[Speex-dev] Echo cancellation with different sound card for speaker and microphone
gisle at snirklasjon.no
Wed Mar 21 03:26:04 PDT 2012
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
"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
"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
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?
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