Real Time Streaming Protocol

lastmod 2025-04-23created 2015-08-1963 edits

Real Time Streaming Protocol (RTSP) is a communication protocol developed by the IETF in 1998. It is defined in RFC 2326. RTSP is used in streaming systems to control media servers remotely. Its commands, such as "PLAY" and "PAUSE", resemble VCR operations, and it accesses the server based on time information.

It does not transmit the actual media streaming data. Most RTSP servers use the RTP protocol as the transport layer to transmit the actual audio/video data.

Categories

• RTSP:Examples:SimplePythonServer
• RFC 2326

RTSP commands

Compared with HTTP, the RTSP protocol is similar in syntax and operation. However, while HTTP is stateless, RTSP is a stateful protocol. An arbitrary session ID is used each time a session is tracked, and this approach requires a persistent TCP connection. RTSP messages go from the client to the server. If an error occurs on the server, the server sends a response code for the error back to the client. The basic RTSP request messages are as follows, and the default port is 554.

DESCRIBE

A DESCRIBE request includes a URL (rtsp://...). The default port 554 is used for both UDP and TCP. The response to DESCRIBE also includes a description of what was requested, usually in SDP format.

SETUP

A SETUP request specifies whether a single media stream should be transmitted. This request must be completed before a PLAY request. The request must include the media stream URL and the transport point. The transport point also includes the port numbers for receiving RTP data (audio/video) and RTCP data (meta information).

PLAY

A PLAY request plays one or all media streams. Multiple PLAY requests are possible. To play all media streams, an aggregate URL must be included in the request. The playback range can also be specified. If no range is specified, the media plays from beginning to end. If playback is paused, it resumes from the paused position.

PAUSE

A PAUSE request pauses one or all media streams. Playback can be restarted with a PLAY request. The request message must include the media stream URL. A range can also be specified when pausing.

RECORD

A RECORD request is the command for recording.

TEARDOWN

A TEARDOWN request is the command for ending a session; it stops playback of all media streams and releases all sessions tied to the related data on the server.

Packet flow

It seemed that RTSP and RTP could be sent together over a single port, so the packets were inspected with Wireshark.

No.     Time           Source                Destination           Protocol Length Info
      5 0.000388       127.0.0.1             127.0.0.1             RTSP     141    OPTIONS rtsp://0.0.0.0:8554/live.sdp RTSP/1.0
      7 0.003347       127.0.0.1             127.0.0.1             RTSP     257    Reply: RTSP/1.0 200 OK
      9 0.004811       127.0.0.1             127.0.0.1             RTSP     167    DESCRIBE rtsp://0.0.0.0:8554/live.sdp RTSP/1.0
     11 0.087192       127.0.0.1             127.0.0.1             RTSP/SDP 698    Reply: RTSP/1.0 200 OK
     13 0.095190       127.0.0.1             127.0.0.1             RTSP     204    SETUP rtsp://0.0.0.0:8554/live.sdp/stream=0 RTSP/1.0
     15 0.096064       127.0.0.1             127.0.0.1             RTSP     281    Reply: RTSP/1.0 200 OK
     17 0.097255       127.0.0.1             127.0.0.1             RTSP     185    PLAY rtsp://0.0.0.0:8554/live.sdp/ RTSP/1.0
     19 0.098056       127.0.0.1             127.0.0.1             RTSP     275    Reply: RTSP/1.0 200 OK
     39 10.419850      127.0.0.1             127.0.0.1             RTSP     167    PAUSE rtsp://0.0.0.0:8554/live.sdp/ RTSP/1.0
     41 10.421940      127.0.0.1             127.0.0.1             RTSP     179    Reply: RTSP/1.0 200 OK
     43 10.422700      127.0.0.1             127.0.0.1             RTSP     196    SETUP rtsp://0.0.0.0:8554/live.sdp/stream=0 RTSP/1.0
     45 10.490884      127.0.0.1             127.0.0.1             RTSP     253    Reply: RTSP/1.0 200 OK
     47 10.492739      127.0.0.1             127.0.0.1             RTSP     185    PLAY rtsp://0.0.0.0:8554/live.sdp/ RTSP/1.0
     49 10.494810      127.0.0.1             127.0.0.1             RTSP     275    Reply: RTSP/1.0 200 OK
     51 10.496769      127.0.0.1             127.0.0.1             RTP      2251   PT=DynamicRTP-Type-96, SSRC=0x19292F8, Seq=3488, Time=1765483086, PT=DynamicRTP-Type-96, SSRC=0x19292F8, Seq=3489, Time=1765483086, PT=DynamicRTP-Type-96, SSRC=0x19292F8, Seq=3490, Time=1765483086, PT=DynamicRTP-Type-96, SSRC=0x19292F8, Seq=3491, Time=1765483086, PT=DynamicRTP-Type-96, SSRC=0x19292F8, Seq=3492, Time=1765483086
     53 10.496959      127.0.0.1             127.0.0.1             RTP      2864   PT=DynamicRTP-Type-96, SSRC=0x19292F8, Seq=3493, Time=1765483086, PT=DynamicRTP-Type-96, SSRC=0x19292F8, Seq=3494, Time=1765483086
     55 10.497185      127.0.0.1             127.0.0.1             RTP      2864   PT=DynamicRTP-Type-96, SSRC=0x19292F8, Seq=3495, Time=1765483086, PT=DynamicRTP-Type-96, SSRC=0x19292F8, Seq=3496, Time=1765483086

