[asterisk-users] Zaptel -> DAHDI: now echo

[Dave Fullerton]

Tzafrir Cohen wrote:
> On Tue, Aug 18, 2009 at 10:00:55AM -0400, Dave Fullerton wrote:
> 
>> Here's my $0.02. If you don't want an echo canceller, specify 
>> echocanceller=none,x-y and have dahdi_cfg print a warning (at any 
>> verbosity level) when an echo canceller is not specified for a channel.
>> Personally, I would also like to see an option that says "Use the 
>> hardware canceller", like echocanceller=hw,x-y. This would have the 
>> added benefit of being able to display an error/warning when the 
>> hardware canceller is specified but no hw canceller is present. It goes 
>> against my grain to not specify a canceller to mean use a harware one if 
>> it happens to exist.
> 
> Though this means you have to explicitly configure hardware echo
> cancellers to work, which is not as before. This leaves even more room
> for error.
> 

It is true that this method would require more configuration work and 
that it would probably throw people off who were used to the old method. 
However, I don't agree that it leaves more room for error. The current 
system, IMHO, has a certain amount of ambiguity to it. If I inherit a 
production system from someone, I can't tell for sure what the echo 
canceller setup is just by looking at system.conf. I have to look at 
system.conf and then know if hardware echo can is present. Aside from 
opening the case or looking at dmesg output, I'm not even sure how to 
see if a hardware echocan is present or not.
The post that started this thread is another example of that ambiguity. 
Not defining an echo canceller to mean "don't use one, or use a hardware 
one if there is one" I think leaves room for confusion and error.

-Dave