RTSP is the Real Time Streaming Protocol, which serves as a control protocol, and as a jumping off point for negotiating transports, such as RTP, multicast and unicast, and negotiating codecs off of servers in a file format independent way.

RTSP was jointly submitted to the IETF in October, 1996 by RealNetworks and Netscape Communications Corporation and with support from over 40 leading media companies. The draft has been through extensive co-development by RealNetworks, Netscape, Columbia University, and the IETF MMUSIC Working Group, and was published as an IETF Proposed Standard in April, 1998.

RTSP (RFC 2326) is a client-server multimedia presentation control protocol, designed to address the needs for efficient delivery of streamed multimedia over IP networks. It leverages existing web infrastructure (for example, inheriting authentication and PICS from HTTP) and works well both for large audiences as well as single-viewer media-on-demand.

RealNetworks, Netscape Communications and Columbia University jointly developed RTSP within the MMUSIC working group of the Internet Engineering Task Force (IETF). In April, 1998, it was published as a Proposed Standard by the IETF.

RTSP is one very important piece in the interoperability puzzle. Interoperability on streaming media systems involves many components (Players, Servers, Encoders/Tools) that must share common mechanisms.

Encoders and content-creation tools must be able to store content in files that servers can read. Servers must be able to stream content using protocols that players can understand. Encoders and tools must also store datatypes in the files in formats that will eventually be understood by players.

Protocols like RTSP are necessary but not sufficient to achieve end-to-end interoperability. File formats like ASF and QuickTime FF act as containers for multimedia data, and datatypes like RealAudio, RealVideo, H.263 and MPEG Audio and Video are all datatypes that can be delivered over such a system.

Here are some key features of "rtspd":

· A modular, object-oriented implementation of the RTSP proxy, with improved support.
· Correct handling of all transport information exchanged by means of the SETUP method.
· Support for Windows platforms.
· Modifications to the command-line parameters.



Here is a list of known RTSP implementations:

· Cisco IP/TV - Video server and viewer which implements RTSP, RTP, H.261, and MPEG video. [Client and Server]
· Columbia University rtspd - Supports serving of .au files via RTSP/RTP for Windows NT and Solaris [Server, source available]
· Darwin Streaming Server - Apple's open source streaming server and proxy. Supports RTSP/RTP serving of MOV files. [Server and Proxy, includes source]
· Helix - Media delivery platform for streaming multimedia productions. Supports RTSP/RTP delivery of AVI, WAV, MP3, and MOV files, as well as RTSP delivery of RealAudio and RealVideo [Server, Proxy, and SDK; source available]
· IBM RTSP Toolkit - IBM's toolkit is based on tools developed for video and other applications in 1995-1996. Their toolkit reflects the Unix philosophy of shells, processes and generic tools, and demonstrate a shell-based implementation of the protocol and its usefulness for non-multimedia applications. [Client, includes source]
· Kasenna MediaBase - Video server with integrated content management and content distribution technology with MPEG-1, MPEG-2, MP3, and QuickTime media streaming. [Server]
· Komssys - RTSP/RTP implementation for multimedia systems researchers who want to investigate protocols and operating systems issues [Server, Client, Proxy; includes source]
· Live.com Streaming Media - C++ libraries for implementing RTSP/RTP. Implements several packetizations: MP3 (RFC 2250, RFC 3119), MPEG Video (RFC 2250), and H.263+ (RFC 2429). Renderers not included. [Client and Server, includes LGPL source]
· MediaTechnik's RTP/RTSP library - ANSI C library which supports H.263 format video streams as specified in RFC 2190, extendable to handle other formats. Designed for portability and integration into applications.
· MPEG4IP - MPEG-4/ISMA interoperability suite produced by Cisco. Supports MPEG-4 Audio (aac), MPEG-4 Video, RTP, RTSP, MP3 (using RFC 2250). Includes client, server (Darwin), and encoding tools. [Client and Server, includes source]
· On2 TrueCast - Server for Windows NT and 2000. Streams VP4 compressed video files.
· Open Mash - Open Mash supports the Mash streaming media toolkit and distributed collaboration applications based on the Internet Mbone tools and protocols. [Client, includes source]
· popCorn - MPEG-1 Streaming Player for Linux produced by eProcess. [Client, includes source]
· QuickTime - Apple's multi-platform multimedia software architecture. Supports RTSP/RTP with H.261, H.263, MPEG 1 Video, Layer 1 and 2 Audio, DVI, mu-Law, a-Law and others. [Client, includes source]
· RealPlayer - RealNetworks cross-platform multimedia player. Supports RTSP/RTP with H.261, u-Law, a-law, MP3, DVI. [Client]
· RTSP Monitor - Tool to check the availability of time-based media files and real-time media streams. Written in Java utilizing JMF.
· RTSP Proxy Kit (RealNetworks) - An open source reference implementation of an application-level firewall proxy for UNIX. This kit includes all source code for the proxy and documentation for building and installing the RTSP proxy. [Proxy, includes source]
· Sentivision RTSP/RTP Streaming Server - Provides real-time video content streaming to IP-enabled Set-Top Box hardware. Features include: multicast, UDP unicast, trick-play, and multiple codec support.
· Sun Java Media Framework - SDK for adding streaming media to Java applications and applets. [Client SDK]
· Sun Streaming Server - Server implementation of RTSP, RTP/RTCP, and SDP. Delivers on-demand streams from hinted MPEG-4 (.mp4), hinted Apple QuickTime (.mov) and hinted 3GPP(.3gp) files. Live streaming is also supported via reflection of RTP sources (Free stream-limited server download)
· Video on Demand - Java-based video server produced by students at Østfold College, Norway.
· Vovida RTSP Stack - The Vovida Open Communication Application Library (VOCAL) is an open source project targeted at facilitating the adoption of VoIP in the marketplace. The Vovida implementation of RTSP includes an RTSP stack and server with playing and recording capabilities of *.au and *.wav file formats. [Client SDK and Server, includes source]