Glossary of Terms

Glossary of terms heading

Technology terminology can sometimes sound like a second language. Peruse the glossary below and broaden your audio/video vocabulary.

Audio Terms

A

  • Active crossover

    Uses active devices (transistors, IC’s, tubes) and some form of power supply to operate.

  • Active Subwoofer

    A speaker designed specifically to reproduce low frequencies only, with a built-in amplifier.

  • Analog

    A continuous movement that takes time to change from one position to another. Standard analog audio signals have an infinite number of levels between their highest and lowest value. (Note: a Digital audio signal represent only two steps: on or off or binary’s one or zero.)

  • Analog-to-Digital Converter

    This electronic device, often referred to as A/D, converts analog signals to digital signals. (Note: a Digital-to-Analog Converter (DAC or D/A) performs the reverse function.)

B

  • Balanced audio

    A method of interconnecting audio equipment using balanced lines. This type of connection reduces the susceptibility to external noise. Balanced connections use three-conductor connectors, usually the XLR connector, with a positive, negative, and ground connection. Audio doesn't travel on the ground or shield connections resulting in lower background noise.

  • Bi-Amplification

    Uses an electronic crossover, or line-level passive crossover, and separate power amplifiers for the high and low frequency loudspeaker drivers.

  • Bit rate

    Bitrate is a measure of data throughput in a given amount of time. Simply put, it's the number of bits that are processed every second. For example, the audio data in an MP3 file which has been encoded with a constant bitrate (CBR) of 128kbps will be processed at 128,000 bits every second. For audio that has been encoded at a variable bitrate (VBR), the displayed value is an average. As a general rule, the higher the bitrate used, the better the sound will be when playing back a lossy audio format. To put digital audio compression into perspective when we talk about bitrates, a standard audio CD which contains uncompressed audio data has a bitrate of 1,411 Kbps -- this is far higher than the best bitrate for MP3s (320 kbps).

C

  • Ceiling Surround Channel/Speaker

    A speaker that mounts in your ceiling and uses its height as a surround channel decoded from the front and rear channels. Its algorithm is similar to that of how center channel audio is extracted and steered front the front left and right signals.

  • Center Channel/Speaker

    The front center speaker, placed between the left and right front speakers. Its primary function is to carry dialogue (movies), but it also carries other sounds, such as that accompanying video movement from one direction to another. It is, therefore, recommended that the center channel be of similar type and timbre as front left and right speakers and to be driven by similar amplification as well for the best clarity.

  • Circle Surround

    This is a multi-channel surround effect produced from two channel sources, using ambient information stored in a stereo recording, a stereo recording encoded for surround, and recordings specifically encoded in Circle Surround. The surround sound information sent to the surround speakers is stereo, as opposed to the monaural approach of Dolby Pro Logic. Circle Surround creates a believable front sound stage, apportioning the stereo signal across three front channels.

  • Clipping

    Distortion of a signal by its being chopped off. An overload problem caused by pushing an amplifier beyond its capabilities. The flat-topped signal has high levels of harmonic distortion which creates heat in a loudspeaker and is the major cause of loudspeaker component failure.

  • Coaxial

    1: A speaker with one driver in front of (and on the same axis of) another driver. 2: An audio or video cable with a single center pin that acts as the "hot" lead and the outer shield acts as the ground.

  • Coloration

    Any change in the character of sound, such as the overemphasis on certain tones, that reduces naturalness.

  • Cone

    Typical shape of a speaker driver.

  • Contrast

    Contrast ratio is the difference between the brightest and the darkest colors that a video display can reproduce. High contrast ratios deliver whiter whites and blacker blacks and a greater degree of shades in between. If the contrast ratio is low, even if the image is bright, ther image will look washed out.

  • Crossover

    An electrical circuit that divides a full bandwidth signal into the desired frequency bands for the loudspeaker components. Crossovers are also commonly built into amplifiers and equalizers.

  • Crossover Network

    Following final amplification in a sound-reproduction system, an outboard circuit facilitates delivery of high- and low-frequency (AF) components to correct drivers in a speaker array. (Passes correct sounds to correct speakers.)

  • Crossover Point

    The frequency that appears in two adjacent outputs of a crossover (such as high and mid) at the same level. For example, if a two-way crossover is set for a crossover point of 100 Hz, a 100 Hz signal will be a the same level in both the high-pass and low-pass output.

