[Asterisk-Dev] IAX to zaptel echo

[Steven Critchfield]

On Thu, 2003-08-21 at 11:10, John James wrote:
> Out of curiosity, isn't echo a function of delay?  It sounds like Claude may be running a this on a small development LAN which should have low latency.  Does anyone know if Asterisk introduces enough latency to cause echo?

It can, remember there is a buffer to compensate for slow packets, and
then you have time running through the echo canceler. Our PtP T1 with
normally only 4ms of latency was enough to cause the jitter buffer to
misbehave and cause sound loss. I'm sure there are occasions where a lan
causes similar problems.  

> -----Original Message-----
> From: asterisk-dev at lists.digium.com
> Sent: 8/20/2003 6:00 PM
> To: asterisk-dev at lists.digium.com
> Subject: RE: [Asterisk-Dev] IAX to zaptel echo
> 
> 
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> I think the local echo is a fact of life for now -- if you
> compile in MARK2 and AGGRESSIVE_SUPRESSOR, the echo will
> usually equalize after 10 seconds of sent audio (or
> thereabouts depending on the speed of your system).  It's
> incredibly annoying, but I know for a fact that many of us
> experience it..  Someday we'll find a way to make it no
> more!
> 
> Vanquish the evil demon that is echo!  Spencer, where are
> youuu? :)
> 
> Pete
> 
> 
> - -----Original Message-----
> From: asterisk-dev-admin at lists.digium.com
> [mailto:asterisk-dev-admin at lists.digium.com] On Behalf Of
> Claude Klimos
> Sent: Wednesday, August 20, 2003 2:17 PM
> To: asterisk-dev at lists.digium.com
> Subject: [Asterisk-Dev] IAX to zaptel echo
> 
> 
> Hi all,
> 
> I am experiencing a problem with the quality of the voice
> communication between an IAX based softphone (WinIAX) and
> an outside line through a FXO port or even with a regular
> analog phone connected to a FXS port. The party using the
> IAX softphone hears his own echo a plit of a second after
> speaking. The party on the analog end does not experience
> any echo. I tried to modify the KFLAG parameter in the
> Makefile of zaptel to change the algorithm without results.
> I also tried to modify the value of the echocancel paramter
> in zapata.conf (tried 32,64,yes/128,256) without success.
> Note the parameter echocancelwhenbridged is set to yes.
> 
> On the other hand, when I establish a communication between
> two IAX softphones, I hear no echo. This leads me to
> suspect the cards I am using. I have one X100P and one
> TDM400P card with 2 modules enabled.
> 
> I would like to know if anyone encoutered this problem and
> how to minimize/eliminate the echo, if possible. Also, we
> will eventually be using a PRI with a T100P or a T400P,
> would the echo problem still be present?
> 
> Regards,
> 
> Claude Klimos
> 
> 
> 
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-- 
Steven Critchfield  <critch at basesys.com>