1. Real Time Streaming Protocol
Sravanthi
Swathi

2. Outline: Introduction RTP Vs RTSP RTSP methods State Diagram
Working of RTSP
RTSP message formats
Security considerations of RTSP
Applications of 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, Rew, 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. RTP Vs RTSP
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. RTSP methods: Options  Get available methods
Setup Establish transport
Announce Change description of media objects
Describe  Get (low-level) description of media objects
Play  start playback, reposition
Record Start Recording
Redirect Redirect client to new server
Pause Halt delivery, but keep state and server resources allocated
Set_parameter Device or encoding controls
Teardown Removes state

8. 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

9. Working of RTSP:

10. Example: Media On Demand

11. Example of RTSP message exchange

12. Cont…

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18. 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.

19. Cont… General syntax for an RTSP method is
{method name} {URL} {protocol version} CRLF
{parameters}
Example of an RTSP request
DESCRIBE RTSP/1.0
CSeq: 312
Accept: application/sdp, application/mheg

20. Cont… General syntax for a method with a body.
{method name} {URL} {protocol version} CRLF
{MIME header field} CRLF
...
CRLF
{optional body, depending on the presence of a "Content-length"}

21. RTSP message types

22. Cont…
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

23. Example of request response pair
C->S:
PAUSE rtsp://example.com/foo RTSP/1.0
CSeq: 834
Session:
S->C:
RTSP/ OK
Date: 23 Jan :35:06 GMT

24. RTSP message fields Different types of header fields
General-header field
Request-header field
Response-header field
Entity-header field
Generic format for a header field is

25. Streaming in multimedia environment

26. Security considerations of RTSP
Concentrated denial of service attack
Session hijacking
Persistently suspicious behavior
Stream securing

27. RTSP applications Streaming of multimedia via internet
Video conferencing and lectures
Broadcasting of entertainment
Remote digital editing
Voice mail

28. Draw backs:
The RTSP protocol says nothing about the problems of recovering state over machine or software failure.
RTSP is a state less protocol