1. Real Time Streaming Protocol (RTSP)
By : RIGIL TEAM
Shahina Ahmed
Kishwer Jabeen
Shilpa Mayanna
Sowmya Ramarao

2. Agenda Introduction RTP Vs RTSP State Diagram Working of RTSP
RTSP message formats
RTSP methods
RTSP Operations
Security Considerations for RTSP

3. Purpose
Streaming????
Streaming breaks the data into packets with size suitable for the transmission between servers and clients.
RTSP establish and controls streams
Client can play the first packet, decompress the second while receiving the third …

4. Introduction
RTSP is an application level protocol for the control of real-time streaming data with syntax and operations similar to HTTP.
IEFT standard  RFC 2326
It uses RTP as the underlying data delivery protocol and offers a VCR-like control to the user: Play, Stop, Pause, FF, Rewind, as well as random access to any part of media clip.

5. Introduction (contd…)
RTSP helps the server to adjust the media bandwidth to the network congestion in order to suit the available capacity.
Multicast data stream
RTSP is able to choose the optimum delivery channel to the client.
For instance, if UDP cannot be used the streaming server has to offer a choice of delivery protocols – multicast UDP or TCP to suit different clients.

6. RTSP Vs RTP
RTSP allows two-way communication; that is, viewers can communicate with the streaming server and do things like rewind the movie, go to a chapter, and so on.
By contrast, RTP is a one-way protocol used to send live or stored streams from the server to the client.

7. Features of RTSP Retrieval and control of media from media server
Invitation of a media server to a conference
Addition of media to an existing presentation

8. Properties of RTSP Extendibility Secure Transport independent
Multi-server capable Control of recording devices
Separation of stream control and conference invitation
Presentation description neutral
Proxy and firewall friendly

9. RTSP Message Format
RTSP is a text based protocol and use the same message format as HTTP.
Text-based protocols have the advantage of easy extendibility and human friendly messages.
Suffer from major overhead that text coding brings about.
RTSP text coding is the optimal choice, due to the nature of the protocol, which is prone to extensions and does not burden the network with frequent or high sized messages.

10. RTSP Message Type
A start-line if sent in a request is called Request-line otherwise if in a response, is called Status-line.
Start-line = Request-Line | Status-Line
Generic format of request line is
Generic format of status line is

11. RTSP State Transitions
Setup: Start an RTSP session and resource allocation for a stream
Play and Record Start data transmission of the stream
Pause Temporarily halt a stream without freeing server resources
Teardown Free resources associated with stream and end of a session

12. RTSP Methods

13. Describe Method Phase of session establishment
Fetch the description of a media object or a presentation
Reply of the server contains a complete description of the requested resource.
C->S: DESCRIBE rtsp://server.example.com/fizzle/foo RTSP/1.0
CSeq: 312
Accept: application/sdp, application/rtsl, application/mheg
S->C: RTSP/ OK
Date: 23 Jan :35:06 GMT
Content-Type: application/sdp
Content-Length: 376

14. Options Method Borrowed from HTTP 1.1
Represents a request for the options associated to a resource or the capabilities of a server
Pause Method
Request the server to interrupt momentarily the delivery of the stream
If client does not resume the state before timeout expiration all resources are released

15. Play Method Set-up Method
Clients to begin or resume the play of a media
Specifying a desired retrieval range
Play requests can be pipelined
Set-up Method
Initializes, or modifies, the transport mechanism to be used between client and server

16. Tear-down Method
Permanently stops the delivery of a media stream, or a presentation
Implies releasing the state associated to the session and freeing the associated resources.
C->S: TEARDOWN rtsp://example.com/fizzle/foo RTSP/1.0
CSeq: 892
Session:
S->C: RTSP/ OK

17. Downloads browser GETs metafile
browser launches player, passing metafile
player contacts server
server downloads audio/video to player

18. RTSP Operation

19. Streaming Vs Downloading
Download: Receive entire content before playback begins
High “start-up” delay as media
file can be large
Streaming: Play the media file while it is being received
Reasonable “start-up” delays
Reception Rate >= playback rate.

20. What RTSP does not do?
Does not define how audio/video is encapsulated for streaming over network.
Does not restrict how streamed media is transported; it can be transported over UDP or TCP.
Does not specify how the media player buffers audio/video.

21. Security Considerations for RTSP
RTSP reuses many of HTTP security features
RTSP presents additional issues
-Denial of service
-Session hijacking
-Authentication

22. Conclusion
RTSP provides a efficient protocol which can be used in streaming system to remotely control a media server
Extensible