Multimedia networking: The term ‘multimedia’ refers to diverse classes of media employed to represent information. The term ‘Networked Multimedia’ refers to the transmission and distribution of multimedia information on the network

1. Multimedia Networking
Dr. Hamdan M. AL-Sabri
King Saud University
College of Computer and Information Sciences
Department of Information Systems

2. outlines
• Introduction
• What is the multimedia
• Various Media Types
• Networked Multimedia
• Major Components of Multimedia Networking
• Application of Multimedia Networking(Wimax)
• Summery
• References
Dr. Hamdan M. Al-Sabri, CCIS-KSU

3. Introduction
• The term ‘multimedia’ refers to diverse classes of
media employed to represent information.
• The term ‘Networked Multimedia’ refers to the
transmission and distribution of multimedia
information on the network
Dr. Hamdan M. Al-Sabri, CCIS-KSU

4. Characteristics of multimedia
• Digital – key concept
• Integration of multiple media type, usually
including video or/and audio
• May be interactive or non-interactive
Dr. Hamdan M. Al-Sabri, CCIS-KSU

5. Multimedia Classification
• Real Time: Require bounds on end-to-end packet
delay & jitter. Subdivided into:
• Discrete Media: MSN/Yahoo Messenger, Stock quotes
• Continuous Media: Continuous message stream with
inter-message dependency. Further divided into:
• Delay Tolerant e.g Internet webcast
• Delay Intolerant e.g. audio, video streams in conferencing
systems
• Non-Real Time: No strict delay constraints (e.g.
text, image files)
• May be highly sensitive to errors
Dr. Hamdan M. Al-Sabri, CCIS-KSU

6. Classification of Media Type
Sound Video
Image
Animation
Text Graphics
Captured
From real world
Synthesized
By computer
Discrete Discrete
Continuous Continuous
Dr. Hamdan M. Al-Sabri, CCIS-KSU

7. Key Components of Multimedia
• Modality
• Channel of communication
• Medium
Dr. Hamdan M. Al-Sabri, CCIS-KSU

8. Modality
• Modality: one of the sensory systems available to
human beings
• The five modalities include:
Sense organSensoryModality
SkinTouchingTactile
TongueTastingGustatory
EyesSeeingVisual
EarsHearingAuditory
NoseSmellingOlfactory
Dr. Hamdan M. Al-Sabri, CCIS-KSU

9. Channel of Communication (CoC)
• Definition: A connection between an encoder and
decoder such that information is encoded by the
encoder, transmitted along the channel and decoded
by the decoder to produce the same information at the
other end of the channel.
• There are various types of channels of communication
• A channel of communication exists within a single
modality, but one modality may include many
channels of communication.
Dr. Hamdan M. Al-Sabri, CCIS-KSU

10. Medium
• Medium: A set of co-ordinated channels spanning one
or more modality which have come, by convention, to
be referred to as a unitary whole, and which possess a
cross-channel language of interpretation.
• Examples:
Television
A book
A radio
A newspaper
Dr. Hamdan M. Al-Sabri, CCIS-KSU

11. Multimedia Requirements
• Guarantees
• Throughput and/or delay guarantees
• Audio requires loss/delay guarantees
• Interactive apps. require low delay
• CBR & VBR
• Variable bit rate places extra burden
Dr. Hamdan M. Al-Sabri, CCIS-KSU

12. Networked Multimedia
• Local vs. networked multimedia
• Local: storage and presentation of multimedia
information in standalone computers
• Sample applications: DVD
• Networked: involve transmission and
distribution of multimedia information on the
network
• Sample applications: videoconferencing, web video broadcasting,
multimedia Email, etc.
Dr. Hamdan M. Al-Sabri, CCIS-KSU

13. Networked Multimedia
Image server
Internet
Video server
A scenario of multimedia networking
Dr. Hamdan M. Al-Sabri, CCIS-KSU

14. Major Components of Multimedia
Networking
1. Data compression.
2. Quality of service .
3. Bandwidth.
4. Interoperability of the network.
Dr. Hamdan M. Al-Sabri, CCIS-KSU

15. Data compression
• Can Multimedia Data Be Compressed?
• The data compression (source encoding) of multimedia
data sources (e.g., speech, audio, image, and video).
For different end terminals to be able to decode a
compressed bit stream, international standards for these
data compression schemes have to be introduced for
interoperability.
Dr. Hamdan M. Al-Sabri, CCIS-KSU

