Multimedia- and Web-based Information Systems

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Multimedia- and Web-based Information Systems

• Lecture 3

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Multimedia Introduction
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Introduction to Multimedia

• The term Multimedia
• Media
• Properties of a data stream

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Multimedia from a users point of view

• Presentation of Information also using Audio and
  Animation
• Information is easier conveyed
• Integration of Media with the Computer allows for
• Interactive Presentations
• Transmission across computer networks

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Multimedia and the Industry

• Sectors affected by the developments in
  Multimedia
• Telecommunications
• Consumer Electronics
• TV- and Radiostations
• Publishing Houses
• gt Convergence of Sectors

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Properties of multimedia processing

• High data troughput
• Realtime
• Synchronisation

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Development of the term Multimedia

• 1950s
• System with more than one medium, e.g.
  Presentation using an overhead projector, a tape
  recorder and a film projector
• 1960s
• Multimedia-Computer used to control analog
  devices

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Development of the term Multimedia

• End of 1980s
• Multimedia-PC, Quicktime
• End of 1990
• Development of Internet applications

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Areas in Multimedia-Systems
Databases
Operating Systems
Communication System
Computer Technology
Memory
Networks
Compression
Audio
Video
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Areas in Multimedia-Systems
User Interface
Applications
Documents
Abstractions
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Terminology

• Multi lat. much, as a Prefix
• Medium, mediating element, means to reproduce
  Information

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The term medium

• Means for the distribution and presentation of
  information
• Examples Text, Figure, Image, Voice, Music
• Further differentiation of the term in the
  MHEG-Standard (1993)
• On the following two slides

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Different media terms

• Perception-Medium
• To See, to Hear (how?)
• Representation-Medium
• JPEG, MPEG (Structure, Coding)
• Presentation-Medium
• Screen, Speakers, Keyboard (Input/Output)

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Different media terms

• Storage-Medium
• Paper, Harddisk, CD-ROM (where from?)
• Transmission-Medium
• Network (on what?)
• Information-Exchange-Medium
• Transmitter / Storage of Information CD, Network
  (higher abstraction)

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Presentation values and domains

• Presentation domains
• Screen, Paper (visual presentation domains)
• Stereophonetics
• Presentation values
• Character, shock wave

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Presentation dimension

• Every presentation domain has presentation
  dimensions
• Screen 2 spatial dimensions
• In Addition, Time as a dimension possible
• Time as additional dimension fundamental for
  multimedia systems

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Classes of media

• Classification using the time dimension
• Discrete Media
• Independent from time
• Examples Text, Figures
• Continuous Media
• Dependent on time
• Examples Sound, Motion Picture

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The Term Multimedia

• Qualitative rather than quantitative
  understanding
• What kind of media instead of multiple media
• A Combination of text and picture is not
  sufficient for the term Multimedia
• Controversial term

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Main properties of a multimedia system

• Combination of Media
• Processing of discrete and continuous media
• Independency
• in the layout of the media in space and time
• Computerized Integration
• Computer as a tool
• (Systems able to communicate)
• Distributed Multimedia-Systems

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Definition of Multimedia

• A multimedia system is defined through the
  computerized, integrated creation, manipulation,
  presentation, storage and communication of
  independent information coded in at least one
  continuous and one discrete medium.

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Usage of the term Multimedia

• In a narrow sense
• Continuous Media
• Borders in Time
• In a broader sense
• Shared processing of multiple media

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Transmission of media data

• Transmission of data of discrete and continuous
  media
• For information exchange
• Based on data streams

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Data stream

• Units (Packets)
• Send from source to sink
• Data stream is a sequence of single packets
• For discrete and continuous media

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Asynchronous Transmission

• No restrictions in time for the packets of the
  data stream
• Example IP
• Normally not suitable for multimedia

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Synchronous Transmission

• Defined Maximum End-To-End Latency
• For multimedia this means a guarantee on when
  packets will be arriving

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Isochronous Transmission

• Defined maximum and minimum end-to-end latency
• Jitter of single packets is restricted
• Buffers can be calculated more exact
• Suitable for Streaming, transmission of very
  large amounts of data

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Data streams of continuous media

• Different Properties
• Time interval between packets
• Amount of data / size of packets
• Correlation of packets
• Possibly because of compression
• Example Audio- and video transmission

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Strongly periodic data stream

• Time interval between neighbouring packets is
  constant
• Example Voice in a telephone operation system

T
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Weakly periodic data stream

• Time interval between packets follows a function
  of finite period duration
• Example Animation

T1
T2
T3
T1
T2
T
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Aperiodic data stream

• Neither strongly nor weakly periodic
• Example Transmission of events (e.g. Mouse
  interactions)

T1
T2
Tn
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Strongly regular

• Constant amount of data of all packets

D1
Dn
t
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Weakly regular

• Amount of data of packets varies periodicly

D1
D2
D3
T
D1
D2
t
D3
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Not regular

• Amount of data is neither constant nor periodic

D1
D2
D3

t
Dn
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Correlation of successive packets

• Coherent data stream
• Packets are transmitted one after another without
  gaps

t

• Incoherent data stream
• Gaps between the data packets

t
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Units of information

• Medium consists of a sequence of single units of
  information
• PDU protocol data unit
• LDU logical data unit
• Example Logical units of a movie sequence
• Movie, Clip, Frame, Raster, Pixel