Hi Isshed, in your example, second offer from A is correct as long as session version id is changed in same session. w.r.t m= line, the second answer sent from B is wrong because it does not contain the same number of m= lines as in second offer from A.
Hope this helps to you. snippet from RFC 3264, 6 Generating the Answer . . For each "m=" line in the offer, there MUST be a corresponding "m=" line in the answer. The answer MUST contain exactly the same number of "m=" lines as the offer. This allows for streams to be matched up based on their order. This implies that if the offer contained zero "m=" lines, the answer MUST contain zero "m=" lines. . . . Thanks and regards, -Praveen On Fri, Jan 10, 2014 at 12:11 PM, isshed <isshed....@gmail.com> wrote: > Hi All, > > Below is offer answer model between UA A and B. > > > [Offer From A] > > v=0 > o=alice 2890844526 2890844526 IN IP4 host.atlanta.example.com > s= > c=IN IP4 host.atlanta.example.com > t=0 0 > m=audio 49170 RTP/AVP 0 8 97 > a=rtpmap:0 PCMU/8000 > a=rtpmap:8 PCMA/8000 > a=rtpmap:97 iLBC/8000 > m=video 51372 RTP/AVP 31 32 > a=rtpmap:31 H261/90000 > a=rtpmap:32 MPV/90000 > > > [Answer From B] > > v=0 > o=bob 2808844564 2808844564 IN IP4 host.biloxi.example.com > s= > c=IN IP4 host.biloxi.example.com > t=0 0 > m=audio 49172 RTP/AVP 0 8 > a=rtpmap:0 PCMU/8000 > a=rtpmap:8 PCMA/8000 > m=video 0 RTP/AVP 31 > a=rtpmap:31 H261/90000 > > [Second-Offer From B] > > v=0 > o=alice 2890844526 2890844527 IN IP4 host.atlanta.example.com > s= > c=IN IP4 host.atlanta.example.com > t=0 0 > m=audio 51372 RTP/AVP 0 > a=rtpmap:0 PCMU/8000 > > [Second-Answer From A] > > v=0 > o=bob 2808844564 2808844565 IN IP4 host.biloxi.example.com > s= > c=IN IP4 host.biloxi.example.com > t=0 0 > m=audio 49172 RTP/AVP 0 > a=rtpmap:0 PCMU/8000 > m=video 0 RTP/AVP 31 > a=rtpmap:31 H261/90000 > > > Is it a valid offer answer model, as [Second-Offer From B] removes > one of the m line? > > Thanks. > _______________________________________________ > Sip-implementors mailing list > Sip-implementors@lists.cs.columbia.edu > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > -- ------------------------------ Thanks and Regards, Praveen _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
