Video Master Glossary A - E
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A/A ROLL EDITING
Editing from a single source VCR using a freeze frame as a
transition from the source VCR to itself (source "A" to "A").
A/B ROLL EDITING
Editing from two source VCRs to a third recording VCR. A switcher
or mixer is used to provide effects such as dissolves.
ADO (Ampex Digital Optics)
Trade name for digital effects system manufactured by Ampex.
AGC (Automatic Gain Control)
A circuit that automatically adjusts audio or video input levels.
ALIASING
Undesirable video display effects caused by excessive high
frequency video information. Three examples are: Jaggies or
Stair-stepping - Stepped or jagged edges of angled lines,
especially at the slanted edges of letters. Raster scan aliasing
- e.g., twinkling or strobing effects on sharp horizontal lines
Temporal aliasing - e.g., rotating wagon wheel spokes
apparently reversing direction.
ANALOG
An electrical signal using continuously varying electrical
voltages. Analog video that is copied or edited several
generations suffers from generation loss and is subject to
degradation due to noise and distortion.
ALPHA CHANNEL
An 8-bit, gray-scale representation of an image used to create a
mask for keying images.
ANIMATIC
Simple animation consisting of art work designed to be
used as a video tape storyboard. Most commonly used for test
commercials.
ANTI-ALIASING
The process of electronically reducing aliasing, especially
letters and genlocked graphic elements.
AM (Amplitude Modulation)
Amplitude modulation is a process used for some radio (AM
broadcast) and television video transmission. A low frequency
(program) signal modulates (changes) the amplitude of a high
frequency RF carrier signal (causing it to deviate from its
nominal base amplitude). The original program signal is recovered
(demodulated) at the receiver. This system is extensively used in
broadcast radio transmission because it is less prone to signal
interference and retains most of the original signal quality. See
Frequency Modulation.
AMIGA
The video computer that created the desktop video revolution.
APERTURE
An adjustable opening in a lens which, like the iris in the human
eye, controls the amount of light entering a camera. The size of
the aperture is controlled by the iris adjustment and is
measured in f-stops. A smaller f-stop number corresponds to a
larger opening which passes more light. F-stop examples are F2,
F2.8, F4, F5.6, F8, F11. F-stops are logarithmic. Each stop
admits 100% more light than the previous one.
ASPECT RATIO
Ratio of picture height to picture width in video and TV systems.
The standard is 3:4.
ASSEMBLY EDIT
An edit wherein all existing signals on a tape, if any, are
replaced with new signals. Assembly edits cannot be used for
editing because since they erase the control track portion of the
video tape. (See also Insert Edit)
AUTO ASSEMBLY
Process of assembling an edited video tape on a computerized
editing system using an edit decision list.
B ROLL
Cutaway shots which are used to cover the visual part of
an interview or narration. The term is often used in TV news.
BETACAM
The most common broadcast quality video format. Also Betacam SP,
the enhanced version.
BETAMAX
The obsolete home video format. Lost the format battle to VHS
even though it was slightly superior. The cassette size, however,
went on to become BETACAM.
BLACK BURST
A composite color video signal comprised of sync, color burst
and black video. Used to synchronize (genlock) other video
sources to the same sync and color information. Black burst
generators are used in editing systems "lock" the entire
facility to a common signal ("house sync" or "house black").
BLACK LEVEL
Voltage in a video signal which corresponds to black.
BLANKING LEVEL
Also known as the pedestal, it is the voltage level produced at
the end of each horizontal picture line which separates the
portion of the video signal containing the picture information
from the portion containing the synchronizing information. This
voltage makes the electron beam "invisible" as it moves to draw
the next visible line.
BLANKING INTERVAL (Horizontal & Vertical)
The horizontal blanking interval is the time between the end of
one scan line and the beginning of the next. The vertical
blanking interval is the time between the end of one video field
and the beginning of the next. Blanking occurs when a monitor's
electron beam is positioned to start a new line or a new field.
