[SIP Beyond VoIP] sylkserver direction:active

Juha Heinanen jh at tutpro.com
Tue Nov 18 01:01:46 CET 2014


Saúl Ibarra Corretgé writes:

> That sounds a bit like comedia mode. Since we use PJMEDIA as our RTP
> transport, which is SDP aware, it should probably added there.

a=direction:active/passive has existed for a long time and is widely
supported.  when sylkserver receives INVITE with a=direction:active in
sdp: 

v=0.
o=- 3398176050 259176475 IN IP4 10.0.2.15.
s=-.
c=IN IP4 10.0.2.15.
t=0 0.
m=audio 10070 RTP/AVP 96 97 98 8 0 101.
b=AS:125.
a=rtpmap:96 opus/48000/2.
a=fmtp:96 stereo=1;sprop-stereo=1.
a=rtpmap:97 speex/16000.
a=fmtp:97 mode="7";vbr=off;cng=on.
a=rtpmap:98 speex/8000.
a=fmtp:98 mode="7";vbr=off;cng=on.
a=rtpmap:8 PCMA/8000.
a=rtpmap:0 PCMU/8000.
a=rtpmap:101 telephone-event/8000.
a=fmtp:101 0-15.
a=sendrecv.
a=label:1.
a=rtcp-rsize.
a=ssrc:323105805 cname:sip:test at test.tutpro.com.
a=rtcp-mux.
a=ptime:20.
a=direction:active.

it should respond with a=direction:passive, but it does not:

v=0.
o=- 3625257322 3625257323 IN IP4 182.9.211.197.
s=SylkServer-2.7.2.
t=0 0.
m=audio 60006 RTP/AVP 97 101.
c=IN IP4 182.9.211.197.
a=rtcp:60007.
a=rtpmap:101 telephone-event/8000.
a=fmtp:101 0-15.
a=sendrecv.
a=rtpmap:97 speex/16000.

so as you say, looks like pjmedia does not support direction attribute.

-- juha


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