[Speex-dev] Echo Cancellation Problem -- with sound sample

Mihai Balea mihai at hates.ms
Sun Sep 23 06:06:07 PDT 2007

On Sep 22, 2007, at 7:10 AM, Eddy wrote:

> Thank you for you quick reply, Jean-Marc.
> I have just used a human voice to replace the sine wave, but the  
> result is like a broken voice after tens of seconds. Do you have  
> some sample voice in .sw that I can test with? I want to have one  
> set or a few sets of sample voice that work for my understanding  
> and debugging.
> This is the output from echo_diagnostic.m in my human voice test:
> Far end to near end delay is 231 samples
> Delay looks OK.
> Drift estimate is 0.009063% (14 samples)
> There may be (not sure) excessive clock drift. Is the capture and  
> playback done on the same soundcard?


I'm evaluating echo cancellation in 1.2beta2 myself and I got pretty  
decent results.  A couple of things to keep in mind:
- if there's clock drift between your output and input devices, then  
EC will not work properly.
- you might want to link EC with the preprocessor, so you eliminate  
residual echo as well...

In my tests I have a wave file containing speech played back on my  
speakers.  My test app then records whatever comes in from the  
microphone and applies speex_echo_cancellation and then  
speex_preprocess_run.  The resulting sound is saved in another wave  
file.  I am getting pretty good results with this setup, with echo  
being almost completely eliminated.


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