[Speex-dev] Backup Echo Suppression

[Jean-Marc Valin]

Selon "Coffey, Michael" <mcoffey at avistar.com>:
> Believe me; I've "played with" priorities and buffering.

Then either you haven't played well enough or you're using a braindead OS.

> Did you just say you have no idea how the Speex residual echo suppressor
> works? If that is the case, can you tell me where I could get some
> information about it?

What I'm saying is that I've no idea how the residual echo suppressor reacts
when it's used in a way it wasn't designed for (i.e. working around broken
audio capture/playback).

   Jean-Marc

> -----Original Message-----
> From: Jean-Marc Valin [mailto:jean-marc.valin at usherbrooke.ca]
> Sent: Friday, June 29, 2007 7:38 PM
> To: Coffey, Michael
> Cc: speex-dev at xiph.org
> Subject: Re: [Speex-dev] Backup Echo Suppression
>
> Coffey, Michael a écrit :
> > I realize that the preprocessor echo suppression is not designed
> > specifically to counter the effects of data loss. On the other hand, as
> > much as I might like to, I do not have the option to "fix that problem
> > for real." The sad truth is that some end users have systems that may
> > drop samples, or do other unfathomable things, no matter what I do. I
> > can not rewrite their drivers, firmware, or operating system. My job is
> > to do the best I can in a difficult situation.
>
> Actually, there's still a lot you can do. You can reduce the amount of
> sample drops by playing with the priority and the amount of buffering
> you do. Also, there are sometimes ways to make sure that the drops don't
> change rec/play synchronisation (the key is the sync, not the lost
> samples). As for how the residual echo suppression works, I've no idea,
> you need to try.
>
> > I initially assumed that the echo suppressor is similar to other echo
> > suppressors (also called "nonlinear processors" or "loss controls").
> > Those suppressors use cruder algorithms that exhibit artifacts but that
> > may not depend on the fine time structure of the audio signals. Is this
> > not true of the preprocessor echo suppressor?
>
> Not sure what other echo suppressors do. Some are actually designed to
> act alone while others (like the Speex one) are designed only to
> suppress the echo that was left by a first echo canceller.
>
> 	Jean-Marc
>
> > -mjc
> >
> > -----Original Message-----
> > From: Jean-Marc Valin [mailto:jean-marc.valin at usherbrooke.ca]
> > Sent: Tuesday, June 26, 2007 8:49 PM
> > To: Coffey, Michael
> > Cc: speex-dev at xiph.org
> > Subject: Re: [Speex-dev] Residual Echo Suppression by the Preprocessor
> >
> > The residual echo suppression is supposed to be working decently well
> > now. However, it's not designed to counter the effects of samples being
> > dropped off the soundcard. You'll just need to fix that problem for
> > real.
> >
> > 	Jean-Marc
> >
> >
> >
>
>