Resources - Level Audio Video

Glossary

Aspect Ratio: The width-to-height ratio of a visual image. Standard television sets have an aspect ratio of 4:3 (1:33:1). Widescreen television sets (and HDTV sets) have an aspect ratio of 16:9 (1:78:1)

Banana Jack: A small tubular connector found on A/V receivers and power amplifiers for connecting speaker cables terminated with banana plugs.

Banana Plugs: Use these instead of bare wire at the end of your speaker cables for convenient plug-in speaker (high-level) connections between your A/V receiver's speaker output terminals and your loudspeakers. No improvement in sound quality over bare wire. Virtually all 5-way binding posts on newer speakers and subwoofers accept either single or dual banana plugs. Many A/V receivers' speaker outputs also accept banana plugs if there is enough space. Note: Banana plugs won't work with older speakers' and receivers' plastic spring "push" connectors, which accept only bare wire.

Bass: Sounds in the low audio range, generally 20Hz-300Hz.

Big Screen: A large-screen direct-view television set or rear-projection set. Usually reserved for sets with diagonal dimensions greater than 40”.

Blu-ray: A new High Definition video disc standard that is not compatible with existing DVD players. This type of disc will not play on a conventional DVD player; however, a Blu-ray or HD-DVD player will play conventional DVDs with the existing video quality.

Center Channel Speaker: The speaker in a home theatre system located on top of, beneath, or behind the visual image; reproduces center-channel information such as dialog and other sounds associated with onscreen action.

CRT (cathode-ray tube): The familiar heavy glass "picture tube" common to TV displays.

Coaxial Cable: Standard 2-conductor shielded cable comprised of an outer woven metal shield (the ground connection) covered with plastic/nylon insulation and further insulated from the inner "hot" or positive wire. Used with RCA male plugs on each end for routing low-level analog audio signals from CD players, DVD players, cassette decks, set-top TV converter boxes, and satellite receivers to A/V receivers and amplifiers. The RCA plugs are often color-coded red for Right channel and white (or black) for Left. Also used for composite video connection (color-coded yellow) and may be used for digital coaxial audio connection as well. Coaxial audio cable is also used between the A/V receiver's subwoofer output jack (color-coded purple) and the subwoofer line-in connection.

Component Video: Used for both Standard-quality video and High Definition video, it uses three coaxial cables with RCA male plugs color-coded red, green and blue (the three cables may be wrapped together for convenience) to carry analog Standard or High-Definition video between a set-top satellite or cable-TV box to the A/V receiver and TV display or projector. Most new A/V receivers include component video inputs and outputs that let you switch between different video sources. Component video cables do not carry audio signals. You must connect separate audio cables (either analog or digital) to carry the sound portion of DVD and cable/satellite TV signals. Component video connections deliver the best picture quality other than HDMI or DVI connectors.

Composite Video: A single video connector that combines all the color and brightness signals into one cable (hence "composite") using a single RCA male connector. Often color-coded yellow, it is the most common type of analog video connection between older VCRs and TVs (except for RF connectors). Use composite video only if your TV, VCR or DVD player lacks S-video or component video connectors. Composite video will not carry High Def or progressive-scan video signals.

DLP (digital light processing): A TV projection technology that uses a light source (projector bulb) bounced off the surface of a tiny chip, a digital micro-mirror device (DMD) whose surface is covered by many thousands of tiny, moveable mirrors. Maintenance-free and capable of bright, high-contrast images with good blacks and rich color.

Dolby Digital 5.1 (DD 5.1): This digital surround format delivers up to 5.1 channels of sound. Used throughout the world as the standard soundtrack format for DVDs and High Definition TV as well as for the vast majority of movie soundtracks. All six channels are carried on one digital coaxial cable or optical digital link from the DVD player to the AV receiver. Dolby Digital may also be used for as few as 2 channels, in which case it's DD 2.0. Not all movies are mixed in 5.1 channels.

dts (Digital Theater Sound): A rival digital soundtrack format to Dolby Digital that is an option on some DVDs. Also used in many movie theaters. It is not a required standard for DVD soundtracks but may be included at the option of the producer. Virtually all DVD players and A/V receivers will decode dts or Dolby Digital soundtracks.

