[Speex-dev] AEC strangest behavior

Jean-Marc Valin
Mon, 15 Mar 2010 15:46:50 -0000

If more than one speaker receives the *same* signal, it doesn't matter the
number of speakers. It only gets tricky when the speakers are playing slightly
different signals (e.g. from a stereo song).

   Jean-Marc

Quoting Greger Burman <greger at mobile-robotics.com>:

> One thing I can think of is if you are using two or more speakers. If the
> speakers are not at the exact same distance from the mic, you will get more
> than one echo. AEC can not handle that. Try disconnecting all but one
> speaker and see if it makes any difference.
>
> cheers
> Greger
>
> 2010/3/15 Anton A. Shpakovsky <saa at tomsksoft.com>
>
> >  Hello.
> >
> > I have the following situation. AEC is used in network chat software
> >
> > over DirectSound API. Echo and reference signals are almost aligned
> >
> > (delay is no more than 30ms). When echo is emulated in notebook
> >
> > (built-in speakers + mic) everything goes fine and echo is cancelled.
> >
> > But when configuration includes stand-alone speakers and mic no echo
is
> >
> > removed. Audio is in 22050 hz at 16 bit mono format, number of samples
> >
> > to process were 441 and tail was used 4096.
> >
> >
> >
> > Dumps are here:
> > http://rapidshare.com/files/317389207/speex_AEC_test.rar.html
> >
> > nb_*** - working configuration (notebook)
> >
> > sa_*** - standalone speakers with no echo removed
> >
> >
> >
> > Can it be because of differences in fixed and arbitrary acoustic
systems?
> >
> > I will appreciate any of your advises or thoughts.
> >
> >
> >
> > Thanks!
> >
> >
> >
> > Anton A. Shpakovsky
> >
> > Multimedia Software Developer
> >
> >
> >
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> >
>