Resource Center: How to Speak A/V
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Entries starting with: gain: How much the level of incoming signals is changed by a circuit or antenna, usually in decibels (dB). Gain can be positive, for amplification; negative, for attenuation; or 0 dB for no change, or “unity gain.” gamma: A numerical specification of the relationship between video signal level and image brightness. Gamma is important both in video cameras (and video encoding of movies) and in video displays. Ideally, the gammas of recording and playback devices should be identical. In practice, displays normally have to incorporate some correction to compensate for how they inherently translate video levels into light levels. Otherwise, some scenes or parts of scenes would appear darker or lighter than they should. This is especially problematic for display technologies, like LCD, that cannot produce true black. It’s hard to achieve a single gamma setting that looks right for all input signals, especially if they originate in different media (like film, video, and computer graphics). giga (G): The metric prefix for billion. gigabyte (GB): One billion bytes, a measure of digital information storage capacity; commonly specifies the data-storage capacity of such media as DVDs and hard-disk drives. graphic equalizer: An equalizer with control bands that are fixed in frequency but variable in level; the slider controls for the various bands provide a rough graphic representation of the selected frequency-response curve. graphical user interface (GUI): Any “point-and-click” control system for an electronic component that uses menus and icons displayed on a screen instead of (or in addition to) physical pushbuttons and other controls. grayscale: On a video display, the intermediate steps of gray between absolute black (0 IRE) and white (100 IRE). In the analog NTSC TV system used in the U.S., black level is specified as 7.5 IRE; for all other TV systems and progressive-scan DVD outputs, black should be 0 IRE. ground: In an electrical circuit, the reference for 0 volts, above and below which other (AC) signals may vary. Abbreviations |
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