What is RTSP (Real Time Streaming Protocol)? Camera streaming explained

RTSP (Real Time Streaming Protocol)

Real Time Streaming Protocol, or RTSP, is the network control protocol that IP cameras use to stream live video to a VMS, NVR, or recording server. Defined in RFC 2326 (1998), RTSP runs on TCP port 554 and operates like a remote-control channel: it tells the camera 'set up a stream, play it, pause it, tear it down.' The actual video and audio data flows over RTP, a separate companion protocol. RTSP is what makes mixed-vendor IP-camera installs work alongside ONVIF.

The short definition

RTSP runs as a control channel between a client (a VMS, NVR, or VLC media player) and a streaming server (a camera). The client opens a TCP connection to port 554 and exchanges text-based methods: DESCRIBE, SETUP, PLAY, PAUSE, TEARDOWN. The server responds with session details and a stream description in SDP (Session Description Protocol) format. Once setup completes, the actual video and audio data flows over RTP (Real-time Transport Protocol), usually on UDP for low latency or TCP-interleaved for reliability. That two-protocol split (RTSP for control, RTP for data) is why some firewall rules block one but not the other and the install fails halfway through: both ports need to pass for video to arrive.

RFC 2326 and the protocol's history

RTSP was defined in RFC 2326 in 1998 by the IETF, with an updated version (RTSP 2.0) in RFC 7826 in 2016. The original use case was streaming media on early-internet platforms (RealMedia, QuickTime, Windows Media). The IP-camera industry adopted it because the fit was clean: cameras are streaming servers, VMS platforms are streaming clients. ONVIF Profile S, released in 2011, formalized RTSP as the streaming requirement for conformant cameras. That single decision is why a Genetec VMS can talk to a Hanwha camera and why a Milestone install can pull from a Bosch fleet: the transport is RTSP underneath, regardless of vendor. For the configuration side, see the ONVIF entry.

RTSP URL structure per vendor

Every manufacturer publishes its RTSP URL pattern in API documentation. Common examples:

Axis. rtsp://user:pass@ip:554/axis-media/media.amp
Hanwha (Wisenet). rtsp://user:pass@ip:554/profile1/media.smp
Bosch. rtsp://user:pass@ip:554/?h26x=4&line=1&inst=2
Hikvision (excluded for NDAA-compliant installs). rtsp://user:pass@ip:554/Streaming/Channels/101
Avigilon. rtsp://user:pass@ip:554/defaultPrimary?streamType=u

Most of the time the VMS handles URLs automatically through ONVIF. Hand-built URLs come up when integrating a camera into a non-VMS system: a remote analytics workload, a streaming-to-cloud pipeline, or a quick test in VLC during commissioning.

Common RTSP failure modes

Three patterns we see during commissioning:

Firewall blocks RTP, not RTSP. Port 554 is open and control messages flow, but the video doesn't. RTP usually runs on dynamic UDP ports negotiated during SETUP. Open the dynamic range or force RTP-over-TCP interleaved mode.
Stale stream sessions on the camera. Cameras have a session limit (often 8 to 16 concurrent RTSP clients), and a stuck VMS or misbehaving test client can use them up. A reboot clears it; better practice is to call TEARDOWN explicitly when ending a session.
Codec mismatch. The camera offers H.265 in the SDP description but the VMS only decodes H.264. The stream connects but no frames render. Switch the camera's main stream to H.264 or upgrade the VMS decoder.

When to ask Tec-Tel about RTSP

RTSP comes up most when integrating older cameras with a new VMS, adding cloud analytics on top of an existing fleet, or when a firewall change broke video and nobody can pin down which port. We troubleshoot the protocol-level issues during a free working session.

Frequent buyer questions

What's the difference between RTSP and ONVIF?

RTSP is a streaming protocol; ONVIF is an interoperability standard. ONVIF tells a VMS how to discover a camera, configure it, and request its RTSP stream URL. RTSP is what actually delivers the video. ONVIF Profile S includes RTSP streaming as one of its requirements. You can talk RTSP without ONVIF (vendor-specific drivers), but most modern VMS-camera pairings use both: ONVIF for setup, RTSP for video.

What does an RTSP URL look like?

Format is typically rtsp://username:password@camera-ip:554/path. The path varies per manufacturer. Axis cameras often use /axis-media/media.amp, Hanwha uses /profile1, Hikvision uses /Streaming/Channels/101. Each manufacturer publishes the URL pattern in its API documentation. The VMS handles the path automatically when ONVIF is in play; you only build URLs by hand for vendor-specific integrations.

Is RTSP secure?

Plain RTSP is not encrypted. Credentials and metadata travel in cleartext, and the video payload (carried over RTP) is also unencrypted. RTSP over TLS (RTSPS, port 322) and SRTP (Secure RTP) encrypt the payload. Enterprise installs typically isolate camera traffic on a separate VLAN with no internet access rather than relying on RTSP encryption alone.

RTSP vs RTMP: what's the difference?

RTSP is for live, low-latency, two-way streaming on local networks (cameras to VMS). RTMP is a Flash-era protocol used for one-way live broadcast to platforms like YouTube and Twitch. Most IP cameras don't speak RTMP natively; if you need to push a camera stream to a streaming service, you typically transcode RTSP to RTMP at a server in between.

Why is RTSP still used after 25 years?

It works, it's simple, and the entire VMS and NVR ecosystem expects it. WebRTC and SRT are newer protocols with better encryption and lower latency, but adoption in security IP cameras is gradual. RTSP also handles low-bandwidth links well: TCP transport on the control channel, UDP option on the video for installs where dropped frames are acceptable.

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