Hi,
Some more info on this. With the "soundcard_buffer_size = info.bytes;" line in the code, which looks correct to me, my system exhibits bi-stable behaviour.
Sometimes MythTv runs fine without juddering and sometimes it starts this juddering. It seems that there is an unstable timing control issue in "AudioOutputBase::OutputAudioLoop". This would be affected by other timings, hence others may not see the problem ...
When juddering the CPU usage goes from about 18% to 95%. One little point, which may not be related, I am running MythTv as root. This means that some threads are running as real-time threads. I believe that a small usleep() in a real-time thread is implemented as a CPU loop ...
I will further delve into this issue as time permits.
Terry
Terry Barnaby wrote:
Hi,
I have narrowed down the problem to the changes from MythTv CVS 2004-11-29 to 2004-11-30.
I have further narrowed this down to the file:
libs/libmyth/audiooutputoss.cpp, Line: 112
"soundcard_buffer_size = info.bytes;"
This line was added in 2004-11-30. On my system this sets soundcard_buffer_size from 0 to 65536.
If I remove this line the "juddering" goes away ....
Note that my system is currenly using the OSS driver, although I had the same problem with the ALSA driver.
Terry
Ed Wildgoose wrote:
The other other one on that same day at a different time was mythtv/libs/libmyth/audiooutputbase.cpp .
Thanks, yes I saw that when I was editing the audio code. I had to get my calculator out and have a think if it was sensible or not and nearly reversed it actually. Doesn't cause me any problems though. In retrospect, at least in theory, the audio loop changes seemed quite sensible and reasonable even in the case of my funny pro audio card, but hey just occured to me that it might be related to the jerky output reports...
Any of you folks having trouble actually tried this yet?
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