Dolby Pro Logic: A type of Dolby Surround decoder with improved performance over standard Dolby Surround decoding. Specifically, Pro Logic decoding provides greater channel separation and a center speaker output. A Dolby Pro Logic decoder takes in a 2-channel, Dolby Surround encoded audio signal and splits those signals up into left, center, right, and surround channels. Nearly all A/V receivers and A/V controllers include Dolby Pro Logic decoders.

Dolby Pro Logic II (DPLII; DPLIIx): Introduced in late 2001, Pro Logic ll provides superior decoding of 2-channel music and film sources compared with Pro Logic.

DVD-Audio: A high-resolution multi-channel audio format that uses six or eight shielded RCA coaxial audio cables (sometimes bundled together) to carry analog surround-sound output from a DVD player capable of DVD-Audio playback. Many new A/V receivers have a six or eight-channel Multichannel analog input set that accepts the multichannel analog audio output of DVD-Audio or SACD players. Don't confuse DVD-Audio with the usual Dolby Digital 5.1-channel or dts digital surround soundtrack of DVDs. DVD-Audio discs are playable only on Universal DVD players.

DVI (Digital Visual Interface): A large computer-like 18-pin connector that carries digital video signals, including High Definition signals, between a set-top HD cable or satellite box or DVD player and an HDTV set. DVI digital video signals are protected by HDCP (High-bandwidth Digital Content Protection) protocol, which prevents you from copying high-quality digital video. DVI is gradually being replaced by smaller HDMI connectors (see below). DVI/HDMI adaptors are available, and many HDTV displays and projectors have both types.

DVR (digital video recorder): An outboard video recorder often supplied by cable TV or satellite TV systems which use a large-capacity hard drive to record and store video programs, either in Standard Definition or High Definition along with the digital audio surround soundtracks. Often integrated with the cable-TV HD tuner or satellite tuner.

Fiber-Optic (also called Toslink): A thin plastic or glass-fibre cable that carries digital audio signals in an optical format via pulses of light. Uses a small, square plastic male connector on each end. Most modern A/V receivers and DVD players have both Toslink optical digital as well as coaxial digital audio connectors. No difference in sound quality between optical or coaxial digital connections, but optical links are not susceptible to hum or interference.

Front Projector: A video display device that projects an image from a distance onto a separate screen.

Full-Range Speaker: A speaker that reproduces bass as well as midrange and treble frequencies.

HD-DVD: A new High Definition videodisc standard that is not compatible with existing DVD players. A rival standard, Blu-ray (see above) developed by Sony is currently engaged in a format "war" to decide which will become the High Definition video disc standard. Capable of delivering spectacular HD image quality on HDTV displays. This type of disc will not play on a conventional DVD player; however, a Blu-ray or HD-DVD player will play conventional DVDs with the existing video quality.

HDMI (High-Definition Multimedia Interface): Much smaller and more convenient than DVI, HDMI is a USB-like digital video connector that carries the same digital video signals as DVI (High Definition and Standard Definition) but with the added advantage of conveying a Dolby Digital surround sound bit stream. No image superiority of one over the other. May or may not produce a slightly better picture quality than component video.

HDTV (High-Definition TV): The new digital TV standard that features increased horizontal and vertical resolution, a choice of progressive or interlaced scanning, and a widescreen aspect ratio of 16:9 (the ratio of a screen image's width to its height) that conforms to the widescreen visual format of modern movies (older analog TVs have a squarish-looking 4:3 aspect ratio). The most common HD formats are either 720p (720 progressively scanned lines) or 1080i (1080 interlaced scanned lines) or some variation of these. DVDs, although digital, are Standard Definition (480i), which may be displayed as 480p. Some of the latest HD video displays are capable of 1080p clarity, a slight improvement over 720p or 1080i.

