RTSP

What is RTSP?

The Real-Time Streaming Protocol (RTSP) is a network protocol designed for controlling the delivery of data with real-time properties. It’s used to establish and maintain multimedia sessions like video and audio live streams.

RTSP was developed by the Internet Engineering Task Force (IETF) and published in 1998 as RFC 2326. It is a text-based protocol that uses the same syntax and commands as HTTP. Unlike HTTP, however, RTSP establishes a constant connection for the entire media session and maintains control of the media stream.

How RTSP works

RTSP operates as a stateful protocol, meaning it maintains information on the session as a whole instead of following individual transactions. It uses a client-server model, where the client sends a request to the server, and the server responds accordingly.

RTSP uses several methods to control the media stream. It’s responsible for setting up the session, starting the stream of media, halting the stream when requested, and ending the session as needed. These commands allow the client to have full control over the media stream, including the ability to play, pause, rewind, and fast forward.

The role of RTP and RTCP

While RTSP controls the delivery of the media stream, it doesn’t actually deliver the data. This task is handled by the Real-Time Transport Protocol (RTP). RTP is used in conjunction with RTSP to deliver media data, while RTSP acts as the control interface for the network.

The RTP Control Protocol (RTCP) is also used alongside RTSP and RTP. RTCP provides out-of-band statistics and control information for an RTP session. The protocol works hand-in-hand with RTP and RTSP to provide a complete solution for streaming media over the internet.

Applications of RTSP

RTSP is widely used in various applications that require the streaming of real-time media. These include internet radio and television, on-demand video services, and video conferencing systems. It is also used in the context of live streaming for the delivery of real-time video from content creators.

One of the key advantages of RTSP is its ability to control media delivery on a per-user basis. This means that each user can use RTSP to control their own media stream, allowing for a personalized viewing experience. This feature is particularly useful for on-demand video services, where users can control the playback of their chosen content. You can pause and resume live streams on demand because of RTSP, for example.