[asterisk-dev] Jitterbuffer and FAXes with E1

Martin Vít vit at lam.cz
Tue Jul 31 11:04:43 CDT 2007


The main problem was in sangoma hardware echocanceler which has some 
noise filter. Sangoma today announced new drivers, which this filter 
turns off. I've tested it and fax are now going well.

Martin Vít wrote:
> Hello,
>
> I'm testing 1.4.5 (no modifications) with E1 card and i've found problem.
>
> I've this scenaro
>
> FAX -> SIP - ATA -> asterisk -> E1 port A --loopback--> E1 port B --> 
> iaxmodem.
>
>
> When jbenabled is off FAX is delivred OK. But when jbenable = on FAX are 
> failing in almost every line. I've compared WAV extracted from network 
> with WAV recorded (app monitor) before it gets to iaxmodem and there is 
> small differences. Network jitter is about 2ms (lab environment).
>
> Where could jitterbuffer modifies frames? I've tried to disable plc in 
> plc.c but without success. Any idea?
>
> thanks in advance
>
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-- 
Martin Vít
LAM plus s.r.o.
http://www.lam.cz/
Tel.: 605 267 610




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