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LECTURE 8:
DIGITAL VIDEO
TECHNOLOGY
EVI INDRIASARI MANSOR
Email: evi@fsktm.upm.edu.my
Tel ext: 1741
Outline
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Using video
How video works?
Broadcast video standards
Analog video
Digital video
Video recording and tape formats
Video editing technology
Optimizing video files for CD-ROM
Learning Outcomes
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Summarize the implications of using digital video in
multimedia
Illustrate video recording and its relation to multimedia
production
Prepare digital video and images for conversion to
television
Using video
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Video is an excellent for delivering multimedia
Video places the highest performance demand on
computer and its memory and storage
Digital video has replaced analog as the method of
choice for making and delivering video for multimedia
Using video (cont)
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Digital video device produces excellent finished
products at a fraction of the cost of analog
Digital video eliminates the image-degrading analog-todigital conversion
Many digital video sources exist, but getting the rights
can be difficult, time-consuming, and expensive
How video works
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Light reflected from an object through the camera’s lens
is converted into electronic signal by charge-coupled
device (CCD)
This electronic signal contains three channels of color
information and synchronization pulses (sync)
Several video standards exist that deal with the amount
of separation between the components of the signal
How video works (cont)
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Broadcast video standards
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National Television Standards Committee (NTSC):
 These standards define a method for encoding
information into electronic signal that creates a
television picture
 It has screen resolution of 525 horizontal scan lines
and a scan rate of 29.97 frames per second
Broadcast video standards (cont)
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Phase Alternate Line (PAL) and Sequential Color and
Memory (SECAM):
 PAL has a screen resolution of 625 horizontal lines
and a scan rate of 25 frames per second
 SECAM has a screen resolution of 625 horizontal
lines and is a 50 Hz system
 SECAM differs from NTSC and PAL color systems in
its basic technology and broadcast method
Your TV
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Each frame is a single picture
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When played rapidly one after another, it gives the illusion of motion
 Everybody knows that, right?
Take NTSC as an example:
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The overall signal has 525 lines (only 480 are actually visible, the extra 45 gives the
TV time to reset the electronic beam to the top of the screen)
A single frame is ‘painted’ on the screen in an INTERLACED fashion
(line-by-line)
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Firstly: Odd-numbered lines (i.e. 1,3,5, …, 479) – takes ~1/60 seconds
Then: Even-numbered lines (i.e. 2,4,6, …, 480) – takes ~1/60 seconds
You might notice after this seeing 480i (or 525i). This means 480interlaced!  [Later you’ll see 480p? Apa itu?]
BTW, all the above is called Standard Definition TV – Digital TV
format which is 480i
Your TV ... As it gets bigger 
When screens get bigger, scan lines during interlacing
become visible. This produces ‘jaggedies’… No body
likes ‘jaggedies’… (19” vs 60” example)
 Solution: PROGRESSIVE SCANNING!!!
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ALL the lines from 1-480 are ‘painted’ on the screen at just
one single pass!!!
 Feasible with today’s technology since coding and transfer
speeds have dramatically improved
 This called for a new name…  Henceforth – Enhanced
Definition TV was born [more of a marketing gimmick
though… but hey, who really cares?]
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480p, 525p
EDTV’s advantage
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Most TVs cannot handle 480p 
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And what if we’re still getting interlaced signals? Won’t a
progressive scan system be a waste, then?
EDTV can take interlaced signals, and pass them
through a DEINTERLACER/LINE-DOUBLER
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1st: All the odd and even numbered scan lines are combined.
This also improves smoother (‘jaggedies’ are smoothed out)
 525i is converted to 480p here 
 BTW, all of this is also done @ 1/60 second
 2nd: The next 1/60 is used to feed the frame
a second time!
Increases brightness and stability of the frame
 Eliminates or reduces jaggedies, giving a cleaner picture
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HDTV (High Definition TV)
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What HDTV does?
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1. Increases number of scan lines
2. Widens aspect ration from 4:3 to 16:9  (baru la mcm wayang sikit, ye
dok?)
