Session Descriptions

The local client application and the remote client application can negotiate the session description used to establish a media session. This session description can be any generic type of session description, or it can be a private session description used only by the two endpoints.

The Session Description Protocol (SDP) described in RFC 2327 is commonly used to describe a multimedia session for the purpose of initiating a session. The SDP is used to advertise a multimedia conference and convey information about the media streams. The SDP contained in the SIP INVITE request includes details of the session, such as the session name and purpose. Technical details of the session, such as the type of media, the transport protocol, and the IP address and port pair to receive the media on, are also included in the SDP. The SDP contains sufficient information for members to join in the session.

Although the RTC Client API uses the SDP to negotiate session media streams, the application may decide to provide another type of session negotiation protocol in the body of the SIP INVITE request. The media stream negotiations are entirely up to the parties involved in the negotiations. The application is responsible for forming the body of the SIP INVITE message and sets the data in the bstrSessionDescription parameter of the IRTCClient2::CreateSessionWithDescription or IRTCSession2::AnswerWithSessionDescription method.