Re: [GnomeMeeting-devel-list] Choppy Audio / Audio Dropout

[Damien Sandras <dsandras seconix com>]

Hi,

I'm interested in a patch, then I can see with Craig if we can submit it
to CVS.

Le jeudi 30 mars 2006 à 11:34 +0100, Craig Shelley a écrit :
> Hello list,
> 
> I am new to this list, so please forgive me if I am barging in.
> 
> I have been using ekiga 2.0.1 for a couple of weeks now, and will
> continue to do so because I think this is an excellent piece of
> software, Well Done!
> 
> On my system I have been experiencing gaps and clicks in the audio while
> in a call. This tends to occur while graphics operations are happening,
> eg when switching between windows, or dragging windows around.
> 
> After much searching on the net, and on mailing lists, I found people
> describing similar problems, and it seems that 2.6 kernels, certain
> graphics drivers (eg radeon), and low latency audio don't mix too well.
> I have also tried all the usual stuff like changing PCI latencies,
> interrupt priorities, and changing the real-time scheduling attributes
> of the ekiga process.
> 
> After a lot of testing, I came to the conclusion that the dropouts in
> the audio were occurring because the ekiga process, under slight load
> conditions, was not delivering the audio on-time, and not reading the
> audio on-time.
> 
> Looking more closely at what was going on in pwlib, I could see the
> buffer time was something quite small like 40mS. On my system, in order
> to eliminate the dropouts on audio playback, this had to be increased to
> 300mS.
> This solved the problems on audio receiving audio, but the audio from my
> mic was still choppy with slight CPU load. Unfortunately, it wasn't just
> a case of increasing the buffer size for recording because for some
> reason alsa would only allow 2 periods in the record buffer. Therefore a
> separate buffer thread was required in order to fix the recording
> problems.
> The buffer thread uses high priority realtime scheduling (SCHED_FIFO),
> and seems to have been quite successful in completely solving the
> problem with choppy recording.
> 
> At the moment, I am testing this mod as a proof-of-concept fix, and all
> seems well so far.
> I appreciate that the problems I have been encountering are most likely
> related to hardware/drivers, and the mods I have been doing are all
> within pwlib source, and not ekiga or opal.
> 
> If anyone is interested, let me know and i'll post the code/patch, but I
> must warn you, this is a real hack, the code is very very bodgey.
> 
> Regards,
> 
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-- 
 _      Damien Sandras
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