[Speex-dev] Echo Canceller on Windows Mobile

Dennis Liu dennis.liu at mobidia.com
Fri Feb 8 16:47:26 PST 2008

I've worked on implementing Speex AEC to smartphone on the exactly same
platform as you have. The result is pretty good. I can remove most of the
acoustic echo. I'm still tuning the performance to minimize the remaining
echo. Here are the key points: 

1.	You have to sync microphone and speaker properly; otherwise it
wouldn't give you a good result.
2.	You have to optimize Speex AEC in order to run on mobile device in
real time.







From: speex-dev-bounces at xiph.org [mailto:speex-dev-bounces at xiph.org] On
Behalf Of Mohammed Sulaiman
Sent: Friday, February 08, 2008 7:55 AM
To: Speex-dev at xiph.org
Subject: [Speex-dev] Echo Canceller on Windows Mobile


Hi Jean Marc,


We are running the speex echo canceller code on a Windows Mobile smartphone
using a TI OMAP 201MHz 850. We are making voip calls and audio is working
without echo canceller code. Simply adding the following 2 functions whether
the echo cancellation is wired in (ie  we use the output frame ) or not
performance becomes terrible. Note 2 separate threads are used to handle


Playing Audio thread:

Write to codec

speex_echo_playback(echo_state, echo_frame);


Capturing audio thread:

Receive buffer

speex_echo_capture(echo_state, input_frame, output_frame);


We have compiled for fixed point.

We are using codec buffer size of 256 bytes ie 128, 16bit samples.


SpeexEchoState* iEchoState = speex_echo_state_init(ECHO_FRAME_SIZE,





Any ideas?


Do you know whether any one has this running on Windows Mobile platforms





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