16. Quality of service
• The second major component of multimedia
networking, quality of service(QoS) issues which
include packet delay, packet loss, jitter, etc. These
issues can be dealt with either from the network
infrastructure or from an application level
Dr. Hamdan M. Al-Sabri, CCIS-KSU

17. Bandwidth
• In ensuring the effective dissemination of compressed
multimedia data over IP-based wireless broadband
networks, the main challenges result from the
integration of wired and wireless heterogeneous
networking systems; in the latter the QoS is further
degraded by the dynamically changing end-to-end
available bandwidth caused by the wireless fading or
shadowing and link adaptation.
Dr. Hamdan M. Al-Sabri, CCIS-KSU

18. Interoperability of the network
• The fourth major component of multimedia
networking consists of ensuring that the multimedia-
networked content is fully interoperable, with ease of
management and standardized multimedia content
adapted for interoperable delivery, as well as
intellectual property management and protection (i.e.,
digital rights management, DRM), effectively
incorporated in the system
Dr. Hamdan M. Al-Sabri, CCIS-KSU

19. Multimedia Applications
• Video-on-demand
• Near-video-on-demand
• Travel/training videos
• Interactive games
• Teleconferencing
• IP Telephony
Dr. Hamdan M. Al-Sabri, CCIS-KSU

20. Multimedia Networking Systems
• Live media transmission system
• Capture, compress, and transmit the media.
• Send stored media across the network
• Media is pre-compressed and stored at the server. This system
delivers the stored media to one or multiple receivers.
• Differences between the two systems
• For live media delivery:
• Real-time media capture, need hardware support
• Real-time compression– speed is important
• Compression procedure can be adjusted based on network
conditions
• For stored media delivery
• Offline compression – better compression result is important
• Compression can not be adjusted during transmission
Dr. Hamdan M. Al-Sabri, CCIS-KSU

21. MM Networking Applications
Classes of MM applications:
1) Streaming stored audio and video
2) Streaming live audio and video
3) Real-time interactive audio and video
Dr. Hamdan M. Al-Sabri, CCIS-KSU

22. Streaming stored audio and video
• audio or video stored in file
• files transferred as HTTP object
• received in entirety at client
• then passed to player
Dr. Hamdan M. Al-Sabri, CCIS-KSU

23. 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!
Dr. Hamdan M. Al-Sabri, CCIS-KSU

24. Example: Streaming Live
Multimedia
• How to stream to large numbers of clients?
• Example: A popular sporting event
• Use multicast/broadcast
• What about client heterogeneity?
• E.g., clients might have different available b/w
• Use layered/scalable video
Internet
Video Server
ADSL
Dial-up
High-speed
AccessDr. Hamdan M. Al-Sabri, CCIS-KSU

25. Real-time interactive audio and
video
applications: IP telephony, video
conference, distributed interactive worlds
• 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?
Dr. Hamdan M. Al-Sabri, CCIS-KSU

26. Multimedia &Protocols :TCP vs.
UDP
• TCP
• No loss
• Retransmits all lost messages
• Potentially large latency
• UDP
• Potentially unbounded loss
• Does no retransmission
• Minimal latency
Dr. Hamdan M. Al-Sabri, CCIS-KSU

27. Multimedia Delivery
• Even when using UDP, applications should respond to
congestion end-to-end.
• Need to promote “nice” behavior or “TCP-friendly”
behavior.
• Emerging applications shouldn’t kill the performance
of “nice” applications.
Dr. Hamdan M. Al-Sabri, CCIS-KSU

28. Solution:
A Selective Retransmission Protocol
• Balances the extremes of TCP and UDP
• Tradeoff between loss and latency
• Retransmits a percentage of lost packets
• If end-to-end delay is large, may accept loss
• If end-to-end delay is small, may always request
retransmission
• If loss rate is very high, may request retransmission
• How to decide?
Dr. Hamdan M. Al-Sabri, CCIS-KSU

29. Sample SRP Session
Data
Block
Time
Client Server
Request retransmission
(Sequence
Numbers)
Dr. Hamdan M. Al-Sabri, CCIS-KSU

30. QoS Infrastructure to Support
Multimedia Communications
• Principles
• Policing
• Scheduling
• RSVP
• Integrated and Differentiated Services
Dr. Hamdan M. Al-Sabri, CCIS-KSU

31. Components of Interactive
Multimedia
• Asset – an object which encapsulates a single piece of ‘media’
(e.g. video, sound clip, graphic)
• Information – the collection of data by a particular encoding
• Knowledge – the interpretation and understanding of information
Dr. Hamdan M. Al-Sabri, CCIS-KSU

