- 1.78:1
The shape of a wide-screen HDTV (16 × 9); this is why a small bar is present on 16 × 9 televisions when showing a wide-screen movie.
- 1.85:1
The most common wide-screen aspect ratio used in theatrical films.
- 2.35:1
The widest aspect ratio used in theatrical films today.
- 4:3
The NTSC standard aspect ratio for traditional TVs; a 4:3 picture is four units wide by three units high. Also measured as 1.33:1.
- 5.1
A surround sound system that produces five separate audio channels (front left, front center, front right, surround left, surround right) plus one subwoofer channel—thus the “5.1” designation. Both Dolby Digital and DTS are 5.1-channel systems.
- 6.1
A surround sound system that enhances the standard 5.1 layout with a single rear channel, located directly behind the listener.
- 7.1
A surround sound system that enhances the standard 5.1 layout with rear left and rear right speakers, located behind the listener.
- 16:9
The aspect ratio used in HDTV broadcasts; a 16:9 picture is 16 units wide by 9 units high. The 16:9 aspect ratio presents a wider image area than the traditional 4:3 ratio. Also measured as 1.78:1.
- 480i
The standard definition format used for traditional NTSC television broadcasts; it transmits 480 horizontal scan lines with interlaced scanning.
- 480p
A higher-quality variation on the standard NTSC broadcast format, transmitting 480 horizontal scan lines with progressive scanning.
- 720p
One of the two main HDTV formats in use today; it transmits 720 horizontal scan lines with progressive scanning.
- 1080i
One of the two main HDTV formats in use today; it transmits 1,080 horizontal scan lines with interlaced scanning.
- 1080p
An HDTV format used in some video games and future high-definition DVDs; it transmits 1,080 horizontal scan lines with progressive scanning.
A
- acoustic suspension
A type of speaker enclosure that uses a sealed box to provide accurate, tight bass response.
- amplifier
A component that amplifies audio signals that are then output to one or more speakers.
- analog
A means of transmitting or storing data using a continuously variable signal. Prone to signal degradation, it does not always accurately reproduce the original.
- anamorphic widescreen
A means of storing a wide-screen picture on a DVD so that all the horizontal scan lines are used to display the picture, with none wasted on the black bars above and below the letterboxed picture.
- aspect ratio
The ratio between the width and height of a video display. The NTSC television standard is 4:3, where HDTV uses a 16:9 ratio. Some wide-screen movies use an even wider ratio, either 1.85:1 or 2.35:1.
- ATSC
Advanced Televisions Systems Committee, the industry group that established the new HDTV broadcast television standard. It sometimes refers to the high-definition standard itself. (An ATSC tuner is a television tuner that receives over-the-air HDTV broadcasts.)
- audio/video receiver
A combination of amplifier and preamplifier that controls both audio and video inputs and outputs. Also called an A/V receiver.
B–C
- bandwidth
Refers to the range of frequencies a component can reproduce, or the amount of information that can be carried by a circuit or signal. The larger the bandwidth, the better the sound or picture.
- bass reflex
A type of speaker enclosure that includes a precisely designed or “tuned” opening in the enclosure. Typically louder—though less accurate—than acoustic suspension speakers.
- Blu-ray disc
One of two competing high-definition DVD formats, with a storage capacity up to 50GB for a dual-layer disc.
- brightness
The black level of the picture.
- CD
Compact disc; a laser-based digital format for storing high-quality audio programming.
- CD-R
CD-Recordable; compact discs that can be recorded (once) by home CD recorders.
- CD-RW
CD-Rewritable; compact discs that can be recorded several times by computer-based CD recorders.
- chrominance
The color component of a video signal that includes information about the image’s color (hue) and saturation.
- coaxial cable
A type of cable consisting of a thick copper wire surrounded by aluminum foil shielding. Traditionally used for RF transmissions, it can also be used to carry component video and digital audio signals.
- coaxial digital
A type of connection that transmits digital audio via a copper wire.
- component video
A video signal that has been split up into its component parts: red (Pr), green (Y), and blue (Pb). Component video connections—found on higher-end TVs and DVD players—reproduce the best possible picture quality, with improved color accuracy and reduced color bleeding.
- composite video
A single video signal that contains both chrominance (color) and luminance (brightness) and information. Composite video is typically delivered through a single “video” RCA jack connection and delivers a better-quality picture than an RF signal, but not as good as an S-Video signal.