D

  • Damping

    Of or pertaining to the control of vibration by electrical or mechanical means.

  • Damping Material

    Any material added to the interior of a speaker enclosure to absorb unwanted sound and reduce out-of-phase reflection to the driver diaphragm.

  • Decibel (dB)

    A numerical expression of the relative loudness of a sound. The difference in decibels between two sounds is ten times the Base 10 logarithm of the ratio of their power levels. Defined as one-tenth of a Bel (named after Alexander Graham Bell), this logarithmic ratio is used to measure power, sound pressure level or voltage. A 3dB loss or increase is considered an attenuation or augmentation of half or double its original value; 0dB is the threshold of hearing; 120dB is the threshold of pain. A 3dB loss or increase is considered an attenuation or augmentation of half or double its original value; 0dB is the threshold of hearing; 120dB is the threshold of pain.

  • Diaphragm

    A thin flexible membrane or cone that vibrates in response to electrical signals to produce sound waves.

  • Diffraction

    The breaking up of a sound wave caused by some type of mechanical interference such as a cabinet edge, grill frame or other similar object.

  • Dispersion

    The degree of sound that is spread over a listening area.

  • Distortion

    Usually referred to in terms of total harmonic distortion (THD) which is the percentage of unwanted harmonics of the drive signal present with the wanted signal. Generally used to mean any unwanted change introduced by the device under question.

  • Dolby Atmos surround sound

    Dolby Atmos supports up to 128 uncompressed audio tracks and up to 64 unique speaker feeds. In addition to playing back a standard 5.1 or 7.1 mix, the Dolby Atmos system can also give each loudspeaker its own unique feed based on its exact location, thereby enabling ceiling-mounted height channels for the precise panning of select sounds such as a helicopter or rain.

  • Dolby Digital surround sound

    Dolby Digital contains up to six discrete channels of sound. The most elaborate mode in common use involves five channels for normal-range speakers (20 Hz – 20,000 Hz) (right, center, left, right surround, left surround) and one channel (20 Hz – 120 Hz allotted audio) for the subwoofer driven low-frequency effects.

  • Dolby TrueHD surround sound

    Dolby TrueHD, is an advanced lossless audio codec based on Meridian Lossless Packing. Dolby TrueHD supports 24-bit, 96 kHz audio channels at up to 18 Mbit/s over 14 channels (Blu-ray Disc standards currently limit the maximum number of audio channels to eight). It supports metadata, including dialog normalization and Dynamic Range Control.

  • Dome

    A type of speaker driver shape usually used for tweeters (convex, not concave).

  • Driver

    A speaker without an enclosure.

  • DSD

    Direct-Stream Digital (DSD) is the trademark name used by Sony and Philips for their system of digitally recreating audio. DSD uses pulse- density modulation encoding - a  technology to store audio signals on digital storage media. The signal is stored as delta-sigma modulated digital audio; a sequence of single-bit values at a sampling rate of 2.8224 MHz (64 times the CD Audio sampling rate of 44.1 kHz)

  • DTS (Digital Theater Sound)

    This originated as a digital 5.1 surround scheme developed for the movies by MCA/Universal and Steven Spielberg. DTS was first employed in Spielberg’s Jurassic Park film (Summer 1993). DTS Coherent Acoustics Coding (CAC) maps discrete 6-channel, 20-bit encoded data onto the 16-bit PCM digital audio stream, which is found on either a laserdisc or compact disc. DTS' CAC signal is passed via the digital output (either coaxial or optical) present on many laserdisc, CD and DVD players. (Note: While Dolby Digital uses perceptual coding to reduce the bit rate, DTS uses compression technology and the CAC algorithm with a higher bit rate than Dolby Digital.) The compression ratio is 3.75:1 of a 20-bit PCM digital audio stream with an eight times oversampling rate. It has a typical data rate of 1,411kBps (as opposed to 384kBps of Dolby Digital). The CAC algorithm is a scaleable digital coding methodology which operates on a multirate filterbank. It has been designed to filter the audio signal into frequency bands, which match the critical perceptual bands of the human ear. Within each frequency band, the signals are re-quantified at a variable resolution. This is determined by the available bit-rate and an analysis of the long/short periodicity of the audio signal in each frequency band. Essentially, this allows six channels of transparent quality 24-bit recorded material at 48kHz with less digital compression.

