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

[Jeff LaCoursiere]

On Wed, 19 Aug 2009, Dave Fullerton wrote:

> 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
>

I feel like I must be missing something here.  In 1.4, to my knowledge, if 
hardware echo cancellation was present, it would be used automatically. 
Further, software echo was enabled by default.  If hardware was available 
the software would turn itself off automatically.

What was wrong with this setup?  There was no ambiguity, and there was no 
confusion.

Have I assumed the above in error all this time?

So in 1.6 the hardware echo is on if available, and its only that you must 
enable software cancellation if you want it by adding the appropriate 
module.  Is that right?

It seems then that we would be back to the 1.4 situation if asterisk 
shipped with one of the SEC modules enabled by default, and you could 
change it or turn it off if you wanted.  Kevin seemed to confirm that this 
was the plan.  Sounds good to me.

Cheers,

j