[Speex-dev] speex AEC lighter configuration

Victor Librado vlibrado at bioingenieria.es
Tue Jun 19 08:59:53 PDT 2007

Hello all,

I'm just new to this list.
I'm user of a voIP application which uses Speex Acoustic Echo Canceller 
(so only user of speex). The only parameter it has to tune is the length 
of the ec tail. I'm testing the echo canceller on an arm9 platform. 
Tests made only allow me to raise the length of the tail until 250 msec 
(upper the cpu power consumption is 100% and there are audio losses) 
getting bad results (still echo !).

I have get the beta source of speex and checked that it can be compiled 
to use fixed point arithmetic plus assembler code for my architecture. 
Now I'm trying to recompile the speex library which these options and 
get better results. However I have some doubts:

- Which is the value of the tail length to get good results?

- May I specify some other options (at configuration time or may be at 
source) to get the speex AEC lighter, so that I can raise the tail 
length and get best results?

- May be speex AEC tunned with another parameters to improve echo 
cancellation results?

- AEC uses floating point in some cases (altough fixed-point specify)? 
(soft floating point is slow...)

Sorry if this seems to be very obvious...

Best regards,


 Victor Librado Sancho

Departamento I+D

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