[asterisk-users] about application Jack and its runtime

[Russell Bryant]

On Sep 11, 2008, at 2:18 PM, Julien Claassen wrote:
>   Does application Jack run the whole time, the conversation is going?
>   If so: is there a SIMPLE extensions.conf-only-based way to put it  
> in the
> "background"? I know AGI and other applications... :-(

Yes.  When you use the Jack application, it runs as blocking.  It will  
not exit until the call is over.  However, there is another option,  
which is the JACK_HOOK function.

The Jack application acts as an endpoint for a call.  The JACK_HOOK  
function is different.  It allows you to hook into the audio stream  
for a channel while the channel goes off and executes other Asterisk  
applications.  Your hook can be listen-only, write-only (which would  
replace the channel's audio with something), or as a manipulate  
audiohook.  The manipulate version is the most common because you have  
full access to the audio stream for a channel and can do whatever you  
want with it.

When I wrote JACK_HOOK, the idea I had in mind was being able to use  
some external application using jack to add sound effects, like a  
vocoder.

Some more information about these interfaces can be found here:

http://www.russellbryant.net/blog/2008/01/13/jack-interfaces-for-asterisk/

--
Russell Bryant
Senior Software Engineer
Open Source Team Lead
Digium, Inc.