Re: Codec Negotiation and renegotiataion
"Siddiqui, Noman" <[email protected]> Wed, 13 Jul 2011 17:54:28 +0200
| Newsgroups | gmane.ietf.sip |
|---|---|
| Message-ID | <7B5D2E520D838A45838DE68F4030DC2D0444DB1983@MCHP057A.global-ad.net> |
--===============0493820940808734781== Content-Language: en-US Content-Type: multipart/alternative; boundary="_000_7B5D2E520D838A45838DE68F4030DC2D0444DB1983MCHP057Agloba_" --_000_7B5D2E520D838A45838DE68F4030DC2D0444DB1983MCHP057Agloba_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Hi Atul, Please see inline. Kind Regards, Noman Siddiqui ________________________________ From: [email protected] [mailto:[email protected]] On Behalf Of atul = garg Sent: Wednesday, July 13, 2011 11:30 AM To: [email protected] Subject: [Sip] Codec Negotiation and renegotiataion Hello All, I have very basic question regarding the codec negotiation in SIP, I will t= ry to summarize my queries below - 1) If A is initiating the call and sending the supported codec list say (1,= 2,3) A --> INVITE (SDP-> audio 1 2 3) --> B ( B supports 1 , 3, 5) A <-- 200 OK ( SDP -> what will be here 1, 2 ,3 OR 1, 3, 5) <-- B [Mohammed Noman Siddiqui] B would send 1, 3 in 200 OK if it is 1, 3, 5 then what will be the response to B ?? [Mohammed Noman Siddiqui] What do you mean by response to B. B is sending t= he response to A as above 2) If A is initiating the call and sending the supported codec list say (1= ,2,3) A --> INVITE (SDP-> audio 1 2 3) --> B ( B supports 2 , 3, 5) A <-- 200 OK ( SDP -> what will be here 2 , 3 OR 2 , 3, 5) <-- B [Mohammed Noman Siddiqui] 2,3 if it is 2 , 3 then what will be the response to B ?? if it is 2 , 3, 5 then what will be the response to B ?? 3) If A is initiating the call and sending the supported codec list say (1= ,2,3) A --> INVITE (SDP-> audio 1 2 3) --> B ( B supports 4, 5,6) A <-- 200 OK ( SDP -> what will be here ??) <-- B and what will be the d behaviour of A .... [Mohammed Noman Siddiqui] B would send 488 Not Acceptable here 4) Re-Negotiation - If A is initiating the call and sending the supported codec list say (1,= 2,3) A --> INVITE (SDP-> audio 1 2 3) --> B ( B supports 1 , 2, 3) A <-- 200 OK ( SDP audio1, 2 ,3 <-- B A --> ACK --> B ( I guess the rtp will use codec 1) [Mohammed Noman Siddiqui] Yes, RTP will use codec 1, however both sides sho= uld be able to dynamically switch the payload to either 2 and 3 Now during the call say A wants to change the codec to 2, will it send th= e re-invite or SDP session has some provision for it( I just want to confir= m, is it possible to change the codec without sending any SIP message) [Mohammed Noman Siddiqui] Yes, dynamic payload switching based on the negot= iated codecs list is permitted. Unfortunately, many devices do not support = this and hence its better to do the re-negotiation. PS: I know i have made a lengthy mail, but it is very much required for me= to understand some network behaviour and implementation. Regards Atul --_000_7B5D2E520D838A45838DE68F4030DC2D0444DB1983MCHP057Agloba_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=3DContent-Type content=3D"text/html; charset=3Dus-ascii"> <META content=3D"MSHTML 6.00.2900.6082" name=3DGENERATOR></HEAD> <BODY> <DIV dir=3Dltr align=3Dleft><FONT face=3DArial color=3D#0000ff size=3D2><SP= AN=20 class=3D687135015-13072011>Hi Atul,</SPAN></FONT></DIV> <DIV dir=3Dltr align=3Dleft><FONT face=3DArial color=3D#0000ff size=3D2><SP= AN=20 class=3D687135015-13072011></SPAN></FONT> </DIV> <DIV dir=3Dltr align=3Dleft><FONT face=3DArial color=3D#0000ff size=3D2><SP= AN=20 class=3D687135015-13072011>Please see inline.