[Speex-dev] Echo Cancellation not working on WinCE

Tim Na hna at alu.edu
Thu Sep 11 21:40:40 PDT 2008

I am working on AEC on windows Vista/XP and I tried all sort of calibration with WaveIn/Out API but it seems they are useless for speex AEC on those platform. 
You can search thru this mailing list thread to find that even a little difference between input and output frame rate (may not be accruate explanation) would make speex echo cancellation useless.
Currently I am looking into using DMO interface from Windows SDK which already provides AEC function. I was running some test on DMO's AEC and it seems to be working in vista, hopely it does on XP as well. Not sure if it is also provided for WinCE.


From: Yogesh ( Hey Shona ) 
Sent: Thursday, September 11, 2008 9:03 PM
To: speex-dev at xiph.org 
Subject: [Speex-dev] Echo Cancellation not working on WinCE

Hello Friends,

I am trying to use speex-1.2beta3 version for echo cancelling.
On my WinCE board I am using WaveIn/WaveOut functions to record and playback audio.
I am receiving audio data on udp socket, then playing it on speaker using WaveOutWrite function.
I registered callback to capture microphone data, then data chunk came from socket ( which I played on speaker) and data captured from microphone is provided for echo cancellation function, but no echo getting canceled, instead after 10-15 seconds output of echo canceler audio having lots of breaks. 
My microphone and speaker are on same sound card and running at same clock rate.
Does anybody tried echo cancellation using WaveIn/WaveOut functions?
I also want to know that how to find delay between speaker data and data captured from microphone on Windows(WinCE).
Please help me.
Thanks in advance.

Yogesh Ahire


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