Streaming Video

1
Streaming Video

• Mohammed S Halim
• Jacob Christianson
• Sam Daley

2
Streaming Video

• Streaming Streaming is the process of playing a
  file while it is still downloading.
• Streaming Video A sequence of moving images
  that are sent in compressed form over the
  internet and display by the viewer as they arrive.

3
The evolution of Streaming Video

• 1994 Video was accessible only by user with
  high-end workstation.
• 1995 Progressive download technology allows
  audiences with standard personal computers to
  view video files as they are being download.
• 1997 The first all-in-one, audio-video players
  was released.
• 1999 True streaming was introduced to the
  general market.
• 2001 First implementations of MPEG-4

4
What makes Streaming Video different?

• Until recently, video on the web was primarily a
  download-and-play technology.
• Now a days, streaming video files begin playing
  almost immediately, while data is being sent,
  without having to wait for the whole file to
  download.

5
The primary characteristics of Streaming Video

• Streaming video technology enables real-time or
  on-demand access to video via the Internet or an
  intranet.
• Streaming video is transmitted by a media server
  application, and is processed and played back by
  a client player application, as it is received.
• A streamed file is received, processed, and
  played simultaneously and immediately, leaving
  behind no residual copy of the content on the
  receiving device.

6
Common need for Streaming Video

• Various media are used in Internet
• They are used for different application Such as
• Entertainment application
• Video conferencing
• Video archives and libraries
• Remote learning
• Multimedia presentations
• Video on demand
• Interactive Video Games
• Video surveillance
• And many more..

7
How does it work

• Links are added to a website
• User click on the links
• Media network streams the clip directly to the
  viewers PC.
• Because the media files are hosted on a separate
  network, the streaming has no impact on any
  existing web servers.

8
Key Terminology (some of them)

• Buffering
• Codec
• Encoding
• Stream
• Multicast
• Streaming
• On-Demand

9
Streaming Video Challenges

• Require real-time traffic
• Higher bandwidth needed
• Unpredictable availability of network bandwidth

10
Video Compression

• Streaming for the Internet available in all
  formats.
• To allow the playback of video over the web, the
  video must be compressed into a particular
  computer file format.
• Streaming created from any video and audio
  format.
• It is possible to compress from any video source
  to..
• -AVI -ASF
• -QUICK TIME -REALVIDEO
• -MPEG-1,2,4 -WAV
• -ASF -AIFF

11
Video Data Requirements

• 640 x 480 pixels x 640
• 24 bits/pixel x
• 30 frames/sec 480
• 221 Mbps

12
Delivery Methods

• Video On-demand
• Live Video
• Simulated Live Video

13
Video On-Demand

• Video is prerecorded
• User can request the streamed video at any time
• User can rewind, fast-forward, or pause the
  video at any time

14
Live Video

• Transmitting video as it happens, (i.e. not
  recorded)
• Can not fast-forward, rewind, pause, etc.

15
Simulated Live Video

• Same as Live Video except that the stream is
  prerecorded
• Also uses unicasting, splitting, multicasting
• Not used as much as VOD or Live Video

16
Protocols Used in Streaming Technology

• Hypertext Transfer Protocol (HTTP)
• User Datagram Protocol (UDP)
• Session Description Protocol (SDP)
• Real Time Transport Protocol (RTP)
• Real Time Control Protocol (RTCP)
• Real Time Streaming Protocol (RTSP)

17
Hypertext Transfer Protocol (HTTP)

• Allows the data to be played as it comes from the
  network or save to a file to play later
• Lacks control uplinks
• May be unable to skip to different parts of the
  video (like Microsofts .asf format)
• Or replay a section that just downloaded
• Can be used to download a small redirect file
  that connects to a normal stream

18
User Datagram Protocol (UDP)

• Real-time data-transfer protocol
• Receives high priority for internet transmission
• If data is lost or corrupted during a
  transmission, the receiver does not request that
  it be resent
• Basis for SDP, RTP, RTCP, RTSP

19
Session Description Protocol (SDP)

• Purpose Convey information about media streams
  in multimedia sessions to allow the recipients of
  a session description to participate in that
  session.
• Multimedia Session Set of media streams that
  exist for some duration of time
• Primary Functions
• A means to communicate the existence of a session
• A means to convey sufficient information to
  enable joining and participating in the session

20
SDP (cont.)

• Session name and purpose
• Time(s) session is active
• The media comprising the session
• Information to receive those media
• Information about the bandwidth to be used by the
  conference
• Contact information for the person responsible
  for the session

