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Introduction

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  • 1. Introduction Jiangchuan Liu Fall 2007 CMPT 880 Selected Topics on Multimedia Networking
  • 2. CMPT 880 Multimedia Networking
    • Jiangchuan (JC) Liu  School of Computing Science TASC8031
    • E-mail: jcliu@cs.sfu.ca  
    •   Class Period and Venue:
      • Wednesday  2:30-3:20 (1 hr)   RCB5120
      • Friday          1:30-3:20 (2 hrs)  AQ5006
    •   Office Hours:
    • You may send me email to schedule meeting
    • Course Web:
    • http://www.cs.sfu.ca/~jcliu/cmpt880-2007/
  • 3. Multimedia Networking : What’s it ?
    • Key issue: Media Streaming:
    • Media (audio/video) at source
    • transmitted to client
    • streaming: client playout begins before all data has arrived
  • 4. Streaming Multimedia: What’s it ? Cumulative data time streaming: at this time, client playing out early part of video, while server still sending later part of video
  • 5. MM Networking Applications
    • Fundamental characteristics:
    • Typically delay sensitive
      • end-to-end delay
      • delay jitter
    • But loss tolerant : infrequent losses cause minor glitches
    • Opposite to data, which are loss intolerant but delay tolerant.
    • Classes of MM applications:
    • 1) Streaming stored audio and video (YouTube, GoogleVideo …)
    • 2) Streaming live audio and video (IPTV, P2PTV)
    • 3) Real-time interactive audio and video (Online game, distance learning)
      • Jitter is the variability
      • of packet delays within
      • the same packet stream
  • 6. (1) Streaming Stored Multimedia Cumulative data time 1. video recorded 2. video sent 3. video received, played out at client streaming: at this time, client playing out early part of video, while server still sending later part of video network delay
  • 7. (1) Streaming Stored Multimedia: Interactivity
    • VCR-like functionality: client can pause, rewind, FF, push slider bar
      • 10 sec initial delay OK
      • 1-2 sec until command effect OK
      • RTSP often used (more later)
    • timing constraint for still-to-be transmitted data: in time for playout
  • 8. (2) Streaming Live Multimedia
    • Examples:
    • Internet radio talk show
    • Live sporting event
    • Streaming
    • playback buffer
    • playback can lag tens of seconds after transmission
    • still have timing constraint
    • Interactivity
    • fast forward impossible
    • rewind, pause possible!
  • 9. (3) Interactive, Real-Time Multimedia
    • end-end delay requirements:
      • audio: < 150 msec good, < 400 msec OK
        • includes application-level (packetization) and network delays
        • higher delays noticeable, impair interactivity
    • session initialization
      • how does callee advertise its IP address, port number, encoding algorithms?
    • applications: IP telephony, video conference, distributed interactive worlds
  • 10. When media meet Internet … Multimedia applications: network audio and video (“continuous media”) network provides application with Quality-of-Service needed for application to function. QoS
  • 11. Internet: Vehicle for Media Distribution
    • Heterogeneous network
      • Protocols, routing, links, network technologies, end-hosts, bandwidth, delay, etc
    • Best effort service
      • Available BW is unknown and variable
      • Loss rate and loss pattern are unknown and variable
    • Resources are shared
      • TCP/IP is the dominating protocol stack
  • 12. Multimedia Over Today’s Internet
    • TCP/UDP/IP: “best-effort service”
    • no guarantees on delay, loss
    But you said multimedia apps requires them to be effective! ? ? ? ? ? ? ? ? ? ? ?
  • 13. The Reality
    • Rapid growth of multimedia streaming
      • Popularity of the Web and the Internet
      • High-bandwidth access (Cable, DSL, LAN)
    • High overhead imposed on the Internet
      • Long, high-bandwidth streams
      • Unfriendly to traditional TCP traffic
    • Poor and inconsistent quality of streams
      • Small picture size
      • Low frame rate
      • Fluctuation in quality
  • 14. How should the Internet evolve to better support multimedia?
    • 1. Laissez-faire
    • no major changes
    • more bandwidth when needed
    • 2. Integrated services philosophy:
    • Fundamental changes in Internet so that apps can reserve end-to-end bandwidth
    • 3. Differentiated services philosophy:
    • Fewer changes to Internet infrastructure, yet provide 1st and 2nd class service.
    What’s your opinion?
  • 15. Alternatively…
    • Media adaptation
    • Can media (audio/video) adapt to network ?
    • How to do ?
      • Network monitoring
      • Adaptive coding
    • Where to do ?
      • Source
      • Enroute
  • 16. Architecture: Client-Server?
    • Limited scalability
    • Single point of failure
    • Limited & unstable quality
    • Asynchronous access could be inefficient
    • Increasing network capacity doesn’t solve these problems?
      • Multicasting ?
    Server Client Client Client Internet
  • 17. New Distribution Architectures
    • Extending client-server architecture
      • Proxy Caching
      • Content Distribution Networks (CDN)
    • Replacing client-server architecture
      • Peer-to-Peer Networks
  • 18. Proxy Caching for Streaming Media Internet ISP Campus Client Client Client Client Client Server1 Server2 Client Client Proxy Proxy
  • 19. CDN for Streaming Media Internet ISP Campus Client Client Client Client Client Server1 Server2 Client Client Server1 Server1
  • 20. Peer-to-peer Streaming Internet ISP Client Client Client Client Client Server1 Client Client Server2
  • 21. What will be covered in this course ?
    • Media compression and representation: Overview
      • Digitization
      • Transform coding and entropy coding
      • Motion estimation and compensation
      • Video/audio standards MPEG-1,2,4,7, H.261/263/26L, JPEG, MP3
    • Transport layer issues
      • UDP/TCP protocol
      • TCP fairness/TCP modeling/TCP friendly rate control
      • ITU/IETF media streaming protocols
        • H.323 video conferencing
        • Realtime Transport Protocol (RTP)/RTCP/RTSP, SAP/SDP
    • Network layer issues
      • Current and next-generation Internet
      • Best-effort model
      • Integrated Service (IntServ) model: RSVP
      • Differential Service (DiffServ) model
      • Multicasting: routing and scalable video multicast
  • 22. What will be covered in this course ?
    • Application layer issues
      • Proxy caching
      • Peer-to-peer networks
    • Wireless Basics
      • Wireless basics TDMA/FDMA/CDMA
      • From 1G to 4G wireless networks
      • Error correction/Concealment
        • Reversible VLC, Bit Toggling
      • Media over wireless
    • Research in multimedia networking (or in general, networking area)
      • How to select a topic ?
      • Important journals/conferences
  • 23. The course: From another viewpoint - Support multimedia applications has become one of the most important objectives for next generation Internet/wireless networks So this course can be (partially) viewed as a course about advanced network architecture.
  • 24. Class Information
    • Pre-requisites
      • Multimedia encoding/networking, but overview will be provided
    • Class structure
      • Lectures (mainly on multimedia networking)
      • Paper presentation and summary
      • Project (if you want to receive A+)
    • Goals:
      • To become familiar with research issues, proposed interesting ideas, design and evaluation methodologies in Multimedia Networking (and advanced network architectures)
      • To evaluate previous work and identify interesting open research problems in this area
  • 25. Grading Scheme (Tentative) Most important: what you have learnt in this course? 60% Paper presentation/Summary 40% Course participation