19ECE01 - MULTIMEDIA COMPRESSION
AND COMMUNICATION
Dr. I.S.AKILA
Associate Professor
Department of ECE
Coimbatore Institute of Technology
Syllabus
COURSE OUTCOMES
Upon completion of this course the students will be able to demonstrate an ability to
CO1 : Illustrate various multimedia components and its characteristics.
CO2 : Determine the average length of text and image by various compression techniques, and
calculate the compression ratio.
CO3 : Interpret the various techniques for audio and video compression.
CO4 : Illustrate the network architecture and various communication protocols for VoIP. Identify
the challenges and key factors to improve the performance and QoS parameters of VoIP.
CO5 : Analyze the various multimedia networking protocols to provide the best effort service for
Real time interactive multimedia application.
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
2
Syllabus
MULTIMEDIA COMPONENTS
• Introduction - Multimedia skills - Multimedia components and their characteristics text, sound, images, graphics, animation, video, hardware.
(9)
TEXT AND IMAGE COMPRESSION
• Compression principles-Source encoders and destination encoders-Lossless and
lossy compression-Entropy encoding –Source encoding- Text compression -Static
Huffman coding , Dynamic Huffman coding - Arithmetic coding - Lempel Ziv-Welsh
Compression- Image compression - Graphics interchange formate - Tagged image
file format – JPEG
(9)
AUDIO AND VIDEO COMPRESSION
• Audio compression-DPCM-Adaptive DPCM -Adaptive Predictive Coding-Linear
Predictive Coding-Code Excited LPC- Perceptual coding - Video compression
principles-H.261, H.263, MPEG 1, 2, 4.
(9)
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Syllabus
VoIP TECHNOLOGY
• Basics of IP transport, VoIP challenges, H.323/ SIP -Network Architecture,
Protocols, Call establishment and release, VoIP and SS7, Quality of Service CODEC Methods-VOIP applicability. (9)
MULTIMEDIA NETWORKING
• Multimedia networking- Applications- Streamed stored and audio-making - Best
Effort service-Protocols for real time interactive applications- Distributing
multimedia- Beyond best effort service- Secluding and policing MechanismsIntegrated services, Differentiated Services-RSVP. (9)
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Syllabus
TEXT BOOKS
1. Fred Halshall,"Multimedia communication-Applications, Networks, Protocols and Standards",
Pearson Education, 2013.
2. Tay Vaughan, "Multideai: Making It Work", 7/e, TMH, 2007.
REFERENCES
1. Kurose and W. Ross, "Computer networking, A Top down Approach", Pearson education, 3rd
Edition, 2010.
2. Marcus Goncalves, "Voice over IP Networks", McGraw Hill, 2nd Edition,1999.
3. KR. Rao,Z S Bojkovic, D A Milovanovic, "Multimedia Communication Systems : Techniques,
Standards and Networks", Pearson Education,2007.
4. R.Steimnetz, K. Nahrstedt, "Multimedia Computing, Communications and Applications",
Pearson Education,1st Edition, 1995.
5. Ranjan Parekh, "Principles of Multimedia", 3rd Edition, 2010.
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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MULTIMEDIA
• Multi: more than one
• Media: means for conveying information
• Mass media
•
press, newspaper, radio and TV context
• Transmission Media
•
Guided or Unguided
• Storage media
•
floppy, CD, DVD, HD, USB
• Interaction media
•
text, image, audio, video ….
• Multimedia is a presentation of a computer application
incorporating media elements such as text, graphics,
animations, audio, and video.
