lecture #2: introduction to multimedia computing ...introduction to multimedia computing &...

Lecture #2:Lecture #2:

Introduction to Multimedia Introduction to Multimedia Computing & CommunicationComputing & Communication

Lecturer: Lecturer: Abdusy SyarifAbdusy Syarif

Undergraduate CourseUndergraduate CourseInformatic Engineering Dept.Informatic Engineering Dept.

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IntroductionIntroduction

WHAT ARE WHAT ARE MULTIMEDIA MULTIMEDIA

COMPUTING AND COMPUTING AND COMMUNICATIONS ?COMMUNICATIONS ?

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Search for Multimedia resourceSearch for Multimedia resource

Search EngineSearch Engine➢ Google: Approximately 150 million Google: Approximately 150 million

searches per day ( per Google’s web searches per day ( per Google’s web site)site)

➢ Inktomi :Approximately 80 million Inktomi :Approximately 80 million searches per day (per searches per day (per SearchEngineWatch.comSearchEngineWatch.com))

➢ AltaVista : Approximately 50 million AltaVista : Approximately 50 million searches per day (per searches per day (per SearchEngineWatch.comSearchEngineWatch.com))

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Search for Multimedia resource (Con’t)Search for Multimedia resource (Con’t)

Search Engine (con’t)Search Engine (con’t)➢ Direct Hit : Aapproximately 20 million Direct Hit : Aapproximately 20 million

searches per day (per searches per day (per SearchEngineWatch.comSearchEngineWatch.com))

➢ FAST :Approximately 12 million FAST :Approximately 12 million searches per day (per searches per day (per SearchEngineWatch.comSearchEngineWatch.com))

➢ Galaxy: Approximately 100,000 visitors Galaxy: Approximately 100,000 visitors per day (per Galaxy’s web site)per day (per Galaxy’s web site)

Search Key Word, Search Option, File Search Key Word, Search Option, File typetype

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MediaMedia

Media Media refer to the types of refer to the types of information or types of information or types of information carriers, such as information carriers, such as alphanumeric data, images, alphanumeric data, images, audio, and video. audio, and video.

Common classifications of Common classifications of Media are based on Media are based on physical physical formatsformats and and media media relationships with time.relationships with time.

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Media ClassesMedia Classes

There are two classes of There are two classes of media: media:

1. Static 1. Static do not have a time dimension their contents and meanings do not

depend on the presentation time. Static media include alphanumeric

data, graphics, and still images.

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Media ClassesMedia Classes

2. D2. Dynamic (or time ynamic (or time continuous)continuous) have a time dimension, the meanings and correctness

depend on the rate at which they are presented.

these media include animation, audio, and video (which have their intrinsic unit interval or rate).

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Example:Example:

• To have a perceptually smooth movement, video must be played back at 25 frames (or 30 frames, depending on the video system used) per second.

• Similarly, when we play back a recorded voice message or music, only one playback rate is natural or sensible. Playback at a slower or faster rate distorts the meaning or the quality of the sound.

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Media ClassesMedia Classes

Because the media must be played back continuously at a fixed rate, they are often called continuous media.

They are also called isochronous media because of the fixed relationship between each media unit and time.

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DefinitionDefinition

So what is the definition So what is the definition for for multimedia systemsmultimedia systems ? ?

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DefinitionDefinition

SystemsSystems which are capable of which are capable of handling at least one type of handling at least one type of continuous media in digital formcontinuous media in digital form as well as static mediaas well as static media

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Multimedia System functionsMultimedia System functions

Common Functions:Common Functions:• CapturingCapturing• TransmissionTransmission• PresentationPresentation• GenerateGenerate• StoreStore• SearchingSearching• RetrievalRetrieval• ProcessProcess• RecognitionRecognition• EnhancementEnhancement

MultimediaMultimediaInformationInformation

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Multimedia System aspects Multimedia System aspects

2 common aspects:2 common aspects:• CapturingCapturing• TransmissionTransmission• PresentationPresentation• GenerateGenerate• StoreStore• SearchingSearching• RetrievalRetrieval• ProcessProcess• RecognitionRecognition• EnhancementEnhancement

Communication Communication aspectaspect

ComputingComputingaspectaspect

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Example:Example:

Compression ?Compression ?

