ratio, and widescreen.
3-2 pulldown processing
Video processing common to digital TVs and progressive-scan
DVD players. 3-2 pulldown corrects for artifacts and distortion that occur when
film-based material (24 frames per second) is converted to video (30
frames per second), then de-interlaced
to create a progressive-scan signal.
Video images that have been "squeezed" to fit a video frame when
stored on DVD. These images must be expanded by the display
device. When anamorphic video is displayed on a typical TV with 4:3
screen size, the images will appear unnaturally tall and narrow.
Unwanted visible effects in the picture created by disturbances in the video
transmission or processing. Examples include "dot crawl" in analog pictures, or "pixelation" in
The ratio of width to height for an image or screen. The NTSC
television standard uses the 4:3 (1.33:1) ratio. More and more
direct-view and projection TVs use the wider 16:9
ratio (1.78:1) to better display widescreen material like DVDs
and HDTV broadcasts.
Advanced Television Standards Committee. Formed to establish technical
standards for the U.S. digital television system.
Using a TV's A/V inputs to connect a DVD player, VCR, camcorder or
other video component provides improved picture and sound quality compared
to using the one-wire RF antenna-style input.
Rear A/V inputs are used for components you normally leave connected to your
TV. Front A/V inputs allow you to quickly connect / disconnect a camcorder.
Stereo audio jacks that let you connect your TV to your stereo or home
theater system. There are two types, fixed and variable.
Measured as "bits per second," and used to express the rate at
which data is transmitted or processed. The higher the bitrate, the more
data that is processed.
Digital video formats typically have bitrates measured in
megabits-per-second (Mbps). The
maximum bitrate for DVD playback is 10 Mbps; for HDTV it's 19.4 Mbps.
The color component of a video signal that includes information about hue
(shade) and saturation (intensity).
A comb filter removes residual chrominance (color) information
from the luminance (brightness) signal. Comb filtering enhances fine detail,
cleans up image outlines, and eliminates extraneous colors. Comb
filters are not required and not used with S-video or component video
connections since those connections carry the chrominance and luminance
The three-jack component video connection splits the video signal into three
parts (one brightness and two color signals). Component video has increased
bandwidth for color information, resulting in a more accurate picture with
clearer color reproduction. A growing number of TVs
include component video jacks to provide the best possible picture quality
(better than S-video
video) when connected to a compatible DVD player.
Special wide-bandwidth component video connections are capable of
carrying wider bandwidth video signals, like progressive-scan DVD and
TVs include at least one set of wide-bandwidth connections for connecting a HDTV tuner
or progressive-scan DVD player.
A single video signal that contains luminance
(brightness) and chrominance
(color) information. A composite signal is better than an RF signal, but not
as good as S-video
video. A composite video jack is usually a single yellow RCA-type.
Cathode ray tube. A CRT (picture tube) is a vacuum tube in which images are created when an electron beam
scans back and forth across the back side of a phosphor-coated screen. Each
time the beam makes a pass across the screen, it lights up a horizontal line
of phosphor dots on the inside of the glass tube. By rapidly drawing
hundreds of these lines from the top to the bottom of the screen, images are
The process of converting an interlaced-scan video signal (where each frame
is split into two sequential fields) to a progressive-scan signal (where
each frame remains whole). De-interlacers are found in digital TVs and
progressive-scan DVD players. More advanced de-interlacers include a feature
pulldown processing. For TVs, de-interlacing is often referred to as
"line-doubling" or "upconversion."
Digital audio output
A connection found on HDTVs and HDTV tuners for sending the Dolby Digital
5.1 audio of HDTV broadcasts to an A/V receiver with Dolby Digital decoding. The
two most common types of digital output are coaxial and optical.
The conventional and most common type of TV, which uses a single large CRT
to display images.
DLP (Digital Light Processing)
A projection technology developed by Texas Instruments, based on
their Digital Micromirror Device (DMD) microchip. Each DMD chip has hundreds
of thousands of tiny mirrors which are used to create the image. DLP
technology is used in both front- and rear-projection systems.
There are two basic types of DLP projector: "single-chip"
projectors use a single DMD chip along with a spinning color wheel, while
much more expensive "3-chip" projectors dedicate a chip to each
basic color: red, green, and blue.
A multi-channel digital audio format that is the official audio
standard for HDTV (and DVD). Dolby Digital is normally associated with 5.1
channel surround sound. Though this channel configuration is common, it
is only one of several possible variations — a "Dolby Digital"
soundtrack can mean anything from 1 to 5.1 channels.
A term used to describe the format conversion from a higher resolution input
signal number to a lower display number, such as 1080i input to 480i
display. Some HDTV tuners are able to downconvert digital HDTV signals for
display on a regular analog TV.
