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CS 584 / CMPE 584
Multimedia CommunicationsSpring 2006-07
Shahab Baqai
LUMS
2
Administrative
Website– http://suraj.lums.edu.pk/~cs584s06
Readingso Multimedia Communications Applications, Networks, Protocols &
Standards, Fred Halsall, 2001, Pearson Education LtdISBN 81-7808-532-1
o Multimedia Communication Systems, techniques, standards and networks, K.R. Roa, Zoran S. Bojkovic and Dragorard A. Milanvanovic, Pearson Education Inc. 2002
o Selected papers
3
Grading Instruments
Quizzes & HWs: ~10%
Project: ~30%– Proposals 5%– Peer Project Reviews 6%– Interim Progress Report 8%– Final Report/ Demo 16%
Midterm: ~25%
Final Exam: ~35%
4
Introduction
A brief history of (electronic) image communicationInvention of photography and cinema Invention of televisionIntroduction of television broadcasting
Recent advances in digital image communicationKey role of compressionWhat will be covered in this course? Organization
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Perspective Projection
Censored
6
Perspective Projection
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Photography and Cinema
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Nipkow Disk I
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Nipkow Disk II
10
Image Transmission by Line Scanning
11
Cathode Ray Tube (Braun)
12
History of Electronic Image Communication I
13
History of Electronic Image Communication II
14
Recent Developments: 1990s
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Motivating Image Compression
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Motivating Video Compression
17
Distributed Multimedia Systems
Applications:– non-interactive: net radio and TV, video-on-demand, e-learning, ...– interactive: voice &video conference, interactive TV, tele-medicine,
multi-user games, live music, ...
18
Characteristics of multimedia applications
Large quantities of continuous dataTimely and smooth delivery is critical– deadlines– throughput and response time guarantees
Interactive MM applications require low round-trip delaysNeed to co-exist with other applications– must not hog resources
Reconfiguration is a common occurrence– varying resource requirements
Resources required:– Processor cycles in workstations – and servers– Network bandwidth (+ latency)– Dedicated memory– Disk bandwidth (for stored media)
At the right timeand in the right quantities
19
Application requirements
Network phone and audio conferencing– relatively low bandwidth (~ 64 Kbits/sec), but delay times must be short ( <
250 ms round-trip)
Video on demand services– High bandwidth (~ 10 Mbits/s), critical deadlines, latency not critical
Simple video conference– Many high-bandwidth streams to each node (~1.5 Mbits/s each), high
bandwidth, low latency ( < 100 ms round-trip), synchronised states.
Music rehearsal and performance facility– high bandwidth (~1.4 Mbits/s), very low latency (< 100 ms round trip), highly
synchronised media (sound and video < 50 ms).
20
Networking: Historical PerspectiveLate 1960’s - Early 1970’s– Basic Concepts (Packet Switching etc.)– Resource Sharing --- ARPANET
Mid 1970’s - Mid 1980’s– LANs– Connectivity
Mid 1980’s - Mid 1990’s– Internetworking– Global Connectivity
Mid 1990’s ---– Meeting the needs of Applications
MultimediaIntegrated Services
– Taking advantages of advances in technology
21
Traditional Applications
Resource sharing
Remote Login
Electronic mail
File transfer
and more recently
World-Wide-Web
22
New Applications
News
Collaboration
Distance Learning
Tele Medicine
Telephony
Video Conferencing
Etc.
23
Categories of Applications
Communication among people
News and Entertainment
Education and Training
Business Applications
Medical Applications
24
Communication Among People
Voice Communication (VoIP, IP Telephony)– ubiquity of the Internet– alternative to Telcos– integration with other applications– new functionality
conferencing (made easier)storage (record, play-back, index, edit, integrate…)
25
Communication Among People
Video Conferencing– A picture is worth a thousand word
facial expressions, gestures, reactions…– Same advantages as with voice communication– Insertion of video clips– Fly-on-the-wall– Quality
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Communication Among People
Collaboration– shared white board
more frequent meetings
27
News and Entertainment
News in all its forms (paper, audio, video, web, combination; live and stored)– selectivity (on-line, by profile…)– accessibility without frontiers– urgent notification– linkage among various sources– archival
28
News and Entertainment
Movies and TV programming– Movie-on-demand (pay-per-view)
large selectionfull VCR functionality
– Live broadcasts (sports, weddings, …)– Wider audience
Interactive Games
29
Education and Training
Distance Learning– distance independence
Asynchronous Learning– time-independence
Flexible curriculum
Flexible pace
Monitoring
30
Education and Training
Two concrete examples:– Stanford University
Stanford-on-line– Harvard Business School
on-line case studies
The Virtual classroom– the real-experience– many other benefits
31
Education and Training
Desktop training– criticality– efficiency– productivity– convenience
Example– Professionals (lawyers, medical doctors)
32
Business Applications
Information kiosks
Corporate communication
Factory floor reference
Banking
Home Shopping
E-Commerce
Publishing
etc.
33
Medical Applications
Medical Imaging
Tele-surgery!
