[Asterisk-Users] IAX Jitter Buffer

Rich Adamson radamson at routers.com
Fri Jun 18 06:24:04 MST 2004

> When we enabled jitterbuffer the sound quality seemed to improve but we
> noticed some problems:
> (a) sometime we would get only one-way audio;
> (b) other times we would experience no audio in one direction for between 1
> and 4 seconds and then things would seem to work fine;
> (c) some times users reported a "clipped" and almost "half duplex" sound
> quality as the flow of the conversation shifted back and forth.
> We also noticed some wingnut values for Lag and Jitter such as:
> Lag: -65476ms
> Jitter: 12897799ms
> PSTN gateway is "CVS-04/20/04-01:11:29 "
> Client machine is "CVS-HEAD-06/02/04-07:56:41"
> Searching the Asterisk bug lists shows some significant fixes (1696, 1643).
> Q2: Is jitterbuf working well enough to try again?
> Q3: Any other suggestions for improving voice quality with IAX links?

A google search of the asterisk-cvs list indicates there has been several
iax changes in the last several months. Iax2 with gsm is working very well
between * systems using the current cvs Head.

I was told specifically by Mark to include jitterbuffer=no in the iax.conf,
but with no explanation as to why. Although I'm not a programmer, causual
browsing of the source code would seem to suggest that some sort of 
dynamic jitter buffer function is in use and attempts to over-ride it
might not be a reasonable thing to do. 

I'd suggest bumping both systems up to current cvs Head, add the statement,
and eval the result.

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