DTV (Digital Television)
The digital broadcast TV standard, which began operation in
late 1998, and will eventually replace the 60-year-old analog NTSC
system. DTV comes in two basic flavors: widescreen, HDTV
(High-Definition Television) with Dolby Digital audio, and medium-quality SDTV
DVI (Digital Visual Interface)
A multi-pin connection intended to carry High-Definition
video signals from digital set-top boxes (HDTV-capable DIRECTV, DISHNetwork,
and cable boxes) to HDTV monitors with a compatible connector. The signals
are encrypted with High-bandwidth Digital Content Protection (HDCP) to
Electronic program guide
EPG provides an on-screen listing of all available programming for an extended
time period (typically 36 hours or more).
In interlaced-scan video, each complete frame is split into 2 sequential
fields, each of which contains half the scanning lines of the frame. One
field contains the odd scanning lines, and the other field the even lines.
A complete, individual picture in a movie. In a video signal, a frame
contains all of the picture's scanning lines. The frame rate of a
progressive-scan format is twice that of an interlaced-scan format.
The rate at which frames are displayed. The frame rate for movies is 24
frames per second (24 fps). In regular NTSC video, the frame rate is 30 fps.
The frame rate of a progressive-scan format is twice that of an
interlaced-scan format — example: the frame rate for 480i DVD is 30 fps
(or 60 interlaced fields per second); for progressive-scan DVD at 480p, 60 fps.
A 2-piece display system consisting of a separate projector (often
ceiling-mounted) and screen. Generally found in high-end home theaters,
front-projection systems can display images up to 20 feet across, or larger.
Types of front projectors include CRT,
HDMI (High-Definition Multimedia Interface)
Audio Video connection for standard and high definition digital audio and video. Uses a multi-pin cable capable of 720p, 1080i, 1080p High Def video and up to 8 channel digital audio. The interface has undergone many revisions with increasing capabilities. Cable connections are Type A (19 pin), Type B (29 pin) and Type C (mini version for portable devices). Found on DVD, HDTV, camcorders and set-top-box devices.
HDTV (High-Definition Television)
HDTV refers to the highest-resolution formats of the 18 total
DTV formats. True HDTV is generally considered to be
1,080-line interlaced (1080i) or 720-line progressive (720p) or 1,080-line progressive (1080p).
TVs which can display digital high-definition
TV formats when connected to a separate HDTV tuner. These TVs
generally have built-in tuners for receiving NTSC broadcasts, but
not digital. An HDTV-ready TV may also be referred to as an HDTV
IEEE 1394 (FireWire or i.LINK)
First conceived by Apple Computer (as FireWire®), then developed by the
IEEE (Institute of Electrical and Electronics Engineers), this high-speed
2-way connection allows easy transfer of digital data between electronics gear and computers. Found on some HDTV-capable TVs, tuners, and
Interlaced scan refers to the process of
re-assembling a picture from a series of video signals. The NTSC system uses 525 scanning lines to create a picture
(frame). The frame/picture is made up of two fields: The first field has
262.5 odd lines (1,3,5...) and the second field has 262.5 even lines
(2,4,6...). The odd lines are scanned in 1/60th of a
second, and the even lines follow in the next 1/60th of a second. This
presents an entire frame/picture of 525 lines in 1/30th of a second.
Analog NTSC video uses interlaced scanning, as do several digital television
formats. Formats that include an "i" (1080i, 480i) use interlaced
scanning. See also progressive
LCD (Liquid Crystal Display)
Liquid Crystal Display technology is one of the methods used to create
flat-panel TVs. Light isn't created by the liquid crystals; a light source (CCFT
bulb) behind the panel shines light through the display. The display
consists of two polarizing transparent panels and a liquid crystal solution
sandwiched in between. An electric current passed through the liquid causes
the crystals to align so that light cannot pass through them. Each crystal
acts like a shutter, either allowing light to pass through or blocking the
light. The pattern of transparent and dark crystals forms the image.
LCD technology is used in direct-view,
TVs, and is fundamentally different from the CRT
technology used in conventional TVs.
A method for displaying the entire picture as seen in a movie theater. The
resulting image width is much greater than its height. On a TV screen with
standard aspect ratio (4:3), letterboxed videos appear with horizontal black
bars above and below the image.
The brightness or black-and-white component of a color video signal.
Determines the level of picture detail.
Equal to one million Hz. Video signal bandwidth is typically expressed in
The video compression standard used for digital television, DVD, and
small-dish satellite TV. This adaptive, variable bitrate process is able to
allocate more bits for complex scenes involving a lot of motion, while
reducing the bits in static scenes. MPEG stands for Moving Picture Experts
MTS (Multichannel Television Sound)
The method of broadcasting stereo sound over ordinary analog TV channels.
