Re: [Iaxclient-devel] codec negotiation ?

[Steve K. <st...@st...>]

Gary wrote:

>I have noticed lack of codec negotiation with calls thru a registrated
>asterisk box.
>
>No seen problems with outbound calls, (though I haven't specifically
>tried it), but the problem exists inbound.
>
>Easiest method for testing this was ring in via a sip client set to
>ulaw, ringing a registered iaxcomm extension.
>
>currently using iaxcom-win-20040228
>
>
>
>I might add DIAX.097a continually bombs out on making calls as well.
>
>current machine here is a compaq 910a running xp-home.
>
>Any thoughts of what I might have missed ??
>  
>

You forgot to write the code to support multiple codecs :)

Ok, seriously -- iaxclient currently supports only GSM.  Nobody has 
stepped up to write the code necessary to support multiple codecs.  At 
some point, I probably will, if only because I spend more time talking 
about it than it would take to do it.

On a similar note, I benchmarked GSM vs Speex vs ILBC.  GSM is fastest 
to encode, but speex is fastest to decode.  Speex and ILBC are similar 
in encode speed.  (Speex encode speed depends on the quality/bitrate 
settings you use; ILBC/GSM have no such settings).

Speex would be easiest to do (along with uLaw), but it shouldn't be much 
harder to include iLBC (just need to ensure the 30ms frames are dealt 
with), except for licensing issues (you can't use iLBC with GPL, for 
example).

Back to your question, though:  Asterisk should translate codecs for you 
in this case, as your call from Sip-client to iaxclient needs to go 
through asterisk.  There may be a setting in iax.conf to tell asterisk 
we only support GSM. [but we probably should be able to tell asterisk 
this in our protocol exchange].


-SteveK