32. Relationship between the Internet,
Libraries and Multimedia
Dr. Hamdan M. Al-Sabri, CCIS-KSU

33. Internet Multimedia: bag of tricks
• use UDP to avoid TCP congestion control (delays) for
time-sensitive traffic
• client-side adaptive playout delay: to compensate for delay
• server side matches stream bandwidth to available client-
to-server path bandwidth
• chose among pre-encoded stream rates
• dynamic server encoding rate
• error recovery (on top of UDP)
• FEC, interleaving
• retransmissions, time permitting
• conceal errors: repeat nearby dataDr. Hamdan M. Al-Sabri, CCIS-KSU

34. Multimedia on the Internet
• The Media Player
• Streaming through the Web
• The Internet Phone Example
Dr. Hamdan M. Al-Sabri, CCIS-KSU

35. The Media Player
• End-host application
• Real Player, Windows Media Player
• Needs to be pretty smart
• Decompression (MPEG)
• Jitter-removal (Buffering)
• Error correction (Repair)
• GUI with controls (HCI issues)
• Volume, pause/play, sliders for jumpsDr. Hamdan M. Al-Sabri, CCIS-KSU

36. Streaming through a Web
Browser
Must download whole file first!
Dr. Hamdan M. Al-Sabri, CCIS-KSU

37. Streaming through a Plug-In
Must still use TCP!
Dr. Hamdan M. Al-Sabri, CCIS-KSU

38. Challenges to the Current Internet
• TCP/UDP/IP suite provides best-effort, no guarantees on
expectation or variance of packet delay
• Streaming applications delay of 5 to 10 seconds is typical
and has been acceptable, but performance deteriorate if
links are congested (transoceanic)
• Real-Time Interactive requirements on delay and its jitter
have been satisfied by over-provisioning (providing plenty
of bandwidth), what will happen when the load
increases?...
Dr. Hamdan M. Al-Sabri, CCIS-KSU

39. Challenges to the Current Internet
• Most router implementations use only First-Come-First-
Serve (FCFS) packet processing and transmission
scheduling
• To mitigate impact of “best-effort” protocols, we can:
• Use UDP to avoid TCP and its slow-start phase…
• Buffer content at client and control playback to remedy
jitter
• Adapt compression level to available bandwidth
Dr. Hamdan M. Al-Sabri, CCIS-KSU

40. Multimedia & Security
• Integrity
• Authenticity
• Encryption
• Intellectual rights protection
• Digital watermarking techniques embed extra
information into multimedia data
• Imperceptible to normal user and irremovable
Dr. Hamdan M. Al-Sabri, CCIS-KSU

41. Summery
• Multimedia is everywhere
• multimedia applications and requirements
• making the best of today’s best effort
service
• scheduling and policing mechanisms
• next generation Internet: Intserv, RSVP,
Diffserv
• Exciting, industry relevant research topic
• Multimedia is everywhereDr. Hamdan M. Al-Sabri, CCIS-KSU

42. References
• Bloch, Pigneur, and Segev (1996). On the Road of
Electronic Commerce: a Business Value Framework,
Gaining Competitive Advantage and Some Research
Issues.
http://pages.stern.nyu.edu/~mbloch/docs/roadtoec/ec.ht
m [Accessed 22 June 2002].
• Clarke, R. (2000). Roger Clarke's Electronic Commerce
Pages.
http://www.anu.edu.au/people/Roger.Clarke/EC/.
[Accessed 22 June 2002]
Dr. Hamdan M. Al-Sabri, CCIS-KSU

43. References
• Elsom-Cook, M. (2001). Principles of Interactive
Multimedia. New York; London : McGraw-Hill.
• http://sunsite.berkeley.edu/ARL/definition.html
• Philip A. Chou, Mihaela van der Schaar University of
California, Los Angeles, MULTIMEDIA OVER IP AND
WIRELESS NETWORKS COMPRESSION,
NETWORKING, AND SYSTEMS
• Computer Networking: A Top Down Approach Featuring
the Internet, 3rd edition. Jim Kurose, Keith Ross
Addison-Wesley, July 2004. : Multimedia Networking
Dr. Hamdan M. Al-Sabri, CCIS-KSU

44. References
• Shashank Khanvilkar, Faisal Bashir, Dan Schonfeld, and
Ashfaq Khokhar
• Mike Piecuch, Ken French, George Oprica and Mark
Claypool,Computer Science Department,Worcester
Polytechnic Institute,Proceedings of SPIE Multimedia,
Systems and Applications Conference Boston, November
2000
•
Dr. Hamdan M. Al-Sabri, CCIS-KSU