[Speex-dev] Bitrate problem

[Shantanu Gramsci]

Thanks all for your prompt reply.

I agree with Alex. I think jitter buffer will have to
drop packets if its input bitrate is higher than it is
configured for.

I never tried speex jitter buffer. What does it do
when input bitrate is higher or lower ?

As an alternate solution, I was thinking to play with
directsound playrate [using SetFrequency()]. Has
anyone used it to solve such problem?

Any comment is appreciated.

-- Shantanu


--- Alex Bakaev <Alex.Bakaev at citrix.com> wrote:

> But that's what a jitter buffer will do, eventually
> -
> drop a packet. And it's better to drop a silence
> packet.
> 
> Cheers,
> .a 
> 
> -----Original Message-----
> From: Jean-Marc Valin
> [mailto:jean-marc.valin at usherbrooke.ca] 
> Sent: Wednesday, December 21, 2005 3:39 PM
> To: Alex Bakaev
> Cc: Shantanu Gramsci; speex-dev at xiph.org
> Subject: RE: [Speex-dev] Bitrate problem
> 
> On Wed, 2005-12-21 at 15:29 -0800, Alex Bakaev
> wrote:
> > This is a common problem. Sound cards run at
> different
> clock speeds 
> > (but your difference seems kinda high).
> > What I'd suggest is dropping silence packets once
> in a
> while.
> 
> Or just use a decent jitter buffer!
> 
> 	Jean-Marc
> 
> > .a
> > 
> > -----Original Message-----
> > From: speex-dev-bounces at xiph.org
> > [mailto:speex-dev-bounces at xiph.org] On Behalf Of
> Shantanu Gramsci
> > Sent: Wednesday, December 21, 2005 2:05 PM
> > To: speex-dev at xiph.org
> > Subject: [Speex-dev] Bitrate problem
> > 
> > Hello all,
> > 
> > This is a bit off topic but I am sure many of you
> can
> answer it.
> > 
> > I use speex and speex-wb in my VOIP application.
> With
> speex [at 8 KHz] 
> > bitrate is arround 30KBPS, including UDP,RTP
> headers.
> This is OK for 
> > me and I get good quality audio.
> > 
> > Problem is, if call is made from a HIGH END
> machine
> [like
> > P4 3.2 GHz with good soundcard] to a LOW END
> machine
> [like P3 550 
> > MHz], high end pc sends at more bitrate than as
> usual
> [arround 
> > 31Kbps].And apparently low end PC receives this
> HIGH
> bitrate.
> > 
> > So, slow end PC receives audio packets at arround
> 8100
> Hz but it is 
> > confiured for 8000 Hz. So there are overflows in
> the
> directsound 
> > buffer at receiver end at periodic interval [in my
> case
> after every 30 
> > sec], than I flush the buffer which makes some
> distortion.
> > 
> > What should be approapriate solution for this
> resynch
> problem?
> > 
> > 
> > Thanks
> > 
> > Shantanu
> > 
> > 
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> 


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