OCR
Optical Character Reader or Optical Character Recognition. A device or method that reads characters as images and converts them into text to be used in a computer. This can also be done through software.
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Octave
The musical spacing between a frequency and its double. For example, the distance between "A" (440Hz) and "high A" (880Hz) is an octave. The audible range from 20 Hz to 20,000 Hz encompasses about ten and one-half octaves.
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Octave Band
A frequency spectrum which is one octave wide (i.e. all frequencies from 125 Hz to 250 Hz). In recording and audio testing the octave itself is divided into thirds for better accuracy. Ohm A unit of electrical resistance equal to that of a conductor in which a current of one ampere is produced by a potential of one volt across its terminals.
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Off-Axis
Any angular direction that does not coincide with the axis of an object.
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Off-Screen Sound
Refers to sound effects or dialogue occurring off-screen of the image.
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Ohm
The electrical unit of resistance, transmitting a current of 1 amp when subjected to a potential difference of 1 volt. Represented by x or Z.
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Omni-Directional
Equally sensitive to sound from all directions. Out of phase Two related signals offset in time.
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On Axis
Coincident with an object’s axis.
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On Screen Display
Method of showing video picture control status within the picture area.
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Open Architecture Design
Concept for display device and electronics design to enable components to adapt to multiple transmission and audio standards the way a computer adapts to different operating systems.
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Optical
The photographic recording of sound onto film. Optical film soundtracks comprise two types, variable density, and variable area. Mono films have a single optical soundtrack; Dolby Stereo matrix encoded films have the two-channel stereo variable area (SVA) track. See Optical Soundtrack.
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Optical Output Connection
A type of digital data transmission between audio components using fiber-optic cable and special jacks (i.e. Toslink).
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Optical Recorder
The machine that transforms a completed mix on magnetic tape into an optical soundtrack. It creates a photographic negative of the optical track, which is combined ("married") with a negative of the picture to create a theatrical release print. See Printer.
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Optical Soundtrack
A photographic strip adjacent to the picture on a 35mm film print, varying in some way with the variations in sound. Analog optical soundtracks vary in width, while digital optical soundtracks have patterns of dots. See Analog Vs. Digital and Variable Area. Because optical soundtracks are printed at high speed at the same time as the picture, the theatrical release prints are economical, as opposed to magnetic prints whose soundtracks are recorded in real time for optimal quality as a separate step. With an optical soundtrack, as the film is pulled through the projector’s soundhead, a narrow light beam passes through the moving soundtrack, which causes the intensity of the beam to vary. The varying light falls on a sensor to create electrical signals for the theatre’s loudspeakers to convert back to sound.
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Oscilloscope
A test device that allows measurement of electronic signals by displaying the waveform on a CRT.
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Output
The product of an operation by a device going to some external destination, such as another device, a video screen, image or hard copy. The signal derived from any audio or video device. The physical connection that delivers the result of what the device does, such as a signal. In A/V industry output is often used (erroneously) as a verb. (i.e. "This device outputs composite video.")
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Overhead Projector
A device which produces an image on a screen by transmitting light through a transparent acetate placed on the stage of the projector. Can project transparencies up to 10" x 10." Can also be supplied with a continuous roll of acetate which can be moved over the stage by means of a crank.
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Overscan
The amount of picture that is lost beyond the edges of the screen that is not the complete area of an image displayed. The result of the TV scan lines exceeding the boundaries of the display screen. Overscan prevents the ragged edges of the picture from becoming visible when low AC line voltage shrinks the raster width. Power supply regulation reduces the need for overscan. About 5 percent in from the outside edge of each side of the SMPTE Resolution Chart there is a white line that forms a rectangle around the chart. If any of that border line can’t be seen,more than 10 percent of the picture area is missing. Ideally a set should show all the way out to the edge of the picture being transmitted.
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Overshoot
A condition in which abrupt changes in luminance level momentarily exceed their new level, due to an excessively high sharpness setting. Overshoot is visible as a think light border at both sides of sharply focused black objects.
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Overtone
A component of a complex tone having a frequency higher than the fundamental.
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