  • Dynamic Range

    The range between the quietest and the loudest sounds a device can handle (often quoted in dB).

E

  • Efficiency

    The acoustic power delivered for a given electrical input. Often expressed as decibels/watt/meter (dB/w/m).

  • Efficiency Rating

    The loudspeaker parameter that shows the level of sound output when measured at a prescribed distance with a standard amount of energy fed into the speaker. Efficiency rating standard is 1-watt at 1-meter and is measured in decibels.

F

  • Flat Response

    The reproduction of sound without alternating the intensity of any part of the frequency range.

  • Frequency

    Audio frequencies are commonly defined as ranging from 20 to 20,000 cycles per second (Hz), assuming that the air pressure 20 or 20,000 times each second can be heard.

  • Frequency Response

    A measure of what frequencies can be reproduced and how accurately they are reproduced.

H

  • Harmonic Distortion

    This is distortion caused when audio equipment adds unwanted overtones to an original signal.

  • Headroom

    The difference, in decibels, between the peak and RMS levels in program material.

  • Hz (Hertz)

    Unit of frequency equivalent to the number of cycles per second. Something that repeats a cycle once each second is moving at a rate of 1 Hz.

I

  • Imaging

    To make a representation or imitation of the original sonic event.

  • Imaging

    The ability to reproduce sound so accurately that listeners can imagine the sound sources (such as musicians) sharply, clearly, accurately and their correct placement in a recording.

  • Impedance

    The total opposition offered by an electric circuit to the flow of an alternating current of a single frequency. It is a combination of resistance and reactance and is measured in ohms. Remember that a speaker’s impedance changes with frequency, it is not a constant value.

  • Impedance

    A measure of how much something resists (impedes) the flow of electricity. Large numbers mean more resistance. Measured in Ohms.

  • In-Cabinet Speaker

    A self contained speaker designed to be installed into a cabinet (entertainment center) or other enclosure to be concealed from sight. Typically any speaker designed void of aesthetic appeal for the purpose of being concealed.

  • In-Room Speaker

    A self contained speaker designed for the purpose of either floor-standing or to be placed onto a bookshelf or speaker stand.

  • In-Wall Speaker

    Any speaker designed for the purpose of being installed into a wall or ceiling. Typically uses the wall cavity as the enclosure unless noted as a "self-contained" in-wall, in which case it has a full enclosure.

k

  • kHz

    One thousand Hz; 1 kHz equals 1,000 Hz and 20 kHz is 20,000 Hz.

M

  • Meridian Lossless Packing

    Meridian Lossless Packing, also known as Packed PCM is a proprietary lossless compression technique for compressing PCM audio data developed by Meridian Audio, Ltd. Dolby TrueHD, used in Blu-ray, employs MLP, but adds higher bit rates, 8 full-range channels, extensive metadata, and custom speaker placements.

  • Midbass

    The middle of the bass part of the frequency range, from approximately 50 to 100 Hz (upper bass would be from 100 to 200 Hz). Also drivers designed and used produce both bass and midrange frequencies.

  • Midrange

    The middle of the audio frequency range, from approximately 200 to 3,150 Hz. A "midrange driver" typically produces the "voice" or vocals in music or cinema.

  • MP3

    The MP3 compression format creates for audio creates digital files that don't sound exactly like the original recording -- it's a lossy format. In order to decrease the size of the file significantly, MP3 encoders have to lose audio information. Lossless compression formats don't sacrifice any audio information. But that also means that lossless compression files are larger than their lossy counterparts.

O

  • Ohm

    A measure of how much something resists (impedes) the flow of electricity.

  • On-Wall Speaker

    A self-contained (fully enclosed) speaker typically designed with a low-volume (low-profile) enclosure intended to be installed (or hung) onto a wall.

P

  • Passive crossover

    Uses no active components (transistors, IC’s, tubes) and needs no power supply (AC, DC, battery) to operate. The crossover in a typical loudspeaker is of the passive variety. Passive crossovers consist of capacitors, inductors and resistors.

  • Passive Radiator

    An undriven loudspeaker cone that is mounted in a bass-reflex (sealed) enclosure with other, actively driven speakers to aid in the tuning of output.

  • Passive Subwoofer

    A speaker designed specifically to reproduce low frequencies only, which requires a separate amplifier to drive it.