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Definition
Computer-based techniques of text, images,
audio, video, graphics, animation, and any
other medium where every type of
information can be represented, processed,
stored, transmitted, produced and presented
digitally
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Benefits of Multimedia
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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MEDIA COMPONENTS
• Text - ASCII/Unicode, HTML,
Postscript, PDF
•
Audio – Sound, music, speech,
structured audio (e.g. MIDI)
•
Musical Instrument Digital Interface
•
Still Image - Facsimile, photo,
scanned image
•
Video – Movie, a sequence of
pictures
•
Graphics – Computer produced
image
• Animation – A sequence of
graphics images
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Captured Versus Synthesized Media
• Captured media refers to information
types captured from the real world.
 e.g. Still pictures, moving pictures, and sound
• Synthesized media refers to information
types synthesized by the computers
e.g. Text, graphics and computer animation
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Discrete Versus Continuous Media
• Discrete media refers to media involving space
dimension only - length, breadth, height, and time
• e.g. Still images, text and graphics
• Discrete media is also referred to as static media
or non-time-based media or non-temporal media
or space-based media.
• Continuous media refers to time-based media
• e.g. Sound, moving images, and animation
• Continuous media is also referred to as dynamic
media or time-based media or temporal media.
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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CLASSIFICATION OF MEDIA TYPES
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Characteristics of Multimedia System
• Computer-controlled
 User is able to view, hear, and see using a Multimedia PC
System.
• Integrated
 At least one discrete and one continuous media combined for
information presentation design sharing
• Digital representation
 Consists of various form of media i.e. text, graphics, audio,
video, and animations; created, stored, processed, and
transmitted DIGITALLY.
• End User Interface – permit interactivity
 User is able to navigate, interact, create, and
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
communicate.
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BASIC TOOLS
• World Wide Web (browser-based playback) - HTML 5, CSS,
Flash, Dreamweaver
• Programming Applications (native playback) - Director,
LiveCode
• Artwork Development - Photoshop, Illustrator
• Animation Development (2D and 3D) - After Effects, Maya
• Audio Editing - Sound Forge, Audition
• Video Editing - Final Cut Pro, Premiere Pro
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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General Overview of a Multimedia System
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Applications
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Elements
• text
• images,
• audio
• video and
• animation
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Text
•
Text
is
most
commonly
used
to
communicate
information
• alphanumeric characters & special characters
• Use of text types, sizes, fonts, colours and background
colours
•
Multimedia applications support linked content, through
Hypertext
• Examples:Text in SMS, FAX, Email
•
TXT, DOC, DOCX, PDF
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Images
• Images/Illustrations are the oldest form of media
• illustrate ideas through still pictures
• There are two types of images:
- Bitmaps
- Vector
• Bitmap images are real images captured from cameras
• Vector graphics are created using software in the computer
• This multimedia element enables to generate, represent, process,
manipulate, and display pictures
• File Format: JPG, PNG, TIF, BMP
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Audio
• speech, music and sound effects - digital audio
• sound elements:
 website or presentation can add audio files from a musical
background
 voiceover / spoken explanation
•
There are two basic type of audio or sound;
 analog and digital.
• File Format:
 MP3, WAV, WMA
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Video
•
Video presents moving pictures
• Combination of images and sound
• Video  records, synthesizes, and displays images
known as frames in sequences moves at a fixed speed
• Watch a video without any interruption, video device
must display 25 to 30 frames/second
• File Format: AVI, WMV, FLV, MOV, MP4
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Animation
• Animation is the process of making a static image to look as if it is
moving
• It helps in creating, developing, sequencing, and displaying a set of
images technically known as frames
• Digital animation can be classified as 2D and 3D
• Graphic Image Files (GIFs), are small files that present a single
image or rapidly display a sequence of a few images to give the
appearance of motion.
•
Adobe Flash is the most common tool for creating these
animations.
• File Format: GIF, FL
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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• Codeword- unique combination of fixed number of bits
• Analog signals
• Transmission –BW limited
channel
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Encoder
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of ECE, CIT
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Contd..
• Bandlimiting filter
• Sampling Rate
• Antialiasing filter
• Quantization
• Dynamic Range
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Decoder
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Text
• Unformatted Text
• Formatted Text
• Hypertext
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Unformatted Text
• Plain Text- ASCII character set
• 7 bit binary codeword  2^7  128 characters
• Printable characters  alphabet, numeric & punctuation
• Control characters
 Format control characters  DEL, ESC, BS(Backspace) etc.
