[Ekiga-list] Poor audio quality

[Damien Sandras]

Hi,


The jitter buffer is the reception buffer where audio frames gets
accumulated until they are ready to be played.

It explodes with DMIX because DMIX is adding much latency.

2.0.4 will have a workaround for that.

I am waiting that the Ubuntu guys sort #359655 before releasing 2.0.4,
but I think I won't wait a long time anymore because they seem unable to
test if the proposed patch fixes the problem. Ah well, Ubuntu Edgy...
Our daily nightmare.

Le dimanche 12 novembre 2006 à 16:25 +0000, Mario Rossi a écrit :
> Hi
> 
> I've finally installed ekiga 2.0.3 (compiled from sources) and I've
> done some testing using the dmix plugin.
> 
> During the tests I've used no webcam (so to avoid any overload of the
> system) and tried the echo server of ekiga.
> 
> Using the direct alsa output, jitter buffer goes at 20 and the quality
> is very good. In my tests sometimes it increases to 40, most of the
> times stays at 20.
> 
> Using the "default" (i.e. dmix) the quality is bad while the jitter
> buffer increases.
> In the worst cases it keeps increasing till 500 (very fast), other
> times it slowly increases, sometimes it stabilises at around 300.
> Usually (but not always) the quality improves when the jitter stops.
> 
> If there is an other application playing sond, the growth of the
> jitter to 500 is usually faster.
> 
> Sorry about my ignorance, but what is the jitter buffer? How does it
> interact with dmix and alsa?
> 
> I've found that using the sound event settings I can have the "ring"
> with dmix and then before answering I have to stop other applications
> playing sound, so in my case the limitation of dmix is not really that
> big, but anyway...
> 
> Thanks
> 
> >>
> >> If I use the hardware directly the quality improves but I still have
> >> some problems when I set the full screen.
> >>
> >> Is there any setting that could affect audio quality?
> >>
> 
> >If it happens when you set to fullscreen, you are probably using too
> >much CPU ressources.
> 
> >Be careful also that you are perhaps wasting your bandwidth with too
> >large video transmission or too high settings.
> 
> >Just check the value of your jitter, it will help a lot to determine if
> >there is a problem related to CPU/Bandwidth (if it goes over 500ms, then
> >the problem is at this side, if not, then the problem is on the ALSA
> >side).
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 _      Damien Sandras
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