VideoPertemuan 7

Matakuliah : O0414 - Computer / Multimedia

Tahun : Feb - 2010

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Learning Outcomes

Pada akhir pertemuan ini, diharapkan mahasiswa akan

mampu :• Menerapkan Penggunaan Video pada Aplikasi

Multimedia

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Outline Materi• Different Kind of Movies• Analogue Video• Digital Video• Compression Technique• Broadcast Video Standards• Digital Video Format• Using Digital Video

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Different Kind of Movies

Movies from Film

Analog Video

Digital Video

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Movie From Film

• Sequential image frames are recorded on film using a light sensitive technology similar to still photography.

• Film must be chemically developed

Movie From Film

• Editing requires physically cutting and splicing the film

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Analogue video• Video information that is stored using television video signals, film,

videotape or other non-computer media

• Each frame is represented by a fluctuating voltage signal known as an analogue wave form or composite video.

• Composite analogue video has all the video components: brightness, colour and synchronization

• Then, combined into one signal for delivery

• Usage : television

• Problems: colour blending, low clarity, high generation lost, difficult to edit

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Digital Video

• Digital video is the digitisation of analogue video signals into numerical format

• It creates the illusion of full motion by displaying a rapid sequence of changing images on a display device.

• Conversion from analogue to digital format requires the use on an ADC (Analogue to Digital Converter)

• A Digital to Analogue Converter (DAC) can be used to output digital video on analogue equipment

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File Size Considerations• Frame rate

– Number of images displayed within a specified amount of time to convey a sense of motion

– Usually measured in frames per second– Standard video movie 30 fps– Movie film 24 fps– Video digital at least 15 fps

– Computer?

File Size Considerations• Frame or Image size

– The width and height of each individual frame or image

– Determines the quality of the image displayed and the processing involved to display that image

– Standard full screen resolution is 640x480 pixels

– Video screen display is one fourth the size of the full window screen (320x240)

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File Size Considerations• Color depth/Resolution

– Number of colors displayed on the screen at one time– Ranging from 1 bit to 8 bit, 16 or 24 bit per pixel

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File Size Considerations• Quality directly related to frame size and color depth.

• Quality also depends on content. Motion picture needs higher frame rate

• File size depends on quality and duration

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Compression techniques• Since the size of raw digital video is so prohibitively large we need some

means to compress the information

• Video compression and decompression program, known as Codecs

• Lossy compression techniques cause some information to be lost from the original image

– Redundant information – Example: Image and video

• JPEG and MPEG• Intraframe and Interframe

• Lossless compression techniques do not lose information throughout the compression and decompression process

– Example use in text images• Exactly same before and after compression• Technique is identify repeating words and assign them a code.• Decompression, the code would be changed back to the actual word.

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Analog video editing

• Analogue tape editing is a linear process– To find the section you want, you

may have to forward or rewind the video tape

– To move a section to another place in the sequence you have to either re-record the section onto another tape or physically cut and splice the video tape

Digital video editing• Digital video editing can be non-linear process

– You can move sections around inside the computer and play those sections back in any order

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Interlaced video

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Broadcast Video Standards

• NTSC– North America, South

America, Japan– 525 interlaced resolution lines– 30 frames per second (fps)

• PAL (Phase Alternate Line)– Australia, South Africa,

Europe– 625 interlaced resolution lines– 25 frames per second (fps)

• SECAM– France, Russia– 625 interlaced resolution

lines– 25 frames per second (fps)

• HDTV– Six different formats– Aspect ratio is 16:9

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Overscan

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Digital Video File Formats• .MOV signifies Quicktime, an Apple standard. It is

playable on Macintosh and Windows machines. • .AVI is a Microsoft standard that is playable on Windows

and Macintosh machines.• .MPEG (.MPG) is playable on Unix and Windows

machines. Macintoshes can play MPEG, but may have trouble with the audio track.

• .RM files are used by RealNetworks streaming. They are playable on Windows, MacOS, and Unix computers.

• .WMV files are a Microsoft format used in Microsoft MovieMaker

• .FLV files are popular format used to deliver video on internet using Adobe Flash Player

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How Video can be used effectively• Showing physical procedures. Some uses are:

– Installing a board in a PC

– Adjusting engine timing

• Attracting and holding attention. Some uses are:– Advertising products and services

– Teaching new skills to busy employees

• Presenting scenarios. Some uses are:– Training technicians to respond to equipment malfunctions

– Demonstrating possible uses for a product

• Analyzing motion . Some uses are:– Body motion to improve athletic performance

– Traffic patterns for transportation planning

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Advantages and Disadvantages of using video

• Carefully planned, well-executed video clips can make a dramatic difference in a multimedia project

• Use video only when all other methods (text, still images) are not enough; don’t use it just because it’s possible

• Video adds visual impact to multimedia applications:– Advantages

• Captures interest• Increase retention• Clarifies complex physical actions and relationships• Can incorporate other media

– Disadvantages• Is expensive to produce• Requires extensive memory and storage• Requires special equipment• Does not effectively illustrate abstract concepts and static situations