GSoc idea: Echo cancellation for voice calls.

Mark Doliner mark at
Tue Mar 20 03:01:48 EDT 2012

On Mon, Mar 19, 2012 at 7:02 PM, Ethan Blanton <elb at> wrote:
> Stefan Kriwanek spake unto us the following wisdom:
>> If you like the idea, I'd be happy to elaborate upon the
>> implementation part.
> I encourage you to do so, and apply with this project.

I also like this idea.  There are a few concerns in my mind that I
would want to see addressed (either in further discussion on this
mailing list, or in your application, assuming you do decide to
apply).  One concern is that this might be re-implementing the wheel.
The blog post you linked to mentions that they implemented echo
cancellation as a set of patches to Pulse Audio.  If those patches
were accepted then it would be easy for Pidgin to take advantage of
it.  But maybe their patches weren't accepted?  And of course, not
everyone uses Pulse Audio (I don't).

You also mentioned that several other open source VoIP solution do
echo cancellation.  Maybe there is a library that Pidgin could use to
provide echo cancellation regardless of the audio output mechanism
used?  Or maybe this is something that should be provided by

I would also like to make sure this feature is surfaced to the user in
appropriate ways.  Ideally it would be automatic and the user wouldn't
know it was happening and wouldn't need the ability to turn it off or
on.  But if it doesn't work flawlessly, maybe we would need to give
the user an option to disable it?  Or if it only works when using
Pulse Audio, maybe we need to provide messaging to the user that they
might get better audio quality if they use Pulse Audio?

Please don't let me discourage you!  This sounds very promising!

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