Re: [Ekiga-devel-list] More analysis of Alsa vs Pulse

[Damien Sandras <dsandras seconix com>]

Le mercredi 28 janvier 2009 à 21:45 +0000, Andrea a écrit :
> Andrea wrote:
> > Hi,
> > 
> > 
> > What happens when using the pulse-alsa module is that there are many underruns after calling
> > snd_pcm_writei().
> > 
> > In order to fix the underrun snd_pcm_prepare is called and I think this is responsible for the very
> > bad quality AND for the fact that the stream volume controller in the PulseAudio Volume Manager
> > keeps disappearing and reappearing.
> > I've tried snd_pcm_recover() but there is no difference.
> > 
> > It seems that each time an underrun occurs, a nasty glitch can be heard.
> > 
> > I have no idea what causes the underrun.
> > 
> > Does anybody have a better understanding of all that?
> 
> I've tried to change some values in the PTLib and if I increase the size of the storedPeriod in
> PSoundChannelAlsa (e.g. in PSoundChannelALSA::SetBuffers() to twice the input value) then I don't
> get any more underruns and the quality of the ring tone is as good as when ekiga play to ALSA directly.
> Moreover in the PulseAudio Volume Control the Ekiga Playback stays there smoothly.
> 
> Maybe it is only a matter of tweaking some buffers when running through pulse-alsa module?

Lennart, the author of pulseaudio, has promised last week to analyze and
fix the problems we have when using Ekiga together with pulseaudio.

I'm not expert enough to help you with this.
-- 
 _     Damien Sandras
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