Speex dev - Mar 2012 - Echo cancellation with different sound card for speaker and microphone

I'm developing an application that have a video conference component. 
For that I need echo cancellation, and is looking around for 
algorithms/implementations of that, and the one in speex is an 
alternative. In the documentation for speex I find the following 
sentence however.

"Using a different soundcard to do the capture and plaback will *not* 
work, regardless of what you may think."

If this still is true, the Speex echo canceller is basicly a no-go for 
us. There is no way I can get the customers to understand why they can't 
use e.g the microphone in their webcam together with the speakers 
connected to the built-in soundcard, and have to go buying a separate 
microphone. In the release notes for 1.2beta2, there is the following 
sentece however:

"The echo canceller should now converge faster, be robust and tolerant 
of incorrect capture-playback synchronisation."

This sounds for me like the above problem has been solved, or that at 
least it now works in some cases even if the speakers and microphone are 
unsynchronized, and that it thus may work with speaker and mic on 
different soundcards.

My question is: Can I use  Speex 1.2rc1 ?

If not, my experience with other systems is that it is possible to do 
echo cancellation with mic and speakers on different soundcards. If not 
guaranteed always work, at least in many circumstances in practice. My 
quetion then is: what algorithm should I use? And why does speex fail to 
work in these circumstances?

-Gisle

Hello Gisle,
> This sounds for me like the above problem has been solved, or that at 
> least it now works in some cases even if the speakers and microphone are 
> unsynchronized, and that it thus may work with speaker and mic on 
> different soundcards.
maybe have a look at PulseAudio and the pluggable echo cancellation 
modules, Speex among them; your best bet may be the echo canceller 
from webrtc which is also supported

some drift / delay compensation is implemented there

regards, p.

-- 

Peter Meerwald
+43-664-2444418 (mobile)

+1 for the WebRTC audio enhancement stack (including AEC).

Ken Smith
Cell: 425-443-2359
Email: ken at alanta.com
Blog: http://blog.wouldbetheologian.com/


On Wed, Mar 21, 2012 at 5:33 AM, Peter Meerwald <pmeerw at pmeerw.net>
wrote:
> Hello Gisle,
>
> > This sounds for me like the above problem has been solved, or that at
> > least it now works in some cases even if the speakers and microphone
are
> > unsynchronized, and that it thus may work with speaker and mic on
> > different soundcards.
>
> maybe have a look at PulseAudio and the pluggable echo cancellation
> modules, Speex among them; your best bet may be the echo canceller
> from webrtc which is also supported
>
> some drift / delay compensation is implemented there
>
> regards, p.
>
> --
>
> Peter Meerwald
> +43-664-2444418 (mobile)
> _______________________________________________
> Speex-dev mailing list
> Speex-dev at xiph.org
> http://lists.xiph.org/mailman/listinfo/speex-dev
>
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