[Speex-dev] echo cancellation

Alfredo Moreira alfredo.moreira at neolinks.com
Thu Dec 30 12:35:13 PST 2004

I'm going to test the echo cancellation...
but before doing something wrong, i want to know what is the right way 
to use it...

short * speakerSample; //will contain what the speakers are going to play
short * microphoneSample; //what the microphone is going to register
short*  cancelledSample; //the ouput without echo
int*      cancelledSpectrum; //output cancelled spectrum

//now i assume that i should initialise everything like that:

SpeexEchoState* pechoState = speex_echo_state_init(160,x*160); //do the 
second parameter need to be a multiple of the frame size?

speex_echo_cancel(pechoState, microphoneSample, speakerSample, 
cancelledSample, cancelledSpectrum);
while (!keypressed());


so, do i need to deal with the cancelledSpectrum variable to perform 
echo cancellation in a proper way?
do i need to deal with the delay between the sound being registered by 
the microphone and the one going out of the speakers? (i don't know you 
anderstand what i mean, sorry for my poor english)
also, there is an echo parameter to the preprocess function : int 
speex_preprocess(SpeexPreprocessState *st, short *x, int *echo);
do i need to provide to it my cancelledSpectrum variable?

best regards,

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