The blanking interval is used to instantly reduce the beam's
amplitude so that the return trace is invisible. The screen goes
blank for a fraction of second. (See VERTICAL INTERVAL SWITCHING)
BLUE SCREEN
A special effects procedure in which a subject is
photographed in front of a uniformly illuminated blue or green background. A new
background image can be electronically substituted for the blue or green during the shoot or in postproduction through the use of chroma key to convert analog video to digital form.
BNC connector
A type of professional connector used on some VCRs, cameras and
video equipment providing twist-lock capability.
BOOM
An overhead pole device used to position a microphone close
to the actors, but out of the shot. A FISHPOLE is the portable
version.
BUY OUT
Music or music libraries in which a one-time fee enables
the buyer to legally use the music in many productions without
paying additional licensing or "needle drop" fees.
C.C.D.
Charged Coupled Device. An integrated circuit which captures
video images. It has largely replaced tubes in modern video
cameras.
CCTV (Closed Circuit TV)
A video system used in commercial internal installations for
security, medical and educational.
C.U.
Close-up shot.
C.G. (Character Generator)
An electronic typewriter that creates titles for video.
CATV
Acronym for cable TV, derived from the older term, community
antenna television.
CHROMA
The color information in a video signal, consisting of hue (phase
angle) and saturation (amplitude) of the color subcarrier signal.
CHROMA CORRECTOR
A device used to correct problems related to the chroma of the
video signal, as well as color balance and color noise.
CHROMA NOISE
Noise which manifests itself in a video picture as colored snow.
CHROMA KEY
The process of overlaying one video signal over another by
replacing a range of colors with the second signal. Typically,
the first (foreground) picture is photographed with a person or
object against a special, single-color background (the
key-color). The second picture is inserted in place of the
key-color. The most common example is in broadcast weather
segments where pictures of weather maps are inserted "behind" the
talent.
CHROMINANCE & CHROMINANCE LEVEL
The color portion of a video signal separate from the luminance
component, representing the saturation and tint at a particular
point of the image. Black, gray and white have no chrominance,
but any colored signal has both chrominance and luminance. The
higher the chrominance level, the stronger the color (e.g., a
strong signal produces red, and a weak signal, pink). Color
saturation level can be changed using a proc amp.
CHROMAKEY
Electronically matting or inserting an image from one
camera into the picture produced by another. Also called
"keying." The subject to be inserted is shot against a solid
primary color background. Signals from the two sources are merged
through a special effects generator.
CHROMINANCE
The color portion of a video signal.
CLIPPING
The electronic process of cutting off the peaks of either the
white or black excursions of a video signal to limit the signal.
Sometimes, clipping is performed prior to modulation, and
sometimes to limit the signal, so it does not exceed the limits
of the composite video signal (7.5 and 100 IRE units).
COAXIAL CABLE
A standard cable consisting of a central inner conductor and a
cylindrical outer conductor. Used for many video connections,
especially the cable TV wire that comes into your home.
CODEC
Compressor/decompressor. Any technology for compressing and
decompressing data. Codecs can be implemented in both software and hardware. Some examples of codecs are: Cinepak, MPEG, and QuickTime to convert analog video to digital form.
COLOR BARS
A standard video test pattern which includes samples of primary
and secondary colors. Used to conform the colors in video
monitors and other equipment.
COLOR BURST
The portion of a color video signal which contains a short sample
of the color subcarrier used to add color to a signal. It is used
as a color synchronization signal to establish a reference for
the color information following it and is used by a color monitor
to decode the color portion of a video signal. The color burst
acts as both amplitude and phase reference for color hue and
intensity. The color oscillator of a color television receiver is
phase locked to the color burst.
COLOR CORRECTION
A process in which the coloring in a television image is altered
or corrected by electronic means. (See CHROMA CORRECTOR)
COLOR DECODER
A device which divides a video signal into its basic color
components. In TV and video, color decoding is used to derive
signals required by a video monitor from the composite or Y/C
signals.
COLOR PHASE
The phase of the chroma signal as compared to the color burst,
is one of the factors that determines a video signal's color
balance.
