Transcript Introduction to Multimedia Systems

CGMB 234
Multimedia Systems Design
Chapter 01- Part II
Introduction To Multimedia
Objectives
At the end of this chapter, students should be able to:
 state the FOUR (4) characteristics of multimedia system
 Describe the THREE (3) levels of interactivity
 Classify media according to its types
 Identify the characteristics of multimedia data
 Explain the concept of QoS(Quality of Service) for
multimedia systems
 Identify the FOUR (4) parameters of QoS for multimedia
systems
Multimedia Systems
Multimedia System Characteristics
Digital Format for Multimedia Systems
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A MM system can reproduce, transmit or Copy
its data indefinitely without introducing loss of
data quality
 Loss
is only during conversion from analog to digital
 The same mechanism can be used to store, edit,
send or retrieve different types of data
 Digital data usually take up a lot of storage space
 Digital data consume a lot more bandwidth during
transmission than analog data
Interactivity in Multimedia Systems
Low Level  NAVIGATION
 This
level of interaction focuses on fundamental task
of navigating through the information space, either via
commands, menus, search engines, or hypertext
links.
 The search engine and the hypertext link are the most
sophisticated forms of navigational interactivity.
 However, even in its most sophisticated form it still
limits the user's control to only what they get to
access next.
Medium Level  FUNCTIONAL
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user interacts with the system to accomplish a goal or set of
goals.
That goal may be winning, as in the case of a game, or ordering
a product, as in the case of an online catalog.
Throughout the interaction, the user receives feedback on their
progress, or lack thereof, towards the goal(s).
The user becomes part of a strong feedback loop.
WEB-based applications incorporating functional interactivity are
appearing in ever-increasing numbers.
These range from games to online ordering, and will become
even more common in the future.
High Level - ADAPTIVE
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This is the highest level of interactivity, while the boundary between
functional and adaptive interactivity is blurred, there is a key
difference.
Adaptive interactivity offers a far higher level of creative control to
the user, allowing the user to adapt the application or information
space to fit their goals, or even their personality.
I.e. Websites a higher levels adaptive sites allow users to add or
modify the site itself.
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At this level the distinction between author and reader becomes blurred.
 intelligent hyper adaptive site interacts with the user and adapts itself to fit the
user, readapting as the user's goals, knowledge, or mindset change.
 such a site will thoroughly engage the user, evolving as the user evolves; even
acting as a mentor to the user
Integration in Multimedia System
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The media are treated in
a uniform way,
presented in an
orchestrated way, but
are possible to
manipulate
independently
What is a Multimedia System?
Multimedia
Information
Classification of Multimedia Systems
Classification of Media Types
Time/Space nature
Continuous
(time-based /
temporal)
Discrete
(space-based/
spatial)
Sound
Moving
Images
Still
Images
Animation
Text
Graphics
Origin
Captured
From real-world
Synthesized
By computers
Types of Multimedia Systems
a)
Single user networked applications
•
Digital libraries
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Information Kiosks
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Web Page
•
Video on Demand
b)
Multi-user networked applications
•
E-mail
•
Video phone
•
Video conferencing
•Individual Computer-based Training (CBT)
•Individual Computer-based Education(CBE)
•Multimedia Authoring
Quality of Service (QoS)
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When we deploy multimedia systems over the
internet/network, users are often frustrated by the slow
speeds or by the low quality
Internet = “Best Effort” approach
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No guarantee when the data will be delivered
No guarantee that data will arrive in the same order as they left
the source
Or even that they will be delivered at all!
This does not meet the requirements of multimedia data
very well !!!

Multimedia data, especially audio and video, have FOUR (4)
characteristics
Characteristics of MM Data
Characteristics
Descriptions
Comparisons
1. Time Critical
A continuous stream of data is
required, at a very high rate
100kbps – 1 Gbps
An email can travel at any speed without
affecting the quality of the email
2. Synchronisation
Some temporal constraints on
the arrival of different data types
-i.e audio data has to be sync
with lip motion
Email can have different data types. i.e
images
• It does not matter if the data for the
images arrive at the POP server a little bit
later than the email
3. Order of Arrival
Data can arrive out of order, but
only to a certain extent
Traditional internet services such as email
imposes no constraints at all on the
sequence of data arrival, as long as all the
data arrive safely
4. Tolerance to
Error
Data can be lost without
significantly affecting the quality
up to a certain extent
Traditional internet services such as email
have no tolerance to error
An email msg that misses out 1 byte of
data is regarded as corrupted
Quality of Service (QoS)
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As we can see, there is a severe mismatch between the requirements of
multimedia data and the “best effort” approach of the Internet  new
Paradigm must be adopted
If we have unlimited resources, the simplest solution is to upgrade the
performance of all components in the infrastructure so the infrastructure can
meet the peak demand  BUT this is EXPENSIVE, sometime
IMMPOSSIBLE
Thus, Quality of Service (QoS) is proposed
Quality of Service
The approach of handling data differently, depending on the nature
and requirements, instead of blindly applying the “best effort’
approach to all types of data indiscriminately
Quality of Service (QoS)
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QoS does not create bandwidth, but uses the available bandwidth
more intelligently
i.e. you can choose between surface mail, airmail or speed post to
deliver you letter, depending on how urgent it is.
The Post Office handles these three types of letter differently,
depending on how much you paid..
QoS can be categorized into four different parameters as described
in the following table
Four Parameters of QoS
Parameters
Descriptions
1. Bandwidth
• Required bandwidth to carry the data stream to support the service
• Not only limited by the infrastructure carrying the traffic, but also by other
applications sharing the same resources
2. Delay
• The required time for a packet to travel from the sender to the receiver
• The longer the delay is, the slower the apparent response of the system
• i.e. when user presses the start button on a VOD system, it may take a long time
for the video to come though
3. Delay
Jitters
• variations of the delay
• Jitter certainly has an adverse effect on applications that require a constant stream
of data
• Solution  maintain a buffer of data, but too large buffer is not acceptable for
applications such as videophone
4. Reliability
• Error rate of the transmission system
• we do not need very reliable transmission for audio or video data
•If its lost, it may not make sense to re-send it because it is not needed by the
receiver after a certain amount of time.
•Resending simply increases the load of the sender and the network, and without
improving the perceived quality of the data
Multimedia is Multidisciplinary
Computer
networks,
operating system
Image, audio,
speech
processing
Human computer
interaction
Multimedia
computing
Computer vision,
pattern recognition
Computer
graphics
Multimedia Systems
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Multimedia systems involve some basic
enabling techniques:
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Multimedia data representation and compression.
• Multimedia data processing and analysis.
• Transmitting multimedia data through
communication networks.
• Multimedia database, indexing and retrieval.