21
Real Time Transport Protocol (RTP)

• TCP/UDP are not suitable for real-time
  applications
• RTP is a thin protocol that provides real-time
  support
• Timing reconstruction
• Loss detection
• Security
• Content identification
• Does not have a delivery mechanism
• Can be used without RTCP
• Usually implemented within the application

22
RTP (cont.)

• Applications typically run RTP on top of UDP as
  part of the transport layer protocol
• RTP data in an IP packet

23
Real Time Control Protocol (RTCP)

• Control protocol that works in conjunction with
  RTP
• Provides support for real-time conferencing for
  large groups, including source identification and
  support for gateways and multicast-to-unicast
  translators

24
RTCP - Functions

• Provide information to the application
• Each packet contains report statistics
• Identify RTP source
• RTCP carries a transport-level identifier for an
  RTP source
• Used to keep track of the participants in an RTP
  session
• Control RTCP transmission interval
• Convey minimal session control information

25
Real Time Streaming Protocol (RTSP)

• Application-level protocol
• Aim to provide a robust protocol for streaming
  media
• One-to-many applications
• Unicast and multicast
• Support interoperability between clients and
  servers
• Different vendors

26
RTSP (cont.)

• RTSP is considered more of a framework than a
  protocol. It is intended to control multiple data
  delivery sessions, provide a means for choosing
  delivery channels such as UDP, TCP, IP Multicast,
  and delivery mechanisms based on RTP. Control
  mechanisms such as session establishment and
  licensing issues are being addressed. RTSP is
  being designed to work on top of RTP to both
  control and deliver real-time content. Thus RTSP
  implementations will be able to take advantage of
  RTP improvements, such as the new standard for
  RTP header compression. Although RTSP can be used
  with unicast in the near future, its use may help
  smooth the transition for environments transiting
  from unicast to IP multicasting with RTP.

27
RTSP How does it work?

• Breaks data into packets sized according to the
  bandwidth available
• When the client receives enough packets, software
  can
• Play one packet
• Decompress another
• And download a third
• Applies to live data feeds as well as stored clips

28
RTSP Functions of

• Provides on-demand access of multimedia items
• Provides control and delivery of real-time media
  as well as associated events between a media
  server and large numbers of media clients
• Addresses key concerns
• Quality of service
• Efficiency of delivery
• Rights management
• Measurement

29
RTSP Relationships with other Protocols
30
RTSP - Operation
31
RTSP Operation (cont.)

• Sending a control request
• Client constructs a line consisting of the
  method, the request URL, and the protocol version
  number
• Client includes a general header, a request
  header, and possibly an entity header (as for the
  HTTP protocol)
• Server executes the request if possible
• Server returns a response containing a
  status-line and general response and entity
  headers
• Status-line protocol version, numeric status
  code, textual description

32
RTSP Operation (cont.)

• Media streams are left unspecified
• Could be RTP streams or any other form of media
  transmission
• RTSP only specifies control
• Client and server software must maintain the
  mapping between the control channel and the media
  streams
• Control request and responses may be sent via TCP
  or UDP, which are sequenced (order matters!)
• UDP requires construction of retransmission
  mechanisms
• There are few times when UDP is used

33
RTSP - Sessions

• Client requests a presentation to be started by a
  server
• Receives a session identifier (used in all
  controls)
• Represents the shared state between the client
  and the server
• If the state is lost, the protocol relies on the
  transport of the media to stop automatically
• Client may request a teardown of the session
  (releases resources)

34
RTSP Request/Response

• Request
• Client to server or vice versa
• Includes the method to be applied to the resource
• The identifier resource
• Protocol version in use
• Response
• Includes protocol version
• Numeric status code
• 3-digit integer result code of the attempt to
  understand and satisfy the request
• A reason phrase is included for the human user
• Textual phrase associated with the status code

35
RTSP - Headers

• Request
• Media description format
• Encoding of media format
• Human language
• Authentication
• Client bandwidth available
• Conference identifier
• Name of requester
• Conditional retrieval
• Time range to play
• How did we get here?
• Speed-up delivery
• Software

• Response
• Redirection
• Authentication to proxy
• Methods supported
• Busy, Comeback later
• Server software
• Cache
• Request authorization

36
RTSP - Methods

• DESCRIBE
• retrieves the description of the presentation or
  media object identified by the request URL
• The DESCRIBE reply-response pair constitutes the
  media initialization phase
• ANNOUNCE
• GET_PARAMETER
• OPTIONS
• PAUSE
• Halts the stream delivery (temporarily)
• Server resources are kept, unless paused longer
  than the timeout parameter specifies
• PLAY
• Tells the server to start sending data
• Client must not issue a PLAY request until SETUP
  request have been acknowledged successfully