COLOR TEMPERATURE
A method for measuring the overall color of a light source,
measured in degrees Kelvin (deg.K). Higher numbers indicate bluer
light, lower numbers indicate a warmer light. The color
temperature of the lighting must match the color temperature of
the camera. In video this is accomplished by setting the white
balance of the camera. Sunny Daylight is approximately
5500 deg.K. Overcast daylight is higher. Fluorescent Lights are
approx. 4100 deg.K. Indoor incandescent lights are 2800 deg.K and
professional Movie Lights are 3200 Deg. K
COLOR SUBCARRIER
The carrier frequency (3.58 MHz in NTSC and 4.43 MHz in PAL) on
which the color information is impressed. Color TV sets use
special circuits which decode the color component for accurate
display.
COMMUNICATION PROTOCOL
A software language for linking computers, VCRs or edit
controllers to allow bi-directional "conversation" between the
units.
COMPONENT VIDEO
Video signal in which luminance and synch information are
recorded separately from the color information. Formats such as
Betacam, SVHS and Hi-8 use component signals to achieve maximum
quality. Component video comes in several flavors: RGB (red,
green, blue), YUV (luminance, sync, and red/blue) and Y/C
(luminance and chrominance). Y/C is also called S-Video used in
the S-VHS and Hi-8 formats.
COMPOSITE VIDEO
A video signal in which the luminance and chrominance elements
have been combined in formats such as VHS.
COMPOSITE SYNC
A signal consisting of horizontal sync pulses, vertical sync
pulses and equalizing pulses only.
COMPRESSION
The process of electronically processing video signals so that it
requires less storage on a computer hard drive. A 5:1 compression
requires more storage space, but yields better quality than a
10:1 compression. See Main Menu Desktop Video Handbook Part 1.
CONTRAST
The degree to which luminance values contain very dark and
very light values. A high-contrast picture has more black and
white values with fewer values in between. A low contrast picture
has more middle tones without very dark or very light areas.
CONTROL-L
Sony's editing control protocol, also called LANC (Local
Application Control), which allows two-way communication
between a camcorder or VCR and an edit controller.
CONTROL-M
Panasonic 5-pin edit control protocol. Similar to Control-L, but
not compatible.
CONTROL-S
Sony transport control protocol which duplicates a consumer VCR's
infra-red remote transport control. Unlike Control-L, Control-S
does not allow the controller to read tape counter information.
CONTROL TRACK
Type of video editing that controls the in and out points of
edits by counting pulses on a control track portion of the
videotape. The pulses are counted by the edit controller to
perform fairly accurate editing. Edit controllers which read time
code make more accurate edits.
CONFORMING
Online editing to create the final edit master. The offline edit
master is used as a guide.
CONTINUITY
Controlling the elements in a shot to insure that edits will flow
smoothly and produce a coherent motion picture story without
jarring the viewer.
CRAWL
Text that moves horizontally across the screen.
CROSSFADE
The audio equivalent of the video picture dissolve. The first
sound track gradually fades out while the second sound track
simultaneously replaces it.
CROSSTALK
The interference between two audio or two video signals. In audio
crosstalk this signal leakage may occur between the left and
right channels. It can be caused by poor grounding connections or
improperly shielded cables. In video, crosstalk between channels
can be luminance/sync crosstalk or chroma crosstalk. Video
crosstalk can cause ghost images from one source appear over the
other.
CUE CARD
A card with the actor's lines written on it to enable
the actor to read or remember his lines.
CUTAWAY
A shot of something outside the frame which can be used to hide
an edit, e.g. during a testimonial.
CYCLORAMA
A background where all corners and intersections are rounded.
D1/D2/D3
Professional digital video formats. The D1 system uses component
video. The D2 and D3 systems use composite video. There is no D4
format. Digital formats do not suffer from the generation loss
inherent in analog formats.
D.V.E.