• Information separator
 File separator
 Record separator
• Transmission Control Characters
 ACK, SYN, NAK etc
• Mosaic Characters  teletext and videotex
 Create graphic images – television broadcasting
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Contd..
ASCII Characters
Mosaic characters
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Videotex/ Teletext
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Formatted Text
• Produced - word processing packages
• Publishing sectors
 Papers, books, magazines, journals etc
• Command  reserved format-control character –
alphabets or numeric
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Hypertext
• Enables an integrated set of documents which have defined linkages
between them
• The linked set of pages stored in a particular server are accessed using a
client program known as BROWSER
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Contd..
• Associated with each set of linked
pages is the HOME PAGE
•
An index to the linked pages
•
Hyperlink takes the underlined text string form and
the user initiates by clicking the mouse on it.
• In addition to textual name of the link,
a unique network-wide name known as
URL is used.
• Includes the host computer where the page
is located, name of the file…
• Hypertext language: HTML, SGML,
TEX, LATEX…
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Images
• Includes Computer-generated images called graphics
• Displayed as 2-D matrix of individual picture elements
called pixels
• Graphics  Software tools
 Creation/ editing- object
 Composed of visual objects including lines, arcs, squares,
rectangles…
 Clipart
 3D effect
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Images
• A computer’s display screen is considered
as 2D matrix of Picture elements
• Ex: Video Graphics Array(VGA)
display with 640X480 pixels with 8 bits per
pixel to have one of 256 different colors
All objects-including freeform objects are
made up of series of short and long lines.
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Graphics Principles
36
• Objects – attributes
Size, shape, color, position, shadow etc
• Object
Open
Closed
• Same color- rendering
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Computer Graphics
• Representation
• High-level Version
 Less BW, less memory
 Destinations must be able to interpret the various high-level
commands
• Low-level machine code




Eg: bit – map format
Widely & standardized form
GIF – Graphical Interchange Format
TIFF – Tagged Image File Format
• SRGP – Simple Raster Graphics Package
 High level into pixel forms
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Digitized Documents
•
Eg. Documents produced by the
scanner associated with a
FACSIMILE (fax).
•
Scans each page from L to R-starts
at the top of the page and end at the
bottom.
•
They use a single binary digit to
represent each pel,
 0-White
 1-Black
•
A page produces stream of about
2million bits
•
Best suited for bi-tonal images
comprising mainly textual
information.
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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DIGITIZED PICTURES
•
A good quality black and white picture needs 8 bits/pel to yield 256 gray levels.
COLOUR PRINCIPLES
•
Human eye sees just a single color when a set three primary colors are mixed
•
Whole spectrum of colors known as COLOUR GAMUT can be produced by using different
proportions of the three primary colors (R,G,B)
MIXING TECHNIQUE
•
Additive Color mixing: Produces black when all three primary colors are zero.
•
•
•
Useful in producing color image on a blank surface. Eg. Display applications
Subtractive color mixing: Produces white when all three primary colors (C,M,Y) are zero.

Useful in producing color image on a white surface.

Eg. printer applications
https://www.youtube.com/watch?v=Qqv0K0Y7uO8
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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RASTER SCAN PRINCIPLE
•
Used by picture tubes in television sets
•
Contains a finely-focussed electron beam scanned over the complete
screen
•
Scan consists of a number of horizontal lines (frame) starting from top
left to bottom right.

Repeats again; PROGRESSIVE SCANNING
•
Display screen is coated with a light-sensitive PHOSPHOR that emits
light when energized by electron beam-Brightness.
•
B & W picture tubes – single electron beam
•
Color-3 separate closely located beams
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Display Technologies
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Cathode-ray tube (CRT) Picture Tube/ Monitors
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Contd..
• Each pixel comprises of three
color-sensitive phosphors (one
for R, B and G)-PHOSPHOR
TRIAD
• Each pixel has shape of a
SPOT which merges with its
neighbors.
• Spot size is 0.025 inches(0.635
mm) looks as continuous color
image at distance.
