Codec Negotiation and renegotiataion
atul garg <[email protected]> Wed, 13 Jul 2011 20:59:40 +0530 (IST)
| Newsgroups | gmane.ietf.sip |
|---|---|
| Message-ID | <[email protected]> |
--===============2499247264962649826== Content-Type: multipart/alternative; boundary="0-644347746-1310570980=:43882" --0-644347746-1310570980=:43882 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Hello All, =A0 I have very basic question regarding the codec negotiation in SIP, I will t= ry to summarize my queries below - =A0 1) If A=A0is initiating the call and sending the supported codec list say (= 1,2,3) =A0=A0=A0=A0=20 =A0=A0=A0 A -->=A0 INVITE (SDP-> audio 1 2 3) --> B=A0=A0=A0=A0=A0 ( B supp= orts 1 , 3, 5) =A0=A0=A0 A <--=A0 200 OK ( SDP -> what will be here 1, 2 ,3 OR 1, 3, 5)=A0= <-- B =A0 =A0=A0 if it is 1, 3, 5 then what will be the response to B ?? =A0 2)=A0 If A=A0is initiating the call and sending the supported codec list sa= y (1,2,3) =A0=A0=A0=A0=20 =A0=A0=A0 A -->=A0 INVITE (SDP-> audio 1 2 3) --> B=A0=A0=A0=A0=A0 ( B supp= orts=A0 2 , 3, 5) =A0=A0=A0 A <--=A0 200 OK ( SDP -> what will be here=A02 , 3 OR=A0 2 , 3, 5= )=A0 <-- B =A0 =A0=A0 if it is=A02 , 3 =A0then what will be the response to B ?? =A0=A0 if it is=A02 , 3, 5=A0=A0then what will be the response to B ?? =A0 3)=A0 If A=A0is initiating the call and sending the supported codec list sa= y (1,2,3) =A0=A0=A0=A0=20 =A0=A0=A0 A -->=A0 INVITE (SDP-> audio 1 2 3) --> B=A0=A0=A0=A0=A0 ( B supp= orts=A0 4, 5,6) =A0=A0=A0 A <--=A0 200 OK ( SDP -> what will be here=A0??)=A0 <-- B =A0 and what will be the d behaviour of A .... =A0=A0=20 4) Re-Negotiation - =A0 =A0=A0 If A=A0is initiating the call and sending the supported codec list s= ay (1,2,3) =A0=A0=A0=A0=20 =A0=A0=A0 A -->=A0 INVITE (SDP-> audio 1 2 3) --> B=A0=A0=A0=A0=A0 ( B supp= orts 1 , 2, 3) =A0=A0=A0 A <--=A0 200 OK ( SDP audio1, 2 ,3=A0=A0 <-- B =A0=A0=A0 A --> ACK --> B =A0 ( I guess the rtp will use codec 1) =A0 =A0 Now during the call say A wants to change the codec to 2, will it send = the re-invite or SDP session has some provision for it( I just want to conf= irm, is it possible to change the codec without sending any SIP message) =A0 PS: I know i have made a lengthy mail, but=A0=A0it is very much required fo= r me to understand some network behaviour and implementation. =A0 Regards Atul --0-644347746-1310570980=:43882 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable <table cellspacing=3D"0" cellpadding=3D"0" border=3D"0" ><tr><td valign=3D"= top" style=3D"font: inherit;"><DIV>Hello All,</DIV> <DIV> </DIV> <DIV>I have very basic question regarding the codec negotiation in SIP, I w= ill try to summarize my queries below -</DIV> <DIV> </DIV> <DIV>1) If A is initiating the call and sending the supported codec li= st say (1,2,3)</DIV> <DIV> </DIV> <DIV> A --> INVITE (SDP-> audio 1 2 3) -->= B ( B supports 1 , 3, 5)</DIV> <DIV> A <-- 200 OK ( SDP -> what will be here= 1, 2 ,3 OR 1, 3, 5) <-- B</DIV> <DIV> </DIV> <DIV> if it is 1, 3, 5 then what will be the response to B ??</= DIV> <DIV> </DIV> <DIV>2) If A is initiating the call and sending the supported co= dec list say (1,2,3)</DIV> <DIV> </DIV> <DIV> A --> INVITE (SDP-> audio 1 2 3) -->= B ( B supports 2 , 3, 5)</DIV> <DIV> A <-- 200 OK ( SDP -> what will be here= 2 , 3 OR 2 , 3, 5) <-- B</DIV> <DIV> </DIV> <DIV> if it is 2 , 3 then what will be the response = to B ??</DIV> <DIV> if it is 2 , 3, 5 then what will be the r= esponse to B ??</DIV> <DIV> </DIV> <DIV>3) If A is initiating the call and sending the supported co= dec list say (1,2,3)</DIV> <DIV> </DIV> <DIV> A --> INVITE (SDP-> audio 1 2 3) -->= B ( B supports 4, 5,6)</DIV> <DIV> A <-- 200 OK ( SDP -> what will be here= ??) <-- B</DIV> <DIV> and what will be the d behaviour of A ....</DIV> <DIV> </DIV> <DIV>4) Re-Negotiation -</DIV> <DIV> </DIV> <DIV> If A is initiating the call and sending the supporte= d codec list say (1,2,3)</DIV> <DIV> </DIV> <DIV> A --> INVITE (SDP-> audio 1 2 3) -->= B ( B supports 1 , 2, 3)</DIV> <DIV> A <-- 200 OK ( SDP audio1, 2 ,3  = ; <-- B</DIV> <DIV> A --> ACK --> B</DIV> <DIV> </DIV> <DIV>( I guess the rtp will use codec 1)</DIV> <DIV> </DIV> <DIV> Now during the call say A wants to change the codec to 2, will = it send the re-invite or SDP session has some provision for it( I just want= to confirm, is it possible to change the codec without sending any SIP mes= sage)</DIV> <DIV> </DIV> <DIV>PS: I know i have made a lengthy mail, but it is very much = required for me to understand some network behaviour and implementation.</D= IV> <DIV> </DIV> <DIV>Regards</DIV> <DIV>Atul</DIV></td></tr></table> --0-644347746-1310570980=:43882-- --===============2499247264962649826== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Sip mailing list https://www.ietf.org/mailman/listinfo/sip This list is essentially closed and only used for finishing old business. 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