  • Phase

    The amount by which one sine wave leads or lags a second wave of the same frequency. The difference is described by the term phase angle. Sine waves in phase reinforce each other; those out of phase cancel.

  • Polarity

    The condition of being positive or negative with respect to some reference point or object.

R

  • Resistance

    That property of a conductor by which it opposes the flow of electric current, resulting in the generation of heat in the conducting material, usually expressed in ohms.

  • Resonance

     The effect produced when the natural vibration frequency of a body is greatly amplified by reinforcing vibrations at the same or nearly the same frequency from another body.

  • RMS (Root Mean Square)

    A measurement of the continuous power output produced by an amplifier. The higher the RMS number, the cleaner and louder (without distortion) the sound will be. (Note: one of the primary specs on which to base an amplifier purchase.)

S

  • Sampling rate

    In digital audio, sampling rate is the number of times an analog signal is measured (sampled) per second. The unit of sample rate is "samples per second". This is often expressed in kiloHertz (kHz). For example, "CD quality" sound has a sample rate of 44.1 kHz.

  • Sound Field

    A volume of space or material containing sound waves. Commonly refers to the area in which a speakers or speakers direct sound.

  • Soundstage

    The area that seems to be occupied by sonic images. Like a real stage, a soundstage should have width, height and depth.

  • Subwoofer

    A speaker designed and dedicated to reproduce low frequencies (bass) from the .1 LFE Dolby Digital or DTS channel, and/or from the bass received from other channels if their lower frequencies are crossed-over to the sub with a low-pass control. Bass being non-directional, placement of the subwoofer can be anywhere in a listening area. Subs (or woofers) can range in size from five to 18 inches in diameter and come in active or passive applications. Some of these enclosures are ported (with a hole on the side or bottom), which helps to add a thump to bass response.

  • Surround Channels/Speakers

    Typically placed to the sides or rear of listening area, these speakers carry directional effects (Dolby Digital/DTS) or sound field enhancements (Dolby Digital, DTS, Pro Logic, Circle Surround). Surround channels/speakers can also be placed in the rear as an additional center speaker or in the ceiling for added surround effect. Speakers for discrete, full-bandwidth surround formats, like Dolby Digital/DTS, should be capable of handling a full frequency response of 20-20kHz and be sufficiently larger to handle loud passages. Rear surround speakers are either bipole or dipole, by design. Dipoles produce sound from the rear and front speakers out-of-phase from each other. For bipoles, the front and rear speakers are in-phase and sound equal.

T

  • THD

    The abbreviation for total harmonic distortion. (See Distortion)

  • Timbre

    This is the tonal characteristic of a sound determined by its harmonic structure.

  • Transient

    Applies to that which lasts or stays but a short time. A change from one steady-state condition to another.

  • Transient Response

    A term frequently used to describe a driver's (speaker's) time measurement for peak to peak movement; the distance at which a speakers maximum and minimum excursion and incursion begin.

  • Treble

    The higher part of the audio signal range, approximately 3,150 Hz and up.

  • Tweeter

    A speaker driver designed to reproduce very high frequencies, those over approximately 5,000 to 10,000 Hz.

U

  • Unbalanced audio

    An unbalanced cable uses a single center conductor, and the shield, for the audio signal to travel on. Audio travels on the shield of the cable, which means that any interference that the shield picks up, will be inserted on the audio signal. This could come across in any number of audible ways, from hums to radio stations.

W

  • Wavelength

    The distance measured in the direction of progression of a wave, from any given point characterized by the same phase.

  • Woofer

    A speaker driver designed to reproduce low frequencies.

X

  • XLR connector

    Originally designed for professional audio use, XLR audio cable and connectors are used primarily with high-performance audio gear. The connector has three terminals — a positive conductor, a negative conductor, and a ground. See balanced audio

Video Terms

A

  • ADC

    Analogue to Digital converter. A device that converts analog signals into digital signals.

  • Aliasing

    Something other than what it appears to be. Aliases are caused by sampling and can be reduced or eliminated by pre-filtering, which can appear to be a blurring effect. Defects in the picture typically caused by insufficient sampling (violation of the Nyquist sampling rate) in the analog to digital conversion process or poor filtering of digital video. Defects are typically seen as jaggies on diagonal lines and twinkling or brightening in picture detail. Examples are: Temporal Aliasing — such as rotating wagon wheel spokes appearing to rotate in the reverse direction. Raster Scan Aliasing — such as sparkling or pulsing effects in sharp horizontal lines. Stair-Stepping — stepped or jagged edges in diagonal lines or the diagonal parts of a letter.

