[Asterisk-Users] Best CoDec for high network latency

[Alexander Lopez]

You need to use the 'over' codec. It has been used for years with half-duplex conversations.

OVER

.....
 

> -----Original Message-----
> From: asterisk-users-bounces at lists.digium.com 
> [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of 
> Jean-Michel Hiver
> Sent: Saturday, January 28, 2006 1:45 PM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [Asterisk-Users] Best CoDec for high network latency
> 
> Guillermo Salas M a écrit :
> 
> >Hi,
> >
> >I need to have some SIP extentions on remote places where 
> the latency 
> >from my asterisk box with public ip is 1~1.5 seconds.
> >
> >What codec will work fine on this sceneary? I'm planning to 
> use iLBC, 
> >is a good choice?
> >  
> >
> There are basically three parameters I can think of when 
> speaking of voice over ip quality:
> 
> 1 - Lag. In your case, a ping from your Asterisk box is 1 to 1.5 ms. 
> Changing codecs is not going to help you here.
> 
> 2 - Jitter. In your case, if the ping does vary between 1 and 
> 1.5, that's 500ms "ping jitter", which is high. You might 
> want to have a large jitter buffer to compensate for it. But 
> this increases lag even more...
> 
> 3 - Packet drop. iLBC is meant to cope "better" with packet 
> drop than other codecs, although in my experience any codec 
> with too much packet drop will sound dreadful.
> 
> If you have the bandwith and no packet loss, I would 
> recommend that you bump up the jitter and stick with ulaw. 
> While there might be a lot of lag - "half duplex" kind of 
> conversations... - the audio should remain clear.
> 
> If you are having packet loss on top of this, you might want 
> to try iLBC...
> 
> At any rate, nothing is going to replace trying out some 
> settings for yourself...
> 
> BTW: How come the latency is so high? The worst I've seen so 
> far was a link varying between 600 and 1200ms and the quality 
> varied from "good enough" to "pretty horrible"...
> 
> Cheers,
> Jean-Michel.
> 
> --
> Jean-Michel Hiver - http://ykoz.net/
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> 
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