[SIP Beyond VoIP] opus codec negotiation

Juha Heinanen jh at tutpro.com
Thu Jun 12 13:21:00 CEST 2014


James Cloos writes:
> >>>>> "JH" == Juha Heinanen <jh at tutpro.com> writes:
> 
> JH> i made a call from baresip to blink and noticed that blink didn't
> JH> choose opus codec although i have it on top of the list.  the same
> JH> problem with another way around.
> 
> What did the offer/answer look like in the other direction?
> 
> They may not be offering opus the same way.

see below.  both baresip and google/firefox webrtc use this kind of
rtpmap for opus:

a=rtpmap:109 opus/48000/2.

-- juha

v=0.
o=- 3611560662 3611560662 IN IP4 192.98.102.30.
s=Blink 0.7.0 (Linux).
c=IN IP4 192.98.102.30.
t=0 0.
m=audio 50002 RTP/AVP 113 104 103 0 8 101.
a=rtcp:50003.
a=rtpmap:113 opus/48000.
a=fmtp:113 useinbandfec=1.
a=rtpmap:104 speex/32000.
a=rtpmap:103 speex/16000.
a=rtpmap:0 PCMU/8000.
a=rtpmap:8 PCMA/8000.
a=rtpmap:101 telephone-event/8000.
a=fmtp:101 0-15.
a=crypto:1 AES_CM_128_HMAC_SHA1_80 inline:EQ14NUda7S8CBrC04b2oCWKpGJGHva34RuTTZmHK.
a=crypto:2 AES_CM_128_HMAC_SHA1_32 inline:o72h6aKPzO8FUSdItvb+8JLbzsOnsIZeXPILuKBF.
a=sendrecv.

v=0.
o=- 180852747 1296883921 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 10728 RTP/AVP 103 0 8 101.
b=AS:125.
a=rtpmap:103 speex/16000.
a=fmtp:103 mode="7";vbr=off;cng=on.
a=rtpmap:0 PCMU/8000.
a=rtpmap:8 PCMA/8000.
a=rtpmap:101 telephone-event/8000.
a=fmtp:101 0-15.
a=sendrecv.
a=label:1.
a=rtcp-rsize.
a=ssrc:915366953 cname:sip:test at test.tutpro.com.
a=rtcp-mux.
a=ptime:20.


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