  • Analog

    A continuous electrical signal that carries information in the form of variable physical values, such as amplitude or frequency modulation. A signal which moves through a continuous range of settings or levels. An adjective describing any signal that varies continuously as opposed to a digital signal that contains discrete levels representing the binary digits 0 and 1.

  • Artifact

    A defect or distortion of the video image, introduced along the sequence from origination and image capture to final display. Artifacts may arise from the overload of channel capacity by excess signal bandwidth. Artifacts may also result from: sampling effects in temporal, spatial, or frequency domains; processing by the transfer functions; compromises and inadequacies in the system employed; cascading of minor defects; basically any other departure of the total system from “complete transparency” resulting in visual errors.

  • Aspect ratio

    Aspect ratio describes the proportional relationship between the width and its height of an image. It is commonly expressed as two numbers separated by a colon, as in 16:9. There are 3 common aspect ratios for video displays; 4:3 (also 12:9 or 1.33:1), 16:9 (1.78:1) and 21:9 (2.35:1)

  • ATSC

    An acronym for "Advanced Televisions System Committee", the organization that defines the standard for high-definition TV in the United States.

  • Automatic Brightness Control

    In display devices, the self-acting mechanism which controls brightness of the device as a function of ambient light.

B

  • Bandwidth

    The range of signal frequencies that a piece of audio or video equipment can encode or decode; the difference between the limiting frequencies of a continuous frequency band. Video uses higher frequency than audio, thus requires a wider bandwidth.

  • Bit

    Short for "Binary Digit". The smallest piece of binary digital data and is represented by either 0 or 1.

  • Bit Depth

    The number of levels that a pixel might have, such as 256 with an 8-bit depth or 1024 with a 10-bit depth.

  • Bit Rate

    a) The rate at which the compressed bit stream is delivered from the storage medium to the input of a decoder. The digital equivalent of analog bandwidth. b) The speed at which bits are transmitted, usually expressed in bit/s (sometimes abbreviated "bps"). video information, in a digitized image for example, is transferred, recorded, and reproduced through the production process at some bit rate appropriate to the nature and capabilities of the origination, the channel, and the receptor. c) The amount of data transported in a given amount of time, usually defined in Mbit/s. Bit rate is one means used to define the amount of compression used on a video signal. The uncompressed D1 format has a bit rate of 270 Mbit/s. MPEG-1 has a bit rate of 1.2 Mbit/s.

  • Blu-Ray

    Blu-ray Disc (BD) is a digital optical disc data storage format designed to supersede the DVD format, in that it is capable of storing high-definition video resolution (1080p). The disc is the same size as DVDs and CDs.

  • Brightness

    The attribute of visual perception in accordance with which an area appear to emit more of less light. (Luminance is the recommended name for the photo-electric quantity which has also been called brightness.)

  • Broadband

    In TV system use, a device having a bandpass greater than the band of a single VHF TV channel.

C

  • Chroma

    The quality of color that embraces both hue and saturation. White, black, and grays have no chroma.

  • Clipping

    An electronic limit usually imposed in cameras to avoid overly bright or dark signals. When improperly applied can result in loss of picture information in very bright or very dark areas; Also used in switchers to set the cutoff point for mixing video signals. The electronic process of shearing off the peaks of either the white or black excursions of a video signal for limiting purposes. Sometimes, clipping is performed prior to modulation, and sometimes to limit the signal, so it will not exceed a predetermined level.

  • Coaxial Cable

    A particular type of cable capable of passing a wide range of frequencies with very low signal loss. Such a cable in its simplest form consists of a hollow metallic shield with a single wire accurately placed along the center of the shield and isolated from the shield.

  • Compression

    a) The process of electronically processing a digital video picture to make it use less storage or to allow more video to be sent down a transmission channel. b) The process of removing picture data to decrease the size of a video image. c) The reduction in the volume of data from any given process so that more data can be stored in a smaller space. There are a variety of compression schemes that can be applied to data of which MPEG-1 and MPEG-2 are called lossy since the data produced by compression is not totally recoverable. There are other compression schemes that are totally recoverable, but the degree of compression is much more limited.

  • Contrast

    The range of light to dark values in a picture or the ratio between the maximum and minimum brightness values.

