[Freeswitch-users] Codec negotiation bug?

Juan Antonio Ibañez Santorum juanito1982 at gmail.com
Sat Apr 13 02:00:44 MSD 2013


Hello,

   I am doing some codec negotiation (early) tests but FS does not work as
I expected.

I can read at wiki: "When FS calls leg B, the list of codecs in
outbound-codec-prefs for the SIP profile is reorganized by pushing the
codec negotiated above for leg A at the top. If B does not accept any of
the codecs, the calls fails, obviously"

Codec prefs setted as:

  <X-PRE-PROCESS cmd="set" data="global_codec_prefs=G729,G7221 at 32000h
,G7221 at 16000h,G722,PCMU,PCMA,GSM"/>
  <X-PRE-PROCESS cmd="set" data="outbound_codec_prefs=G729,PCMU,PCMA,GSM"/>

FS select PCMA for A leg

FS offers following SDP to B leg:

 v=0
   o=FreeSWITCH 1365781615 1365781616 IN IP4 176.31.117.49
   s=FreeSWITCH
   c=IN IP4 176.31.117.49
   t=0 0
   m=audio 19780 RTP/AVP 8 101 13
   a=rtpmap:101 telephone-event/8000
   a=fmtp:101 0-16
   a=ptime:30
   m=audio 19780 RTP/AVP 18 0 8 3 101 13
   a=rtpmap:101 telephone-event/8000
   a=fmtp:101 0-16
   a=ptime:20

Session progress from B leg contains:

   v=0
   o=root 3311 3311 IN IP4 91.192.110.234
   s=session
   c=IN IP4 91.192.110.234
   t=0 0
   m=audio 16194 RTP/AVP 18 8 0 101
   a=rtpmap:18 G729/8000
   a=fmtp:18 annexb=no
   a=rtpmap:8 PCMA/8000
   a=rtpmap:0 PCMU/8000
   a=rtpmap:101 telephone-event/8000
   a=fmtp:101 0-16
   a=silenceSupp:off - - - -
   a=ptime:20
   a=sendrecv

FS codec comparison debug look as:

sofia_glue.c:5094 Audio Codec Compare
[G729:18:8000:20:8000]/[PCMA:8:8000:30:64000]
sofia_glue.c:5094 Audio Codec Compare
[G729:18:8000:20:8000]/[G729:18:8000:20:8000]
sofia_glue.c:3077 Set Codec sofia/external/0034950004588 G729/8000 20 ms
160 samples 8000 bits

FS start comparing G729 instead PCMA selected in A leg

Is that ok? is there any way to get selected PCMA for B leg without using
late negotiation nor disabling transcoding

Regards
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