Glossary of Video Terms and Acronyms - Isotest

Video Terms and Acronyms
Glossary
Tint function in that it changes color saturation as well as type of color. In
most cases where ACC is present, it cannot be defeated. Adjusting the
color and tint controls, using the SMPTE Color Bar pattern and the blue filter
will result in a gross misadjustment of color level on the set. The color
level may have to be reduced by as much as half the value calibrated with
the SMPTE Color Bar pattern.
Automatic Focus – A feature on most consumer and industrial video
cameras and camcorders that automatically makes minor focal length
adjustments, thus freeing the videographer from focusing concerns.
Automatic Frequency Control (AFC) – Automatic frequency control.
Commonly used to lock onto and track a desired frequency.
Automatic Gain Control (AGC) – a) Circuitry used to ensure that output
signals are maintained at constant levels in the face of widely varying input
signal levels. AGC is typically used to maintain a constant video luminance
level by boosting weak (low light) picture signals electronically. Some equipment
includes gain controls that are switchable between automatic and
manual control. b) Electronic circuitry that compensates for either audio or
video input level changes by boosting or lowering incoming signals to match
a preset level. Using AGC, changing input levels can output at a single constant
setting. c) A feature on most video cameras and camcorders that,
when engaged, boosts the signal to its optimum output level. Automatic gain
control (AGC) is available for video, and less frequently audio use.
Automatic Iris – A feature on most video cameras and camcorders that
automatically creates the lens aperture that allows the imaging device to
perform under optimum conditions.
Automatic Level Control (ALC) – Circuitry used to automatically adjust
the audio recording level to compensate for variations in input volume.
Some equipment includes level controls that are switchable between automatic
and manual control.
Automatic Picture Stop – The disc player will automatically take the program
from the play mode to a still frame mode according to information
programmed in the vertical interval of the disc’s video.
Automatic Route Selection – An important part of an automatic leastcost
routing system.
Automatic Shut-Off – A device (usually a mechanical switch) incorporated
into most tape recorders that automatically stops the machine when the
tape runs out or breaks.
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Auto-Pan – A feature exclusive to AVC series switchers causing a positioned
pattern to center itself as it grows in size.
Autotiming – 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.
Auto-Transition – a) The ability to electronically simulate a fader motion
over an operator-specified duration. b) An automatic transition where the
motion of the switcher lever arm is electronically simulated when the AUTO
TRANS pushbutton is pressed. The duration of the transition in television
frames or seconds is indicated by the rate display LED.
Auxiliary Bus – A bus which has the same video sources as the switcher
but whose crosspoints may be remotely controlled, independently of the
switcher console.
Auxiliary Channel (AUX) – In a video editing system, a channel reserved
for connection to an external audio and/or video device.
AVI (Audio Video Interleaved) – The Video for Windows file format for
digital video and audio. An AVI (.avi) file is a RIFF file format used with
applications that capture, edit and playback audio/video sequences. AVI
files contain multiple streams of different types of data. Most AVI
sequences will use both audio and video data streams. Specialized AVI
sequences might include control track as an additional data stream. See
Video for Windows.
A-Vision – An ATV system proponent.
AWGN – Additive White Gaussian Noise.
Axis – An imaginary line through the video image used as a reference
point for rotation and movement. The three axes are H (horizontal), Y (vertical),
and A (depth).
Azimuth – The angle of a tape head’s recoding gap relative to the tape.
Azimuth Alignment – Alignment of the recoding and reproducing gaps so
that their center lines lie parallel with each other and at right angles to the
direction of head/tape motion. Misalignment of the gaps causes a loss in
output at short wavelengths. For example, using a track width of 50 mils, a
misalignment of only 0.05 degrees will cause a 3 dB loss at a wavelength
of 0.1 mil.
Azimuth Loss – High frequency losses caused by head misalignment.