Jargon Buster

Acoustic Suspension

A sealed speaker enclosure that uses the air trapped in the cabinet as a reinforcing spring to help control the motion of the woofer(s).

Active:

Powered. An active cross-over is electrically powered and divides the line-level signal prior to amplification. An active speaker includes an active crossover and built-in amplifier.

Amplifier:

A component that increases the gain or level of an audio signal.

Amplifier:

A component that increases the gain or level of an audio signal.

Anamorphic:

Process that horizontally condenses (squeezes) a 16:9 image into a 4:3 space, preserving 25 percent more vertical resolution than letterboxing into the 4:3 space. For the signal to appear with correct geometry, the display must either horizontally expand or vertically squish the image. Used on about two or three promotional laser discs and many DVDs. Also called Enhanced for Widescreen or Enhanced for 16:9.

Aspect Ratio:

The ratio of image width to image height. Common motion-picture ratios are 1.85:1 and 2.35:1. Television screens are usually 1.33:1 (also known as 4:3), which is similar to the Academy standard for films in the '50s. HDTV is 1.78:1, or 16:9. When widescreen movies (films with aspect ratios wider than 1.33:1) are displayed on 1.33:1 televisions, the image must be letterboxed, anamorphically squeezed, or panned-and-scanned to fit the screen.

Balanced Input:

A connection with three conductors: two identical signal conductors that are 180 degrees out of phase with each other, and one ground. This type of connection is very resistant to line noise.

Bandwidth:

In audio, the range of frequencies a device operates within. In video, the range of frequencies passed from the input to the output.

Bass:

Low frequencies; those below approximately 200 Hz.

Cathode Ray Tube:

(CRT) Analogy display device that generates an image on a layer of phosphors that are driven by an electron gun.

Compact Disc. Ubiquitous digital audio format. Uses 16-bit/44.1-kHz sampling rate PCM digital signal to encode roughly 74 or 80 minutes of two-channel, full-range audio onto a 5-inch disc.

Brightness:

For video, the overall light level of the entire image. A brightness control makes an image brighter; however, when it is combined with a contrast, or white level control, the brightness control is best used to define the black level of the image (see Black Level). For audio, something referred to as bright has too much treble or high-frequency sound.

ANSI lumen

A measurement of light that has been standardized by ANSI. It is commonly used to rate the brightness of a data projector. An ANSI lumen rating uses an average of several measurements taken across the face of the light source. A small room typically requires from 1500 to 2000 ANSI lumens, whereas a large room may require from 2500 to 3000. A large auditorium may need 4000 or more.

ANSI

American National Standards Institute.

CD-R

Recordable Compact Disc

CD-RW

Rewritable Compact Disc

Channel:

In components and systems, a channel is a separate signal path. A four-channel amplifier has at least four separate inputs and four separate outputs.

Chrominance:

Coaxial:

1) A speaker typically with one driver in the middle of, and on the same axis as, another driver. 2) An audio or video cable with a single centre pin that acts as the hot lead and an outer shield that acts as a ground.

Component Video:

A signal that's recorded or transmitted in its separate components. Typically refers to Y/Pb/Pr, which consists of three 75-ohm channels: one for luminance information, and two for colour. Compared with an S-video signal, a Y/Pb/Pr signal carries more colour detail. HDTV, DVD, and DBS are component video sources, though most DBS material is transcoded to component from composite signals.

Composite Video:

: A signal that contains both chrominance and luminance on the same 75-ohm cable. Used in nearly all consumer video devices. Chrominance is carried in a 3.58-mHz sideband and filtered out by the TV's notch or comb filter. Poor filtering can result in dot crawl, hanging dots, or other image artefacts.

Contrast:

Relative difference between the brightest and darkest parts of an image. A contrast control adjusts the peak white level of a display device.

Decibel (dB):

): A logarithmic measurement unit that describes a sound's relative loudness, though it can also be used to describe the relative difference between two power levels. A decibel is one tenth of a Bel. In sound, decibels generally measure a scale from 0 (the threshold of hearing) to 120-140 dB (the threshold of pain). A 3dB difference equates to a doubling of power. A 10dB difference is required to double the subjective volume. A 1dB difference over a broad frequency range is noticeable to most people, while a 0.2dB difference can affect the subjective impression of a sound.

