Grass Valley Dictionary
Grass Valley Dictionary
Dictionary of Technical Terms - A
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
See A-B roll.
Videotape editing arrangement in which scenes on
tape are played alternately on VTRs A and B and recorded on VTR C.
Typically, the final output recorded on VTR C contains some scenes
from VTR A and some scenes from VTR B with transitions (cuts,
mixes, wipes etc.) between the scenes.
In telecommunications, attenuation of the optical
signal within the fiber optic transmission medium. Usually
specified in terms of dB/km.
A method of coupling one circuit to another through
a capacitor or transformer so as to transmit the varying (AC)
characteristics of the signal while blocking the static (DC)
characteristics. In some analog GVG distribution amplifiers, when
the AC coupling mode is selected, a feedback loop maintains the
output signal at an average DC level of 0 volts regardless of APL
(average picture level) or DC offset of the incoming signal.
May also be called simply DC coupling. Coupling
between circuits which accommodates the passing of both AC and DC
See key accumulation.
A feature of some GVG keyers that allows combining
of several key sources in a single keyer.
active picture period
That portion of the video signal that produces the
viewable part of the television picture as distinguished from that
portion of the video signal that occurs during blanking (horizontal
and vertical retrace).
The portion of a video signal that contains picture
The window in a software application that is
currently selected for use.
Able to adjust or react to a video condition or
application, as an adaptive circuit. This term usually refers to
ADC (A-D, A/D, A-to-D)
Method of keying in which two complementary video
signals that have already been shaped by multiplication with a key
signal are added to create a composite image.
Addition of two video images together without
attenuation of either signal.
1. A precise frame location on a videotape, usually
identified by a time code number. 2. A memory location or device
identifier in microprocessor and computer terminology.
Audio Engineering Society.
Informal name for a digital audio standard
established jointly by the AES and EBU organizations. The sampling
frequencies for this standard varies depending on the format being
used; the sampling frequency for D1 and D2 audio tracks is 48
Audio follow video.
Automatic gain control.
To broadcast a signal.
alarm indication signal (AIS)
In telecommunications, an all 1's signal (generally)
generated by in-line equipment to indicate to down line devices
that an input has failed. See also blue signal.
A storage place within a video editing application
for cataloguing and archiving clips, effects, and other production
Defects or distortion in a television picture. In
analog video, aliasing is typically caused by interference between
two frequencies such as the luminance and chrominance frequencies
or the chrominance and field scanning frequencies. It appears as
moire or herringbone patterns, straight lines that become wavy, or
rainbow colors (See cross color). In digital video, aliasing is
caused by insufficient sampling or poor filtering of the digital
video. Defects are typically seen as jagged edges on diagonal lines
and twinkling or brightening in picture detail.
The adjustment of components in a system for optimum
all inputs hostile
Measurement technique, particularly for crosstalk,
using worst case conditions (typically, full chroma signal on all
inputs other than the one under test).
A digital signal consisting of data that contains
all logical ones. In telecommunications, a test signal consisting
A display symbol set consisting of the twenty-six
letters of the alphabet and the digits 0 through 9.
alternate mark inversion (AMI)
In telecommunications, an encoding protocol where
successive data 1's are transmitted as alternate, equal positive
and negative pulses, and data 0's are sent as spaces, each of zero
The temperature of the surrounding medium, typically
the air, which comes into contact with a device. Room
See sequential assembly.
Unit of measure of electrical current.
A connector manufacturer.
The magnitude of a signal in voltage or current.
Frequently expressed in terms of peak, peak-to-peak, or RMS.
amplitude modulation (AM)
A method of imposing information on a carrier
signal, such as a sine wave, by varying its amplitude.
1. An adjective describing any signal that varies
continuously as opposed to a digital signal, which contains
discrete levels. 2. A system or device which operates primarily on
Another name for component video, such as RGB or Y,
R-Y, B-Y, as opposed to digital component video. See component
analog component island
A discrete set of analog component equipment within
a non-component facility.
A circuit that uses digital sampling to convert an
analog signal into a digital representation of that signal.
A feature of some video devices, such as character
generators, which minimizes aliasing by filtering and other
techniques. See aliasing.
Alternate Operator Service.
The enhancement of a video signal to increase image
sharpness. Aperture correction is employed to compensate for the
finite size of a scanning beam or a pixel.
APL (average picture level)
The average level of the active video (portion of
video between blanking pulses), expressed as a percentage or in
In video devices capable of creating key frame
effects, a mode that permits new key frames to be added to an
existing key frame effect to make the effect longer.
