3.3.1 Stream Content Using RTSP-WME
The following diagram shows the communication flow between the media player application and the server during playback using Real-Time Streaming Protocol (RTSP) Windows Media Extensions (RTSP-WME).
Figure 16: Unicast playback communication flow using RTSP-WME
Content request: The trigger for the unicast playback is the media player application providing the content URL to the media player client. The media player client uses the content URL to initiate the discovery. For examples of the exact message content and format, see the individual member protocol TDs. After receiving the request to stream from the media player application, the media player client establishes a TCP connection to the server by using the IP address and port number obtained from the URL that is provided by the media player application. With the IP address known, the client can request to configure the server for streaming. How this is accomplished is protocol-specific. For examples of the exact message content and format, see [MS-RTSP] section 3.1.4.2.1.
Content response: The media player client obtains information on the stream itself. With RTSP-WME, this data includes the Describe response. For examples of the exact message content and format for the Describe response for RTSP-WME, see [MS-RTSP] section 3.1.5.4. The Describe response includes stream-specific information.
After the client receives a response from the server, if the client is using the TCP transport, it can request packet-pair bandwidth estimation. See section 3.3.3 for more details.
Stream selection request: To specify which stream to play, the media player client makes a request to the server for a specific stream based on the packet-pair statistics that it received during packet-pair testing. For examples of the exact message content and format on stream selection, see [MS-RTSP] section 3.1.4.3.1.
There can be more than one SelectStream request with RTSP-WME, because the setup method is used for each selected stream. For more information, see [MS-RTSP] section 2.2.7.10.
Stream selection response: After receiving the stream request, the server sends a response. For examples of the exact message content and format for RTSP-WME, see [MS-RTSP] section 3.2.5.6.
Play request: After the stream or streams have been selected by the media player client, a request will be made to play the file. For examples of the exact message content and format for RTSP-WME, see [MS-RTSP] section 3.1.5.9.1.
Play response: The server responds to the Play request with a Play response. For examples of the exact message content and format for RTSP-WME, see [MS-RTSP] section 3.1.5.10.
Playback packets: After the Play requests, the server begins to send the packets to the client. For examples of the exact message content and format for RTSP-WME, see [MS-RTSP] section 2.2.1.
End of stream: When the server has completed playing the file, it notifies the media player client that playback is completed. For examples of the exact message content and format for RTSP-WME, [MS-RTSP] section 3.2.4.1. After receiving the playback complete notification from the media server, the client sends a playback complete notification to the media player client application.