Distribution Amplifier:

A device which distributes one video and/or audio source to several video/audio acceptors for simultaneous recording or monitoring. A good quality distribution amplifier amplifies the incoming signal (video and audio), pre-compensates the signal for potential losses (resulting from the use of long cables, for example) and generates several identical buffered and amplified outputs. Distribution amplifiers are mainly used in duplication studios where many copies of a tape must be simultaneously generated from one source. Often, a video processor* is inserted between the source and the distribution amplifier for correction and fine-tuning of the source signal before multiplication, so that all copies are corrected in the same way.

DLP:

Digital Light Processing. A Texas Instruments process of projecting video images using a light source reflecting off of an array of tens of thousands of microscopic mirrors. Each mirror represents a pixel and reflects light toward the lens for white and away from it for black, modulating in between for various shades of grey. Three-chip versions use separate arrays for the red, green, and blue colours. Single-chip arrays use a colour-filter wheel that alternates each filter colour in front of the mirror array at appropriate intervals.

DVD

Digital Versatile Disk (formerly: Digital Video Disk). A recently introduced video media, allowing playback of video and audio from a digitally recorded disk which resembles a CD*. The disk allows playback of a full feature movie of more than 2 hours. MPEG* compression is used for recording. The audio section is digitally recorded as well, with various surround sound schemes, such as Dolby AC3*. The world was divided into several "zones" incompatible with each other. Several different standards exist, similar to PAL and NTSC, and some manufacturers have released Multi-standard / Multi-zone players. Copy protection schemes are built into the DVD player in order to avoid piracy. The single layer DVD capacity is about 4.7 gigabytes and the double layer capacity is 8.5 gigabytes. DVD players are available for the PC as well, which also allow playback of regular data CD-ROMs as well as music CDs. Recordable and rewritable DVD (named DVD RAM or DVD RW) have recently been introduced. Deliberations on the final standard, though already agreed upon by many manufacturers, were reopened recently and therefore, the final format is not yet set. It is not unlikely that several DVD recording formats will co-exist in the future, which will be very confusing for the end users. In DVD, as the signals are recorded digitally, quality is expected to be very high, and fast, random access to any part of a movie will allow fast and easy editing. Once released, the same very high-density media can also be used for computer data recording and archiving.

DVD-R

A recordable DVD format similar to CD-R in that it is a write-once medium. Backed by Pioneer, Panasonic, Toshiba, and others.

DVD+R:

A recordable DVD format similar to CD-R in that it is a write-once medium. Backed by Sony, Philips, Yamaha, HP, and others.

DVI:

Digital Video Interface. Used in Multimedia* applications, where computer generated text and graphics are merged into a video production, for educational, advertising and post-production purposes. The DVI is based on specific chip-sets* designed for this application.

Equalization:

Loosely, any type of relative frequency adjustment. Specifically, the process of changing the frequency balance of an electrical signal to alter the acoustical output.

Equalizer:

A component designed to alter the frequency balance of an audio signal. Equalizers may be graphic, parametric, or a combination of both.

Fibre Optic Cable:

Glass, plastic, or hybrid fibre cable that transmits digital signals as light pulses

FM:

Frequency Modulated.

Frequency:

The number of cycles (vibrations) per second. In audio, audible frequencies commonly range from 20 to 20,000 cycles per second (Hz). In video, frequency is used to define the image resolution. Low-frequency video images depict large objects or images. Higher frequencies depict smaller objects (finer details).

Format (VIDEO)

There is an enormous variety of video formats. They vary in tape width - 4mm, 8mm, 1/2 inch, 3/4 inch, 1 inch, etc.; in signal formats - composite, YC and component video; and in operation - analog or digital. In addition, digital formats themselves take various forms - no single standard prevails. Also, all formats exist in PAL, NTSC and SECAM and their sub-standards, which implies that any video production studio requires an extensive range of interface devices to enable equipment designed for a specific format to work with devices designed for other formats.

