[Speex-dev] speex voice seems to be bit breaking over long distance.

[Jean-Marc Valin]

> Ok, what you suggest sound logical to me. Currently, I
> have done a small trick to prevent this problem. What
> I did is that whenever windows request a voice packet
> from me and if I do not have the voice packet, I
> repeat the previous packet. Hence, all the breaking
> portion is filled with previous packet. This trick
> seems to work so far. I am not sure what is the side
> effect.

Actually, Speex has Packet Loss Concealment (PLC) builtin. If a packet
is missing, instead of repeating the previous one, just try decoding by
passing NULL instead of the SpeexBits struct.

> I think jitter buffering is more correct way to solve
> this problem but I think this is not so easy. Is there
> got any source code to reference from?

Look for the speex_jitter.h header.

	Jean-Marc

> Regards,
> YueWeng 
> 
> --- "Kleijn, J.S. de" <J.S.d.Kleijn at student.tue.nl>
> wrote:
> > Hi,
> >  
> > You should implement a jitter buffer, this buffers
> > the audio to prevent the 'breaking'.
> >  
> > My VoIP application called VoIPerized has a jitter
> > buffer. You can try it to see if you then don't
> > experience the breaking of the voice.
> >  
> > Greetings Jeroen de Kleijn
> > 
> > 	-----Oorspronkelijk bericht----- 
> > 	Van: speex-dev-bounces at xiph.org namens Tay YueWeng 
> > 	Verzonden: ma 18-4-2005 11:28 
> > 	Aan: speex-dev at xiph.org 
> > 	CC: 
> > 	Onderwerp: [Speex-dev] speex voice seems to be bit
> > breaking over long distance.
> > 	
> > 	
> > 
> > 	Dear all,
> > 	I have implemented speex. Under LAN environment,
> > 	everything is working fine. However, when the
> > source
> > 	and destination is about 20 hrs away, with ping
> > 	response time of about 800ms, the voice is
> > breaking.
> > 	Breaking means you can not hear a smooth voice.
> > Like
> > 	the voice is being "chopped" into many pieces.
> > 	
> > 	The amount of packet lost is less than 10%. I have
> > 	tried 8KHz, 16KHz, 32KHz. The bigger it gets, the
> > more
> > 	lousy the quality. I believe I have enough
> > bandwidth
> > 	since the packet lost is less than 10%.  The only
> > 	factor that could affect the quality is may be
> > 	delayed.
> > 	
> > 	Any one have any idea of what is wrong?
> > 	
> > 	Regards,
> > 	YueWeng
> > 	
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> > 
> > 
> 
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-- 
Jean-Marc Valin <Jean-Marc.Valin at USherbrooke.ca>
Université de Sherbrooke