[Speex-dev] Echo cancellation in speex 1.2 beta1 problem

andrey zhukov apater at mail.ru
Fri Oct 27 04:01:36 PDT 2006

Hi Speex Developers,

I'm Andrey Zhukov, the developer of PI-CONSULT GMBH company.

Building a voip application that uses your libraries, i have found the strange problem with the latest version of Speex Libs.
Our application works under win32, and i used before version speex 1.1.12 ( were built from sources).

It seems i have resolved the known problem with clock drift of audio cards using the developed Windows compensation algorithm .
(I use sync. call speex_echo_cancel(...).The remain syncronisation between in and out frames is my own. 

The previous 1.1.12 cancellation works moreless well, and after appearance of new version i desided to try use it.
The result is:
In real condition case 8 from 10 times cancellation is very unstable and starts generate a noise signal. I think this happens on fast learning stage of EC algotithm.
When  EC learning stage finished normally (2 from 10 times ) after 2- 5 seconds cancelletion works better than previous version.

Could you please suggest to do something  to stabilize EC in new version 1.2 beta1?
Do you plan release the new version in nearest time?
Can i help to accelerate resolving the problem (deep investigation, testing or something else)? 

Best regards.
Andrey Z.
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