Multimedia Technology SMD151 Lecture 1

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Multimedia TechnologySMD151Lecture 1

• Peter Parnes
• peppar_at_sm.luth.se

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Today

• Course information
• Overview of the multimedia area

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Who am I?

• Dr Peter Parnes Assistant Professor
• peppar_at_sm.luth.se
• http//www.cdt.luth.se/peppar/
• http//www.parnes.com/blog/
• 0920/492421
• 070/6614567
• A3307
• E-meeting in the CDT session
• ICQ (4208035)
• Microsoft Instant Messenger (peppar_at_cdt.luth.se)

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Course Goal

• Understanding the area of distributed multimedia
• Media coding
• Real-time communication
• Architectures for distributed multimedia
  applications
• And much much more -)

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Course Overview

• Three major parts
• Lectures
• 8 in total
• Covers material from the book
• Also much additional material will be presented
• Slides available on-line
• Seminars
• ....
• Labs
• ....

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Seminars

• Groups of 3
• Find an interesting subject
• Do a literature study
• Write a scientific report
• Verbal presentation (9 minutes long)
• Subject deadline 030905 12.00
• More info on the course page(http//www.cdt.luth.
  se/peppar/kurs/smd151/)

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Labs

• Groups of 3
• More information from Johan now
• Presented in written reports (on the web) and as
  running applications when applicable
• More information on the web

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Grade

• Final grade
• 25 written exam
• 25 seminars
• 50 labs

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Deadlines!!!

• All parts in the course will have deadlines.
• Honor them and get the grade you deserve.
• Be on time for lectures!!!
• PLEASE!

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E-Mail List

• Join the course e-mail list.
• Announcement, course news, questions etc.
• Do not hesitate to use it for your questions!
• Subscribe smd151-request_at_cdt.luth.se
• Post smd151_at_cdt.luth.se

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The Book

• Loads of text...
• Reading instructions on the course page later...

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Questions?

• Questions now?
• Please ask question at any time in the course!!!!
  
• Protest!! Interact!!
• Send suggestions via email (to the list or
  directly to me).
• Do not be afraid to critique me, I can take it
  -)

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Multimedia ???

• What is multimedia???

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What is Multimedia?

• Multimedia is a very broad area
• Mainly undefined with many different views.
• Multi many
• Media plural of medium middle, center,
  intermediary
• Multiple intermediaries

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The Information Field

• The word multimedia is used in various fields in
  information handling
• Storing and processing in computing
• Production in publishing
• Distribution in mass media
• Transmission in telecommunications
• Presentation in interaction between people and
  systems
• Perception in peoples interaction with outside
  world

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Digital Multimedia

• What is digital multimedia?
• Digital multimedia is the field concerned with
  the computer-controlled integration of text,
  graphics, still and moving images, animation,
  sounds, and any other medium where every type of
  information can be presented, stored and
  processed digitally.
• F. Fluckiger

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Multisensory Systems

• Humans are multisensory.
• Sight, hearing, smell, touch and taste.
• Visual media
• Audio media
• Multimedia Systems
• ! Multisensory Systems

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Multisensory Systems

• Advantages of multisensory systems
• Appear more natural and friendly
• Redundant information more possible
• Complementary information improves memorization
• Emotional information easier to convey

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Classification of Media
Time/space nature
Continuous (time-based)
Animation
Moving Images
Sound
Discrete (space-based)
Still Images
Text
Graphics
Origin
Captured from real-world
Synthesized by computers
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Networked Multimedia

• This course is really about networked
  multimedia.
• Two main categories
• Genuinely networked applications
• Client-Server model based applications

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Example Desktop audio/video
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• Integrating Digital Information

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Multimedia Systems

• Essential characteristics of multimedia systems
• Computer controlled
• Integrated
• Digitally represented information
• Optionally offer interactivity

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Computer Controlled

• Rather obvious
• One or several computers have to be involved in
  the presentation of the information.
• E.g. a CD-player is not a multimedia system.

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Integration

• A multimedia system should handle producing,
  storing, carrying and presenting information in
  an integrated way.
• E.g. Computer Integration
• E.g. Network Integration

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Integration
Presentation integration
Storage integration
CD-ROM
video window
Magnetic Disk
text window
text
Capture integration
Network integration
video camera
Single Network
integrated microphone
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Digital Representation

• What is digitization?
• The transformation from an analog signal to a
  digital signal
• An analog signal varies continuously and is said
  to be analogues to the measured value

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The Digitization Process
sampled signal
analog signal
Sampler
Quantizer Coder
digitized signal
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Conversion
digital signal
analog signal
A/D converter
(011001101 ...)
D/A converter
analog signal
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Why Digital Representation?

• All types of information can be represented as
  bits
• Can be moved over digital networks
• No loss in copy
• Easy to maintain the information error free

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Drawbacks of Digital Rep.

• Distortion
• Might require high bit-rates to transfer
• Fast networks...
• Large storage needed...