Well.. That’s basically it… Comes with the same variation
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1080i – interlaced. However, since there are so many lines, the
jaggedies aren’t that visible (illusion of better quality!)
1080p – progressive scanning… but, do you really need it? … You
yourself will be the decider (bionic eyes vs. normal human eyes)
Marketing hype however, will tell you otherwise 
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Full HD – max resolution possible (1920X1080)
HD-ready – Meaning ure non-HD TV can be connected to an HD
external box if you want to received HD signals
HD – Takes the full HD signal and resizes it down a bit
HDTV (High Definition TV)
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Alternatively, the 720-lines progressive scan or
720p is also available
 However,
some interlacing artifacts might still be visible
at 1080i
 Therefore, video with rapid motion would not be
suitable at 1080i, and would be nicer to view @ 720p
 For drama swasta (soap operas), 1080i would be nice
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SDTV, EDTV and HDTV side-by-side
The different TV resolutions 
Analog video
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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
Analog video (cont)
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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
Analog video (cont)
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Video color:
 Television sets use composite input. Hence colors are
less pure and less accurate than computers using
RGB component
 NTSC television uses a limited color palette and
restricted luminance (brightness) levels and black
levels.
 Some colors generated by a computer that display
fine on a RGB monitor may be illegal for display on a
NTSC TV.
 While producing a multimedia project, consider
whether it will be played on a RGB
monitor or a conventional television set.
Analog video (cont)
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Interlacing effects:
 In television, the electron beam makes two passes on
the screen while drawing a single video frame
 It first lays down all the odd-numbered lines, and then
all the even-numbered lines, hence they are
interlaced
 While capturing images from a video signal, they can
be filtered through a de-interlacing filter provided by
image-editing applications
Analog video (cont)
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Text and titles for television and taking care of
analog tapes:
 Titles for video productions can be created with an
analog character generator.
 Computers can create titles digitally using video and
image-editing software.
 New tapes should always be fast-forwarded to the
end and then rewound, to ensure even tape tension.
Digital video
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Video clip stored on any mass-storage device can be
played back on a computer’s monitor without special
hardware
Setting up a production environment for making digital
video, requires some hardware specifications
Some specifications include computer with FireWire
connection and cables, fast processor, plenty of RAM,
fast and big hard disk
Digital video (cont)
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Digital video architecture
 Digital video architecture consists of a format for
encoding and playing back video files by a computer
 Architecture includes a player that can recognize and
play files created for that format
Digital video (cont)
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Digital video compression
 Digital video compression schemes or codecs is the
algorithm used to compress (code) a video for
delivery
 The codec then decodes the compressed video in
real-time for fast playback
 Streaming audio and video starts playback as soon as
enough data has transferred to the user’s computer
to sustain this playback
Digital video (cont)
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Digital video compression (cont)
 MPEG is a real-time video compression algorithm
 MPEG-4 includes numerous multimedia capabilities
and is a preferred standard
 MPEG-7 (or Multimedia Content Description Interface)
integrates information about motion video elements
with their use [NOT A COMPRESSION STANDARD]
Digital video (cont)
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Digital video compression (cont)
 The video compression/decompression programs are
used so that video can fit on a single CD and the
speed of transferring video from a CD to the computer
can be increased
 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 second
 To overcome large video size, CODECS were
developed
Digital video (cont)
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Digital video compression (cont)
Compresses when
saved
CODEC
File format used such
as: Avi, Mpeg, Mov
Decompresses when
needed for display
Digital video (cont)
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Digital video compression (cont)
 Digital video compression schemes or codecs is the
algorithm used to compress (code) a video for
delivery
 The codec then decodes the compressed video in
real-time for fast playback
 Streaming audio and video starts playback as soon as
enough data has transferred to the user’s computer
to sustain this playback
FULL
VIDEO
Taken from the CD
into memory buffer
MEMORY BUFFER
DISPLAY ON
SCREEN
Digital video (cont)
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Digital video compression (cont)
 Two types of COMPRESSION:
 Lossless compression
 preserves the exact image throughout the
compression and decompression process
