Real Time Streaming Protocol
The Real Time Streaming Protocol (RTSP), developed by the IETF and created in 1998 as RFC 2326, is a protocol for use in streaming media systems which allows a client to remotely control a streaming media server, issuing VCR-like commands such as “play” and “pause”, and allowing time-based access to files on a server.The sending of streaming data itself is not part of the RTSP protocol. Most RTSP servers use the standards-based RTP as the transport protocol for the actual audio/video data, acting somewhat as a metadata channel. The RTSP server from RealNetworks also features Real’s proprietary RDT as the transport protocol.The protocol is similar in syntax and operation to HTTP but RTSP adds new requests. While HTTP is stateless, RTSP is a stateful protocol. A session ID is used to keep track of sessions when needed. This way, no permanent TCP connection is needed. RTSP messages are sent from client to server, although some exceptions exist where the server will send to the client. Below are the basic RTSP requests. A number of typical HTTP requests, like an OPTION request, are also frequently used.