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Contd..
• Television picture tubes-moving images- screen refresh.
• FRAME REFRESH RATE: High enough to ensure eye is
not aware that the display is continuously refreshed.
 Low refresh rate leads to FLICKER
 A refresh rate of at least 50/60 times per second is required
 Depends on electric supply – 60 Hz North & South America & Asia, 50
Hz in Europe
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Raster-Scan Display Architecture
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Pixel Depth
8
• The number of bits per pixel
determines the range of different
colors that can be produced.
• In practice, a selected subset of
the range is used.
8
8
Red
Green
Blue
• The selected colors in the
subset is stored in a table and
each pixel value is used as an
address to a location within the
table called COLOR LOOK UP
TABLE.
•
24 bits plane, 8 bits per color gun.
•
224 = 16,777,216 colors
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Aspect ratio
•
The number of pixels per scanned line and the number of lines per frame
vary.
•
It is the ratio of screen width to height.
•
4:3 - standard aspect ratio for older television screens and computer
monitors
•
16:9 - standard aspect ratio for modern high-definition (HD) television
screens, computer monitors, and most widescreen displays
 Used for movies, videos, and multimedia content.
•
21:9 - ultra-wide or cinematic aspect ratio It is often used
 High-end computer monitors and cinematic productions to provide a
more immersive viewing experience.
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Screen Resolution
• Television Standards






Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
NTSC – US
PAL – UK
CCIR – Germany
SECAM – France
NTSC-525
Other 3  625 lines
50
Memory Requirements
Standard
Resolution
Number of Colors
Memory Required
per Frame
VGA
(Video Graphics
Array)
640x480x8
256
307.2 kB
XGA
(Extended Graphics
Array)
640x480x16
1024x768x8
64 K
256
614.4 kB
786.432 kB
SVGA
(Super VGA)
800x600x16
1024x768x8
1024x768x24
64 K
256
16M
960 kB
786.432kB
2359.296kB
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Digital Cameras and Scanner
• IMAGE SENSOR  2-D grid of lightsensitive cells called PHOTOSITES
• Charged Coupled Device (CCD)
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Contd..
•
An image is captured within the camera using solid-state device called an IMAGE
SENSOR. It is a silicon chip and consists of a 2-D grid of light-sensitive cells called
PHOTOSITES.
•
When the camera shutter is activated, each photosites stores the level of intensity of
the light that falls on it.
•
Charged Coupled Device (CCD) is an image sensor which consists of array of
photosites that converts the level of intensity that falls on it into an equivalent
electrical charge.
•
It is then converted into digital values using an ADC.
•
For color images, the color associated with each pixel is obtained by,
•
Each photosite is coated with either a R,G or B filter in a 3x3 grid so its charge is
determined by the level of RGB light that falls on it. The color associated with
each photosite is determined by the output with each of its 8 neighbors. The
levels of the other two colors is estimated by interpolation involving nine values.
Used with most customer-quality cameras
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Contd..
• Involves three separate exposures of a single image
sensors for R,B and G. Since three separate
exposures are needed for image not used with video
cameras. Used for high resolution still-image cameras
such as in studios.
• Involves three separate image sensors, each coated
with separate R,B and G filters. Used in professional
quality high resolution still and moving images.
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Audio- PCM Speech
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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CD-Quality Audio
 Speech – 15 Hz to 20 KHz
 Sampling Rate = 40 ksps
Bit rate per channel = Sampling
rate * bits per sample
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Video
• Entertainment
Broadcast television
VCR/ DVD
• Interpersonal
Video telephony
Video conferencing
• Interactive
Short video clips
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Broadcast television
• National Television Standards Committee
(NTSC)
• Sequential Color and Memory (SECAM)
• Phase Alternate Line (PAL)
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Interlaced Scanning
• Interlaced scanning
 Bandwidth and flicker reduction
 Constructing each frame from two consecutive fields
•
Fields are sampled at different times such that
consecutive lines belong to alternate fields
 US a 60 Hz format
 Europe a 50 Hz format
• Fresh rate is reduced to 30/25 frames per second
Dr.I.S.Akila, Associate Prof., Dept. of
ECE, CIT
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Interlaced Scanning
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of ECE, CIT
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Interlaced Scanning
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Color Signals
• Monochrome – Black & White
• Color Broadcast – R,G & B
• Color Properties:
• Brightness:
 relative darkness or lightness of a color
 Varies on grey scale from black to white
 Independent of the color of the source
• Hue: Actual color of the source
• Saturation:
 Strength or vividness of the color
 Pastel color has a low level than a red color
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Contd..