  • Core Components

    Equipment in the video system that can change the video signal, thereby affecting the quality of the delivered video.

D

  • D-ILA

    D-ILA, or Direct-Drive Image Light Amplification, uses liquid crystal on silicon, or LCOS.

  • Definition

    The aggregate of fine details available on-screen. The higher the definition of an image, the greater the number of details that can be discerned by the human eye or displayed. During video recording and subsequent playback, several factors can conspire to cause a loss of definition. Among these are the limited frequency response of magnetic tapes and signal losses associated with electronic circuitry employed in the recording process. These losses occur because fine details appear in the highest frequency region of a video signal and this portion is usually the first casualty of signal degradation. Each additional generation of a videotape results in fewer and fewer fine details as losses are accumulated.

  • Display

    The ultimate image presented to a viewer; the process of presenting that image.

  • DLP

    DLP (Digital Light Processing) is a technology that uses a digital micromirror device. In DLP projectors, the image is created by microscopically small mirrors laid out in a matrix on a semiconductor chip, known as a Digital Micromirror Device (DMD). These mirrors each represent one pixel in the projected image.

  • DVD

    An acronym for "Digital Versatile Disk". It is the same size as a compact disc (CD). A single layer DVD has a storage capacity of 4.7gb and a dual layer disc has a capacity of 8.5gb.

  • DVI

    Digital Visual Interface (DVI) is a video display interface developed by the Digital Display Working Group (DDWG). The digital interface is used to connect a video source, such as a display controller to a display device, such as a computer monitor.

F

  • Fiber Optics

    Use of light transmitted through fibers. The technology of transferring information, e.g., in communications or computer technology, through thin flexible glass or plastic tubes of optical fibers using modulated light waves.

H

  • HDCP

    HDCP (High-Bandwidth Digital Content Protection) is a copy protection scheme to eliminate the possibility of intercepting and illegally copying digital data between the source and the display. The HDCP 1.0 specification was developed by Intel, with contributions from Silicon Image in February 2000 to protect DVI outputs from being copied by providing a secure digital link between a video source and a display device. HDCP offers authentication, encryption and renewability.

  • HDMI

    HDMI (High-Definition Multimedia Interface) HDMI is a multi-pin connection used for passing standard- and high-definition digital video signals, as well as multi-channel digital audio, through a single cable. HDMI passes uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controller, to a compatible computer monitor, video projector, digital television, or digital audiodevice. Signals are encrypted with HDCP (High-bandwidth Digital Content Protection) to prevent recording.HDMI is a digital replacement for existing analog video standards.

  • HDTV (high-definition television)

    a) General term for standards pertaining to consumer high-resolution TV. b) A TV format capable of displaying on a wider screen (16:9) as opposed to the conventional 4:3 and at higher resolution. Rather than a single HDTV standard the FCC has approved several different standards, allowing broadcasters to choose which to use. This means new TV sets will have to support all of them. All of the systems will be broadcast as component digital.

  • Hue

    Corresponds to colors such as red, blue, etc. A color wheel contains basic pigments. All the hues of the rainbow encircle the cone’s perimeter. The wavelength of the color that allows color to be distinguished such as red, blue and green. Often used synonymously with the term tint. It is the dominant wavelength that distinguishes a color such as red, yellow, etc. Most commonly, video hue is influenced by a camera’s white balance or scene lighting. Video color processors, such as the video equalizer, are the main tools used to adjust and correct hue problems.

I

  • Impedance (input or output)

    The total of the resistance, measured in ohms, that a circuit presents to the flow of alternating current at a given frequency (Columbia University). The characteristics of a system component that determines the type of transmission cable to be used. The cable used must have the same characteristic impedance as the component. Video distribution has standardized on 75-ohm coaxial and 124-ohm balanced cable.

L

  • LCD

    A liquid-crystal display (LCD) is a flat panel display, or video display that uses the light modulating properties of liquid crystals. Liquid crystals do not emit light directly but are arrayed in front of a light source (backlight) to create images.

  • LCOS

    LCOS, or Liquid Crystal on Silicon is like a hybrid of DLP and LCD technologies. A layer of liquid crystal sits on top of a reflective surface. The light created by the lamp reflects off this surface. LCOS designs are able to offer higher contrast ratios than LCD or DLP technologies.

