Hi My name is Shahar and I am a part of a team which develop video conference using SIP. During implementation of SIP I faced some question I hope this forum would help me with. Lets say I am a user who would like to initiate AUDIO/VIDEO session using SIP. My name is Alice and the target user name is Bob. In order to begin the session Alice sends an Invite to Bob with SIP+SDP message. Lets say Alice can support 5 different Vocoders and Bob only 2. 1. Questions : 1.1 What exactly does the SDP's media descriptor describes ? Is it what Alice capable to receive ( e.g. Vocoders types )? is it what Alice would like to send ? both maybe ? 1.2 Is it possible for Alice to declare that she is going to send MPEG4 (with out the capability to receive MPEG4 ) and capable to receive MPEG2 (with out the capability to send MPEG2 ) Now Bob receives the message . 2. Questions : 2.1 What exactly does this SDP's media descriptor describes ? 2.2 what are the possible conversion Bob can do to the SDP message ? 2.3 What does it means when Bob delete a Media Description Line ? Add a media description line ? change a Media Description line ? 2.4 What Bob would do if he can support only part of the Media Description. After Bob convert the SDP message he would send it back with the response to Alice. Alice receive the message with the SDP message. 3. Questions : 3.1 What exactly does this SDP's media descriptor describes ? 3.2 In case Alice "dislike" the SDP message would she Initiate BYE method or ACK and then BYE. 3.3 In case Alice reply with ACK , would she attach a SDP message to the ACK message ? What for ? 3.4 What this SDP message means ? 3.5 What would Bob understand from Alice not sending an SDP message with the ACK message. Thank you very much for your help shahar Pavel Shahar Emblaze Research Ltd. [EMAIL PROTECTED] Phone: +972-9-8658570/320 Cell: +972-53-253576 _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
