[Speex-dev] Re: aec

[Jason Harper]

Thanks for alerting me to the new changes.  I just
tried the latest code from SVN, but unfortunately I
still have just about the same results.  The estimated
echo that gets subtracted from the actual echo is such
a small signal that it doesn't really result in any
noticeable echo attenuation.
I currently have my filter size set to 2 seconds even
though the echo in my microphone file is only about
180ms delayed from the signal in my speaker file.  I
also double checked that the endianess of my is
correct, and that I am providing the files to testecho
in the correct order.
Do you think that there could be some characteristics
to my echo that make it not work with the mdf
algorithm?  How much echo attenuation should I expect
from the mdf algorithm before the preprocess?  Are
there any test speaker and mic files that I could run
against testecho to see how it handles other acoustic
echos?

-Jason

--- Jean-Marc Valin <Jean-Marc.Valin at USherbrooke.ca>
wrote:

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