  • Low-Frequency Distortion

    An undesired change in a waveform or signals which occur at low frequencies. In television, generally considered as any frequency below the 15.75-kHz line frequency.

M

  • Megapixel

    The term pixel comes from the phrase picture element. One megapixel is equal to 1,000,000 (one million) pixels. For the most part, the larger number of pixels, the better the quality of the picture.

O

  • OLED

    An OLED (organic light-emitting diode) is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound which emits light in response to an electric current. OLED displays can use either passive-matrix (PMOLED) or active-matrix addressing schemes. Active-matrix OLEDs (AMOLED) require a thin-film transistor backplane to switch each individual pixel on or off, but allow for higher resolution and larger display sizes.An OLED display works without a backlight; thus, it can display deep black levels and can be thinner and lighter than a liquid crystal display (LCD)

P

  • Pixel

    Short for Picture Element. The most basic unit of an image displayed on a computer or video display screen. Pixels are generally arranged in rows and columns; a given combination among the pixels of various brightness and color values forms an image. More pixels in a given area result in a sharper (higher resolution) picture.

R

  • Resolution

    The act, process, or capability of distinguishing between two separate but adjacent parts or stimuli, such as elements of detail in an image, or similar colors. Vertical resolution refers to the number of horizontal black and white lines that can be resolved in the picture height. Horizontal resolution refers to the black and white lines resolved in a dimension equal to the vertical height and may be limited by the video amplifier bandwidth.

S

  • Saturation

    In color, the degree to which a color is diluted with white light or is pure. The vividness of a color, described by such terms as bright, deep, pastel, or pale. Saturation is directly related to the amplitude of the chrominance signal.

  • Standard Minimum Signal

    1000 µV at 75 ohms (0dB µV) in RF systems; 0.7-VPP non-composite, 1-VPP composite in video systems.

  • SXRD

    An OLED display works without a backlight; thus, it can display deep black levels and can be thinner and lighter than a liquid crystal display (LCD). In low ambient light conditions (such as a dark room), an OLED screen can achieve a higher contrast ratio than an LCD, regardless of whether the LCD uses cold cathode fluorescent lamps or an LED backlight.

V

  • Video

    The electronic representation of a sequence of images, depicting either stationary or moving scenes. It may include audio.

  • Video Amplifier

    A wideband amplifier used for passing picture signals.

  • Video Distribution Amplifier

    A device used to divide single video signals, while boosting their strength for delivery to multiple video devices.

General Terms

B

  • Bandwidth

    The range of frequencies that radio, TV, audio and video operate and let pass through. (Note: the wider the bandwidth, the better the A/V quality; the higher the bandwidth, the better the product performs. In a digital circuit, the bandwidth is measured in bits per second or bps.)

C

  • CODEC (Coding/Decoding)

    a) The algorithm used to capture analog video or audio in digital form. b) Used to implement the physical combination of the coding and decoding circuits. c) A device for converting signals from analog to coded digital and then back again for use in digital transmission schemes. Most codecs employ proprietary coding algorithms for data compression.

F

  • Fidelity

    a) The precision of reproduction field. b) The extent to which an electronic device such as a stereo system or television accurately reproduces sound or images.

J

  • Jitter

    Small, rapid variations in a waveform due to mechanical disturbances or to changes in the characteristic of components. Supply voltages, imperfect synchronizing signals, circuits, frequency pulses, etc.

L

  • Loss

    The ratio of the power at one point in a transmission system to the power at a point farther along the line; usually expressed in decibels. The actual power that is lost in transmitting signal from one point to another through a medium or along a line.

M

  • Mbps (Megabits Per Second)

    Abbreviation of megabits per second. One megabit is equal to one million bits or 1,000 kilobits. It is used to measure high data transfer speeds of connections such as Ethernet and cable modems.

P

  • Phono plug

    Also called RCA connector, it is a widely used cable connector for home audio and video equipment.

  • Power

    Should be well-balanced and clean (free of noise or interference) in any audio/video system, for optimum performance. Components experience degradation in power quality when sharing electrical circuits with appliances or other devices. It is recommended that a separate electrical circuit be used for A/V components, as well as the use of an A/C line conditioner/surge protector.

S

  • Streaming

    A low-bit-rate encoding format intended for use over networks and the Internet. Streaming files match the encoded bit rate to the connection speed of the user, so the remote viewer can play audio or video with minimal stoppage without first downloading the entire video file.