- crossover
A circuit that divides an audio signal into two or more ranges by frequency. Crossovers are typically used in a speaker system to send low-frequency signals to the woofer and high-frequency signals to the tweeter.
- CRT
Cathode ray tube, commonly called apicture tube. Used in all direct view, all rear projection, and some front projection televisions.
D
- dB
Decibel, the standard unit of measure for expressing relative power differences, otherwise known as loudness. One dB is the smallest change in loudness most people can detect; a 10 dB difference produces twice the volume.
- DBS
Digital broadcast satellite, or direct broadcast satellite; the satellite broadcasting system that uses a small round or oval satellite dish to receive signals from a high-powered satellite in geosynchronous orbit.
- digital
A means of transmitting or storing data using “on” and “off” bits (expressed as 1 or 0). It’s known for its highly accurate reproduction, with little or no degradation from the original.
- digital compression
Any algorithm that reduces the storage space required to store or transmit information. MPEG-2 and MPEG-4 are the most popular digital compression schemes in use today.
- digital television
Television signals broadcast digitally. DTV comes in several formats, each with varying types of picture resolution and sound quality. The highest quality of these formats is called HDTV.
- DIRECTV
One of the two main providers of digital satellite programming.
- Dish Network
Owned by EchoStar, one of the two main providers of digital satellite programming.
- direct view
Any video display in which the picture is produced on the viewing surface itself. Popular direct view technologies include cathode ray tube (CRT), LCD flat panel, and plasma.
- DLP
Digital Light Processor, a type of microdisplay technology used in some rear projection TVs. DLP displays utilize DMDs to reproduce the final picture.
- DMD
Digital micromirror device, the component in a DLP display that uses thousands of micromirrors.
- Dolby AC-3
The previous name for Dolby Digital.
- Dolby Digital
Surround sound format that can incorporate up to six discrete digital audio channels: front left, front center, front right, surround left, surround right, and a “low frequency effects” channel for subwoofers.
- Dolby Digital EX
Extended version of the Dolby Digital surround sound format, with 6.1 channels. The extra channel is a matrixed rear surround channel positioned at the rear of the room, behind and between the left and right surrounds.
- Dolby Digital Plus
New version of the Dolby Digital surround sound format designed for high-definition DVDs, offering high-bit rate performance for up to 7.1 discrete channels.
- Dolby Digital TrueHD
New version of the Dolby Digital surround sound format designed for high-definition DVDs, offering lossless encoding for up to 7.1 discrete channels of 24-bit/96KHz audio.
- Dolby Pro Logic
The predecessor to Dolby Digital, with only four channels: front left, front center, front right, and a single “surround” channel. The single surround channel is typically sent to two or more rear speakers. Dolby Pro Logic channels are matrixed into a left and right output, whereas Dolby Digital uses six discrete outputs.
- Dolby Pro Logic IIx
A newer version of Dolby Pro Logic that, in addition to traditional Pro Logic decoding, also creates virtual surround channels from standard two-channel sources.
- DSP
Digital signal processing, computer-based circuitry used in some surround sound receivers that creates different simulated sound fields.
- DTS
Digital Theater Systems, a 5.1 surround sound format that competes with Dolby Digital.
- DTS ES
A 6.1 version of DTS surround sound; the extra channel is a discrete rear surround positioned behind and between the left and rear surrounds.
- DTS-HD
New version of the DTS surround sound format designed for high-definition DVDs, offering an unlimited number of discrete channels with lossless encoding.
- DTS:Neo 6
A matrix surround sound system from Digital Theater Systems that can feed up to six speakers—front left, front center, front right, surround left, surround right, and subwoofer. Like Dolby Pro Logic IIx, it can also create virtual surround channels from standard two-channel sources.
- DTV
See digital television.
- DVD
An audio/video laser-based disc format with storage capacities ranging from 4.7GB to 17GB.
- DVD-Audio
An audio-only DVD format that delivers better-than-CD quality sound; it competes with SACD.
- DVD-R
DVD-Recordable; DVD discs that can be recorded (once) by home DVD recorders. There are actually two types of DVD-recordable discs—DVD-R and DVD+R, both of which work in similar fashion but are largely incompatible with each other.