MTS reception capability is built into all stereo TVs and HiFi
National Television System Committee, which established 525-line analog broadcast TV standard about 60 years ago. Although
it is referred to as a "525-line" standard, we're only able to see
480 lines on a TV display. The new DTV
digital broadcast standard will eventually replace NTSC.
The process of transferring a movie or other source material to
videocassette, DVD, or broadcast so that it fits the 4:3 aspect ratio of the
NTSC system, as well as most current TVs. This results in a significant
amount of lost picture information, particularly in the width of the image.
At the beginning of a movie on videocassette, you'll usually see a
disclaimer about the movie having been "...formatted to fit your
TV." That means it's been converted to pan-and-scan.
There are two basic types: 1-tuner picture-in-picture models require that
you connect a VCR or other video component to provide the source for your
second picture. 2-tuner picture-in-picture models have two built-in TV
tuners, so you can watch two shows at once using only the TV.
Short for picture element. The smallest bit of data in a video
image. The smaller the size of the pixels in an image, the greater the
Gas-plasma technology is one of the methods used to create flat-panel
Besides enabling thin, lightweight TVs that can be hung on a wall, plasma
offers other advantages. The display consists of two transparent glass
panels with a thin layer of pixels sandwiched in between. Each pixel is composed of three gas-filled cells or sub-pixels (one
each for red, green and blue). A grid of tiny electrodes applies an electric
current to the individual cells, causing the gas to ionize. This ionized gas
(plasma) emits high-frequency UV rays which stimulate the cells' phosphors,
causing them to glow, which creates the television image.
Some digital television broadcast formats (720p, 480p), and some higher-end
DVD players, use a type of video signal known as progressive scan. Instead
of splitting each video frame into two sequential fields like standard interlaced
NTSC video, progressive-scan video displays the entire frame in a single
sweep. Where standard NTSC video displays 30 frames (60 fields) per
second, progressive scan displays 60 full frames per second.
Displaying progressive-scan video requires more bandwidth (there's twice as
much vertical information) and a faster horizontal scan frequency than
interlaced video. For progressive-scan viewing, you'll need
a TV that's HDTV-ready.
Typically referred to as "big-screen" TVs, these large-cabinet TVs
generally have screens measuring at least 40". In the past, all
rear-projection TVs used three CRTs,
which projected images against a mirror inside the cabinet, so that the
images were then reflected onto the built-in screen. Newer rear-projection
technologies include LCD,
The sharpness of a video image, signal or display, described
either in terms of "lines of resolution," or pixels.
The resolution you see depends on two factors: the resolution of your
display and the resolution of the video signal. Since video images are
always rectangle-shaped, there is both horizontal resolution and vertical
- Vertical resolution: The number
of horizontal lines (or pixels) that can be resolved from the top of an
image to the bottom. The vertical resolution of the
standard analog NTSC
TV standard is 525 lines. But, some lines are used to carry other data
like closed-captioning text, test signals, etc., so we end up with about
480 lines in the final image, regardless of the source. All
of the typical NTSC sources — VHS VCRs, cable and over-the-air
broadcast TV (analog), non-HD digital satellite TV, DVD players,
camcorders, etc. — have vertical resolution of 480 lines. DTV
(Digital Television) signals have vertical resolution that ranges from
480 lines for SDTV, to 720 or 1080 lines for true HDTV.
- Horizontal resolution: The number
of vertical lines (or pixels) that can be resolved from one side of an
image to the other. Some examples for typical sources: VHS VCRs (240 lines), analog
TV broadcasts (330 lines), non-HDTV digital satellite TV (up to 380
lines), and DVD players (540 lines). DTV signals have horizontal
resolution that ranges from 640 lines for SDTV, to 1,280 lines for 720p
HDTV and 1,920 lines for 1080i HDTV.
SDTV (Standard-Definition Television)
A digital television system that is similar to NTSC standards in picture
resolution and aspect ratio. The picture and sound will be clearer than NTSC,
and its digital base will allow more than one program to be broadcast over
the same bandwidth at the same time. Typical SDTV resolution is 480i or
Set-top box (STB)
Also called converter boxes, these receivers convert broadcasts (either
analog cable, digital cable, or HDTV) for display on a television.
HDTV-ready TVs (those without a built-in HDTV tuner) must be connected to a
compatible HDTV tuner set-top box in order to receive digital television
This 4-pin connector provides a sharper, higher resolution picture by transmitting the
chrominance and luminance portions of a video signal separately. The signals
can then be processed separately, reducing interference.
The conversion of a lower resolution to a
higher one. This process increases the number of pixels and/or frame rate
and/or scanning format used to represent an image by interpolating existing
pixels to create new ones at closer spacing.
Widescreen refers to an aspect
ratio of 16:9, which is the optimum ratio for viewing DVDs and HDTV