 e.g.,: text images is to identify repeating words
and assign them a code
Digital video (cont)
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Digital video compression (cont)
 Lossy compression
 Eliminates some of the data in the image and
therefore provides greater compression ratios than
lossless compression
 Applied to video because some drop in the quality is
not noticeable in moving images
Digital video (cont)
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Digital video compression (cont)
 Two types of CODEC (lossy):
 Spatial compression
 Digital
compression of video data that
compresses the size of the video file by
compressing the image data of each frame
 Compression is done by removing redundancy
from data in the same frame
Digital video (cont)
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Digital video compression (cont)
 Temporal compression
 Digital compression of video data that uses
similarities of sequential frames over time to
determine and store only the image data that
differs from frame to frame
 Compression is done
by removing similarity
between successive
video frames
Digital video (cont)
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Digital video compression (cont)
 Flavors of file formats brand to choose:
 Microsoft’s AVI format
 QuickTime
 MPEG
 Div-X
 Wmv (Windows Media Video)
Digital video (cont)
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Digital video compression (cont)
 Standards have been established for compression
programs, including
 JPEG (Joint Photographic Experts Group) and
 MPEG (Motion Picture Experts Group)
Digital video (cont)
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Digital video compression (cont)
 JPEG (spatial)
 Often areas of an image (especially backgrounds)
contain similar information
 JPEG compression identifies these area and stores
them as blocks of pixels instead of pixel by pixel
reducing the amount of information needed to store
the image
 These program reduce the file size of graphic
images by eliminating redundant information
Digital video (cont)
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Digital video (cont)
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Digital video compression (cont)
 MPEG (temporal)
 The changes in the image from frame to frame
 Key frames are identified every few frames the
changes that occur from key frame
 Provide greater compression ratios than JPEG
 Initially, it requires extra hardware for multimedia
Digital video (cont)
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Digital video compression (cont)
 MPEG (temporal) – (cont)
 MPEG – real-time video compression algorithm
 MPEG-4 includes numerous multimedia capabilities
and is a preferred standard
 MPEG-7 (or Multimedia
Content Description
Interface) integrates
information about
motion video elements
with their use
MPEG compression
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On how MPEG compression works, please view
these videos
http://www.youtube.com/watch?v=kyztYavfFMs
 http://www.youtube.com/watch?v=P7abyWT4dss
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Skip the technical (maths) parts in the second video,
instead focus on the concept of how things are done

Video recording and tape formats
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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
Video recording and tape formats (cont)
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File size and formats (cont)
 Frame Rate
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animation is an illusion caused by the rapid
display of still images.
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television and movies play at 30 fps but
acceptable playback can be achieved with 15 fps
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[Show VirtualDub Example]
Video recording and tape formats (cont)
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File size and formats (cont)
 Image Size
 A standard full screen resolution is 640x480 pixels
but to safe storing space a video with 320x240 for a
computer display is still acceptable
 New high-definition televisions (HDTV) are capable
of resolutions up to 1920×1080 , p60,
 1920 pixels per scan line by 1080 scan lines,
progressive, at 60 frames per second
Digital video (cont)
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Video recording and tape formats (cont)
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File size and formats (cont)
 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
Video recording and tape formats (cont)
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File size and formats (cont)
 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
24 bit
16 bit
8 bit (256 colors)
Video Compression
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Digitizing full-motion video in the computer requires transfer of ENORMOUS
amounts of data in a short period of time 
•
Consider this:
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Frame rate = 25 fps (FR)
Color depth of each frame = 65,536 colors (thus a bit depth of 16-bits) (BD)
Frame size = 320 X 240 pixel dimension (D)
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FORMULA FOR VIDEO SIZE (per second) = FR X BD X D
For this particular video… the UNCOMPRESSED video would be:
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25 X 16 X (320 X 240)
30,720,000 bits / second
3.67 Mbytes / second
This is just for 1-SECOND!!! And we’re not even talking about AUDIO yet 
A 1-hour video would thus be  3.67 X 60 X 60 = 13,212 Mbytes
Which is equals to = 12.9 Gigabytes  … Now… try fitting that onto a CD 