RTP packet No. 55 looks like this:

No.     Time           Source                Destination           Protocol Length Info
     55 10.497185      127.0.0.1             127.0.0.1             RTP      2864   PT=DynamicRTP-Type-96, SSRC=0x19292F8, Seq=3495, Time=1765483086, PT=DynamicRTP-Type-96, SSRC=0x19292F8, Seq=3496, Time=1765483086

Frame 55: 2864 bytes on wire (22912 bits), 2864 bytes captured (22912 bits) on interface 0
Null/Loopback
Internet Protocol Version 4, Src: 127.0.0.1, Dst: 127.0.0.1
Transmission Control Protocol, Src Port: 8554, Dst Port: 52409, Seq: 6830, Ack: 854, Len: 2808
RTSP Interleaved Frame, Channel: 0x00, 1400 bytes
Real-Time Transport Protocol
RTSP Interleaved Frame, Channel: 0x00, 1400 bytes
Real-Time Transport Protocol

You can see that RTP packets are delivered through the RTSP Interleaved Frame.

It is not a part of RTSP OPTION response but an option allowing to send RTP by the same TCP channel as controlling RTSP session, seeRFC 2326
It is not part of the RTSP OPTION response, but an option that allows sending RTP over the same TCP channel that controls the RTSP session. (seeRFC 2326)

See the "Embedded (Interleaved) Binary Data" section of RFC 2326.

Libraries and examples

Most recommended

• aiortsp - An asyncio-based RTSP library (python)
• rtsp-simple-server - ready-to-use RTSP / RTMP server and proxy that allows to read, publish and proxy video and audio streams (Go)
  • Move to MediaMTX - A ready-to-use RTSP / RTMP / LL-HLS / WebRTC media server and media proxy that can read, publish, and proxy video and audio streams.
    • gortsplib - RTSP 1.0 client and server library for the Go programming language, written for MediaMTX.
• RTSPATT - Multipurpose RTSP media server that can simulate RTSP cameras, broadcast RTSP streams and even create test videos or serve video files - Deprecated
  • Simple streaming with Docker: docker run --rm -p 8554:8554 ullaakut/rtspatt
  • https://github.com/Ullaakut/RTSPAllTheThings
• Simple Realtime Server (srs; SRS)
• Streamedian - HTML5 RTSP streaming video player over WebSocket
• Github - vladpen/python-rtsp-server - Lightweight, zero-dependency proxy and storage RTSP server
• Github - runtheops/rtsp-rtp - RTSP client and RTP packet parser

