[Freeswitch-users] mod_conference wrong codec for auto_outcall b-leg

[Oliver Saggau | Sysvision GmbH]

Hi everyone,
I got a strange problem with mod_conference and auto_outcall taking the 
wrong codec for b-leg. For what I can see from the log everything seems 
fine. The a-leg calls with the following SDP:

2012-09-18 08:57:47.410023 [DEBUG] sofia.c:6293 Remote SDP:
v=0
o=- 3556961565 3556961565 IN IP4 10.20.30.125
s=pjmedia
t=0 0
m=audio 4000 RTP/AVP 99 101
c=IN IP4 10.20.30.125
a=rtpmap:99 SILK/24000
a=fmtp:99 useinbandfec=0
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
a=rtcp:4001 IN IP4 10.20.30.125

And the SILK/24000 codec is accepted according to the log file:
2012-09-18 08:57:47.650018 [DEBUG] sofia_glue.c:3077 Set Codec 
sofia/internal/1000004 at 10.20.30.240 SILK/24000 20 ms 480 samples 40000 bits
2012-09-18 08:57:47.650018 [DEBUG] switch_core_codec.c:111 
sofia/internal/1000004 at 10.20.30.240 Original read codec set to SILK:120
2012-09-18 08:57:47.650018 [DEBUG] mod_sofia.c:836 Local SDP 
sofia/internal/1000004 at 10.20.30.240:
v=0
o=FreeSWITCH 1347951445 1347951446 IN IP4 10.20.30.240
s=FreeSWITCH
c=IN IP4 10.20.30.240
t=0 0
m=audio 21622 RTP/AVP 99 101
a=rtpmap:99 SILK/24000
a=fmtp:99 useinbandfec=0; usedtx=0; maxaveragebitrate=40000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=silenceSupp:off - - - -
a=ptime:20
a=sendrecv

The conference get's created and activates the read/write codecs for the 
first member:
2012-09-18 08:57:47.990021 [DEBUG] mod_conference.c:7092 Raw Codec 
Activation Success L16 at 24000hz 1 channel 20ms
2012-09-18 08:57:47.990021 [DEBUG] mod_conference.c:7137 Raw Codec 
Activation Success L16 at 48000hz 1 channel 20ms

After that he's trying to do the auto_outcall and that's where things 
get weird:
EXECUTE sofia/internal/1000004 at freeswitch.aws.hosts.corpex.de 
conference_set_auto_outcall(sofia/internal/sip:1000003 at 10.20.30.108:63741;transport=UDP;ob)
2012-09-18 08:57:47.990021 [NOTICE] switch_channel.c:951 New Channel 
sofia/internal/sip:1000003 at 10.20.30.108:63741 
[0236d005-1ff0-4f13-9370-bf7736087dd0]
2012-09-18 08:57:47.990021 [DEBUG] sofia_glue.c:2637 Local SDP:
v=0
o=FreeSWITCH 1347952749 1347952750 IN IP4 10.20.30.240
s=FreeSWITCH
c=IN IP4 10.20.30.240
t=0 0
m=audio 20318 RTP/AVP 98 0 8 101 13
a=rtpmap:98 SILK/8000
a=fmtp:98 useinbandfec=1; usedtx=0
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=ptime:20
a=sendrecv
2012-09-18 08:57:52.590016 [DEBUG] mod_conference.c:7092 Raw Codec 
Activation Success L16 at 8000hz 1 channel 20ms
2012-09-18 08:57:52.590016 [DEBUG] mod_conference.c:7137 Raw Codec 
Activation Success L16 at 48000hz 1 channel 20ms

Why is FS only offering SILK/8000 for b-leg? My outbound_codec_prefs is 
configured like this:
outbound_codec_prefs=silk at 24000,silk at 16000,silk at 8000,PCMU,PCMA,GSM

Thanks for your help,
Oliver