Health education
34
Multimedia Applications Characteristics
Applications involving many types of media
Data/Text
Audio
Video
Images
Graphics
35
Data Applications Requirements
Bursty sources
Relatively low average data rate per source
Full end-to-end reliability is required
No latency requirements
Mostly point-to-point
Traffic pattern is bursty
All applications exhibit similar behavior and have
similar requirements– no service differentiation requirement
36
Voice Communication
Voice traffic is Stream-Oriented– continuous flow of data– duration of a call is on the order of minute to an hour
Relatively low data rate per stream (2 to 64 Kbps)
Some data loss may be tolerated (1 to 2 %)– clipped segments below 50 ms cause degradation in the form of background
noise– larger segments cause intelligibility to be affected
Strict end-to-end latency requirement– below 150 ms for interactive voice communication
Very low degree of burstiness (silence suppression)
37
Video Based Applications
Video traffic is stream-oriented
Wide range of data rates– 10’s of Kb/sec to 10’s of Mb/sec– data rate depends on content and quality requirement
Latency requirements depending on application:– interactive communication: 100 ms– one-way broadcast: 1 sec– Video-on-Demand: 1 sec
Burstiness depends on a number of factors– content and quality requirement– compression scheme
38
Shared White Board
Relatively low data rate
full reliability requirement
low latency requirement
39
Multimedia Applications Requirements
Digital Video Data Rates
Low quality or talking heads (video conferencing)– 64 kb/s to 784 kb/s
Business quality (training, video mail)– 1 Mb/s to 2 Mb/s
Broadcasting quality (NTSC, PAL)– 4 Mb/s to 8 Mb/s
High-Definition TV– 20 Mb/s
Studio quality– 10 Mb/s to 45 Mb/s
40
High Bandwidth Requirement
41
Multicasting Requirement
Many multimedia applications involve multiple participants
Size of multicast depends on applications– Videoconferencing (3-4 participants, many-to-many)– group meeting (10’s of participants, one-to-many)– video broadcasting (100’s of participants, one-to-many)
Two models– fixed (closed) predefined set of participants– open set of participants
42
Integrated services Requirement
Coexistence of different media within same application
Coexistence of different applications within the same network
Must deal with:– high and low data rates– bursty and stream traffic– real-time and non-real-time traffic– point-to-point and multi-point modes of communications
43
Networking Requirements
Network Infrastructure– network technologies– network protocols:
routing
Multicasting,
resource reservations
Higher Layer Protocols– end-to-end data transport protocols– session layer protocols
Media Servers
44
Multimedia Application Requirements
1. Bandwidth Requirement– High bandwidth– Guaranteed bandwidth
2. Latency Requirement– Guaranteed maximum end-to-end latency– maximum jitter
3. Multicasting Requirement
4. Integrated Services Requirement
45
Data Traffic MM TrafficData Rate Low High
Traffic Pattern Brusty Stream OrientedHighly Brusty
Reliability Req. No Loss Some Loss
Latency Req. None May be Small
Communication Mode
Point-to-Point Multipoint
Temporal Relationships
None Synchronized Transmission
Type of Service Single Traffic Type Multiple Types
Applications Characteristics
46
Networking Requirements
Network Infrastructure– network technologies– network protocols:
RoutingMulticasting,resource reservations
Higher Layer Protocols– end-to-end data transport protocols– session layer protocols
Media Servers
47
System support issues and requirements
Scheduling and resource allocation in most current OS’s divides the resources equally amongst all comers (processes)– no limit on load– ∴ can’t guarantee throughput or response time
MM and other time-critical applications require resource allocation and scheduling to meet deadlines– Quality of Service (QoS) management
Admission control: controls demandQoS negotiation: enables applications to negotiate admission and
reconfigurationsResource management: guarantees availability of resources for
admitted applications– real-time processor and other resource scheduling
48
Typical infrastructure components for multimedia applications
Microphones
Camera
Screen
Window system
CodecD
BMixer
PC/workstation PC/workstation
C Videostore
Networkconnections
K
L
M
CodecA G
CodecH
Windowsystem
Video file system
: multimedia stream
White boxes represent media processing components, many of which are implemented in software, including:
codec: coding/decoding filtermixer: sound-mixing component
Component Bandwidth Latency Loss rate Resources required
Camera Out: 10 frames/sec, raw video640x480x16 bits
Zero
A Codec In:Out:
10 frames/sec, raw videoMPEG-1 stream
Interactive Low 10 ms CPU each 100 ms;10 Mbytes RAM
B Mixer In:Out:
2 44 kbps audio1 44 kbps audio
Interactive Very low 1 ms CPU each 100 ms;1 Mbytes RAM
H Windowsystem
In:Out:
various50 frame/sec framebuffer
Interactive Low 5 ms CPU each 100 ms;5 Mbytes RAM
K Networkconnection
In/Out: MPEG-1 stream, approx.1.5 Mbps
Interactive Low 1.5 Mbps, low-lossstream protocol
L Networkconnection
In/Out: Audio 44 kbps Interactive Very low 44 kbps, very low-lossstream protocol
This application involves multiple concurrent processes in the PCs
Other applications may also be running concurrently on the same computers
They all share processing and network resources