RTSP (from English Real Time Streaming Protocol) is a network protocol designed to control real-time streaming of audio and video data. It enables playback, pause, seek, and stop operations for multimedia streams between a client and a server. RTSP itself does not transmit media data — that task is handled by RTP (Real-time Transport Protocol) and RTCP (Real-time Control Protocol).
Principle of Operation
RTSP operates on a client–server model, where the client (such as a media player or surveillance system) sends commands to the server, and the server controls the data stream accordingly.
Typical RTSP commands include:
- DESCRIBE — requests a description of the media stream;
- SETUP — configures transmission parameters;
- PLAY — starts playback;
- PAUSE — suspends playback;
- TEARDOWN — terminates the session.
RTSP works over TCP or UDP, providing low latency during transmission. To describe multimedia streams, RTSP uses the SDP (Session Description Protocol) format, which includes details such as codecs, frame rate, ports, and other parameters.
Applications
RTSP is widely used in systems that require control over streaming content:
- video surveillance (IP cameras) — for transmitting real-time video streams to servers or client applications;
- streaming platforms and media servers — for delivering live or on-demand video and audio;
- online broadcasting and conferencing — for controlling media streams in interactive systems;
- IoT devices — for transmitting multimedia data from cameras and sensors.
For example, most IP cameras support RTSP, allowing users to access the live stream directly through a media player (e.g., VLC) using a link like:
rtsp://username:password@ip_address:port/stream
Advantages
Main advantages of RTSP include:
- control — ability to manage streams (play, pause, seek);
- low latency — suitable for live broadcasts and surveillance;
- flexibility — supports multiple codecs and formats through RTP;
- compatibility — widely adopted across professional and consumer video systems.
Example of Use
A video surveillance system can use RTSP to stream video from an IP camera to a recording server. The administrator can send RTSP commands to control playback of archived footage or access the live feed in a media player.