- DVD-RW
DVD-Rewritable; DVD discs that can be recorded several times by home or computer-based DVD recorders. There are actually two types of DVD-rewritable discs—DVD-RW and DVD+RW, both of which work in similar fashion but are largely incompatible with each other.
- DVI
Digital video interface; a type of video connection that carries the signal in pure digital format. There are three types of DVI connections—DVI-D (digital-to-digital, used in most home theater set-ups), DVI-A (digital-to-analog), and DVI-I (capable of carrying either digital-to-digital or analog-to-analog signals).
- DVR
Digital video recorder, a device that records programming digitally on a large hard disk. Also known as a personal video recorder (PVR) or hard disk recorder.
- dynamic range
The difference between loud and soft sounds.
E–F
- EDTV
Enhanced definition television, with 480p resolution.
- EPG
Electronic program guide, an onscreen listing of television, cable, or satellite programming for several days at a time.
- field
When using interlaced scanning, half of a frame of picture information.
- flat-panel display
One of several technologies that provides a video display on a flat, thin screen. Today’s most popular flat-panel displays utilize either LCD or plasma technology.
- FPTV
Front projection television, a video display device that projects a picture onto the front of a separate screen.
- frame
One single still image that, when played in rapid succession with other frames, creates a moving picture.
- frequency response
The range of frequencies accurately reproduced by a particular component; the wider the range, the better.
G–H
- hard disk recorder
See DVR.
- HD DVD
One of two competing high-definition DVD formats, with a storage capacity of up to 30GB for a dual-layer disc.
- HDMI
An advanced form of connection that carries both audio and video signals in digital format. HDMI cables can carry up to 8 channels of digital audio, in addition to the digital video signal.
- HDTV
High-definition television, a subset of the new digital TV standard that reproduces pictures in either 780p or 1080i resolution, with a 16:9 aspect ratio and Dolby Digital 5.1 surround sound.
- home theater
The attempt to reproduce, as accurately as possible, the experience of watching a film in a movie theater. It typically involves a high-quality video source (such as DVD), an audio/video receiver, surround-sound speakers, and a large video display device.
- home theater PC
See Media Center PC.
- horizontal resolution
The sharpness of a video display, measured in terms of horizontal lines that can be resolved from one side of the screen to the other. Broadcast television has a horizontal resolution of 330 lines; DVDs deliver 500 lines; and HDTV can deliver up to 1,080 lines of horizontal resolution.
- Hz
Hertz, a unit of measurement for the frequency of sounds. 1Hz is equal to one cycle per second, and the range of human hearing is typically 20Hz–20,000 Hz.
I–J
- infrared
An area in the electromagnetic spectrum with a wavelength greater than visible light. Commonly used in handheld remote control devices.
- interlaced scanning
A method of displaying television pictures in which the picture is displayed in two halves (one of odd-numbered lines, one of even-numbered lines) that are interlaced together to create the full picture.
- IR
See infrared.
K–L
- LCD display
A type of flat-panel display comprised of multiple liquid crystal display (LCD) devices.
- LCD projector
A type of microdisplay device that generates a picture using a liquid crystal display, which is then projected through a magnifying lens.
- LCoS
Liquid crystal on silicone; a type of microdisplay technology used in some rear projection TVs, utilizing an LCD-like component.
- learning remote
A handheld remote control that can “learn” commands from other remotes.
- letterbox
A method of displaying an entire wide-screen image on a narrower screen, using black bars above and below the picture.
- LNB
Low noise blocker; a small amplifier located on the arm of a satellite dish that receives digital satellite transmissions.
- luminance
The brightness or black-and-white component of a color video signal; determines the level of picture detail.
M
- Media Center PC
A personal computer designed for home theater use, typically running the Microsoft Windows XP Media Center Edition operating system.
- microdisplay
A miniature device used to generate pictures in some projection television systems. Today’s microdisplay devices use DLP, LCoS, and LCD technologies.
- MiniDV
Digital video recording format for camcorders that uses an ultra-small cassette.
- MPEG-2
The method of compressing digital video signals used by DVDs, digital broadcast satellites, and digital and high-definition television.
- MPEG-4
A newer, more efficient system of compressing video signals.
N–O
- NTSC
National Television System Committee, the industry group that established the current North American analog broadcast TV standard. It sometimes refers to the standard itself.
