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8/13/2019 Lesson8 Video
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Fundamental Concepts in Video
Lecturer
Dr. Aree Ali Mohammed
2012-20134thStage
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Overview
What is digital video?
Video concepts
Analogue Video
Digital Video
File Size and Formats
Video Special Effects
Video Compression
Video H/S
Video Advantages and Disadvantages
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What is Digital Video?
Digital video refers to the capturing, manipulation, and storage ofmoving images that can be displaced on computer screens.
This requires that the moving images be digitally handled by the
computer. The word digital refers to a system based on discontinuousevents, as opposed to analog, a continuous event.
Computers are digital systems; they do not process images the way thehuman eye does.
Advantages of Digital Video Ease of manipulation
Preservation of data
Internet (easy to store, retrieve, and publish)
Compression
Embedding in a web page
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Video Concept Video is an excellent tool for delivering multimedia.
Video places the highest performance demand on computer and itsmemory and storage.
Digital video has replaced analog video as the method of choice formaking and delivering video for multimedia.
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Digital video device produces excellent finished products at a fraction ofthe cost of analog.
Digital video eliminates the image-degrading analog-to-digital
conversion. Many digital video sources exist, but getting the rights can be difficult,
time-consuming, and expensive.
Video Concept
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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 knownas an analogue wave form or composite video.
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Analogue Video
Composite analogue video has all the video components:
brightness, colour and synchronization
Then combined into one signal for delivery
Example : traditional television Problems: colour blending, low clarity, high generation lost,
difficult to edit.
DIGITAL ANALOGUE
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Digitizing Video
Digital video combines features of graphics and audio to createdynamic content for multimedia products.
Video is simply moving pictures.
Digitized video can be edited more easily. Digitized video files can be extremely large.
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Digitizing Video
Digital video is often used to capture content from movies andtelevision to be used in multimedia.
A video source (video camera ,VCR, TV or videodisc) is connectedto a video capture card in a computer.
As the video source is played, the analog signal is sent to the videocard and converted into a digital file (including sound from thevideo).
VCR
Video Overlay BoardVideo Capture CardPC
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Analogue signal from VCRConverted to DIGITALby VIDEO CAPTURE CARD
The convertedsignal isentered inside acomputer
Signal is processedVideo is editedusing video editing
software software
Digitizing Video
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Digital Video
Digital video is the digitisation of analogue video signals into numericalformat
It creates the illusion of full motion by displaying a rapid sequence ofchanging 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 and Formats
There is an important consideration:
file size in digitized video which included
1. frame rate
2. image size
3. color depth.
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File Size and Formats
1. Frame Rate
animation is an illusion caused by the rapid display ofstill images.
television and movies play at 30 fps but acceptableplayback can be achieved with 15 fps.
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File Size and Formats
2. Image Size
A standard full screen resolution is 640x480 pixels but to safe storingspace a video with 320x240 for a computer display is still acceptable.
New high-definition televisions (HDTV) are capable of resolutions upto 19201080p60,
1920 pixels per scan line by 1080 scan lines, progressive, at 60frames per second.
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File Size and Formats
3. Color Depth
The quality of video is dependent on the color quality(related to the number of colors) for each bitmap in the
frame sequence.
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3. Color Depth
The color depth below 256 colors is poorer-quality image.
The frame rate to below 15 fps causes a noticeable and
distracting jerkiness that unacceptable. Changing the image size and compressing the file
therefore become primary ways of reducing file size.
File Size and Formats
24 bit 8 bit (256 colors)16 bit
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Special Effects
Transitions Such as fading, wiping, splatters, scrolling, stipple and many
more are available by simply dragging and dropping that
transition between the two video clips.
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Special Effects
Superimposing The ability to superimpose one clip over another is a valuable
technique.
The technique of green screening is identical except that the colorgreen is used for the screen and later digitally removed.
The blue screen and green screen superimposing are just two of thesuperimposing technique available.
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Video Compression
The video compression/decompression programs are used so that video can fit on asingle CD and the speed of transferring video from a CD to the computer can beincreased.
Let us say that a sequence of 25fps video is about 25MB.
CD-ROM transfer rate is calculated as follows: 1X= 150KB per second
10X=1.5 MB per second
100X= 15 MB per secondt
To overcome large video size, CODECS were developed.
Compresseswhen saved
CODEC
File format usedsuch as: Avi,
Mpeg, MovDecompresses
when needed fordisplay
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Video Hardware and Software
VCR
Video Overlay Board /
Video Capture Card
Video digital
Editing Software
MULTIMEDIA PC
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Video Editing Software
Incorporating transitions such as dissolves, wipes and spin.
Superimposing titles and animating them, such as fly-in logo.
Applying special effects to various images, such as twisting, zooming,
rotating and distorting. Synchronizing sound with the video.
Apply filters that control color balance, brightness & contrast, blurring,distortions and morphing.
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Advantages of using Video
Captures interest
Increase retention Clarifies complex physical actions and relationships
Can incorporate other media
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Disadvantages of using Video
Is expensive to produce
Requires extensive memory and storage
Requires special equipment
Does not effectively illustrate abstract concepts andstatic situations
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Summary
Digital video method is used for making anddelivering video for multimedia.
Compression techniques help to reduce the file sizesto more manageable levels
Two types of compression lossless and lossy.
Standards for compression program are JPEG andMPEG.
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Group Discussion