The ABCs & 123s of HDTV
Part 1 of 4

by Kevin Ray

f you are interested in HDTV, but are intimidated by the language associated with it, here is a comprehensive glossary of terms that you can refer to. If at the end of this four part series you still find yourself confused, a field trip to Custom Audio Video is recommended.

3:2 Pull Down - 3:2 pull down is a process by which manufacturers add six frames to film’s original 24-frames-per-second format so that it can work within the NTSC standard, which is 30 fps. This helps keep the action from stuttering on your television.

4:3 - 4:3 is an aspect ratio of traditional squarish National Television Systems Committee (NTSC) TV screens; it stands for four units of width for every three units of height.

16:9 - 16:9 is an aspect ratio of movie screen and widescreen DTV formats used in all HDTV (High Definition TV) and some SDTV (Standard Definition TV); it stands for 16 arbitrary units of width for every 9 arbitrary units of height.

24P - Terminology for 24 full frames per second digital video progressively captured. In most cases it refers to the HD picture format of 1920x1080, though it is also used with 1280x720 images as well. Often used to loosely describe a capture system that operates at 23.976P as well.

480p - 480p means that the resolution of the picture is 852 vertical pixels by 480 horizontal pixels and p stands for progressive scanning. Although 480p is in the wide-screen format, it is not considered a high definition format. It is related to EDTV and current DVD’s.

720p - 720p means that the resolution of the picture is 1,280 vertical pixels by 720 horizontal pixels and p stands for progressive scanning. Progressive scanning offers a smoother picture as 720 horizontal lines are scanned progressively or in succession in a vertical frame that is repeated 30 times a second.

1080i - 1080i means that the resolution of the picture is 1920 vertical pixels by 1080 horizontal pixels and i stands for interlaced scanning. Interlaced scanning is based on the principle that the screen shows every odd line at one scan of the screen and then all the even lines in a second scan.

1080p - 1080p means that the resolution of the picture is 1,920 vertical pixels by 1,080 horizontal pixels and p stands for progressive scanning. This format works on the same principle as 720p; the only difference is that in this type there are more pixels and the resolution is better.

AC-3 - The 5.1-channel sound system specified in the Standard for Digital-HDTV. Also known as “Dolby Digital,” AC-3 delivers CD-quality digital audio and provides five full-bandwidth channels for front left, front right, center, surround left and surround right speakers, plus an LFE (low-frequency effect) subwoofer, for a total of 5.1 channels.

Addressable Resolution - The highest resolution signal that a TV or monitor can accept. It is important to note that while a particular device (Digital-HDTV) is able to receive the resolution, it may not be capable of displaying it.

Analog TV - Analog technology has been in use for the past 50 years to transmit conventional TV signals to consumers. “Standard” television broadcasts in analog TV. Analog signals vary continuously, creating fluctuations in color and brightness.

Anamorphic video - Video images that have been “squeezed” to fit a video frame when stored on DVD. These images must be expanded (un-squeezed) by the display device. An increasing number of TVs employ either a screen with 16:9 aspect ratio, or some type of “enhanced-for-widescreen” viewing mode, so that anamorphic and other widescreen material can be viewed in its proper proportions. When anamorphic video is displayed on a typical TV with 4:3 screen size, the images will appear unnaturally tall and narrow.

Artifacts - Artifacts are defined as unwanted visible effects in the picture caused by disturbances and errors in the video transmission or digital processing. Artifacts include “edge crawl” or “dot crawl” or “hanging dots” in analog pictures, and “pixelation”, “contouring” or “blockiness” in digital pictures.

Aspect ratio - Aspect ratio is ratio of width to height of a TV screen. It may be either traditional squarish 4:3 ratio of the National Television Systems Committee (NTSC) TV screen or 16:9 ratio of widescreen DTV formats for all HDTV (High Definition) and some SDTV (Standard Definition).

Advanced Television Systems Committee ATSC - An acronym for Advanced Television Systems Committee, which is responsible for developing and establishing Digital-HDTV Standards as well as all 18 formats of Digital TV; and the name of the DTV system used by broadcasters in the U.S.

Bandwidth - Bandwidth, in general, means amount of information that can be carried in a given time period (usually a second). More exactly, it is a range of frequencies used for transmitting picture and sound information from transmitter to your TV. Federal Communications Commission (FCC) has allocated 6 MHz for TV broadcasters for each channel.

Barn Doors - A term used in television production to describe the effect that occurs when a 4:3 image is viewed on a 16:9 screen. When this happens, viewers see black bars on the sides of the screen or “barn doors.”

Bit Rate - Bit rate is measured as “bits per second” (bps) and refers to the rate at which the data is transmitted. For Digital TV, the maximum possible bit rate within the bandwidth is 19.4 Mbps while SDTV has a lower bit rate. The higher the bit rate, the more data is processed which usually results to higher picture resolution or better sound quality.

Burn-in - Burn-in is the result of a static image or pattern appearing so regularly on a screen that it ages the phosphors and remains as a ghost image.

This article provided by Kevin Ray of Custom Audio Video, LLC. Member CEDIA (Custom Electronic Design & Installation Association)