[pulseaudio-discuss] Pulseaudio and Skype

Mark Greenwood fatgerman at ntlworld.com
Mon Mar 15 13:29:20 PDT 2010

On Sunday 14 Mar 2010 11:39:59 Colin Guthrie wrote:
> 'Twas brillig, and Mark Greenwood at 14/03/10 09:56 did gyre and gimble:
> > If I enable pulseaudio, skype automatically sets all the audio
> > options to be pulseaudio - there is no option in this version to use
> > ALSA if pulse is enabled, which is sensible enough I guess.
> Yeah this is definitely sensible. I'm hoping the Skype guys will remove
> the whole dropdown selectors when PA is detected to avoid people
> expecting that alsa and pulse can play nicely together in a system
> without one or other ultimately being locked out at some point.
> > But although I can make calls, and the other end can hear me and I
> > can hear them, the other end can also hear themselves - as loud as me
> > with a slight delay. They all say it's so offputting that they can't
> > hold a conversation.
> Interesting....
> > If I turn my microphone down, the other end says the echo goes away -
> > but they can't hear me either. Moving the microphone away from the
> > speakers isn't an option as this is on a laptop.
> Hmm, it's strange that this is somehow different on PA vs. Non-PA....
> the code for echo cancellation should be the same regardless.
> > Now, I wouldn't be here asking daft questions about closed source
> > software - except that it all works fine when pulseaudio is not
> > involved. It almost appears as if there's some echo cancellation
> > which is broken when pulseaudio is in the mix, or that possibly pulse
> > is feeding the incoming voice conversation back into skype somehow.
> > 
> > Any ideas on how to go about making it work?
> There were some skype related fixes in the stable-queue branch recently.
> I believe all these fixes are in the PPA you mention for Ubuntu. I don't
> think these are related but there are lots of misc bugfixes between
> 0.9.19 and 0.9.21+stable-queue anyway, so it's always best to use that
> version.
> Let us know how you get one with that one.

OK, with 0.9.21+stable-queue the situation is significantly better. Not completely cured, but the other end now reports a slight, quiet, distorted echo which is not distracting. So that's good.

However I notice that CPU usage for pulseaudio during a skype call is 35% (Core II duo, 2GHz) and there seems to be a significant 'lag' effect on other network traffic. This last might just have been a random thing of course but I've never experienced it before. This is not good. I'm going to switch back to plain ALSA and see if the same lag effect happens again - we use Skype for conference calls during online gaming. We all reported very significant in-game lag this time when I was running PA and none of us have ever had this before).


> Col

More information about the pulseaudio-discuss mailing list