The Real Time Streaming Protocol (RTSP) RTSP is industry standard Internet Application level Protocol. RTSP is a framework for the delivery & transmissions of: Multicast data streams Multicast Radio, text & Video RTSP takes advantage of streaming which breaks data into many packets When enough packets have been received by the client, the users software can be playing one packet, decompressing another and downloading a third. Therefore, the user can start listening without having to get the entire media file. Proposed and developed in 1996 by Netscape Communication, RealNetworks and Columbia University, as an internet standard (IETF). Part of the OSI Software layer model RTP actually delivers the media data and RTSP acts as the ‘network remote control’ Multicast – can control broadcast from several servers

RTSP Features RTSP works in conjunction with RTP to deliver streaming video, audio and text content. RTSP maintains a server state during transmission unlike HTTP. Server-client architecture. Avoids shortfalls/limitations in HTTP. RTSP provides synchronisation of events. Enhancement of HTTP functions. RTSP continuously checks the state whereas HTTP simply sends HTTP and TCP/IP protocols were not designed with streaming video in mind With HTTP the data is delivered to the receiver (downloaded) this requires the receiver to wait until the download is complete. Thus live video conferencing is not possible. E.g. Video conference between Boston, Beijing and Birmingham. RTSP synchronises the streaming video.

RTSP Features ( Cont) Real time or near real time system. RTSP stream control working with RTP as the media transport protocol. Internet standard Device control – e.g camera zoom remotely Load balancing using bidirectional connection. Virtual presentations, synchronised playback from multiple servers. The development of an internet standard meant that Multimedia could take off as never before. It allows for new projects to be built around the standard giving access to the media to all.

RTSP Functionality Client - server & server- client Multimedia-demand for continuous mode. Multicast operation & address. Independent stream file format or combinations of subsets. Ability to mix media, audio, images, video & text as part of a stream.

RTSP Applications Streaming of multi-media via Internet Video conferencing & lectures. Broadcasting of entertainment. Remote digital editing Voice mail

RTSP example session TCP connection= RTSP session= session maintained. One TCP connection per session bidirectional. UDP= Multicast, low latency & live events.

RTSP Diagram As you can see from the diagram: Initially the browser opens a connection with the server using HTTP. Once the Media file is requested the RTSP opens and maintains a continuous server state between the Media player and the web server Below this server state the RTP delivers the Media content With RTSP the connection is 2 way, meaning that both content provider and content receiver can communicate allowing uninterrupted play.

RTSP Methods OPTIONS- obtain available methods SETUP- Establish transport ANNOUNCE- alter description of media object. DESCRIBE- get low level description of media object. PLAY- start playback. RECORD- Start recording PAUSE- suspend delivery, keep state SET_PARIMETER- device or encoding control TEARDOWN- remove state. These are the methods or functions provided by RTSP.

RTSP Limitations Bandwidth: 64 – 128 kb/s for talking heads, 1.5Mb/s for movies Quality: packet loss, predictability Reliability: makes CATV look good Billing Infrastructure: pay-per-view? Cheap Receivers: shouldn’t cost more than set-top box