[Speex-dev] Re: aec

Jean-Marc Valin Jean-Marc.Valin at USherbrooke.ca
Fri Nov 4 03:04:13 PST 2005

I've recently made changes to the AEC. Please try the code in SVN and
see if it works better.


Le jeudi 03 novembre 2005 à 22:36 -0800, Jason Harper a écrit :
> I've tried some further debugging to see what mdf is
> actually doing.  Instead of sending:
> tmp_out = (float)ref[i] - st->y[i+st->frame_size]
> to the output, I just sent
> st->y[i+st->frame_size]
> to see what was being subtracted from the microphone
> input.  When I open this in Audacity, I see a very
> small signal at about -40dBm.  The actual echo in my
> sample has a power closer to -20dBm.  So, when the
> -40dBm estimated echo is removed from the -20dBm
> actual echo there is almost no perceived difference in
> the echo power.
> I'm sure that there are others on the list that have
> had good success with the echo cancellation module. 
> Could anyone point me to reference test files that are
> known to work well in testecho.
> I'd like to figure out if there is some characteristic
> of my echo that makes it incompatible with this echo
> cancellation algorithm, or whether there is just some
> configuration problem in my implementation.
> Thanks for your time; advice is greatly appreciated.
> -Jason
> ---
> > I have incorporated the speex echo cancellation into
> > my softphone project, but wasn't getting great
> > results.  I decided to simplify the problem, by
> > recording speaker and mic files and running
> > testecho. 
> > I've been pretty happy with the preprocess module
> > and
> > I wanted to focus on the mdf, so I commented out the
> > call to preprocess in testecho.
> > When I run testecho my output file looks almost
> > identicle to my mic file.  I don't see any reduction
> > in the power level of the echo.  I've looked through
> > some of the previous posts to this group and have
> > tried the obvious, such as increasing my filter
> > length
> > and reversing the order of the files passed into the
> > application.
> > Looking at the files in Audacity, the echo lags by
> > about 180ms.  I have experimented with filter
> > lengths
> > up to 2 seconds.
> > I'm open to suggestions. 
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