videodisc or videodisk, disk used with a special player and television to reproduce both pictures and sound. A videodisc player cannot record television programs off the air for later playback, unlike a videocassette recorder (VCR) or recordable DVD (see digital versatile disc). Videodiscs generally produce pictures that are clearer in detail and truer in color than those produced by VCR tapes, and they also offer better sound quality, but the introduction of the DVD led to their becoming obsolete. Two quite different videodisc systems were developed. One operates much like a record player, using a mechanical stylus that senses varying patterns of electrical capacitance imprinted in grooves on the disc surface. That format fell into disuse, becoming superseded by the laser disc system, which uses a laser to read a track cut in a spiral pattern on the inside surface of the disc. On a laser disc, video is recorded as an analog signal and the soundtrack is either an analog or, in later versions, a digital signal.
More on videodisc from Fact Monster:
See more Encyclopedia articles on: Electrical Engineering