Digital Video Effects. A shot can bend, twist and fold into
various shapes. Before the advent of the VIDEO TOASTER, this
was an expensive post-production special effect. Also, the trade
name for a video system manufactured by NEC.
D.V.I. (Digital Video Interface)
Multimedia standard for computer generated text and graphics
which cab be transferred to video.
D.P.
Director of Photography
DAT (Digital Audio Tape)
An audio recording and playback format developed by Sony, with a
signal quality capability surpassing that of the CD.
dB (Decibel)
A logarithmic unit which expresses the ratio between two amounts
of electric or acoustic signal power. Used for measuring the
strength of audio and video signals.
DECODE
To separate a composite video signal into its component elements.
DELAY CORRECTION
When an electronic signal travels through electronic
circuitry or long cable runs, delay problems may occur. This
causes a displaced image. Special circuits are used to correct
the delay.
DEMODULATOR
An electronic circuit which separates the audio and video
signals from the RF carrier frequency.
DEPTH OF FIELD
The range of objects in front of a camera lens which are in
focus. Smaller f-stops provide greater depth of field, i.e., more
of the scene, near to far, will be in focus.
DIGITAL
A system whereby a variable analog signal is broken down and
encoded into discrete binary bits of ones and zeros. These
numbers represent a mathematical model of the original signal.
When copied, they do not degrade as an analog signal does.
An analog-to-digital (A/D) converter chip takes samples of the
signal at a fixed time interval known as sampling frequency. This
digital stream is can be recorded onto magnetic media. Upon
playback, a digital-to-analog (D/A) converter chip reads the
binary data and reconstructs the original analog signal.
Theoretically, this process should eliminate generation loss
since every copy is an exact duplicate of the original. In
reality, digital systems are not perfect and can introduce their
own problems in maintaining the original signal. Digital signals
are virtually immune to noise, distortion, crosstalk, and other
quality problems.
DIN (Deutsche Industrie Norme)
An international connector standard. DIN connectors carry
both audio and video signals and are common on equipment in
Europe.
DISSOLVE
A video or film transition where one shot gradually fades out
while a second shot fades in.
DISTRIBUTION AMPLIFIER
A device which splits and amplifies an audio and/or video
source tape or signal to several audio/video outputs. Used to
duplicate one videotape to any number of VCRs with minimal loss
of signal strength.
DOLBY (tm)
A compression/expansion (companding) noise reduction system
developed by Ray Dolby, widely used in consumer, professional and
broadcast audio applications. Signal-to-noise ratio improvement
is accomplished by processing a signal before recording and
reverse-processing the signal upon playback.
DOLLY
A camera platform on wheels. To dolly is to smoothly bring the
camera closer or farther from the subject.
DOWNSTREAM KEYING
Electronically superimposing text or graphics over a scene
(luminance key) or of placing one video image into another
(chroma key). The Downstream Key signal must be genlocked to the
other signals.
DROPOUT
A defect on the videotape which causes a brief flash of a
horizontal black line on the screen. Commonly found at the
beginning and end of tapes. The quality of videotape is graded by
the number of dropouts and priced accordingly.
DROP FRAME
A type of SMPTE time code designed to exactly match the real time
of common clocks. To accomplish this, two frames of time code are
dropped every minute, on the minute, except every tenth minute.
This corrects for the fact that video frames occur at a rate of
29.97 per second, rather than an exact 30 frames per second (see
Non-Drop Frame). This time code system is used in television to
insure that broadcast times coincide with real time.
DUB
Duplicate copy of a videotape. Also called a dupe.
EIA RS-170A
The timing specification standard for NTSC broadcast video
equipment.
ENCODE
The process of combining analog or digital video signals, e.g.,
red, green and blue, into a composite signal.
ENCODER
A circuit that combines the primary red, green and blue signals
into a composite video signal.
E.C.U.
Extreme close-up shot.
E.D.L. (Edit Decision List)
A complete list of time code numbers for each shot and sound used
in the offline edit master. These time code numbers are used to
create the final online edit master.
ESTABLISHING SHOT
A wide shot showing much of the location.
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