[Speex-dev] echo canceller

Jean-Marc Valin jean-marc.valin at usherbrooke.ca
Tue Dec 20 21:36:51 PST 2005

> haven't got the chance to sit down and look into it.
> from what I read in the list, double talk detection is 
> in the pipeline... :D. Just 2 quick questions: 
> i) does this canceller handle wideband for speex wideband?

It should, but I haven't tested it (might require a bit of tuning).

> ii) does it handle feedback or howling?

Not explicitly, but just cancelling echo would hopefully reduce that
(the preprocessor even more).

> Lastly, a newbie question for echo cancellation:
> is there a convenient test to ensure that the input and 
> output buffers obtained from the audio IO
> are aligned?  

Save two files, look at waveform.

> and also, does anyone have any rough
> idea what is the tolerated misalignment of the input and 
> output buffers, assuming constant misalignment

Less then one frame size is best. More than the echo tail and you've got
no cancellation at all.


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