response inline... Attila Sipos wrote: > > ref: draft-ietf-mmusic-sdp-offer-answer-02.txt > > I'm looking at section "10.2 One of N Codec Selection". > > At the end, there is the sentence: > > The protocol which > carries offers and answers has to provide a means to resolve these > glare conditions, so that only one offer will be used. > > > This seems to me that: > if an offer has multiple codecs then, eventually, you MUST be > left with JUST ONE selected codec.
Only if that is the desired result of the negotiation. > > Is my above statement correct? > Or can you actually select two codecs if you want to. > You may negotiate any number of codecs, even add them. > > The reason I ask is that I'm trying to understand the > interoperability issues associated with RFC2833. > > Some vendors might "offer" an SDP like this: > m=audio 10016 RTP/AVP 4 8 97 > a=rtpmap:4 G723/8000 > a=rtpmap:8 PCMA/8000 > a=rtpmap:97 telephone-event/8000 > > Seeing as they've offered a "telephone-event" codec AND > some "normal audio" codecs, I believe their intention is to do > BOTH "telephone-event" and "normal audio". > yes, and any of the three encodings can be present in the RTP stream sent to the single address & port pair. > However, I also believe that with this offer they will > only be allowed to do ONE of these! Is this correct? > It depends on the capabilties of your RTP and DSP/codec HW/SW. > > So, I believe that any endpoint that wishes to do > BOTH "normal audio" AND "telephone-event" media > MUST use separate "m=" lines. > > i.e. the offer should be: > m=audio 10016 RTP/AVP 4 8 > a=rtpmap:4 G723/8000 > a=rtpmap:8 PCMA/8000 > m=audio 10018 RTP/AVP 97 > a=rtpmap:97 telephone-event/8000 > > Is this correct? > It is for the RTP and DSP/codec HW/SW that I'm familiar with (I'll admit my familiarity is limited). In fact, the two audio encodings would have to be sent to a different port. Regards, Bert > Any help is much appreciated. > > Regards, > > Attila > > Attila Sipos > Software Engineer > > <mailto:[EMAIL PROTECTED]> > <http://www.vegastream.com> > ______________________________________________________________ > ______________ > ______ > > > VegaStream : A World of difference for your Integrated Communications > > EMEA Office (UK) > Tel + 44 - 1344 784900 Fax + 44 - 1344 784901 > USA Office > Tel + 1 - 561-995-2300 Fax + 1 - 561-995-2600 > > This e-mail and any attachments hereto are strictly confidential and > intended solely for the addressee. If you are not the > intended addressee > please notify the sender by return and delete the message. > You must not > disclose, forward or copy this e-mail or attachments to any > third party > without the prior consent of the sender. > > > > > > > > _______________________________________________ > 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
