Introduction to Multimedia Systems - MetaLab

sourcreamdesignerElectronics - Devices

Nov 15, 2013 (3 years and 8 months ago)

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Chapter 01
-

Part II

Introduction To Multimedia

CGMB 234

Multimedia Systems Design

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


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


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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


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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


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.


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


The media are treated in
a
uniform

way,
presented in an
orchestrated

way, but
are possible to
manipulate
independently





Multimedia
Information


What is a Multimedia System?

Classification of Multimedia Systems

Classification of Media Types

Sound

Moving
Images

Still

Images

Text

Graphics

Animation

Synthesized

By computers

Captured

From real
-
world

Continuous

(time
-
based /

temporal)

Discrete

(space
-
based/

spatial)

Time/Space nature

Origin

Types of Multimedia Systems



Individual Computer
-
based Training (CBT)



Individual Computer
-
based Education(CBE)



Multimedia Authoring

a)
Single user networked applications


Digital libraries


Information Kiosks


Web Page


Video on Demand


b)
Multi
-
user networked applications


E
-
mail


Video phone


Video conferencing

Quality of Service (
QoS
)


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


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


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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
)


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
)


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


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2. Delay



The

required

time

for

a

packet

to

travel

from

the

sender

to

the

receiver


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3. Delay

Jitters



variations of the

delay


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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


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Multimedia is Multidisciplinary

Image, audio,
speech
processing

Computer vision,

pattern recognition

Computer

networks,

operating system

Human computer

interaction

Computer

graphics

Multimedia

computing


Multimedia Systems


Multimedia systems involve some basic
enabling techniques:


Multimedia data representation and compression.


Multimedia data processing and analysis.


Transmitting multimedia data through
communication networks.


Multimedia database, indexing and retrieval.