Gain:

Increase in level or amplitude.

Graphic Equalizer:

A type of equalizer with sliding controls that create a pattern representing a graph of the frequency-response changes. Raising sliders boosts the affected frequencies; lowering sliders cuts (attenuates) the affected frequencies.

Gray Scale:

The ability for a video display to reproduce a neutral image colour with a given input at various levels of intensity.

HDR:

Hard-Drive Recorder. Device that uses a computer hard drive to store compressed digital audio and video signals.

HDMI:

HDTV connection format using a DVI interface that transfers uncompressed digital video with HDCP copy protection and multichannel audio.

HDTV:

High-Definition Television. The high-resolution subset of our DTV system. The FCC has no official definition for HDTV. The ATSC defines HDTV as a 16:9 image with twice the horizontal and vertical resolution of our existing system, accompanied by 5.1 channels of Dolby Digital audio. The CEA defines HDTV as an image with 720 progressive or 1080 interlaced active (top to bottom) scan lines. 1280:720p and 1920:1080i are typically accepted as high-definition scan rates.

Hi-Fi Stereo:

Feature found on VCRs that records or plays back stereo soundtracks with improved fidelity compared to using the linear stereo tracks.

High Gain Screen:

Material that reflects more light than a reference material. Increases a projector's light output at the expense of uniformity.

Home Theatre in a Box:

A complete home theatre system in one box (or at least sold together as a package). Consists of five or more speakers, a subwoofer, and a receiver. May also include a DVD player.

Hz:

Hertz or cycles per second. Something that repeats a cycle once each second moves at a rate of 1 Hz.

Integrated Amplifier:

A combination preamp and amplifier.

Impedance:

A measure of the impediment to the flow of alternating current, measured in ohms at a given frequency. Larger numbers mean higher resistance to current flow.

Keystone:

A form of video image distortion in which the top of the picture is wider than the bottom, or the left is taller than the right, or vice versa. The image is shaped like a trapezoid rather than a rectangle.

LCD

Liquid Crystal Display. A screen for displaying text and graphics based on liquid crystal technology, where minute currents change the transparency of the screen. The advantages of LCD screens are: very low power consumption (can easily be battery driven) and low price of mass-produced units. The LCD system first became wide spread in digital wristwatches which can operate for a very long time on small batteries. The disadvantages were: narrow-viewing angles, slow response (the first ones were too slow to be used for video), invisibility in the dark unless the display is backlit, and difficulties in displaying true colors on color LCD displays. With the introduction of new technology and especially TFT* driven LCD displays, picture quality resembles the quality of a CRT (the Cathode Ray Tube used in televisions and monitors). Brightness has improved dramatically and the price is dropping constantly. There is a good chance that active LCD (TFT* driven) displays will replace TV tubes in the near future, thus providing, at a reasonable cost, a TV to be hung on the wall like a picture.

LCOS:

Liquid Crystal on Silicon

Luminance:

The black and white (Y) portion of a composite, Y/C, or Y/Pb/Pr video signal. The luminance channel carries the detail of a video signal. The colour channel is laid on top of the luminance signal when creating a picture. Having a separate luminance channel ensures compatibility with black-and-white televisions

Interactive TV

A TV system which uses the TV/Cable-network for bi-directional communication. Via TV a user may order groceries, watch a selected movie (VOD- Video On Demand) or get the weather forecast.

Matrix Switching

An audio-video matrix switcher is a device which resembles a telephone switchboard. It is an array of electronic switches, which routes a number of audio-video signals to one or more outputs. An audio-video matrix switcher usually has several video and stereo/audio inputs, which can be directed by the user in any combination to various audio-video output devices connected to the switchers. Monitors, VCRs and other output devices can be arranged. The user can direct camera number 1 to VCR number 2 while simultaneously connecting camera number 8 to monitor number 1. The possibilities are almost endless.

MHz:

Megahertz, or 1 million Hz.

Mono:

Monophonic sound. One channel.

MP3:

MPEG-1 Audio Layer-3. Compression scheme used to transfer audio files via the Internet and store in portable players and digital audio servers.

