-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Elison Niven Sent: Wednesday, June 25, 2008 5:22 PM To: [email protected] Subject: [Sip-implementors] G.723.1 sdp negotiation
_____ From: Elison Niven [mailto:[EMAIL PROTECTED] Sent: Wednesday, June 25, 2008 9:30 AM To: '[email protected]' Subject: G.723.1 sdp negotiation Hi list, I am again sending this mail as I did not find it listed on the official archives. I apologize for any inconvenience caused. Elison _____ From: Elison Niven [mailto:[EMAIL PROTECTED] Sent: Tuesday, June 24, 2008 3:35 PM To: '[email protected]' Cc: '[EMAIL PROTECTED]'; '[EMAIL PROTECTED]' Subject: G.723.1 sdp negotiation Hi List, I know this question has been addressed before but it still isn't very clear. If I send an offer with an SDP like: m = audio 8000 RTP/AVP 4 m = rtpmap:4 G723/8000 And if the answer also does not specify the bitrate in an fmtpmap line for the G723 codec, what codec should be used? Should it be G.723.1 High rate or Low rate? RFC3555 says on G723: "If unspecified, the bitrate may change from frame to frame as indicated inband." The remote end may start sending RTP as either High rate (6.3 Kb/s) or Low rate (5.3 kb/s). How to go about if there is no facility to detect the RTP data received - Is it High rate or Low rate? (Ex: The DSP etc. does not have such support) In that case, I need to know which codec to use from the SDP negotiation itself. I want to show that I support for both G.723.1 6.3 kb/s (High rate) and 5.3 Kb/s (Low rate) in the offer I send. In that case, is the following SDP in the offer valid? m = audio 8000 RTP/AVP 4 5 m = rtpmap:4 G723/8000 m = fmtpmap:4 bitrate=6.3 m = rtpmap:5 G723/8000 m = fmtpmap:5 bitrate = 5.3 (Is it alright to override static payload 5 here?) [Rockson] you cannot do this , you'd better use dynamic payload type, and "a=" for rtpmap and fmtp attribute. Best Regards, Elison _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