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Digital RepresentationDigital Representation

Why Digital Why Digital Representations ?Representations ?

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Advantages of Digital FormAdvantages of Digital Form

computer systems only handle digital data

can easily be integrated with other data types

can share the common computing resources and networks

it is easier to interact with digital media by using a computer system

easier to be secured

more reliable (ie: error tolerance to noise)

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ExampleExample

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MotivationMotivation

• to improve the transfer of information by involving the participant’s simultaneous use of two or more senses.

• to emulate human communications and to assist the human being in organizing and managing vast amounts of information in various media types.

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ApplicationApplication

Video/Movie on DemandVideo/Movie on Demand Information on DemandInformation on Demand EducationEducation TelemedicineTelemedicine Videophone and VideoconferenceVideophone and Videoconference Cooperative WorkCooperative Work

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Video on DemandVideo on Demand

•Currently, we watch TV programs and movies passively: we cannot interact with the programs and cannot control the time we want to watch them.

•Video/movie on demand services are being developed to overcome these limitations and provide other capabilities.

•In VOD, large collections of video are stored on video servers. Users or clients access these videos through a network.

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Distinct features of VOD are: We do not have to leave home to watch our favorite video. Our “advanced

television” is connected to video servers through an advanced network. All we need to do is to dial a number and select the video through a user-friendly menu on the TV screen.

Because video servers are centralized and provide services to a large population, their collections are large and updated. If one video server does not have the video we want, it may refer us to some other servers that likely hold the video. In theory, we can watch what we want without leaving home. Further, many users can view the same video without users’ knowing. So there will be no such problem as “Sorry, the video is out.”

We can watch our favorite video or movies anytime we want. We can pause and fast-forward and -backward. We may also be able to

search for a particular scene. We have guaranteed high quality because video is stored in digital form.

The quality will not degrade with increased viewings.

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Information on DemandInformation on Demand

A similar system to VOD.

The major difference is that IOD stores other types of information as well as video.

IOD systems have many applications, including:

•Acting as a general encyclopedia of general information;

•Providing newspaper and magazine online services;

•Providing home shopping service—one can view the product and service on the screen and order goods and services without leaving home;

•Providing current information on weather, public transport time tables, and the like on-line.

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Classes of Multimedia SystemClasses of Multimedia System

Multimedia systems Multimedia systems can be classified into can be classified into standalonestandalone and and distributed systemsdistributed systems

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Distributed Multimedia SystemDistributed Multimedia System

Four basic classes/services (ITU):

✔Conversational services

✔Messaging services

✔Retrieval services

✔Distribution services

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1. 1. Conversational Conversational SServiceservices

• imply interaction between a human user and another human user or a system.

• includes interpersonal services such as videoconference and videophony.

• also includes services such as tele-surveillance and tele-shopping.

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2. Messaging 2. Messaging SServiceservices

Messaging services cover the non-real-time or asynchronous exchange of multimedia data through electronic mailboxes.

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3. Retrieval 3. Retrieval SServiceservices

• cover all types of access to multimedia information servers.

• typically, the user sends a request to the server and the requested information is delivered to the user in real time.

• VoD is an example of these services.

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4. Distribution services4. Distribution services

• cover services where the information is distributed on the initiative of a server

• An example of these services is TV program broadcast

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ChallengesChallenges

Multimedia data have a time dimension

Multimedia applications normally use multiple related media simultaneously

Multimedia data are data intensive

Multimedia data do not have obvious syntax and semantics

Need QoS guarantees

Efficiently used of system resources

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Central IssueCentral Issue

So, tSo, the central design issue he central design issue of multimediaof multimedia systemsystems:s:

““HHow to provide QoS ow to provide QoS guarantees to applications guarantees to applications

while using system while using system resourcesresources efficientlyefficiently..”..”

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Any Questions / Comments ?Any Questions / Comments ?

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THE ENDTHE END