Multimedia

Hardware and software that merge video, computer graphics and Multi-channel sound in one interactive session. Multimedia can display several live video scenes on one computer screen in small windows, simultaneously, and control position and shape of the windows by a computer mouse and keyboard. Retrieval of music and other audio signals, and of video scenes recorded on a computer hard disk, for educational, presentation and production purposes are only some of the applications made possible by multimedia, which creates a single computer-video entertainment center.

NICAM

Nicam (728) stands for Near Instantaneous Companded Audio Multiplex, and is a system initially developed and adopted by the British BBC for Stereo TV transmissions. The system is being used now in most countries in Europe, and may become the standard in stereo TV transmissions. Audio information is digitally coded and transmitted alongside the video information, allowing mono sound reception in receivers not equipped with the NICAM system (down compatibility). A NICAM TV receiver is equipped with a decoder, which converts the coded digital information into two stereo, analog sound channels

Negative Gain Screen:

Material that reflects less light than a reference material. Often used for DLP and LCD projection systems.

NTSC:

National Television Standards Committee. Government-directed committee that established the U.S. colour TV standard in 1953. Also known, sarcastically, as Never Twice the Same Colour or Never The Same Colour due to the inherent difficulty in achieving proper colour calibration.

Ohm:

A measure of how much something resists (impedes) the flow of electricity. Larger numbers mean more resistance.

Optical Digital Cable:

Fibre optic cable that transfers digital audio signals as light pulses.

PAL

The European color TV broadcasting standard featuring 625 lines per frame and 50 frames per second. It has a more complex color encoding* system than NTSC*, but provides better color fidelity and better resolution.

Passive:

Not active. A passive crossover uses no external power and results in insertion loss. A passive speaker is one without internal amplification.

Phase:

Time relationship between signals; it's all relative.

Pixel

The smallest "dot" on the TV or monitor screen usually comprised of tri-color dots: red, green and blue. The PIXEL size is a measure of the screens' maximal resolution.

Plasma:

Flat-panel display technology that ignites small pockets of gas to light phosphors.

Processors:

Anything that processes an incoming signal in some way. Surround processors, for example, can decode a Dolby Digital signal to send to an amp so you can hear it.

Projection System:

Display that projects image onto a screen.

RCA Jacks:

Receptacles for coaxial cables carrying line-level audio signals. Also called phono-type connectors.

Rear-Projection Television:

Display that projects an image on the backside of a screen material, usually after having been reflected off of a mirror.

Receiver:

Any component that receives, or tunes, broadcast signals, be it NTSC, HDTV, DBS, or AM/FM radio. Typically refers to the single component that includes a preamp, surround processor, multichannel amplifier, and AM/FM tuner.

RF:

Radio Frequency. Television signals are modulated onto RF signals and are then demodulated by your television's tuner. VCRs and DBS receivers often include channel 3 or 4 modulators, allowing the output signal to be tuned by the television on those channels. Also, laser discs used an RF signal for modulating Dolby Digital 5.1 soundtracks on some movies. This requires an RF demodulator (usually referred to as an AC3-RF demodulator) before or in the surround processor to decode the signal.

RGB (Red/Green/Blue)

The basic constituents of a color video signal. By using a color encoder, in conjunction with sync* information, a complete composite video signal comprising luminance*, chrominance* and sync can be generated. Professional processing equipment always employs RGB signals for editing and processing. The use of component video*, of which RGB is one form, results in superior quality output.

RS-232

Communication methods between computers and video equipment that are hardware based and software controlled. In the computers, RS-232 is carried through the serial port* to another serial port, where the data streams serially between the computer and its peripherals - mouse, plotter, printer, etc. In the computer field there is usually a handshake protocol* between the ports that operate bi-directionally. Video equipment can be controlled by either RS-232 or by RS-422 system, and as the RS-422 method connects several devices on the same line in parallel in a simple way, it is more popular in the video market. Computer controlled VCRs, editing controllers, switchers and other studio equipment is found in most video studios. In order to successfully link two pieces of hardware, they must use the same communication protocol*.

