[mythtv] prebuffer audio related?

[Steven]

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: 
http://www.gossamer-threads.com/lists/mythtv/dev/90681?search_string=busy;#90681
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.

Steven