Video Compression
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A simpler example with less big numbers
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Consider this:
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Frame rate = 2 fps … meaning, in every second of the video, TWO pictures are
being displayed continuously (FR)
Color depth of each frame = 4 colors (thus a bit depth of 2-bits) … meaning that
each frame of the video has a maximum of 4 colors (BD)
Frame size = 320 X 240 pixel dimension … each frame’s size (D)
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FORMULA FOR VIDEO SIZE (per second) = FR X BD X D
For this particular video… the UNCOMPRESSED video would be:
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2 X 4 X (320 X 240)
614,400 bits / second
0.073 Mbytes / second  614,400 / 8 / 1024 / 1024
As you can see… this rate is very2 acceptable due to the small data rate 
BUT! Your video is going to be very2 UN-colorful :P If there exists such a word…
Not to mention it being very2 flicker-y…
Video about compression
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•
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The basics of Video Compression
MPEG video
Codecs and Containers (formats) – 1
Codecs and Containers (formats) – 2
Video editing technology
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Linear
 It plays end to end in one direction, usually pertains to
videotape editing specifically the editing of linear tape
segments into one final master tape
Video editing technology (cont)
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Non-Linear
 Refers to the editing of disk-based digital video.
 The software provides an on screen map of what the
final video sequences should look like incorporating
the edits, splices, special effects, transitions and
sound tracks.
Video editing technology (cont)
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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
Video editing technology (cont)
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Special effects (cont)
 Superimposing
 The ability to superimpose one clip over another is a
valuable technique
 The technique of green screening is identical except
that the color green is used for the screen and later
digitally removed
 The blue screen and
green screen superimposing
are just two of the superimposing
technique available
Video editing technology
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Superimposing
Video editing technology (cont)
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Video digitizing
 Digital video is often used to capture content from
movies and television to be used in multimedia
 A video source (video camera ,VCR, TV or videodisc)
is connected to a video capture card in a computer
 As the video source is played, the analog signal is
sent to the video card and converted into a digital file
(including sound from the video)
Video editing technology (cont)
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Video digitizing (cont)
http://alfiantroxion.blogspot.com/2010/06/tv-capture-card-101-macammana-nak.html
VCR
Video Overlay Board
/
Video Capture Card
PC
Video editing technology (cont)
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Video digitizing (cont)
Analogue signal from VCR
Converted to DIGITAL
by VIDEO CAPTURE CARD
The converted signal
is
entered inside a
computer
Signal is processed
Video is edited
using video editing
software software
Video editing technology (cont)
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Video editing software
 Incorporating transitions such as dissolves, wipes and
spin
 Superimposing titles and animating them, such as flyin 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
Advantage of using video
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Captures interest
Increase retention
Clarifies complex physical actions and relationships
Can incorporate other media
Disadvantage of using video
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Is expensive to produce
Requires extensive memory and storage
Requires special equipment
Does not effectively illustrate abstract concepts and
static situations
Shooting and editing video
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Import video and sound at the highest resolution and
with the least amount of compression possible
Resolution should be reduced and footage must be
compressed later according to the requirements
A steady shooting platform should always be used
Shooting and editing video (cont)
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Good and even lighting is extremely important
Blue screen in digital video editing applications is a
popular technique for making multimedia
Wide panoramic shots and camera motion should be
avoided when shooting for a small computer window on
CD-ROM or the Web
Optimizing video files for CD-ROM
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CD-ROMs provide an excellent distribution medium for
computer-based video
When preparing video for CD-ROM distribution,
interleave the audio track(s) with the video track
Key frames should be used every 10 to 15 frames and
the size of the video window must be kept small
The Sorenson codec is optimized for CD-ROM playback
Summary
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Digital video method is used for making and delivering
video for multimedia
Compression techniques help to reduce the file sizes to
more manageable levels
Two types of compression lossless and lossy
Standards for compression program are JPEG and
MPEG