[speex-dev] speex preprocess redux

Tom Harper
Fri, 06 Aug 2004 15:02:05 -0000

Tom,

What you said makes sense - I have been having problems with VAD
clipping when there is no background noise, but that may be caused
by some other part of the system.  Transmitting continuously, as you
said, seems to fix the problem.

I am going to separate my VAD and denoise operations and see how
it sounds to just run the denoiser.

Tom

At 04:51 PM 5/17/2004, Tom Grandgent wrote:
>I'm not sure if this is due to the same problem, but I get the
>same clipping behavior when trying to use VAD+denoiser on a
>particular mic+speaker setup that has significant background noise
>(enough to really foul up the codec should the denoiser be turned
>off.)  Leaving VAD off and transmitting continuously seems to be
>the only way to avoid this clipping.
>
>Another person I regularly communicate with also has a mic+speaker
>setup but not much background noise.  With VAD+denoiser enabled,
>I never have any trouble hearing him.
>
>This gives me the impression that VAD doesn't function too well
>when the input is noisy, even if the denoiser can do an excellent
>job of cleaning up the signal.  So it seems that VAD is being
>done before denoising, and looking at the code for
>speex_preprocess(), I think this is the case.  (Am I wrong?)
>
>Why not do VAD after denoising?  It seems like it would be much
>more reliable.
>
>Tom
>
>Tom Harper (tharper@sightspeed.com) wrote:
> >
> > Steve,
> >
> > The main problem I am having with the system is clipping off the start
> > of someone's speech when they first start talking- the ends of the
> sentences
> > seem to be handled properly.  I am wondering whether this is the fault
> of the
> > audio playback system or whether this is a speex issue-
> >
> > I also get the musical artifacts problem with the denoiser.  This
seems to
> > be more of a problem on open air mics/speaker combinations.  However,
> > this and the issues you pointed out are a minor deal in comparison
with the
> > clipping problem.
> >
> > Tom
>
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--

Tom Harper - tharper@sightspeed.com
Lead Software Engineer
SightSpeed - A Roda Group Affiliated Company

918 Parker St, Suite A14
Berkeley, CA 94710

Phone: 510.665.2920
Cell: 415.378.3779

http://www.sightspeed.com

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