CS代写 CS4551

Multimedia Software Systems CS4551
Introduction to Multimedia
What is Multimedia?
• Whatismultimedia?

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– multi + media
– Multi (multus) : numerous
– Media : means that conveys something such as information
• From wikipedia.org: Multimedia is the use of several different media to convey information (text, audio, graphics, animation, video, and interactivity).
• In our class,
– Multimedia : the use of several different digitized computer media (text,
audio, graphics, animation, video, etc.) to convey information.
CSULA CS451 Multimedia Software Systems by Eun-Young Kang 2

Inherent Properties of Multimedia
• Mixture of different media types
• Digital always
• Voluminous (Multimedia data is huge) • Interactive (data contact human)
• Synchronization
• Real-time
=> Understanding these properties is important to design good multimedia applications.
CSULA CS451 Multimedia Software Systems by Eun-Young Kang 3
Three Processes that are essential to Multimedia Systems
• Multimedia content creation or multimedia authoring
– Theprocessinvolvesdigitizingmedia(audio,images,video)usingcapture devices and assembling/processing them using smart software and hardware.
• Storage and compression
– Theprocessmostlyinvolvesstate-of-the-artcompressionalgorithmsand standards for audio, video, images, and graphics.
• Distribution
– Distribution involves how multimedia content is distributed via various media, such as wired cables, optical networks, satellite, wireless networks, or any combination thereof, to specific platforms ranging from television, computers, personal digital assistants (PDAs), and so on.
CSULA CS451 Multimedia Software Systems by Eun-Young Kang 4

Media Types (Modalities of Multimedia)
• Current Media Types – Text
– Video (Movies, Documentaries, …)
– 2D/3D Graphics (Computer Objects)
– Moving graphics (Games, Animations) – Audio (Speeches, Music, MIDI music)
• Future Media Types?
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• text is a simple media that contains words to express something
This is a line of text to explain that text
does convey information with a hyperlink
• Hypermedia vs. Multimedia
– Hypertext:auserinterfaceparadigmfordisplayingdocumentswhich contain automated cross-references to other documents called hyperlinks.
– Hypermedia : Hyperlinks also referring other than text • Hypermediaisanapplicationofmultimedia.
CSULA CS451 Multimedia Software Systems by Eun-Young Kang 6

• Captured picture or computer generated (synthesized) picture
– In the form of a spatial two dimensional array
– Width and height
– Consists of individual elements called pixels
– Pixel depth (or bit depth) : 1, 2, 4, 8, 16, 24, 30 bits
• No particular structure other than pixel
CSULA CS451 Multimedia Software Systems by Eun-Young Kang 7
Video • How do you describe video?
• Moving images
– Collection of frames
– Frame rates : number of frame displayed per second (fps) – Aspect ratio : ratio of width to height
– Scanning format : interlaced or progressive
– No particular structure other than pixel/frame number
CSULA CS451 Multimedia Software Systems by Eun-Young Kang 8

2D Graphics/3D Graphics
• Computer generated objects
• Vector Graphics, 2D Sprites, etc.
• Contains structure and are revisable (meaning editable)
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• Can be represented by a set of objects and time- dependent directives (programs to be executed at playtime)
• Compactness and revisable
• Requires processing power for the playback
• Can be rendered to a video format (movie)
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• How do you describe audio? – Waveform, structure, …
• Properties
– Sampling rate in hertz : # of samples per second
– Samplesize:numberofbitspersample
– Dimensionality: number of channels (mono or stereo)
– Frequency range or frequency band (narrow band voice vs. wide band music)
• Audio Media is of various kinds – Speech
– Non-speech sound
– MIDI(StructuredAudio)
CSULA CS451 Multimedia Software Systems by Eun-Young Kang 11

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