- optical digital
A type of audio connection that transmits digital signals via fiber-optic cable.
- OTA
Over-the-air television broadcast signals.
P–Q
- PAL
The European broadcast standard.
- pan-and-scan
A technique used to display the most important parts of a wide-screen image on a narrower 4:3 ratio screen. The name comes from the panning and scanning necessary to keep the focus on the most important part of the scene, which is not always in the direct center of the picture.
- PIP
Picture-in-picture, the display of a second picture in a small window within a larger picture.
- pixels
The individual picture elements that make up a video image.
- plasma display
A flat-panel video display that uses plasma gas to “light up” individual pixels in a picture.
- POP
Picture-outside-picture, the display of a second picture in a small window outside the main picture. Typically used on wide-screen displays.
- Preamplifier
A component that controls or switches the various inputs from audio and video sources.
- Progressive scanning
A method of displaying television pictures in which the picture is displayed in a single pass, instead of the two fields used with interlaced scanning. A progressively scanned picture more accurately reproduces fast action and minimizes the visibility of flicker and scan lines.
- Programmable remote
A handheld remote control that can be programmed to perform multiple-component operations, typically via creating multiple-step macros. Many programmable remotes also enable the creation of custom buttons and pages on an LCD touch screen display.
- PVR
Personal video recorder. See DVR.
R
- RF
Radio frequency; any frequency within the electromagnetic spectrum associated with the propagation of radio waves (approximately 10KHz–100MHz).
- receiver
A component that combines a preamplifier, an amplifier, and radio in a single chassis. Receivers that include inputs and outputs for video sources and display are called audio/video receivers.
- resolution
The measurement of picture detail, typically measured in terms of horizontal lines that can be seen or resolved on a display. See also horizontal resolution.
- RPTV
Rear projection television, a video display device that uses CRTs or microdisplay devices to project a picture onto the back of a translucent screen.
S
- SACD
Super-audio CD; a new CD-based format that delivers better-than-CD quality sound. It competes with DVD-Audio.
- scan lines
The horizontal lines, scanned one after another, that comprise the picture on a video display. (Don’t confuse it with horizontal resolution, which measures the visible number of lines in a display.)
- SDTV
Standard definition television; the current 480i broadcast standard.
- signal-to-noise ratio
A measure of the content portion of an audio or video signal in relation to the noise contained in the signal, expressed in decibels (dB). A higher S/N ratio indicates a quieter or less noisy signal. As an example, VHS VCRs have S/N ratios in the 40 dB range, whereas DVDs have S/N ratios approaching 65 dB.
- subwoofer
A speaker specially designed to reproduce a range of very low frequencies—typically 20Hz–200Hz. Subwoofers are commonly used in home theater systems to enhance the reproduction of low bass in movie soundtracks.
- surround sound
The experience of being surrounded by sound from a video or an audio source. This is typically achieved with a surround sound decoder and multiple speakers.
- S-VHS
Super VHS, a variation on the standard VHS format that delivers sharper pictures (400 lines of resolution versus 240 lines for standard VHS).
- S-Video
A four-pin connection that transmits the chrominance (color) and luminance (brightness) portions of a video signal separately, for improved color accuracy and reduced distortion.
T
- THD
Total harmonic distortion, a measurement of the noise generated by an amplifier or a receiver. The lower the number, the better.
- THX
A set of high-fidelity standards, above and beyond the Dolby Digital standard, for both home theater equipment and prerecorded programming.
- timeshift
The process of recording a television program for viewing at a later time.
- TiVo
One of the most popular DVR services.
- tweeter
A small, lightweight driver within a speaker enclosure that reproduces the highest musical frequencies.
U–V
W–X–Y–Z
- Watt
In terms of audio equipment, a measurement of an amplifier’s output power.
- Wi-Fi
Wireless Fidelity; the IEEE 802.11 standard for wireless networking.
- widescreen
A picture with an aspect ratio wider than 4:3 or 1.33:1.
- window pane
A method of displaying a 4:3 ratio picture on a 16:9 ratio screen, using black bars on either side of the picture.
- Windows XP Media Center Edition
The operating system and interface used by many Media Center or home theater PCs.
- woofer
A driver within a speaker enclosure that uses a large cone to reproduce bass frequencies.