[Speex-dev] Speex AEC AND preprocessor

[Jean-Marc Valin]

Aymeric Moizard a écrit :
> 
> I'm working on the echo canceller with the SVN, with Windows Mobile 5
> PocketPC.
> 
> Obviously, I can't make it run correctly.

What happens/doesn't happen?

> My question: If I use the SPEEX_PREPROCESS_SET_ECHO_STATE, I have
> changes in the sound: noise seems to be removed.

Noise should be removed even without SPEEX_PREPROCESS_SET_ECHO_STATE as
long as you use the preprocessor.

> I want to know if I have to use the preprocessor AND that option
> to make the echo canceller to work or if it's optionnal?

The only thing that SPEEX_PREPROCESS_SET_ECHO_STATE allows is for the
preprocessor to also remove part of the echo that
speex_echo_cancellation() (or equivalent call) couldn't cancel.

> Is there any other usefull option to the preprocessor that can
> be needed or helpfull?

There's SPEEX_PREPROCESS_SET_NOISE_SUPPRESS,
SPEEX_PREPROCESS_SET_ECHO_SUPPRESS,
SPEEX_PREPROCESS_SET_ECHO_SUPPRESS_ACTIVE that would be useful. They
control how aggressive the preprocessor will be in removing respectively
the noise, the echo and the echo when the near-end speaker is active.
The value is a negative int (in dB). Defaults are -25, -45, -15.

	Jean-Marc