Hi (trying to catch up on your exchange). In short, IMO you both are saying the right things. My earlier comment about "deficiencies" with SDP-SIP have been solved with the text quoted below. Whether or not two endpoints will "communicate" when using different payload types for the same media will obviously depend on the endpoints' capabilities to send with one and receive with another. The original SDP for A & B can work in this case. However, having endpoints use the same payload type (in both directions) has a greater chance of successfully communicating from a practical point of view IMO.
Regards, Bert [EMAIL PROTECTED] wrote: > > > Hi Attila, > > > Despite your answer, I'm still not convinced > > that you are right (and I'm not convinced that > > my proposed theory is right). > > > > We agree that the answerer must transmit RTP with > > a payload field set as specified in the offerer's SDP: > > > > "In the case of RTP, it [the answerer] MUST use > > the payload type numbers from the offer, even > > if they differ from those in the answer." > > Oops... my apologies, I got a bit confused in the last > mail that you sent... we indeed concur on that :"> > > > However, I cannot see any explicit statement > > regarding the payload field in the offerer's > > RTP packets. > > And apologies again since I wrongly extrapolated that > text from the draft for the offerer too. Your theory > seems to be correct regarding the offerer. > > A more detailed study and I found the following text > in Page 6 (section 5.1) of the offer/answer-02 draft: > > "For sendrecv RTP streams, the payload type numbers > indicate the value of the payload type field the > offerer expects to receive, and would prefer to send. > ^^^^^^ > However, for sendonly and sendrecv streams, the answer > might indicate different payload type numbers for the > same codecs, in which case, the offerer MUST send with > the payload type numbers from the answer." > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > So, .... that would be the right thing to do. Each person > MUST use the payload numbers that the other party wants to > see in the RTP payload. > > I (as the offerer) want to see 119 in whatever RTP I receive > so I give that in the SDP and you MUST use 119 in the RTP packet. > You, on the other hand, want to see 97 in your RTP payload, > so you send 97 in the answer SDP and I MUST use 97 for the > RTP payload. > > Everyone would be happy then and get to see what they want > to see ;) I think I got it right this time (finally :) > > Cheers, > Siddharth. > > ----------------- > Siddharth Toshniwal @ Hughes Software Systems > http://www.hssworld.com > > > _______________________________________________ > Sip-implementors mailing list > [EMAIL PROTECTED] > http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
