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A B C D E F G H I J K [L]M N O P Q R S T U V W X Y Z

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LANC.
Local Application Network Control.

Laser.
A thin, highly concentrated beam of light which is used in audio to read digital media such as CDs, DVDs and laserdiscs.

Laserdisc.
Large 12-inch diameter optical digital format used for playing back images and sound.

Late Reflections.
Sound waves that bounce or reflect off room boundaries and objects reaching a listener relatively long time after the direct signal from the sound source reaches the listener.

Layer.
Part of a computer image, separate from the other parts, which can be changed independently from them, like changing the background behind a cartoon figure.

LCD (Liquid Crystal Display).
A screen for displaying text/graphics based on a technology called liquid crystal, where minute currents change the reflectiveness or transparency of the screen. The advantages of LCD screens are: very small power consumption (can be easily battery driven) and low price of mass produced units. Its disadvantages presently include narrow viewing angle, somewhat slower response time, invisibility in the dark unless the display is back-lit, difficulties displaying true colours and resolution limitations.

LED (Light Emitting Diode).
Solid-state electrical device that emits random light when a forward rushing current is conducted through it.

Lens format.
Describes the size of the lens's focused image. It should match the size of the camera's pickup chip.

Lenticular Gray.
Metallic-looking projection screen with tiny vertical grooves (looks like smooth corduroy) to distribute most reflected light straight back and to the sides (where the audience sits) and reflects very little on the ceiling and floor.

Letterbox.
Format for showing an entire movie image in its wide format on a standard 4-by-3 aspect ratio video display by fitting the image width into the width of the more square format and placing black bars above and below the image (when the wide picture is fit into a comparatively narrow space, the height of the picture does not equal that of the display).

LFE (Low Frequency Effects).
Audio channel found in 5.1 digital surround sound audio schemes (the .1) that carries only low frequency information of 80 Hz and below.

LFO.
A low frequency oscillator that is used to alter a sound's frequency or amplitude.

Librarian.

A category of MIDI software that is used to organize and store a MIDI device's patch (program) data.

Light meter.
Electronic device that measures the brightness of a light (incident light) or the brightness of a scene (reflected light) and gives a readout in footcandles or lux.

Light Valve Projector.
Form of front projection device that provides vastly superior light output compared to a CRT projector with superior picture quality.

Lighting grid.
Framework of pipes connected to the studio ceiling from which lights are hung. Lighting ratio A comparison between the brightest part of a subject and the darkest. If the brightest white in a performer's shirt measured 60 fc (footcandles) and his black hair measured 2 fc, then the lighting ratio would be 60 2 = 30.

Lightning arrester.
Device which clips onto an antenna or cable TV cables, and connects to a grounded wire. It is designed to divert the shock of a lightning bolt so that the current doesn't damage your equipment.

Limiter.
Electronic audio device that automatically reduces the volume of loud audio signals but doesn't change the normal or weak signals.

Linear (or normal) audio track.
Audio recording made in a line along the edge of a video tape (as opposed to hi-fi sound imbedded in the video tracks on the tape).

Linear editing.
Editing using media like tape, in which material must be accessed in order (e.g., to access scene 5 from the beginning of the tape, one must proceed from scene 1 through scene 4).

Linear key.
Key effect where the amount of a colour (or brightness) determines how much of another camera's image will be visible, creating a natural-looking key effect.

Linear Quantisation
The entire range of possible signal amplitudes is divided into equal steps. In non-linear quantisation the amplitude range is divided into unequal steps.

Line compensation.
Use of a video line amplifier to pre-compensate for high frequency video signal transmission losses resulting from long distance cable runs (several hundred meters) by boosting those signal frequencies most effected. Without such compensation, deterioration is manifested as loss of fine details and colour distortion.

Line Conditioner.
Electronic device that "cleans" the electricity coming from a wall outlet to be used by audio/video components and protects them from electric spikes and surges.

Line Doubler.
Video display accessory used to enhance the picture quality of a video image by combining the two interlaced fields (grouping of all the odd or all the even lines that make up a complete image; two fields make a frame or a complete image) and progressively displaying complete frames instead of fields (displaying all the odd and even lines generated in order one, two, three, etc.).