</SPAN></FONT></DIV> <DIV align=3Dleft> <DIV align=3Dleft><FONT size=3D2></FONT> </DIV> <DIV align=3Dleft><FONT face=3D"Comic Sans MS" color=3D#0000ff size=3D2>Kin= d=20 Regards,</FONT></DIV> <DIV align=3Dleft><FONT face=3D"Comic Sans MS" color=3D#0000ff size=3D1>Nom= an=20 Siddiqui</FONT></DIV> <DIV align=3Dleft><FONT face=3D"Comic Sans MS" color=3D#0000ff=20 size=3D1></FONT> </DIV></DIV> <DIV class=3DOutlookMessageHeader lang=3Den-us dir=3Dltr align=3Dleft> <HR tabIndex=3D-1> <FONT face=3DTahoma size=3D2><B>From:</B> [email protected]=20 [mailto:[email protected]] <B>On Behalf Of </B>atul garg<BR><B>Sent:</B>= =20 Wednesday, July 13, 2011 11:30 AM<BR><B>To:</B> [email protected]<BR><B>Subject:= </B>=20 [Sip] Codec Negotiation and renegotiataion<BR></FONT><BR></DIV> <DIV></DIV> <TABLE cellSpacing=3D0 cellPadding=3D0 border=3D0> <TBODY> <TR> <TD vAlign=3Dtop> <DIV>Hello All,</DIV> <DIV> </DIV> <DIV>I have very basic question regarding the codec negotiation in SI= P, I=20 will try to summarize my queries below -</DIV> <DIV> </DIV> <DIV>1) If A is initiating the call and sending the supported co= dec=20 list say (1,2,3)</DIV> <DIV> </DIV> <DIV> A --> INVITE (SDP-> audio 1 2 3)= =20 --> B ( B supports 1 , 3, 5)</DIV> <DIV> A <-- 200 OK ( SDP -> what will b= e=20 here 1, 2 ,3 OR 1, 3, 5) <-- B<BR><SPAN=20 class=3D687135015-13072011><FONT face=3DArial color=3D#0000ff size=3D= 2>[Mohammed=20 Noman Siddiqui] B would send 1, 3 in 200 OK=20 </FONT></SPAN></DIV> <DIV> </DIV> <DIV> if it is 1, 3, 5 then what will be the response to = B=20 ??<BR><SPAN class=3D687135015-13072011><FONT face=3DArial color=3D#00= 00ff=20 size=3D2>[Mohammed Noman Siddiqui] What do you mean by response = to B. B=20 is sending the response to A as above</FONT></SPAN></DIV> <DIV><SPAN class=3D687135015-13072011><FONT face=3DArial color=3D#000= 0ff=20 size=3D2></FONT></SPAN> </DIV> <DIV>2) If A is initiating the call and sending the suppor= ted=20 codec list say (1,2,3)</DIV> <DIV> </DIV> <DIV> A --> INVITE (SDP-> audio 1 2 3)= =20 --> B ( B supports 2 , 3, 5)</= DIV> <DIV> A <-- 200 OK ( SDP -> what will b= e=20 here 2 , 3 OR 2 , 3, 5) <-- B<BR><SPAN=20 class=3D687135015-13072011><FONT face=3DArial color=3D#0000ff size=3D= 2>[Mohammed=20 Noman Siddiqui] 2,3 </FONT></SPAN></DIV> <DIV> </DIV> <DIV> if it is 2 , 3 then what will be the res= ponse=20 to B ??</DIV> <DIV> if it is 2 , 3, 5 then what will be= the=20 response to B ??</DIV> <DIV> </DIV> <DIV>3) If A is initiating the call and sending the suppor= ted=20 codec list say (1,2,3)</DIV> <DIV> </DIV> <DIV> A --> INVITE (SDP-> audio 1 2 3)= =20 --> B ( B supports 4, 5,6)</DI= V> <DIV> A <-- 200 OK ( SDP -> what will b= e=20 here ??) <-- B</DIV> <DIV> and what will be the d behaviour of A ....<BR><SPAN=20 class=3D687135015-13072011><FONT face=3DArial color=3D#0000ff size=3D= 2>[Mohammed=20 Noman Siddiqui] B would send 488 Not Acceptable=20 here </FONT></SPAN></DIV> <DIV> </DIV> <DIV>4) Re-Negotiation -</DIV> <DIV> </DIV> <DIV> If A is initiating the call and sending the=20 supported codec list say (1,2,3)</DIV> <DIV> </DIV> <DIV> A --> INVITE (SDP-> audio 1 2 3)= =20 --> B ( B supports 1 , 2, 3)</DIV> <DIV> A <-- 200 OK ( SDP audio1, 2=20 ,3 <-- B</DIV> <DIV> A --> ACK --> B</DIV> <DIV> </DIV> <DIV>( I guess the rtp will use codec 1)<BR><SPAN=20 class=3D687135015-13072011><FONT face=3DArial color=3D#0000ff size=3D= 2>[Mohammed=20 Noman Siddiqui] Yes, RTP will use codec 1, however both sid= es=20 should be able to dynamically switch the payload to either 2 and= =20 3 </FONT></SPAN></DIV> <DIV> </DIV> <DIV> Now during the call say A wants to change the codec to 2,= will=20 it send the re-invite or SDP session has some provision for it( I jus= t=20 want to confirm, is it possible to change the codec without sending a= ny=20 SIP message)<BR><SPAN class=3D687135015-13072011><FONT face=3DArial=20 color=3D#0000ff size=3D2>[Mohammed Noman Siddiqui] Yes, dynamic = payload=20 switching based on the negotiated codecs list is permitted. Unfortuna= tely,=20 many devices do not support this and hence its better to do the=20 re-negotiation. </FONT></SPAN></DIV> <DIV> </DIV> <DIV>PS: I know i have made a lengthy mail, but it is very= much=20 required for me to understand some network behaviour and=20 implementation.</DIV> <DIV> </DIV> <DIV>Regards</DIV> <DIV>Atul</DIV></TD></TR></TBODY></TABLE></BODY></HTML> --_000_7B5D2E520D838A45838DE68F4030DC2D0444DB1983MCHP057Agloba_-- --===============0493820940808734781== 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. Use [email protected] for questions on how to develop a SIP implementation. Use [email protected] for new developments on the application of sip. 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