37
RTSP Methods (cont.)

• RECORD
• REDIRECT
• SETUP
• Specifies the transport mechanism to be used for
  the streamed media
• Transport header specifies transport parameters
  acceptable to the client
• The response contains the parameters selected by
  the server
• SET_PARAMETER
• TEARDOWN
• Stops the stream delivery for the given URI,
  freeing resources
• If the URI is a presentation, the session is
  closed and thus the identifier is no longer valid

38
RTSP Protocol States

• Minimal state of RTSP

39
Streaming Video Technology

• Real Networks (Progressive Networks)
  Proprietary formats, multi-rate video, etc.
• Windows Media (Microsoft) AVI, ASF (advanced
  streaming format)
• QuickTime (Apple) Basis for MPEG-4

40
What format should you use?

• What time of delivery system will be used?
• How much editability do you need?
• Do you need multirate streaming?

41
Differences

• CODEC Compressor/decompressor, each supports a
  different set of CODECS
• Protocols Some variation in supported protocols
• Costs Players can be obtained for free but
  encoding, server, etc. costs can vary

42
CODECS Windows Media

• Supported CODECS Windows Media Video v7, ISO
  MPEG-4 v7, Windows Media Screen Codec, MPEG-4
  v1,v2,v3

43
CODECS QuickTime

• Supported CODECS Sorenson Video, VP3, Cinepak,
  Indeo 3., Indeo Video Interactive 4, Video,
  Animation, Photo-JPEG, Component Video, MJPEG,
  Graphics, Portable Network Graphic (PNG), MPEG-1

44
CODECS Real

• Supported CODECS RealVideo with Scalable Video
  Technology (SVT),RealVideo, MPEG1, SMIL, VRML,
  RealText, RealPixNot backward
  compatibleRecommended to use older codec for
  upwards compatibility

45
Protocols

• Windows Media TCP, HTTP, UDP, UDP, MMS
• QuickTime HTTP, RTSP, RTP, FTP, SDP, UDP
• Real RTSP, RTP, UDP, TCP, HTTP, UDP

46
Costs

• Windows Media Encoding/Serving is free with
  Windows OS
• QuickTime Low cost if you have Mac OS, but you
  will need to purchase an encoder (i.e.
  QuickTime Pro)
• Real Costs vary but can be very high when using
  large servers

47
Similarities

• Support Netscape/Mozilla, IE
• Live Broadcasting
• Simultaneous Live Streaming
  and recording
• IP Multicast
• Windows OS Mac OS

48
Live Video

• Can be delivered 3 different ways
• Unicasting
• Splitting
• Multicasting

49
Live Video Unicasting

• Video stream goes independently to each user,
  and all users get their own stream
• Simplest
• Most popular
• Little or no configuration is needed

50
Live Video Splitting

• One Media Server shares its live media streams
  with other Media Servers
• User gets the stream from a splitter instead of
  the actual Media Server where the stream
  originated from
• Reduces the load on the Media Server

51
Live Video Multicasting

• Many users share the same stream
• Reduces bandwidth and network traffic

52
References

• Academic Technology Center http//www.cit.cornell
  .edu/atc/itsupport/streaming.shtml
• California Software Labs http//www.cswl.com/whit
  eppr/tech/StreamingTechnology.html
• CISCO http//www.cisco.com/networkers/nw99_pres/6
  08.pdf
• Data Networking and Communications 3e Behrouz A.
  Forouzan
• DV Web Video http//www.dvwebvideo.com/2000/0500/
  waggoner0500.html
• Erica Sadun http//www.mindspring.com/erica/stre
  am.html
• Internet RFC/STD/FYI/BCP Archives
  http//www.faqs.org/rfcs/rfc2327.html
• Internet RFC/STD/FYI/BCP Archives
  http//www.faqs.org/rfcs/rfc3550.html
• Raj Jain http//www2.ing.puc.cl/jnavon/IIC3582/P
  resent/3/mmip.htm
• A Streaming Media Primer http//www.adobe.com/prod
  ucts/aftereffects/pdfs/AdobeStr.pdf
• Multimedia Networking Goals and Challenges
  http//www2.ing.puc.cl/jnavon/IIC3582/Present/3/m
  mip.htmmultimedia
• Streaming Video Compression Overview
  http//www.ashlandvideo.com/tour_streaming.html
• Streaming Video http//www.cypresslakestudios.com
  /articles/streamingvideotutorial.html
• AOL Stream Info http//stream.info.aol.com/compar
  ison.html
• Windows .NET Magazine http//www.winnetmag.com/
  Article/ArticleID/3117/3117.html