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© Ralf Steinmetz
Multimedia-Systems:
Introduction
Prof. Dr.-Ing. Ralf Steinmetz
Dr. L.Wolf, Dr. S.Fischer
TU Darmstadt - Darmstadt University of Technology,
Dept. of Electrical Engineering and Information Technology, Dept. of Computer Science
KOM - Industrial Process and System Communications, Tel.+49 6151 166151,
Merckstr. 25, D-64283 Darmstadt, Germany, Ralf.Steinmetz@KOM.tu-darmstadt.de Fax. +49 6151 166152
GMD - German National Research Center for Information Technology
IPSI - Integrated Publication and Information Systems Institute, Tel.+49 6151 869869
Dolivostr. 15, D-64293 Darmstadt, Germany, Ralf.Steinmetz@darmstadt.gmd.de Fax. +49 6151 869870
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Contents
1. Preliminary Scope and Notion of “Multimedia”
2. Reference Model
3. Publications and Events in Research
4. Notion of Media
5. Multimedia Systems: Characteristics & Definition
6. Media Streams
7. Media Units
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1. Preliminary Scope and Notion of “Multimedia”
Notion
• Multi
• Many
• Media
• "Things in the middle"
Means to distribute and present information coded as
• Graphics, animation, audio and video (and text, ..)
• by
• Computer, TV, phone, etc.
Key Issues
• Performance
• bandwidth
• storage capacity
• processing
• Quality
• realtime
• error tolerance
• synchronization
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Integration of Industries and Technologies
Combination of several areas:
Today
Computer
Mass
Media
Tomorrow
Telecommunication
Consumer
Technological outlook:
• Networked multimedia computers
are the information tools of the 21st century
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Computer
Consumer Tele
communication
Mass
media
Usage
Services
Systems
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2. Reference Model
Applications
Learning & Teaching
Content
Processing
Documents
Design
Security
Opt. Memories
Group
SynchroCommuninization
cations
...
Databases
Media-Server
User Interfaces
Programming
Operating Systems
Communications
Quality of Service
Networks
Basics
Compression
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Computer
Architectures
Image &
Graphics
Animation
Video
Audio
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3. Publications and Events in Research
Books
• e.g.
Journals
• acm/Springer Multimedia Systems Journal
• IEEE Multimedia Magazine
• IEEE Transactions on Multimedia
• Multimedia Tools and Applications
• and many other ...
Workshops and Conferences
• ACM Multimedia conference
• IEEE Multimedia conference
• and many more ....
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4. Notion of Media
Media determine
• For what purpose computers are used
• How computers are used
• Who can use computers
• When computers are used
Examples
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Examples
New applications
• electronic commerce in the Internet
• distributed games
New interfaces
• from windows, icons, desktop
• to 3D virtual interfaces, video walls, etc.
Conclusion:
• Multimedia systems affect our view of computing in general,
• not just specific application areas
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Media
Perception: How do humans perceive Information?
• aural sense, visual sense
Representation: How is information coded?
• ASCII, GIF, JPEG, ...
Presentation: Which “medium” is used to convey (in-/output) information?
• paper, monitor, loudspeaker, ..
Storage: Where is information stored?
• paper, CD-ROM, ...
Transmission: Which “medium” is used to transmit information?
• optical fiber, ..
Information exchange: Which “medium” is used to exchange information?
• CD, JAZ-Drives, optical fiber, ..
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Media Presention Dimentions
Media transport information appealing to human senses:
• Presentation space:
• Sense of vision (paper or computer displays)
• Sense of hearing (stereophonic sound)
• Sense of touch (pressure gloves)
• Sense of balance (pneumatic simulators)
• Presentation values:
• Characters
• Pressure waves
Value classes:
• Self-contained values:
• Temperature, taste, smell
• Agreed-upon values (symbols):
• Text, spoken language, gestures
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5. Multimedia Systems: Characteristics & Definition
Time-Dependence of Media
Time-independent media:
y
This is
plain text
Discrete media
Spread
Sheet
x
Time-dependent media:
y
...
time
Continuous media
x
Note: "Continuous" refers to the user’s impression of the data,
not necessarily to its internal representation.
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Properties of a Multimedia System and Definition
Combination of media
• continuous media
• discrete media
Flexibility:
• Provide mechanisms to handle all kinds of media,
in particular, discrete and continuous media
• A VCR and a desktop publishing system for text and graphics
are no multimedia systems.
• An editor with voice annotation is a multimedia system.
Integration:
• Independent media handling/manipulation
• Computer-controlled media combination
Definition:
A multimedia system is characterized
by the integrated computer-controlled handling
of independent discrete and continuous media.
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6. Media Streams
Characterization in terms of communications
• Asynchronous
• Synchronous
• Isochronous
Components
• Media Units
Note: Timing of Media Units is important!
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Timing: Start of Consecutive Media Units
strongly periodic (streng periodischer Datenstrom)
• interval constant
T
t
weakly periodic (schwach periodischer Datenstrom)
• function describes periodicity within finite interval
T1
T2
T3
T1
t
T2
T
aperiodic (aperiodischer Datenstrom)
• no analytic (function) description
T1
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T2
Tn
t
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Timing: Duration of Media Units
strongly regular stream (streng gleichmäßiger Datenstrom)
• duration equal
D1
D1
t
weakly regular stream (schwach gleichmäßiger Datenstrom)
• duration variies, but with predefined pattern
D1
D2
D3
D1
D2
D3
t
irregular stream
• no analytic description / regularity
D1
D2
D3
Dn
t
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T
T
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Timing: Time between Adjacent Media Units
Coherent stream (zusammenhängend)
• no gap between adjacent media units
D1
D2
D3
D4
Dn
t
D
non-coherent stream (unzusammenhängend)
• may be gaps
D1
D2
D3
D
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Dn
t
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7. Media Units
Example: Video
Movie
Clip
Frame
Area
Pixel
Logical Data Units
• at different “levels”
• at different granularities
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