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Digital Representation
Memorandum This is a note to inform you that ...
one page formed of digital characters
4 000 bytes
50 000 bytes
Memorandum This is a note to inform you that ...
same printed page scanned and digitized
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Two Modes of Presentation

• Two basic modes of presentation
• Passive or Linear
• TV, movies, radio
• Interactive or Non-linear
• The receiver can modify the presentation
• Time
• Order 4 degrees of customization
• Speed
• Form
• Newspaper, book, computer game

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Examples

• PocketPro
• MPEG4

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Handheld Audio/Video
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MPEG-4 Video
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Questions?

• ?

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Media

• Media definitions
• Media parts
• Text, graphics, images, video, animation and
  sound.
• Might sound trivial but notions needed.
• Most from the human-computer interaction HCI
  world.

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Text
This is an unformatted text also called plain
text. All the characters have the same style and
font and their pitch is the same. Regular human
computer interfaces use plain text. An advantage
is that v e r t i c a l a l i g n m e n t
is easier.

• This is an example of rich text.
• Characters can have different styles and their
  pitch is variable.
• They may also us different fonts.
• They may also respect certain formatting
  rules.

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Graphics vs. Images
Graphics
Images

• graphics are revisable documents
• the document format must retain structural
  information
• the semantic content is preserved in the
  representation
• described as objects

images are not revisable the document format is
unaware of any structural information the
semantic content is not preserved described as
bitmaps formed of individual pixels
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Still Images

• Format bitmap
• Picture elements pixels
• Pixel/Amplitude depth
• 1,8,16,24,32 bpp bits per pixel
• Common formats JPEG, GIF, PNG, TIFF
• Compression of images

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Moving Images

• Movies consists of a series of frames or still
  images
• Frame rates and human perception
• lt10 sequence of still images
• 10-15 jerky effect
• gt15 movie effect
• Formats
• MPEG1,2,4
• AVI, QuickTime (containers)

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Frame Rates

• Movies 24 fps
• TV
• American 30 fps
• European 25 fps
• HDTV 60 fps

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Sound

• Speech vs. Non-speech sounds
• and computers
• Speech coding
• Use computers to communicate with humans
• Speech recognition and understanding
• to computer
• Speech synthesis
• from computer

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Enabling Technologies

• We need some technologies to be able to do
  networked multimedia )
• Computers....
• CPU, RAM, storage space, display etc.

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Central Memory
Memory bus
network
CPU
DMA
Bus Interface
Disk controller
Comm. Interface
Peripheral bus
Audio player
Audio A/D
Video compression
VCR
Display controller
Video A/D
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Transmission

• Terrestrial transmission
• Metallic cables
• Twisted Pair, TP (shielded or unshielded)
• Optical fibers
• Modulated light

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Aerial Transmission

• Surface transmission
• Radio, microwave, IR-light, laser
• Radio up to 200 Mbps
• Radio affordable at 11 to 54 Mbps
• Satellite transmission
• High delay, 100-300 ms

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Base band Transmission

• Apply the signal to be sent directly on the
  cable.
• Only one bit can be sent at one time.

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Synchronous Time Division
fixed time slots dedicated to data from A, B and
C
A
B
C
A
B
C
A
B
C
time
Synchronous Time Division Multiplexing System
Input line A
Input line B
Output line
Input line C
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Asynchronous Time Division
variable time slots allocated to data from A, B
and C
A
B
C
B
C
A
c
C
time
Asynchronous Time Division Multiplexing System

Input line A
Input line B
Output line
Input line C
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Broadband Transmission

• Modulate a carrier signal
• E.g. Change the amplitude of the carrier
• Allows us to send several signals in the same
  wire at the same time.
• We use a
• Modulator-demodulator modem

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Network Topologies

• Full connection
• Star topology
• Tree/Mesh topology
• Routers and switches needed as junctions
• Bus
• Send the signal in both directions to everybody
• Ring

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Bus Topology
station transmitting at a given instant
destination station
flow of transmitted data
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Ring Topology
station transmitting at a given instant
flow of transmitted data
destination station
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Tree structures

• Internet!
• Routers, switches, hubs
• Packets...

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Communication Protocols

• Computers need a predefined language to
  communicate,
• Just like humans!
• Thus, protocols!
• Protocols are layered into stacks
• Suites Internet Protocol, OSI, DNA, SNA

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Packet vs. Circuit switching

• Circuit
• Physical or virtual path created
• Dedicated bandwidth per circuit
• Wastes bandwidth
• Packet
• Chop up data into packets
• Send and forward them when necessary
• Multiplexing

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Connections...

• Connection-oriented
• Create a virtual connection
• The network knows that A and B want to
  communicate
• Connectionless
• Just send data
• Network forwards the data

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L,C,M,W,PAN

• Local Area Network LAN
• Campus Area Network - CAN
• Metropolitan Area Network MAN
• Wide Area Network WAN
• Personal Area Network PAN

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Summary

• Course introduction
• Digital Media and Representation
• Computers
• Communications and Networks

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• Questions?