Degauss
To erase or remove recorded data from a magnetic
medium by subjecting the recording to an alternating
magnetic field of gradually diminishing strength.
To remove residual magnetism from audio or video
heads that could materially degrade the signal
or affect the recorded signal on the magnetic
medium.
D-1 Format
A digital recording standard
in component form used for both studio and post
production applications. Its advantages include
excellent color keying capabilities and the ability
to copy many generations with almost no degradation
of the video signal. Its primary disadvantage
is that each digital VCR costs over $100,000.
Recording time is limited to two sizes of cassette,
either 34 minutes or 76 minutes on standard tape.
The D-1 format has high performance standards
than the D-2 format. topˆ
D-2 Format
A composite digital recording standard used in
studio and post production applications. Its basic
advantage is that the VCRs are less expensive
than those used in the D-1 format. The D-2 format
offers up to 208 minutes of recording on a special
19mm (¾ inch) videotape. It also is capable
of producing more generations than standard analog
composite recording without noticeable degradation
and gives very good slow motion performance. The
D-2 format is generally used in cases where the
higher performance of the D-1 VCR is not needed.
It has made inroads in broadcasting in automated
playback applications. It seems a likely replacement
for the type "C" VTR. topˆ
Drop
Frame Time Code
An SMPTE Time Code (TC) option that allows indicated
TC to agree with clock time. The color frame rate
for color TV is actually 29.97 frames per second,
not 30, so that over a 60 minute period a TC reader
would count 108 frames (3.6 seconds) short. To
correct this situation, at the beginning of each
minute frames 0 and 1 are "dropped"
so that the frame count starts at 2. This would
result in 120 frames added in an hour, 12 more
than needed. By negating this correction at the
beginning of every 10th minute, time code is forced
to agree with clock time.
When the drop frame mode is
selected on a Time Code Generator (TCG), a bit
is set in the code that tells the reader and editing
systems that they are dealing with drop frame
TC. Many editors prefer to work with non-drop
frame TC to eliminate the confusion caused by
the missing frames.
Note that color is always 29.97
frames/second, but that is not necessarily synonymous
with drop frame. See Time
Code, Non-Drop
Frame Time Code. topˆ
Dropout
A loss of picture information that may appear
as a short white flash and include one or more
picture scan lines. Dropouts are caused by minute
imperfections in the surface of the tape stock
or by dust particles attracted to the tape by
static electricity. Stock imperfections are not
easily corrected, but if a dropout is caused by
dust, then re-recording that section of tape will
generally eliminate the dropout. topˆ
Dropout
Compensator (DOC)
An electronic device in a VCR or VTR that detects
the presence of a dropout and replace is with
information from the preceding line, thereby covering
up the dropout. topˆ
Dub
In television, a copy of a videotape. dub is more
commonly used than dupe (short for duplicate),
which generally applies to film copies.
In film, to mix and compose audio sound tracks
from several elements by balancing for levels,
proportion, and equalization. topˆ
Edit
Decision List (EDL)
A structured compilation of time code information
defining each edit in a sequence. The list may
or may not be constructed for use in a computerized
editing system. If it is, another compatible computer
editing system should be able to use the EDL to
edit or conform a videotape or audiotape. The
EDL consists of pertinent information such as
time code edit points, notes, and switcher data.
topˆ
Editing
System (Video)
A configuration of hardware and software designed
to allow a user to build continuity on videotape
in a linear or nonlinear fashion. The following
items constitute a basic video editing system:
Computer hardware to interface
with VCRs or VTRs and a keyboard or keypad for
entering data.
Software designed for videotape editing.
Controllers to communicate between the computer
and the VCR or VTR.
A basic switcher to switch video sources from
one or more play machines to the record VTR or
VCR.
A program monitor to view edits and optional source
monitors for each playback machine
A floppy or hard disk for storing the operating
program and edit decision lists.
An optional printer for paper printouts of edit
decision lists (EDLs)
A joystick to control the tape motion (optional).
topˆ
Edit
List Management
The organizing and processing of time code data
that make up an edit ecision list (EDL). When
an editor creates an EDL, there may be some unwanted
edits, over recordings or edits out of place.
Some computer editing systems offer good list
management features, allowing the editor to clean
the list before using it to build a finished master.
Others have limited or no list management capabilities
and the editor must rely on commercial software
to perform this function. topˆ
Electronic
Editing
A method by which pictures and sound recorded
on videotape are transferred from one videotape
to another by electronic means. In essence, the
original material is played back through electronic
circuits and is copied to another tape. This new
copy is regarded as a second-generation tape.
The advantages of this method are:
That the original source material
is never altered in any way.
That this same material may be used as source
as many times as desired with minimum degradation
since the audio and video signals are merely copied
electronically from one tape to another.
Today, virtually all videotape editing is done
in this matter, as opposed to the physical cutting
and joining of the desired portions of tape as
in film editing. topˆ
Field
One-half of a NTSC television frame. A field contains
262.5 lines and has duration of 1/60th of a second.
The odd numbered scanning lines are known as field
1, the even numbered as field 2. When these fields
are combined by interlacing, a 525 line frame
results. See Frame, Interlace. topˆ
Flying
Spot Scanner
A TV scanning device that scans the film frame
in a continuous motion using an electronic shutter
rather than the conventional claw intermittent
pull-down. The most popular type uses a monochrome
kinescope as the light source and the pickup devices
are red, green, and blue filtered photocells.
This type of telecine device is much easier on
film than an intermittent movement projector because
it does not jerk the film down each time a frame
changes, but rather moves continuously past the
scanner so there is less chance of scratching
or other film damage. topˆ
Frame
A standard unit of video information containing
one complete image. The NTSC system standard in
the United States and many other countries transmits
nominal 30 frames per second. A frame is made
up of two television fields, one odd and one even.
Each field is made up o 262.5 lines of information.
When interlaced the two fields generate a video
frame of 525 lines. See Color Frame. In other
parts of the world, the PAL and SECAM systems
use 25 frames per second, with each frame containing
625 interlaced lines. These systems are not compatible
with NTSC or each other. A standards converter
maybe used to translate one format to another
with some loss of quality.
One motion picture film image. topˆ
Frame
Rate
In video and film, the standard number of frames
continuously displayed per second of viewing time.
TV frame rates were chosen to be one half the
power frequency in use by the country of origin.
There are three main international television
standards;
NTSC system: 30 frames/60 fields
per second (29.97 actual for color).
PAL: 25 frames/50 fields per second.
SECAM: 25 frames/50 fields per second.
Motion picture film for TV is projected at the
standard sound speed of 24 frames per second in
NTSC countries. In PAL and SECAM systems film
is run at 25 f/s, the TV frame rate. See the listing
of International
TV Standards. topˆ
Framestore
A generic name for a solid state digital video
storage device that is capable of storing from
1 to 4 fields for an indefinite period of time.
Framestores are used in Frame Synchronizers (FS),
Digital video Effects (DVE), and other devices
where it is useful to manipulate picture elements
(pixels) in time and space. topˆ
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