HDTV T echnology

Outline Introduction HD-History Architecture Characteristics of HD standard Difference b/w HD & Analog Future of HD Summary Conclusion Refrences

WHY HD To Overcome Limitations of Analog Television Noise free pictures Higher resolution images Widescreen / HDTV No Ghosting Enhanced Sound Services Other Data services. 3

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. 4

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. 7

8 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

11 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 pulldown

What is a format? 14 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:

15 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 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

20 Type Of HDTV TypeAdvantageDisadvantage 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 ProjectionLarger screen size at lower cost More bulky then flat panel, more components to fail Front ProjectionBest solution for screens over 60 inches Costly installation, not suitable for rooms with high ambient light

Connecting To Analog TV COAX Composite Or S-Video Composite or S-Video From VCR DVD VCR or Composite or (if available) S-Video Composite or S-Video From VCR

Connecting To Digital TV Digital Signal from Cable or Satellite COAX Component, Composite Or S-Video Composite or S-Video From VCR DVD VCR Cable or Satellite Composite or S-Video or Component Or 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.