[Asterisk-Users] echo canceling algorithm

[gw at adcomcorp.com]

Hello Joe,
I asked the same question.  It is probably a combination of things,
hardware issues like PCI bus latency, plus an issue of interest.  I
suspect the big companies have managed to cover this, but also because
they charge a lot for their equipment.
 
Being open source, yes you could write your own, and their probably are
bounties out there right now (of which I would add to).  I am going with
a hardware tellabs can via a channel bank.  A real solution?  I asked
this a while ago on the list, and my opinion is it probably will not
happen within the next 3-6 months.  After that I would not know either,
but the popularity of asterisk has grown so much that possibly we would
get lucky with some good algo's that cover more diverse situations.
 
I find that digium has a great product, and the echo is a big issue.
Many people can usually tweak it out, some cannot (especially those with
issues on lines or long loops).  Even if you are on a long loop that
does not mean the $1000 card will be perfect.  I spent more than that on
a bank and t1 card, but there is also a lot of flexibility.  
 
If you are running 12 ports I would certainly consider a channel bank or
one of those digium cards (which is actually less than your three
tdm400's I beleive), but keep in mind that using a hardware EC like a
tellabs requires either a shelf, or some good project skills.
 
The aggressive works well, though I cannot say it is 100% perfect.
 
Maybe a pci-express digium card would help :) Just an idea.
 
Greg

________________________________

From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Joe
Pukepail
Sent: Friday, December 02, 2005 6:28 PM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [Asterisk-Users] echo canceling algorithm


I have been wondering about echo canceling, it seems to be one of the
major problems people have with asterisk.  I've gotten it to acceptable
levels (using mark2 aggressive), but everything I've read indicates that
the echo canceling software isn't very effective.  
 
My question would be, what do we need to get an effective echo canceler
(in asterisk software)?  Is it patent issues?  No experience (I know I
don't know anything about how to write a echo can algorithm) or just
getting the right people interested in writing one ($)? 
 
With digium offering hardware echo can, I can only conclude that echo
can can't be done effectively in software?  If it is a matter of money
perhaps a bunch of users can offer bounties for someone (or some
company) to write an good echo canceler? 
 
With the amount of money that a hardware echo canceling card costs
(+$1000 per T1/E1) if half of this were spent on a fund for software
echo cancel it would seem we could do it (if it is even possible using
todays technology??). 
 
I don't mean this as critical of the developers who have done so much,
just an honest question what we (as users) can do to help improve the
product. 

 
On 12/2/05, Patrick Fortin <gestion at royaume.com> wrote: 

	Hi
	
	Just wandering what solution worked to eliminate echo on your
setup.
	
	I am trying every solutions I can find on the wiki and none is
working 
	perfectly.
	
	We have asterisk 1.2.0
	3 x digium TDM400P
	30 Snom320 + 5 Snom360
	
	For now the best setup I have is using Mark2 Echo cancel.
	
	Thanks
	
	Patrick
	
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