[Asterisk-Dev] codecrenegotiation andfax [was:codec negotiationissue]

[Andrew Lindh]

>
>Kevin P. Fleming wrote:
>
>My work has been focused on making Asterisk internals remember what 
>codecs the peers can support, and initiating renegotiation when needed 
>as channels are bridged. Initially my efforts will be focused on making 
>chan_sip react to these requests and renegotiate with its peer(s), but 
>any help available in extending this to IAX2 would be welcome.
>

This would be a great feature as it would allow phones/gateways to use
whatever codec they wanted (G.729, etc) without cost to the Asterisk server.
The big issue here is a G.729 end user talking to a G.711 gateway and
having asterisk waste CPU time and $$$ for G.729 when it should just
reinvite with G.729 (or G.711) for both ends.

I think my vote would to be always renegotiation down in bandwidth.
But now you have several issues of which one do you pick if there
is a choice of several (G.711, G.722, G.729, GSM, etc)

I can see a lot of work required to make fix this everywhere. One example
would be chanspy/monitor/record that now has to switch codecs on the
same channel.

This is a very useful idea for saving CPU cycles and codec (G.729) costs
used in transcoding when both ends support the same codecs but that's
not what they started with...


  Andrew