Hi
Local SDP contains the port numbers where the entity wishes to receive media. By default, RTCP is received on port number one higher than the advertised RTP port. Refer to the following text in Shamik's mail: "For sendonly RTP streams, the address and port number indirectly indicate where the offerer wants to receive RTCP reports. Unless there is an explicit indication otherwise, reports are sent to the port number one higher than the number indicated. " IMO, the SDP in Stephane's mail will be interpreted by the peer entity as follows: - Offerer wishes to receive audio RTP on port 1340. - Offerer wishes to receive video and audio RTCP reports on port numbers 1343 and 1345 respectively (and perhaps video and audio RTP on 1342 and 1344 respectively). m=audio 1340 RTP/AVP 14 0 96 a=recvonly m=video 1342 RTP/AVP 32 34 33 a=sendonly m=audio 1344 RTP/AVP 14 0 a=sendonly Regards Rohit Aggarwal Aricent -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Stephane van Hardeveld Sent: Monday, February 16, 2009 1:56 PM To: [email protected] Cc: [email protected] Subject: Re: [Sip-implementors] Problem with SDP negotiation wrta-synchronousoffer Hi Shamik, So, in short, my interpretation in assuming the ports of the recvonly statement indicate the ports the offerer/caller (via the INVITE) expects to receive multimedia data is correct? And the SIP phone implementation we tested with is not correct in sending this multimedia data to the ports defined as sendonly? With regards, Stephane van Hardeveld Manager R&D, VirtuosoMedia ----- Original Message ----- From: <[email protected]> To: <[email protected]> Cc: <[email protected]> Sent: Monday, February 16, 2009 9:01 AM Subject: RE: [Sip-implementors] Problem with SDP negotiation wrt a-synchronousoffer Hi Stephane, The port numbers that are given for send only streams are the port numbers where it will receive the rtcp reports, In the SDP offer we need not mention the port numbers for a send only stream,as the far-end need not know about the port number from which we are transmitting.I am quoting a section of rfc 3264 which tells about this For recvonly and sendrecv streams, the port number and address in the offer indicate where the offerer would like to receive the media stream. For sendonly RTP streams, the address and port number indirectly indicate where the offerer wants to receive RTCP reports. Unless there is an explicit indication otherwise, reports are sent to the port number one higher than the number indicated. The IP address and port present in the offer indicate nothing about the source IP address and source port of RTP and RTCP packets that will be sent by the offerer. So in your scenario,the SDP that you wants to generate tells that you want to video on 1338,audio on 1340 and receive rtcp reports about the video you sent, on 1342 and audio you sent, on 1344. The SDP for the ip phone tells that it will receive audio on 5004 and vedio on 5006. Thanks and regards, Shamik Saha Project Engineer Voice Protocols Cell : +91-9886704155 ________________________________ "DISCLAIMER: This message is proprietary to Aricent and is intended solely for the use of the individual to whom it is addressed. It may contain privileged or confidential information and should not be circulated or used for any purpose other than for what it is intended. If you have received this message in error,please notify the originator immediately. If you are not the intended recipient, you are notified that you are strictly prohibited from using, copying, altering, or disclosing the contents of this message. Aricent accepts no responsibility for loss or damage arising from the use of the information transmitted by this email including damage from virus." _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
