Helpful Glossary of Videotape Terms A-Z

Burst (Color)
A color reference signal included as part of the overall composite video signal. Eight to ten cycles of color sub-carrier (3.579545 MHz, often abbreviated as 3.58) are inserted before the start of every horizontal line. It can be seen just following the H sync pulse in the H blanking interval. It provides color-synchronizing information for the color decoding circuits in monitors, receivers and other TV equipment.

Chrominance (Chroma)
The color information in a television picture. Seen on a waveform monitor as the color subcarrier riding on top of the luminance signal.

Clipping
A form of video distortion. It is seen as a loss of detail in the black or white areas of the picture. It may be caused by excessive video levels that cannot be handled by the television system.

Color Bars
An electronically generated standard set of colors used as a reference for proper equipment setup. Color bars include the three additive primary colors (red, green, and blue) and their complements (cyan, magenta, and yellow) displayed in vertical rows, plus gray and black. The bars appear left to right in order of decreasing luminance – yellow, cyan, green, magenta, red, and blue.

Component Video
A form of video, in which the luminance and chrominance signals are generated, transmitted and/or recorded on videotape as two independent signals, usually on individual video tracks.

Composite Video
A video signal that combines luminance and chrominance by using one of several world wide electronic encoding methods, such as NTSC, PAL, or SECAM. Encoding a video signal reduces the bandwidth, and therefore the resolution, since a single channel is used to carry all the information.

Control Track
A guide pulse acting as an electronic sprocket hole recorded on the videotape. Control track pulses are used by servo systems to maintain a tape speed that allows precise playback head tracking.

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.

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.

Dropout Compensator (DOC)
An electronic device in a VCR or VTR that detects the presence of a dropout and replaces it with information from the preceding line, thereby covering up the dropout.

Dub
In television, a copy of a videotape. dub is more commonly used than dupe (short for duplicate), which generally applies to film copies.

Edit Decision List (EDL)
A structured compilation of time code information defining each edit in a sequence. The EDL consists of pertinent information such as time code edit points, notes, and switcher data.

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.

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.

Helical Scan
VTR or VCR recording format that wraps the tape around the video scanner in a helix pattern.

Hue
A specific color wavelength in the visible light spectrum, an attribute of color perception. Flesh tones, for example, may be changed by adjusting the hue control (sometimes marked color phase) on a television receiver or monitor.

Interlace
The combining of two sequential television fields that make up a complete frame in the NTSC system. Field 1 contains the odd numbered scan lines, field 2 the even numbered line.

Luminance
The intensity of light: specifically, the monochrome component or the brightness potion of a video image. The symbol "Y" is used to identify the luminance signal in composite and component color systems.

Macrovision Anti-Copy Protection
The Macrovision videocassette anticopy process is the most effective and widely used technology for preventing “back-to-back” copying of videos using two VCRs. The technology consists of a carefully timed sequence of electronic pules that are added to the video signal during duplication to stop pirating of unauthorized duplications.

Noise, Video
A random signal generated by most electronic equipment, which is present throughout the video signal spectrum. Video noise is somewhat analogous to film grain.

Non-Drop Frame Time Code
A time-based reference system for video and audio that was developed and standardized by the SMPTE. The system assigns each frame a distinct eight-digit number that is composed of hours, minutes, seconds, and frames. Because of the nature of the NTSC color television system, non-drop frame time code does not agree with clock time.

Safe Title and Safe Action Areas
Geometric boundaries within the television viewing area used as a guide to insure the correct placement of graphics, titles of other types of art work so as not to lose the desired action or title information as seen on a television receiver.

Saturation
The intensity of the color in a video picture. The greater the color (chroma) saturation, the more intense the color. The amount of color saturation may be seen on a vectorscope.

SCH (SubCarrier to Horizontal Phase)
Refers to the timing relationship that must exist between the color burst and the leading edge of sync to obtain clean color edits. The zero crossing of SCH must be time coincident with leading edge of horizontal sync.

Sync
The pulses in a video signal that provide a synchronizing reference for each frame and scanning line of the picture.Sync, Editorial

Time Base Error
The horizontal and/or vertical jitter inherent in most videotape recording equipment. Broadcast standards require a horizontal line-to-line timing accuracy of better than one part in thousands, which is impossible to attain in a mechanical tape-scanning device. An electronic automatic time delay device, known as a Time Base Corrector (TBC) is necessary in all helical scan VTRs to compensate for this inherent problem if the video is to be broadcast or composited (dissolve, wipe, matte) in any way.

TBC (Time Base Corrector)
An electronic processing device connected to the output of a VCR or VTR that removes or masks the jitter generated by unavoidable mechanical inaccuracies in helical scan recorders. This is accomplished by automatically delaying the video signal so that each line starts at the proper time.

Time Code Generator (TCG)
An electronic clock that generates a digital serial code that can be recorded on an audio track, which assigns to each video or audio frame a unique identification number composed of eight digits.

Tracking
The process by which the video head precisely follows the recorded video signal on playback. Correct tracking assures a noise free reproduction of the picture.

Vectorscope
An instrument used to setup color encoders and to confirm the proper transmission and/or recording of color signal. A CRT displays the color subcarrier in a circular pattern. The graticule contains a pattern of measuring boxes in positions based on the hue and chroma characteristics of the color bar signal. The individual bars appear as bright dots which should fall within the small boxes if the color signal has been correctly encoded and has not been altered in transmission or recording. The angular position of the color vector indicates the hue (phase) of the color. The length of the vector is a measure of the saturation. The color burst reference marker, a horizontal bar situated at the 9 o’clock position on the graticule, is the established reference with respect to the six colors positioned in their respective boxes.

VITC (Vertical Interval Time Code)
Time code that is recorded on two lines of the vertical blanking period in the video signal. Unlike time code recorded on a longitudinal linear audio channel, VITC time code is scanned by the video head even when in still frame. This time code then is converted to a readable time code that may be used to frame accurately, locate, and define edit points.

Waveform Monitor
A display device that shows the electronic pattern of the video signal on the face of a Cathode Ray Tube (CRT). Superimposed on the screen is a scale vertically divided into 140 divisions, termed I.R.E. units. The synchronizing pulses occupy the range between -40 and 0. The video waveform starts at 0 with black at 7.5 and white at 100. A WFM allows the operator to view the video signal and make the appropriate adjustments as necessary to keep the video signal within prescribed limits. It is also used to measure sync signal parameters to be sure that they conform to accepted standards. Common test signals such as color bars, multi-burst, staircase and window can easily be evaluated to determine the performance of an incoming source or the playback of a recorder.

Window Dub
A copy of original videotape with the eight-digit time code displayed in a rectangular area generally at the bottom of the screen. This window area may be surrounded by a black box so that the time code numbers stand out against a light background. The window dub is used only as a viewing copy or may be used as a work copy tape to edit with since the numbers once recorded in the picture cannot be removed.