HDTV Technology

Outline

•Introduction

•HD-History

•Architecture

•Characteristics of HD standard

•Difference b/w HD & Analog

•Future of HD

•Summary

•Conclusion

•Refrences

WHY HD

To Overcome Limitationsof Analog Television

• Noise free pictures• Higher resolution images

Widescreen / HDTV• No Ghosting• Enhanced Sound Services• Other Data services.

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High Definition Television

DEFINITION: HDTV is generally recognized as a digital video broadcast with a minimum resolution of 1280 pixels wide and 720 pixels high, a rate of 30 or more frames/second and usually an aspect ratio of 16:9.

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HDTV History

• Early 1980’s:– Japan created analog HDTV

• Mid-1980s:– US, trying to stay competitive, decided to go

digital– Congress gave stations a separate channel for

transition to digital broadcast with the goal of all stations using digital broadcasts by 2006.

Currently...

• Less than 15% of US homes have HDTV capabilities

• Approximately 21% of stations have digital broadcasts

High Definition Television

A standard definition analog television uses a cathode ray tube with an electron gun to guide the path of an electron beam to “paint” 480 vertical lines across the face of the screen. Each time the beam strikes a dot of phosphor, light is produced. For a color television set, each spot consists of a group of three phosphor elements; one for each primary color.

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HOW HD WORK

Implementation - Display technologies

• Plasma – Like LCD monitors, plasma HDTV sets are thin and are made up of cells that correspond to pixels sandwiched between glass plates. Plasma cells contain three separate gas-fill sub-cells, one for each color. When a current is applied to a sub-cell, it ionizes the gas emitting ultraviolet light. The ultraviolet light in turn excites fluorescent substances in the sub-cells that emit red, blue or green light.

• DLP – Digital light processing is a technology used in projection displays. In DLP monitors, light is reflected off an array of microscopic hinged mirrors. Each tiny mirror corresponds to a visible pixel. The light is channeled through a lens onto the surface of the screen. Single chip DLP projectors can display 16.7 million colors. 3-chip projectors can display 35 trillion colors.

• LCoS – Similar to DLP, LCoS projection systems use liquid crystals instead of mirrors to block light. The liquid crystals are arranged in a grid in front of a highly reflective surface.

Motion Blur

A sequence of images such of a movie or animation

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HD TV Screen Refresh Rates

•A rate of 24 frames/second (progressive) has been the movie film standard since the mid-20’s

•The television industry has used a rate of 60 frames/second (interlaced) since the 40’s

•Newer HDTV’s are being marketed as 120 Hz and 240 Hz using circuitry to help reduce motion blur

Technical Aspects

Interlaced display

Frame rate conversion - 3-2 pulldown

What is a format?

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SMPTE 274 M SMPTE 296 M

Number of active pixels per line

Number of active lines per frame

Picture aspect ratio

Scanning mode

Frame rate

Formats are described by:

Current main standards are:

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Archiving High definition

Standard definition video

720 pixels 576 lines

1- hour programme file size : 72 GB

High definition video

1980 pixels 1080 lines

1- hour programme file size : from374 GB to 673 GB*

To archive HD, Compression could be required.

HDTV & SDTV Comparison

•Judging simply on pixel count, a 1080i HDTV image is 6 - 9 times better than a standard, NTSC image

•Audio is also improved.

HDTV & SDTV Comparison

Advantages

• By using lower-definition signals, one channel can be split into several channels

• Extra channels used for:– information services (datacasting)– music– Internet services

HDTV Features

• Provides up to 60 frames/sec screen writing rate

• Uses MPEG-2 data compression– source info data rate is 1.2Gbps– broadcast data rate is 20Mbps

• Square pixels 1/4 the size of analog TV’s pixels

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Type Of HDTV

Type Advantage Disadvantage

Direct View (CRT) Cheap (if you can find one) Heavy, max screen size limited, soon to be obsolete

LCD Competitive price, suitable for rooms with high ambient light

Motion blur more apparent than Plasma

Plasma Brighter colors, less motion blur, wider viewing angle

More power consumption than LCD, less competitive price

Rear Projection Larger screen size at lower cost More bulky then flat panel, more components to fail

Front Projection Best solution for screens over 60 inches Costly installation, not suitable for rooms with high ambient light

Connecting To Analog TV

COAX

CompositeOr S-Video

Composite or S-VideoFrom VCR

DVD

VCR

orComposite or (if available) S-Video

Composite or S-VideoFrom VCR

Connecting To Digital TVDigital Signal from Cable or Satellite

COAX

Component, CompositeOr S-Video

Composite or S-Video From VCR

DVD

VCRCable or Satellite

Composite or S-Video

or

ComponentOr HDMI

Impact of HDTV

• Broadcasters & consumers spend more $

• Increased visual clarity has forced designers to spend considerably more money on sets, set dressings

• Blu-Ray vs HD-DVD

Future of HD

• DEC 2012: All commercial stations must begin digital broadcasts

• Move will be cheaper, quicker, and easier as products and services become more widespread and people grow accustomed to the new technology.

• Super HD TV

Conclusion

• As NTSC retires, HDTV programming, products, and production services will continue to grow exponentially.

• HDTV has brought a more cinematic experience into viewer’s homes and with digital cinema, delivered the film industry a few of the benefits of television. However, HDTV still has much lower resolution than 70mm film. It’s a matter of time before some will begin pressuring for another increase in quality.

Questions

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