Other recommendations

• PyRTP - Python RTP Library (python) - https://gitlab.com/nickvsnetworking/pyrtp
  • https://nickvsnetworking.com/pyrtp-simple-rtp-library-for-python/
• Sharp RTSP - A RTSP handling library - https://github.com/ngraziano/SharpRTSP
• C# Camera SDK: .Net library to build webcam and IP camera solutions
  • How to connect to an RTSP camera and display the picture in C#
• StreamPlayerControl (C#)
  • https://www.codeproject.com/Articles/885869/Stream-Player-control
  • https://github.com/jacobbo/WebEye/tree/master/StreamPlayerControl
• html5_rtsp_player - html5 player for rtsp stream. https://streamedian.com/docs/
• RTSP parser written in C - https://github.com/mrb113/RTSPlib
• A RTSP client that extract h264 video frames - https://github.com/edsiper/h264dec
• RTSPMultiCam - A RTSP server for streaming combined picture from multiple cameras based on FFMPEG and live555 - https://github.com/jiaxin-du/RTSPMultiCam
• FFMPEG-Live555-H264-H265-Streamer - H264, H265 and more Encoder and Multicast/Unicast Streamer (example of how to use Live555 and FFMPEG) - https://github.com/alm4096/FFMPEG-Live555-H264-H265-Streamer
• MESAI/FFmpegRTSPServer - This is an implementation of an H264 RTSP server using FFmpeg and Live555.
  • http://mesai0.blogspot.com.eg/
  • https://github.com/MESAI/FFmpegRTSPServer
• MMM-RTSPStream - Video Streaming from Live Feeds (Security Cameras) - https://github.com/shbatm/MMM-RTSPStream
• rtsp-stream - Out of box solution for RTSP - HLS live stream transcoding. Makes RTSP easy to play in browsers - https://github.com/Roverr/rtsp-stream
• Video-Streaming-Server-and-Client - https://github.com/TibbersDriveMustang/Video-Streaming-Server-and-Client
• RTSPtoWeb - RTSP Stream to WebBrowser - https://github.com/deepch/RTSPtoWeb
• RTSPtoWebRTC - RTSP to WebRTC use Pion WebRTC - https://github.com/deepch/RTSPtoWebRTC
• rtsp-to-webrtc - Python client library for RTSPtoWeb and RTSPtoWebRTC - https://pypi.org/project/rtsp-to-webrtc/
• rtsp-to-webrtc-client - Python client library for RTSPtoWebRTC - https://github.com/allenporter/rtsp-to-webrtc-client
• SmolRTSP - A lightweight real-time streaming library for IP cameras.
• libsrtp - Cisco's SRTP library (Secure Realtime Transport Protocol)

Local Download

RFC 2326 - Real Time Streaming Protocol (RTSP)

https://tools.ietf.org/html/rfc2326

Rfc2326-ko.txt.zip (Google translate: en -> ko)

See also

• RTP
• RTCP
• FFmpeg
• gStreamer
• live555
• JRTPLIB
• WebRTC
• Session Description Protocol (SDP)
• Media Streaming
  • Media Streaming#Demo video: Collection of sample video URLs for streaming
  • Low Latency Streaming
• Live Streaming

Favorite site

• Wikipedia (en) description of RTSP
• RFC2326
• TTAE.IF-RFC2326 (Korean translation)
• ICT Terminology Explained - Real Time Streaming Protocol (real-time streaming protocol)
• bcknightt - RTSP(Real Time Streamming Protocol)
• [Recommended] 7 ways to stream RTSP on the page ¹ - See Low Latency Streaming.

Guide

• (Network) What is RTSP (Real Time Streaming Protocol)?
• (RTSP) Example of checking IP Camera status with the curl command
• Understanding RTSP (advanced) : Naver Blog - On interleaved mode
• RTSP ALG | Junos OS | Juniper Networks
• Analysis of the RTSPTestServer example - Analyzes the workflow through code
• Point to Point streaming with ffmpeg - Awesome Life

Programming

• [Recommended] Receiving RTSP stream using FFMPEG and OpenCV library
• Issues with OpenCV and RTSP
• Reading a network camera (IP Camera) in OpenCV
• Stackoverflow: OpenCV and Network Cameras -or- How to spy on the neighbors?
• Jetson TK1: Gstreamer application RTSP stream to OPENCV processing
• FFmpeg H.264 RTSP Server Using Live555 (c++/Code on Git)
  • Github: FFmpegRTSPServer (H264 RTSP server using FFmpeg and Live555) ²
• Reading OpecnCV RTSP (IP Camera) video with C++
• How do I access an IP Camera?
• Collection of links on using RTP in C#
• curl - rtsp.c sample

Tips

• Developer - Oh Seung-wook : Naver Blog - RTSP/RTP summary notes
• VLC Player - RTSP Streaming Server setup (using a file)

References