Links to Other Video Glossaries
Many of the glossaries found in Preservation Terms have definitions for general technical video and audio terms.
Glossary of Technical Terms by The International Association of Sound Archives (IASA)
Stauderman , Sarah. Video Format Identification Guide Glossary of Video Terms
Compiled as part of the Electronic Media Special Interest Group of the American Institute for Conservation of Historic and Artistic Works.
A Basic Technical Glossary
This is a brief glossary intended for general interest. The above links contain more and detailed information.
Adjacent layers of the tape as it is wound on the reel stick together. This can be caused by improper storage conditions, winding which is too tight or because of improper manufacturing of the tape.
Creases and wrinkles
Wrinkles or creases pressed into the tape by the capstan/pinch roller assembly on the record/playback deck or by another physical processes. If the tape is played back, the recorded information located on the creased areas breaks up.
If the chroma level is too low, the colors look faded. If the chroma level is too high the colors are overly saturated. If there is noise in the area of the tape which contains the color information, the colors appear to be moving inappropriately.
Refers to the folding over of the tape onto itself on the reel. This results in permanent folds or creases on the tape which cause picture disturbance. This can be caused if the tape has been stopped suddenly on the record/playback machine.
A signal recorded on the edge of the videotape which controls how the tape tracks and its speed. If this track is damaged or improperly recorded, the picture can be unstable or jumpy.
A tape deformity which may cause horizontal or vertical lines in the playback picture.
Crosstalk and Print Through
This refers to interference of the taped signal by another signal, which results in distortion of the image or sound. This can occur if signals on the tape imprint themselves onto nearby areas of the tape where they don't belong. It is most noticeable on audio recordings; you may be able to faintly hear a ghost of the other unwanted signal when the tape is played back.
Dropout appears on the picture as small white spots or streaks. It can be caused by physical deterioration of the tape itself, or by contamination of the tape with dirt or dust. It results in signal loss because the heads that read and display the picture information become clogged or dirty.
Physical damage to either the upper or lower edges of the tape results in playback problems. The type of problem depends on the location of the damage. The upper edge contains audio information. The bottom edge contains control track information.
The top portion of the image appears to be bent horizontally. Also called skewing.
Refers to the number of "steps" away from the original a particular copy is. Because signal information is lost with successive copying of the tapes, generally the further away a tape copy is from the original, the worse the image and sound quality might be.
The heads are responsible for recording and display of the image. If they become dirty, they are not able to record and read the signal information on the tape. This causes poor image quality. If the heads were dirty when the tape was recorded, then the poor quality is on the tape itself. If the heads became dirty when the tape was played back, cleaning the playback deck heads may result in better image display quality.
The black and white part of the video signal, seen as brightness.
Any unwanted signal present in the total signal.
This refers to uneven winding of the tape on the reel. If you look at the tape reel when it is laying horizontally, you will see high or low areas in the winding. If the winding isn't flat, the edges of the tape can be damaged.
The image appears to drift up or down because the synchronization signals recorded on the tape to keep it oriented horizontally and vertically are faulty, or because the recording or display equipment are malfunctioning.
The tape is physically damaged, which results in the appearance of solid lines when the tape is played back.
Shedding and sticky shed
Videotape has a base layer underneath an oxide coating. The oxide coating is the recording surface. If these two layers separate, the oxide may begin to fall off and clog the heads.
Signal-to-noise ratio (S/N)
Refers to the proportion of desired audio and video signal information to undesired audio and video signal information, expressed in decibels (dBs). Higher numbers generally indicate better audio and video.
This problem appears as a bend in the top or bottom portion of the image and can be caused when the playback deck doesn't maintain the correct tension on the tape.
The random speckled black and white pattern that appears when there is noise present.
This problem appears on playback and is caused by dirt or other substances on the playback equipment and also by a loss of lubrication on the tape.
When a tape is played back, it can stick momentarily but repeatedly to one of the heads on the playback deck. The tape sticks, then releases, then sticks again. This can cause squealing and may physically damage the tape itself.
Sticky tape and shedding
This deteriorated tape has a tacky or gummy surface, which is soft. The binder and coating of the tape can separate and the magnetic coating falls off when the tape is played back. This process of shedding produces dropouts and can leave gummy deposits on equipment.
Tape pack slip
A lateral slip of particular tape windings causes high or low spots in an otherwise smooth tape pack. These unevenly wound areas are easily seen when the tape reel lies flat. Pack slip can cause subsequent edge damage when the tape is played, as it will unwind unevenly and may make contact with the tape reel flange.
to complete a circuit by connecting a resistive load to it. A video termination is typically a male BNC connector which contains a 75 ohm resistive load. When there are looping inputs, any unused looping input must be terminated in 75 ohms to ensure proper signal levels and to minimize reflections.
Synchronizing signals are recorded on a tape, along with picture and sound information. This sync information enables the images to be played back in a stable fashion, oriented properly both vertically and horizontally. Changes in these synchronizing or timing signals cause time base errors that result in disturbances to the images.
Tracking information is also recorded on the tape. If this tracking path isn't precisely followed when the tape is played back, the resulting tracking errors can produce unstable images.
Video signal-to-noise ratio
The ratio of usable signal to undesirable noise in a black and white picture.
This refers to the decomposition of an acetate based magnetic tape layer. It causes the tape to smell like vinegar and results in a faster loss of the backing.
The tape should be evenly wound onto the reel, with no high or low areas, and with an even tension, so the tape is not tight in some areas and lose in others. Pack slip refers to uneven winding.