Home Theatre: The combination of high quality sound and video in your home.

Impedance: Resistance to the flow of electrical current.

Infrared (IR): The frequency of light used in remote controls.

IR Repeater: A pair of devices called an IR sensor and IR flasher that together relay IR commands from a remote control to components hidden from the remote control’s view.

Jack: Any female receptacle of an audio or video connector into which the plug, or male connector, is inserted. All connectors have male and female components, RCA plugs and jacks historically being the most common on consumer-grade audio/video equipment. Sometimes the terms jacks and plugs are used interchangeably.

Keystoning: A picture distortion in front projectors in which the top or bottom of the picture is narrower than the opposite edge.

LCD: Liquid Crystal Display, a technology for displaying text or images. Light is projected through arrays of crystals that either pass or block light, according to the signal driving the panels.

LCD Projector: A projector using three LCD panels and an incandescent light source.

LCoS (liquid crystal on silicon): Similar technology to liquid-crystal display (LCD) but uses a light source reflected from the LCD panel rather than shining through it. Also known as D-ILA (direct-drive image light amplifier). Capable of performance comparable to DLP and LCD display.

Letterbox: A video image that results from displaying an image of widescreen aspect ratio on a television set of standard aspect ratio. The picture is presented between black bars above and below the image. Contrast with window box.

Main Channels: In a 5.1-channel surround system, the front left, center, and right channel speakers. In a stereo system, the front left and right speakers.

Mini-jack, mini-plug: A miniature connector, in mono and stereo versions, commonly found on portable audio equipment for headphone and line-out connections. Rare on A/V gear except for "trigger" outputs and inputs that are used to remotely activate electric screens, separate power amplifiers and subwoofers in elaborate custom home theatres and installations.

Multi-Room: A feature on some A/V products that lets you listen to two different sources in two different rooms.

Peak: A short-term, high-level audio signal.

Pixel: The smallest element in a displayed video image. Image resolution is measured in pixels; the greater the number of pixels, the higher the resolution.

Plasma Display Panel: A thin-panel video display that uses a huge array of tiny cells filled with ionized gas (plasma) which activates each cell's color phosphor. Viewable over a wide angle and capable of a brilliant image even in brightly lighted rooms. Has good contrast but tends to use more power than other types of video displays.

RCA Connector: By far the most common small audio or video connector used on consumer audio/video equipment, with a pin (male) plug and female jack. Uses 2-conductor shielded coaxial cable

RGB: A video transmission format similar to component video. Carried on three cables.

RGB/HV: A video transmission format similar to component video, but with the horizontal (H) and vertical (V) synchronization signals carried on separate cables. Carried on five cables.

RG-6 Coaxial Cable: A higher quality version of RG-59.

RG-59 Coaxial Cable: A type of cable that carries television or cable-TV signals.

Rear-Projection TV (RPTV): A video display device, using three CRT tubes mounted inside a cabinet that projects its image off a mirror onto a screen mounted at the cabinet front.

Receiver: An audio component with a built-in radio tuner that will receive radio broadcasts on FM or AM, switch different audio sources, as well as amplify the audio signals for delivery to loudspeakers.

Resolution: The quality of an audio component that reveals low-level musical information; the amount of fine detail in a video display or video source.

SACD (Super Audio Compact Disc): A high-resolution digital multi-channel audio standard that uses DSD (Direct Stream Digital) audio encoding. You'll need a bundled, shielded 6-cable RCA connector set to play back SACD to the A/V receiver as well as an SACD-compatible DVD player. Most inexpensive DVD players will not play SACD or DVD-Audio discs. Only "Universal" DVD players will play these formats as well as conventional DVDs and CDs.

