[SIP Beyond VoIP] opus codec negotiation

Juha Heinanen jh at tutpro.com
Thu Jun 12 11:58:52 CEST 2014


i made a call from baresip to blink and noticed that blink didn't choose
opus codec although i have it on top of the list.   the same problem with
another way around.

i don't know about the specifics of opus sdp lines.  perhaps someone on
the list has an idea why opus was not negotiated?

-- juha

offer:

v=0.
o=- 2078554684 1303266001 IN IP4 192.168.43.146.
s=-.
c=IN IP4 192.168.43.146.
t=0 0.
a=tool:baresip 0.4.10.
m=audio 10106 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:1226403445 cname:sip:test at test.tutpro.com.
a=rtcp-mux.
a=ptime:20.

answer:

v=0.
o=- 3611555637 3611555638 IN IP4 192.168.43.146.
s=Blink 0.7.0 (Linux).
c=IN IP4 192.168.43.146.
t=0 0.
m=audio 50002 RTP/AVP 97 101.
a=rtcp:50003.
a=rtpmap:101 telephone-event/8000.
a=fmtp:101 0-15.
a=sendrecv.
a=rtpmap:97 speex/16000.


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