A software package that runs on a computer
The main or home window displayed by a software
application from which other subordinate windows are accessed.
1. Internal organizational (circuit) structure of an
electronic product. 2. Physical layout and interconnection scheme
of a studio.
Off-line storage of video/audio onto backup tapes,
floppy disks, optical disks, etc.
Undesirable elements or defects in a video picture.
These may occur naturally in the video process and must be
eliminated in order to achieve a high-quality picture. Most common
are cross color and cross luminance.
American Standard Code for Information Interchange.
A standard code for transmitting data, consisting of 128 letters,
numerals, symbols, and special codes each of which is represented
by a unique binary number.
Application specific integrated circuit. An
integrated circuit designed for special rather than general
1. The ratio of television picture width to height.
In NTSC and PAL video, the present standard is 4:3. 2. The ratio of
wipe pattern width to height.
1. A manufactured part made by combining several
other parts or subassemblies. For example, a cable assembly
consists of the cable with connectors at each end. 2. Assembly
assemble edit (assemble mode)
An editing mode that replaces all signals on the
record tape (video, audio, control, and time code tracks) with new
signals. See also insert edit.
A symbolic computer language in which a programmer
can create programs that the computer's assembler program will
translate into machine language for controlling the computer.
Assembly language is a higher level language one step above machine
Lacking synchronization. In video, a signal is
asynchronous when its timing differs from that of the system
reference signal. A foreign video signal is asynchronous before it
is treated by a local frame synchronizer.
Asynchronous Transfer Mode. A data transmission
scheme using self-routing packets of 53 bytes, 48 of which are
available for user data.
atomic frequency standard
In television, an extremely accurate means of timing
using an atomic clock.
Audio tape recorder.
Advanced Television Systems Committee (USA). A group
whose charter is to develop voluntary national standards for high
A physical channel of a digital picture manipulator
is attached to a logical channel of a controller if the physical
channel is successfully acquired by the controller. A physical
channel may be attached to only one logical channel of one
controller at a time.
The decrease in amplitude of a signal.
A circuit that reduces signal amplitude.
Advanced television. High resolution digital
television, several versions of which are in proposal stages in the
US and Europe.
Sound. An electrical signal that carries sound
In telecommunications, a device that mixes multiple
audio inputs and feeds back composite audio to each station, minus
that station's input. Also known as a mix-minus audio system.
audio crosspoint module
Circuit board containing crosspoints for audio
audio distribution amplifier (audio DA)
A device used to replicate an audio signal,
typically providing 6 outputs, each of which is identical to the
An operational mode in which audio and video
switchers are tied together so that when the operator selects the
video source, the audio simultaneously and automatically switches
to the same source.
In video editing, the editing system automatically
records all edits listed in the edit decision list. This allows the
operator to complete an edit decision list and then let the editing
system perform all of the recording automatically.
A feature of GVG editors that automatically cleans
the edit decision list during the course of editing. This removes
duplicate or overlapping edits so that over-recordings are
eliminated. See 409.
A feature of GVG editors that automatically finds a
match to the last record VTR edit and inserts the match at the
proper VTR in the mark table.
automatic changeover switch
Equipment that monitors the outputs of two sync
generators (one in-use and one backup) and automatically switches
to the backup sync generator should there be a failure of the sync
generator in use.
auto select key
A feature of some video keyers that automatically
selects the key source when the operator selects the key fill.
A feature of some GVG chroma keyers that
automatically adjusts the chroma key after the operator identifies
the chroma key background color using a cursor.
Capability of some digital video equipment to
automatically adjust input video timing to match a reference video
input. Eliminates the need for manual timing adjustments.
On a video switcher, an automatic transition where
the motion of the lever arm is electronically simulated.
In some GVG editing systems, AutoTrim allows two
adjacent video clips to be trimmed at the same time. The in point
of one clip is trimmed at the same time that the out point of the
adjacent clip is trimmed.
A single crosspoint bus, typically used in
conjunction with a production switcher. Often used to feed a
digital picture manipulator with the same inputs as the primary
inputs applied to the switcher.
auxiliary channel (aux)
In a video editing system, a channel reserved for
connecting an external audio and/or video device.
Electronic device used as a detector in some fiber
optic transmission systems.
American Wire Gauge.
Relating to digital picture manipulation, the X axis
is a horizontal line across the center of the screen, the Y axis is
a vertical line, and the Z axis is in the third dimension,
perpendicular to the X and Y axes and indicates depth and
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