Audio/Video Glossary

Special effect in which either blacks and whites are reversed or colors are inverted. For example, red becomes a blue-green, green becomes purple, etc. An electronic color filter can be used for fine adjustment of the hues.

NOISE

A general term used in electronics to indicate any unwanted electrical signal, unrelated to the original signal.

In audio, noise is generally manifested as hiss and static.
In video, noise is generally manifested as snow, graininess, ghost images or picture static induced by external sources such as the national power-line grid, electric motors, fluorescent lamps, etc.

NOISE GATE

A device used to modify a signal’s noise characteristics.

In audio, a noise gate provides a setable signal level threshold below which all sound is removed.
In video, noise gates provide optimal automatic suppression of snow (signal noise level).

NOISE REDUCTION

An electronic process used to reduce noise levels in audio and video signals.

In audio, the most effective systems employ an encode/decode scheme, performed before and after recording, such as the Dolby audio noise reduction system. Noise reduction can be performed on an existing audio signal using systems such as DNR (dynamic noise reduction) but are less effective because they also affect the audio signal.
In video, the most effective noise reduction is accomplished by digitizing the video signal and carrying out a computerized pixel by pixel analysis of the data.

NONLINEARITY

The amount by which a measured audio or video signal output differs from the standard signal output.

In audio, any type of distortion that occurs.
In video, the greater this deviation, the greater the video signal distortion and possibility of luminance and chrominance problems.

NONLINEAR EDITING

The process of editing using rapid retrieval (random access) computer controlled media such as hard disks, CD-ROMs and laser discs. Its main advantages are:

Allows you to reorganize clips or make changes to sections without having to redo the entire production.
Very fast random access to any point on the hard disk (typically 10-20 ms)

(See EDITING)

NORMALIZATION

An automatic process available on some DAWs, whereby the gain of all program material can be adjusted so the greatest peak level will just arrive at 0 dBFS. Normalization can be extremely damaging to digital audio if misued. For instance, normalization should never be used to correct the apparent loudness of different tracks on a music album. Truncation distortion may also be introduced if improperly applied.

NTSC (National Television Standards Committee)

Color TV broadcasting standard used mainly in North America, Central America, Japan, and parts of South America, featuring 525 lines per frame and 60 frames per second. (See PAL and SECAM)

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