[Speex-dev] AEC troubleshooting

Tim Na hna at alu.edu
Tue Aug 11 10:35:12 PDT 2009

Ok, let me be more clear on this.
AFAIK, Windows OS doesn't expose speaker input as other OS ( Linux, Mac
OS...). That puts you in bad spot in using Speex AEC with windows.
Only way to work is to use Soundcard with ASIO functionality which does give
you speaker input.  But then you would have to impose that requirement on
all your users.
I heard Speex AEC works great from developer who used windows with ASIO
Vista AEC DMO or XP DirectSound AEC function does reasonable job and that's
what I am currently using.


From: speex-dev-bounces at xiph.org [mailto:speex-dev-bounces at xiph.org] On
Behalf Of Greger Burman
Sent: Tuesday, August 11, 2009 1:15 AM
To: speex-dev at xiph.org
Subject: Re: [Speex-dev] AEC troubleshooting

I actually forgot to mention that I'm using ultra-wideband mode, but seems
like you understood that anyway. Is this true that Speex echo cancellation
only performs well in narrowband mode !? 
I've been using 100 ms as the default tail length. I don't know what the
ideal tail length would be. I have tried shorter and longer tails but it
hasn't made any difference.
Does DirectSound's AEC perform well with high quality recording? Is it the
general opinion that it performs significantly better than Speex AEC?
2009/8/10 Tim Na <hna at alu.edu>

If you search the mail archive, you will see that people were only
successful using narrowband with long tail length.
Unless you have speaker input in perfect sync with mic input, it is
difficult to use Speex AEC.
If you don't have restriction on using Vista's AEC DMO or XP"s DirectSound,
I would recommend using those.


From: speex-dev-bounces at xiph.org [mailto:speex-dev-bounces at xiph.org] On
Behalf Of Greger Burman
Sent: Monday, August 10, 2009 5:40 AM
To: speex-dev at xiph.org
Subject: [Speex-dev] AEC troubleshooting

I'm experiencing little to no damping of acoustic echo from the echo
cancellor and I can't figure out why so far. I thought I should try the
echo_diagnostic tool so I built libspeex.dll and libspeexdsp.dll with the
DUMP_ECHO_CANCEL_DATA flag, but I'm not getting any output files at runtime.
Any ideas?

Build information:
Speex version: 1.2rc1
Target Win32 x86
MS VC++2008 EE
Configuration: Release, Full optimization, _USE_SSE

Greger Burman

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