RS-RS-422

Scan Convertor

A machine that changes the scan rates (sync frequencies and data) of a signal to transform it to another format. If, for example, a VGA signal is to be converted to video, a Scan Converter is needed. The operation is done by converting the analog VGA signal to a digital form using an ADC*, reading the information into a RAM* memory, rescaling the signals and sync information and converting them back to an analog form using a DAC*. Scan converters convert both the sync frequencies and the DATA information simultaneously in order to shift all into another format. Scan Converters are also used in order to match specific monitors to signals of other formats. A good example is in the medical field, where data emerging from medical equipment at non-standard rates (like from Ultra Sound scanners or CT scanners) is to be converted to VGA or video formats for processing or recording. The Scan Converters are usually confined for a specific use in order to keep the price low, but there are expensive Scan Converters that convert between a large number of different formats

SCART

A European video-audio connector widely used in consumer equipment. The Scart connector has 21 pins, carrying two audio channels - in and out, video channels - in and out, RGB signals, ground and some additional control pins. In order to connect two VCRs or a VCR to a monitor only one Scart-to-Scart cable is needed, avoiding the cable jungle of video and audio inputs and outputs, which may confuse the home user. Simplicity of connections is the main advantage of the Scart system, however, it is not recommended for professional use as the physical connection is quite weak and signal leakage is too high.

SECAM

The TV and video standard used in France, Eastern Europe and some Arab countries. The system resembles PAL*; however, due to limitations and the complexity of its color encoding*, serious video production is almost impossible within the framework of the SECAM system. In countries using the SECAM standard most video production is done using the PAL standard and, prior to transmission, tapes are converted to SECAM.

SUPER VHS (S-VHS, s-Video)

A video system which differs from standard Composite video in several crucial ways. The bandwidth is considerably wider as luminance* and chrominance are separated in the signal. This format, named also Y/C, is widely used for production in semi-professional as well as in many broadcast studios.

SUPER-VGA

A computer graphics format beyond VGA*. Super-VGA displays 16 colors at resolutions of 800x600 and 1024x768 pixels, as well as 256 colors at 640x480 and 800x600 pixels resolution. The 640x480 at 256 colors is the most suitable for video use (after conversion to video) with almost natural colors.

Switcher

General term for a device used to route different signals (audio, video or RF*) from various sources to various acceptors. For example, a classic video switcher switches between the pictures from a number of video cameras* to one monitor.

Speaker:

A component that converts electrical energy into acoustical energy.

Subwoofer:

A speaker designed to reproduce very low bass frequencies, usually those below about 80 Hz.

TBC (Time Base Corrector)

A device used to rectify the results of distorted sync* pulses which are due to mechanical faults (tape transport, tape stretch, etc.). TBCs are also used to synchronize two video sources to allow mixing. TBCs employ one of two technologies. In the past, CCD* technology was used to move or alter a video signal in an analog* memory chip and was suitable for simple analog synchronization. However, CCDs had very limited memory capabilities. Therefore, Digital TBCs are now common. They usually break down the video signal to its components. This is extremely flexible as it permits storage of a full frame or more in a digital memory device (RAM chips). It operates in full bandwidth with 8 or more bits conversion scheme and is suitable for professional applications.

Termination Switch

A load device, usually a 75-ohm resistor, connected by a switch to a video transmission line to terminate the line. For a video signal be correctly transmitted without losses, proper impedance is essential at the end of the line. In many video-processing devices, a termination switch is therefore included as a standard feature. When the termination switch is in the Hi-Z position, the video signal is not terminated but looped to the next station. The signal can thus be transmitted in parallel through an almost unlimited number of devices. The termination switch terminates the final device.

TFT Screen

TFT stands for Thin-Film-Transistor. This new technology is mainly used for manufacturing flat computer and video screens, which are superior to classic LCD* screens. Color quality, fast response and resolutions are excellent for video, and therefore, TFT screens are replacing tube-based Wide Screen projectors* as well. In the beginning there were some price and technical problems with TFT screens. The price was high, mainly due to low yield in the wafer production process, the brightness of the screen was quite low and the resolution, although fine for composite video, was not sufficient for high-resolution computer graphics. As technology advanced, most of the problems were solved and now, bright, high-resolution TFT screens are available at very reasonable prices

THX:

: Certification program for home theatre equipment. Uses some proprietary features, but mostly assures a base quality level for a given room size. (See THX Select or Ultra.) Is compatible with any and all soundtrack formats. Stands for either Tom Holman's experiment, after the engineer who drafted the original standard, or is named after the company's founder George Lucas' first movie, THX 1138. Nobody agrees on which.

