
Renicing mythfrontend to -20 doesn't seem to help either.
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