What is RTSP?

RTSP acts as the remote control for a live stream. It runs over TCP or UDP and uses standard HTTP methods like GET, POST, and OPTIONS to manage the session. When a client wants to watch a feed, it sends a DESCRIBE request to check media types. Then it sends a SETUP request to establish the transport channel. Finally, it sends a PLAY request to start the flow.

The actual video and audio data travels separately over RTP (Real-time Transport Protocol). RTSP does not carry the media bits; it only tells the server when to start, stop, or pause the RTP stream. This separation allows the protocol to handle complex media control without worrying about packet loss or jitter in the media stream itself.

Common use cases include IP cameras, video doorbells, and local network media servers. For example, a security camera might expose an RTSP URL that a local NVR (Network Video Recorder) uses to record footage. The NVR sends RTSP commands to the camera, and the camera sends RTP packets back over the local network.

If you own IP cameras, sports facilities, or local broadcast equipment, RTSP is likely your source protocol. Most professional cameras and encoders output RTSP by default. Understanding this protocol helps you connect your source material to a streaming platform.

However, RTSP is not designed for global internet distribution. It lacks built-in adaptive bitrate switching and does not handle network congestion well over long distances. If you try to deliver RTSP directly to mobile phones or web browsers, users will experience buffering and connection drops. Most OTT platforms do not support direct RTSP playback for end users.

Instead, you use RTSP as an ingest method. You send the RTSP stream to a cloud transcoder. The transcoder converts the single-bitrate RTSP feed into multiple adaptive bitrate renditions. These renditions are then packaged into HLS or DASH segments. This conversion process is essential for delivering a smooth viewing experience across different devices and network conditions.

Both RTSP and RTMP are used for live streaming, but they serve different roles in the pipeline. RTSP is primarily a control protocol for media servers and cameras. RTMP is a transport protocol that carries both control signals and media data in a single stream. RTMP is widely used for pushing live streams from encoders to streaming platforms.

• Trying to play RTSP directly in a web player: Browsers do not support RTSP natively. You must convert the stream to HLS or DASH first.
• Ignoring network latency: RTSP over the public internet suffers from high latency and packet loss. Use it for local or controlled networks only.
• Forgetting authentication: Many IP cameras use basic authentication for RTSP. Make sure your ingest server supports the correct auth method.
• Assuming RTSP handles transcoding: RTSP is just a transport and control layer. It does not change video quality or format. You need a separate transcoder for that.