Tweeter:

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

Universal Remote:

Remote that has the commands of numerous brands stored into memory and can control several different devices simultaneously.

VGA

A color graphic standard introduced by IBM for personal computers, which displays either high resolution graphics (640 x 480) or 256 colors simultaneously, albeit at low resolution. Due to excellent aspect ratio, which resembles the standard video aspect ratio, VGA is suitable for video recording (after scan conversion* and encoding*).

VHS

Video Home System. A format developed by JVC(tm) utilizing half-inch tape, which is the most widely used video format.

Video Camera:

A camera which contains an electronic image sensing CCD* (Charged Coupled Device) rather than photographic film. The CCD is scanned rapidly converting light rays to an electric signal. A video camera has additional electronic circuitry which generates color* and sync* pulses. Some cameras are equipped with audio circuitry, e.g., microphone, audio amplifier and additional audio electronics. Professional cameras, in order to obtain a better picture, have a triple CCD system (three tubes in the past) - one for each basic color - red, green and blue. Most professional cameras have genlocking* input, which allows the camera to be synchronized to an external source. Some cameras include additional electronic circuitry such as character generators for titling* and special effects*, Tally*, etc.

Volt:

The unit of electrical potential, or difference in electrical pressure, expressing the difference between two electrical charges.

Wide Screen Projector:

A display device that projects a video or computer image on a large screen, mainly for public viewing. The first wide screen projectors had very poor quality and brightness, but today, quality and brightness is very good. The classic wide screen projector has three color tubes - red green and blue, and the image is created on the screen by blending the three colors. One of the most common problems encountered with wide screen projectors was poor alignment of the three tubes. Nowadays, in most high quality projectors, the alignment required to get a good superimposition of the three images on the screen is almost automatic and much easier than in the past. Recently, LCD* (Liquid Crystal Display) TFT* driven screens, which eliminate alignment problems completely, became the heart of a new series of wide screen projectors. The TFT* based projectors offer better price/performance ratios than three tube projectors. Another new generation of projectors is based on DLP / DMD (Digital Micromirrors Device) technology in which a semiconductor chip is covered with hundreds of thousands of micro mirrors that change their angle to a beam of light shining on them. This system creates an image that is much more saturated and has more contrast.

XLR:

A type of connector, usually of 3 pins (4 and 5 pins are also available), used in professional studio applications. The most familiar use of an XLR connector is in audio - where a balanced* audio signal uses two of the three pins, and the third carries the common ground.

XGA:

These are the main standards of resolution. The resolution is the number of 'pixels' that the projector is capable of displaying. Pixels are the individual dots that make up the image on your computer. SVGA, XGA and SXGA are terms that describe common resolutions used by computers and projectors. WVGA, WSVGA and WXGA are temrs that describe common resolutions used by Widescreen (16:9 aspect ratio) home cinema projectors. The table below shows you the number of pixels that are displayed in each common resolution. Standard (4:3) resolutions Resolution Pixels horizontally Pixels vertically Approx. total pixels (thousands) XGA resolution is 1024 x 768

YC (Luminance and Chrominance)

A complex division of the video signal used in systems such as S-VHS*. Due to the intricacy of YC, special processors, switchers, amplifiers, etc. are needed for video editing*.

YUV

A video system employing luminance* and two chroma components directly related to the red and blue components. Professional component video* systems are used in studios and require special equipment to simultaneously handle the three signals. Interface devices are used to link the various system components - RGB*, YC*, YUV and YIQ (a system similar to YUV used for NTSC).

Zone:

One or more rooms powered by one or more amplifiers, which are all fed by one source. A home can be divided into multiple zones, which can play multiple sources, even though several rooms (say, the kitchen, dining room, and living room) all play the same source.