• Luminance – refer to brightness of source
• Chrominance- related to hue and saturation of the color
• Color produced on the Screen – magnitude of the
electrical signals- energize R,G and B
• 0.299R+0.587G+0.114B  WHITE
• Ys= 0.299Rs+0.587Gs+0.114Bs
• Ys – amplitude of the luminance signal
• Blue Chrominance(Cb) & Red Chrominance(Cr) to
represent hue and saturation
 Cb=Bs-Ys & Cr=Rs-Ys
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Chrominance Components
• Transmission BW (Monochrome+ Color) – Same
• Y,Cb & Cr  Composite Video signal
• Magnitude of chrominance signal are scaled down
• PAL: Y=0.299R+0.587G+0.114B
• U=0.493(B-Y)
• V=0.877(R-Y)
• NTSC: Y=0.299R+0.587G+0.114B
• I=0.74(R-Y)-0.27(B-Y)
• Q=0.48(R-Y)+0.41(B-Y)
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Signal Bandwidth - NTSC
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of ECE, CIT
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Signal Bandwidth - PAL
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Digital Video
• Luminance and 2 color signals instead RGB
• Reduction in bit rate
• CCIR- Consultative Committee for International
Radiocommunications
• CCIR-601
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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4:2:2 Format
•
Used in Television Studios- broadcast Applications
•
BW - 6 MHz for luminance signals & 3 MHz for Cr and Cb
•
Line Sampling Rate  13.5 MHz  Luminance
•
Line Sampling Rate  6.75 MHz  Cr and Cb
52 Micro seconds * 13.5
MHz= 702 samples per
line
lines
Line
Sampling
Rate
Total Line
Sweep
time
Retrace
sweep
time
Active
Sweep
time
Samples
per line
NTSC
525
13.5 MHZ
63.56
micro sec
11.56
micro sec
52 micro
sec
702
PAL
625
13.5 MHZ
64 micro
sec
12 micro
sec
52 micro
sec
702
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
68
Contd..
525 line System Y= 720X480
Cb=Cr= 360X480
625 line System
Y= 720X576
Cb=Cr= 360X576
 MXN
 M Samples/ line
 N line system
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Standards
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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4:2:0 Format
• Bitrate = 162 Mbps
525 line
System
Y= 720X480
Cb=Cr= 360X240
625 line
System
Y= 720X576
Cb=Cr= 360X288
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Contd..
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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HDTV Format
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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Source Intermediate format (SIF)
• 4:1:1 format
• Bit Rate = 81 Mbps
• ½ the refresh rate  temporal resolution
• ½ resolution in vertical and horizontal directions(subsampling)
• Missing Samples – Interpolation method
525 line
System
Y= 360X240
Cb=Cr= 180X120
30 Hz
625 line
System
Y= 360X288
Cb=Cr= 180X144
25 Hz
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
74
Common Intermediate Format(CIF)
• Video Conferencing Applications
• Y= 360X288
• Cb=Cr= 180X144
• 30 Hz progressive Scanning
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
75
Quarter CIF(QCIF)
• Video telephony
• Y= 180X144
• Cb=Cr= 90X72
• Bit rate = 40.5 Mbps
• 4:1:1 format
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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PC Video
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of ECE, CIT
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Thank You
Happy Learning
Dr.I.S.Akila, Associate Prof., Dept.
of ECE, CIT
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