Thanks Paul!

You are totally right, I was looking for the a=rtpmap:18 G729/8000 line. I find it weird that it is automatically inserted for SPEEX, but not for other codecs.

Another thing I noticed, is I can't specify more than one codec, according to what I've read about other issues, this has something to do with a comma parsing problem on the console (for some reason commas can't be escaped, this also affects trying to originate calls from ESL).

So for absolute_codec_string=G729 I get this SDP (with verbose_sdp=true):

   v=0
   o=FreeSWITCH 1303718366 1303718367 IN IP4 127.0.0.1
   s=FreeSWITCH
   c=IN IP4 127.0.0.1
   t=0 0
   m=audio 29882 RTP/AVP 18 101 13
   a=rtpmap:18 G729/8000
   a=rtpmap:101 telephone-event/8000
   a=fmtp:101 0-16
   a=ptime:20


But for absolute_codec_string=G729,PCMU I get no additional m= lines in the SDP:

   v=0
   o=FreeSWITCH 1303716332 1303716333 IN IP4 127.0.0.1
   s=FreeSWITCH
   c=IN IP4 127.0.0.1
   t=0 0
   m=audio 32008 RTP/AVP 18 101 13
   a=rtpmap:18 G729/8000
   a=rtpmap:101 telephone-event/8000
   a=fmtp:101 0-16
   a=ptime:20




On Mon, Apr 25, 2011 at 12:06 PM, Paul Cupis <paul@cupis.co.uk> wrote:
On 25/04/11 16:22, Nicolas Brenner wrote:
> I'm trying to force the use of a specific codec when originating a call from
> the command line.

>    m=audio 17054 RTP/AVP 0 8 98 18 101 13

>    m=audio 24894 RTP/AVP 0 101 13

> And it doesn't matter the value I give to the absolute_codec_string, I will
> get the same SDP, except if I specify SPEEX, then I'll get the same SDP as
> the one above. Am I missing something, or is this the way it's supposed to
> work?

Looks okay to me. Perhaps you are not looking at the m=audio line in the
SDP which you will is different - this reflects the difference in the
offered codecs.

You might be expecting to see all of the codecs itemised in the a=fmtp
lines - this is known as verbose-sdp and is disabled by default.

Have a look at:
http://wiki.freeswitch.org/wiki/Variable_verbose_sdp

Regards,

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