SD: A digital video interface that can carry standard-definition video signals, but not high definition. Used primarily on the outputs of DVD players.

SDTV: Standard-definition digital TV, defined as a 480i signal (480 interlaced scan lines) presented 30 times per second. This is the standard of resolution for all conventional DVDs. Many DVD players may be set to output "progressive scan" 480p signals, which remove the scanning lines producing a smoother film-like picture.

Satellite Speaker: A small speaker with limited bass output, designed to be used with a subwoofer.

Shielded Loudspeaker: A loudspeaker lined with metal to contain magnetic energy inside the speaker. Shielded loudspeakers are used in home theatre because the speaker’s magnetic energy can distort a video monitor’s picture.

Source Component: A/V components that provide audio and video signals to the rest of the home theatre system. VCRs, laserdisc players, DSS dishes, and DVD players are source components.

Source Switching: Function performed by an A/V receiver or A/V controller that selects which source component’s signals are fed to the speakers and video monitor.

Speaker Cable: Available in various gauges or wire thickness, designated by "AWG" followed by a number e.g., AWG12 is 12-gauge speaker cable. The lower the number, the thicker the cable and the less resistance there is to the passage of amplified audio signals (AWG12 is thick; AWG18 is fairly thin) from you're A/V receiver or amplifier. All speaker cable is 99.9% oxygen-free copper. You'll need one 2-conductor cable for each speaker in your home theater system, except the subwoofer. A 5.1-channel system will require five separate speaker cables plus a single coaxial cable for the subwoofer (see Coaxial, above); a 7.1-channel system, seven cables plus a single coaxial sub cable. Choose the speaker cable gauge by the length of the cable run from the receiver/amplifier to the speaker. For runs up to 20 feet, 14-gauge is fine. Use 12-gauge speaker wire for long runs up to 60 feet. Good generic speaker cable can be purchased in bulk. Speaker cable does not impart musical qualities to the movement of electrons. All copper cables of sufficiently thick gauge sound identical.

Subwoofer: A speaker designed to reproduce only very deep bass frequencies from 100 Hz to 20 Hz or lower. Usually contains its own dedicated amplifier. It is the ".1" channel of Dolby Digital 5.1 and dts surround formats.

Surround Channels: A sound field that is 3-dimensional, intended to envelop the listener, rather than a stereo soundstage mainly in front of the listener. Normally achieved with two discrete surround speakers placed (ideally) to each side of the listening area, used to convey ambient sound effects, special effects and musical enhancement for Dolby Digital 5.1 and dts surround soundtracks. Many Dolby Digital and dts decoders in modern A/V receivers will extract and simulate two additional Back or Rear surround channels for 6.1-channel and 7.1-channel surround setups.

S-Video: A small multi-pin connector cable that carries the chrominance (color) and luminance (brightness) video information separately. Not capable of carrying HD video signals but superior in picture clarity to composite video connections. Use this connector for better image quality if your TV, A/V receiver or VCR has S-video inputs and outputs.

1080i: Pronounced ten-eighty interlace or ten-eighty eye. HDTV format in which 1080 scanning lines are presented in interlaced format.

1080p: Stands for 1080 progressive. It means that a video display or video source has the capability to display a high-definition video image made up of 1080 horizontal “lines” progressively scanned from the top to the bottom of the screen.

Throw Distance: The distance between a front projector and the screen.

Tweeter: A speaker driver designed to reproduce treble signals.

2-Way Speaker: A loudspeaker that splits the frequency spectrum into two parts (bass and treble) for reproduction by two or more drivers.

Widescreen: A video display or projected image with an aspect ratio wider than 1.33. Widescreen TVs have an aspect ratio of 1.78 also expressed as 16:9.

Window box: A video image that results from displaying an image of standard (1.33) aspect ratio on a television set of widescreen (1.78) aspect ratio. The picture is presented between black bars to the left and right sides of the image. Contrast with