[Asterisk-Dev] zaptel echo preload

[Richard Lyman]

Richard Lyman wrote:

> Steve Underwood wrote:
>
>> James Harper wrote:
>>
>>> I'm tinkering with a patch to preload echo coefficients at channel
>>> creation time instead of it starting from scratch each time a call is
>>> started.
>>>
>>> Anyone want to have a look once I have something that works?
>>>
>>> Any comments as to if this is a good idea or not? Currently I get quite
>>> a few seconds of echo before it stabilises, so I think that having
>>> something preloaded in there is better than starting from zero. Once I
>>> get it going I'll be able to comment with more authority though :)
>>>
>>> James
>>>  
>>>
>> It depends on what you are trying to achieve.
>>
>> If you are using an analogue interface, it is likely the strongest 
>> echo will be from your local telephone exchange's line card. This 
>> should be pretty consistent from call to call, so using the same 
>> pre-tuned starting point for each call should have benefits. The 
>> canceller still needs to adapt to the echo from the far end 
>> telephone, but you have probably helped reduce the initial echo heard.
>>
>> If you are using a digital interface (BRI. E1, T1, J1) the echo you 
>> need to cancel is only from the far end. Since there is no 
>> consistency from call to call, a pre-tuned echo is completely useless 
>> for this case.
>>
>> Steve
>
>
> he's probably refering to same proto delay.  just for for thought.


sadly, i'm replying to my own post, but it is saturday (here) and i've 
had a few <G>

but, example: using jb for iax2, will cause 40ms delay regardless of 
destination, hell even same nic, hmmm.