Grass Valley Dictionary

Dictionary of Technical Terms - L

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Local Area Data Transport.

Lamina™ Video Compositing

A feature of some GVG switchers that enables four video layers to be composited in one mix/effects. This composite image can then be used as a key source or a background in another mix/effects or the downstream keyer.

Local area network.

See background mix.

A junction diode that emits electromagnetic radiation or light when injected electrons under forward bias recombine with holes in the vicinity of the junction. Used to transmit light signals over fiber optic cables. The term laser is an acronym derived from light amplification by stimulated emission of radiation.

Supplies a signal that modulates a laser driver in a laser-driven communication system.

An undo function included in some GVG E-MEM(R) systems. In video switchers, the Last-X register continuously stores the switcher setup before the last E-MEM register recall. Pressing the Last-X pushbutton recalls the switcher to the setup that existed before the last E-MEM recall. This provides quick recovery from accidental E-MEM recalls.

Local access and transport area.

An electronic circuit that holds a digital signal once it has been selected. To latch a signal means to hold it.

A single video image that is processed so that it can be inserted into the final composite image. There may be other layers in the image, and they can be prioritized as to layer location.

Combining several video images to create a complex effect. With GVG digital switchers, multiple layer effects can be created in one recording pass.

The amount of light actually coupled into an optical fiber from the light source. This is typically expressed in dbm or microwatts.

Light build out. A telecommunications term meaning to simulate cable loss to maintain the required signal template.

The transition of a pulse that occurs first, such as the positive-going transition of a high clock pulse.

The act of storing control panel data (effects setups) into a memory register of an E-MEM system.

Local Exchange Carrier.

Light emitting diode.

1. The clear plastic cover on a pushbutton. 2. The focusing mechanism of a camera.

1. The intensity of an electrical signal. 2. In routing switchers, an independently controllable stratum of signals within a routing switcher. Typically, a routing switcher will have a level of video and one or more audio levels. 3. A mix/effects (M/E) section of a video production switcher.

lever arm (fader arm)

Typically a "T" shaped handle attached to a pair of potentiometers or shaft encoders. Used for manual video transitions on a video switcher or digital picture manipulator. Moving the lever arm between two limits of an arc creates a change in voltage or digital data that is used to control the transition.

light-emitting diode (LED)

A pn junction device that emits light when biased in the forward direction.

A digital picture manipulator function that provides three-dimensional control of light sources in order to create lighting for objects.

lightning display

A method of presentation on a component video waveform monitor that displays luminance and color difference video signals to permit measuring their gain and timing.

A photodiode used for receiving optical signals.

Adjustment of video or audio signal levels.

An electronic device in which some characteristic of the output is automatically prevented from exceeding a predetermined value.

See horizontal line. See program output.

1. Having an output that rises or falls in direct proportion to the input. 2. A straight-line motion path for objects in digital effects devices.

Linear Borderline(R)

Keyer feature that allows key edge effects to be added to linear keys.

A luminance key effect in which the gain of the key is approximately one, preserving the shaping of key source edges produced by anti-aliased character generators and digital video effects devices Linear keying using anti-aliased sources produces smooth key edges.

A keyer that does linear keys.

linear pulse distribution amplifier

Linear pulse DAs amplify and fan-out the signal and will handle up to 4V p-p signals (pulses).

AC power input cable.

line-cord retention hardware

Safety hardware that keeps the power cord from being pulled out of its connections.

See program monitor.

See program output.

Occurring during a horizontal line of the video picture.

line time linear distortion

An unwarranted change in video signal amplitude that occurs in a time frame between 1 and 20 microseonds. The result is a gradual left-to-right shading of the TV picture.

The voltage level of the main power source to a device.

1. A communication path between sites, such as a satellite link or a microwave link. 2. An E-MEM(R) mode of operation where registers are recalled in numerical order every time a transition is performed.

Those Master 21 preset and program sources through which inputs from an expansion router are mapped.

The process of revising an edit decision list to correct duplicate or over-lapping edits so that over-recordings are eliminated.

list management

Editor functions that give you the ability to change the edit decision list.

Local measured service.

An auxiliary switching bus contained within the control panel of a video switcher, as opposed to a remote auxiliary bus panel.

In telecommunications, a communications channel between a subscriber and a local company.

In digital picture manipulators, a transform that allows movement of the picture along the X and Y axes.

To synchronize two or more signals. See gen-lock.

logical channel

In digital picture manipulators, there may be several physical manipulation channels, each of which can be independently assigned to any one of several control panels. If physical channel 2 is the first channel assigned to a control panel, it becomes logical channel 1 for that panel. Thus, logical channels are a method of numbering manipulation channels based on the order in which channels are assigned to a control panel rather than on the physical number of that channel in the electronics frame.

That time at which a new source is placed on the program bus, usually recorded in the station log for FCC accounting and customer billing purposes.

Long distance communications.

look ahead preview (preview)

The output of a switcher that allows you to observe an effect before it is placed on-air.

A test of transmission capability in which a signal is transmitted through a loop that returns the signal to the source. The test verifies the ability of the source to transmit and receive.

loop-through (loop-thru, looping)

A type of video input circuit that provides two or more input connectors. One connector accepts the video input signal for use within the device in question, and the other connector provides a tap off of the input for routing the input signal to another piece of equipment.

1. The amount of anticipated signal loss over a given fiber optic path, including attenuation, connector loss, splice loss, and other losses. 2. The amount of signal loss fiber optic transmission equipment can sustain before exceeding the operating specifications.

low frequency chrominance response

A TV picture anomaly in which a change in time (1 microsecond to 60 microseconds) causes a change in chrominance amplitude. The picture shows unwarranted saturation variations from left to right.

low-pass filter

A filter network that passes all frequencies below a specified frequency with little or no loss but that discriminates strongly against higher frequencies.

Dim lighting of a control panel button. Usually indicates that a source or function is selected but not currently on air.

Least significant bit. The bit that has the lowest value in a binary number or data byte.

Large scale integration.

The measurable, luminous intensity of a video signal. Differentiated from brightness in that the latter is non-measurable and sensory. The color video picture information contains two components: luminance (brightness and contrast) and chrominance (hue and saturation). The photometric quantity of light radiation.

luminance border

A non-color, luminance-only fill video for key borders and drop shadows.

A key effect in which the portions of a key source that are greater in luminance than the clip level cut a hole in the background video.

luminance nonlinearity

A TV picture anomaly in which a change in luminance amplitude causes a change in luminance gain. The picture shows poor resolution between brightness levels in the nonlinear range.

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