Line Level.
Term for a low-level signal sent over patch cables (interconnects) which connect various components within an audio/video system in order to transfer information but not connecting amplifiers to speakers (a high-level signal with much more power needed in order to move the speaker driver).

Line Quadrupler.
Video display accessory that generates a near-HDTV image from standard NTSC video by combining the interlaced fields into progressive frames and then doubling the number of lines in those frames through a process of interpolation.

Lip Sync.
Synchronization between the performers' audible words and the movement of their lips.

Load resistance.
The impedance or resistance (load) that a cable places on a signal being transmitted through it. In the case of a high frequency signal, signal-to-cable matching is essential to prevent signal deterioration. The cable should be terminated by a specific load resistance, usually 50 or 75 ohms. Improper cable loading results in signal distortion, ghost images, colour loss and other adverse phenomena. Most video inputs have the proper termination built in.

Local On/Off.
A three byte channel message that determines the status of the Local On function of a MIDI device. LOCAL ON allows the instrument to produce sounds from incoming MIDI data and its own keyboard. LOCAL OFF states that only external MIDI data is responded to.

Logo.
Symbol or trademark representing a specific company, or organization.

Lossless.
Information in the digital data which can be recovered without any alteration. That is, the decompressed data is the same as the original data.
An example of a lossless data compression process is the use of the Winzip program.

Lossy.
Compression method that discards data and degrades the image quality. High degrees of compression are possible.
An example of a lossy data compression process is MP3 compression

Loop.
To repeat a sequencer pattern or portion of an audio sample repeatedly. The point to which the program returns, whether the beginning or some other point, is usually definable by the user.

Looping.
A term used to describe the chaining of a video signal through several video devices (distribution amplifiers, VCRs, monitors, etc.). A VCR may be hooked up to a distribution amplifier which is supplied with a video input connector and a loop output connector. When a signal is fed to the distribution amplifier, it is also fed unprocessed to the loop output connector (parallel connection) on the distribution amplifier. In turn, the same signal is fed to another device which is attached to the first one and so on. Thus a very large number of VCRs or other video devices can be looped together for multiple processing.

Loudness.
Loudness is a perceived measurement in dbA or acoustic decibels while amplitude refers to the size or how high the sound wave is (peak to through) and volume refers to the amount of sound moved through vibration.

Low-Pass Crossover.
Type of crossover that only allows low frequencies to pass cutting off or attenuating frequencies above the crossover point (crossover frequency).

LP.
Long play - the 4-hour speed of a VHS VCR.

LPTV.
Low-Power Television-the technique of broadcasting local programming through a very low-power, inexpensive VHF TV transmitter. Limited signal range keeps LPTV stations from interfering with distant TV stations using the same channel frequency.

LTC (Longitudinal Time Code).
SMPTE (Society of Motion Picture and Television Engineers) time code standard usually recorded onto the linear audio track of a VCR or audio tape machine. Lumen Measurement unit of illumination.

Luminance.
The degree of brightness (black and white portion of the video signal) at any given point in the video image. A video signal is comprised of luminance, chrominance (colour information) and sync. If luminance is high, the picture is bright and if low the picture is dark. Changing the chrominance does not affect the brightness of the picture.

Luminance noise.

Noise which manifests itself in a video picture as white snow, typically caused by one of the following situations:

Low signal level due to poor lighting conditions.
Poor video signal processing.
Low quality videotapes.
Excessively long video cables used without pre-compensation.
Dirt on the video recorder heads which interferes with reading and writing.
Over-enhancement of the video signal.

LUX.
A measurement of light intensity, which is used in photography for the comparison of camera sensitivities. (1 Footcandle = 10.76 Lux).

LZW Compression.
“Lempel-Ziv-Welch” (LZW) compression algorithm
LZW Characteristics :
Most effective when bit depth is small
Typical examples: diagrams, cartoons
GIF format allows a bit-depth of up to 8.

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