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 That format fell into disuse, becoming superseded by the laser disc system, which uses a laser to read a track cut in a spiral pattern on the inside surface of the disc.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.

Rigid circular plate of either metal or plastic used to record video and audio signals for playback. It resembles a phonograph record and can be played on a machine attached to a conventional television receiver. There are two major classes of videodiscs, magnetic and nonmagnetic. Magnetic videodiscs have an oxide-coated surface onto which input signals are recorded as magnetic patterns in spiral tracks. Nonmagnetic videodiscs use either a mechanical recording system analogous to that used in phonograph records, or optical technology that uses a laser to read data coded as a sequence of pits on the disc. The most common type of videodisc today is the DVD.

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Videodisc (or video disc) is a general term for a laser- or stylus-readable random-access circular disc that contains both audio and video signals recorded in an analog form. Typically, it is a reference to any such media that predates the mainstream popularity of the DVD format. Such formats include:

• MCA/Philips DiscoVision (early name for laserdisc format) (1978)
• Pioneer Corporation LaserDisc (1980)
• RCA SelectaVision brand of CED players and discs (1981)
• VHD, a videodisc format that was marketed predominantly in Japan by JVC (1983)
• Laserfilm, a videodisc format developed by McDonnell Douglas (1984)
• MovieCD, by SIRIUS Publishing, Inc. (1995?)

Unlike the battles between VHS and Betamax, there was no serious format war between early video disc formats as the LaserDisc proved to be technologically superior to all challengers of its time. Even the LaserDisc, though, failed to achieve much market traction against videotape, due to the latter's ability to allow consumer recording. Only with the introduction of the modern DVD format did a disc technology take hold for video. The modern DVD format also had little competition; only the short-lived DIVX format (not to be confused with the DivX video codec).

References

• Cowie, Jefferson R. Capital Moves: RCA's Seventy-Year Quest for Cheap Labor. Ithaca, N.Y.: Cornell University Press, 1999. ISBN 0-8014-3525-0.
• Daynes, Rob and Beverly Butler. The VideoDisc Book: A Guide and Directory. New York: John Wiley and Sons, 1984. ISBN 0-471-80342-1.
• DeBloois, Michael L., ed. VideoDisc/Microcomputer Courseware Design. Englewood Cliffs, N.J.: Educational Technology Publications, 1982. ISBN 0-87778-183-4.
• Floyd, Steve, and Beth Floyd, eds. The Handbook of Interactive Video. White Plains, NY: Knowledge Industry Publications. 1982. ISBN 0-86729-019-6.
• Graham, Margaret B.W. RCA and the VideoDisc: The Business of Research. (Also as: The Business of Research: RCA and the VideoDisc.) Cambridge: Cambridge University Press, 1986. ISBN 0-521-32282-0, ISBN 0-521-36821-9.
• Haynes, George R. Opening Minds: The Evolution of Videodiscs & Interactive Learning. Dubuque, Iowa: Kendall/Hunt Publishing Co., 1989. ISBN 0-8403-5191-7.
• Isailovi´c, Jordan. VideoDisc and Optical Memory Systems. Englewood Cliffs, N.J.: Prentice-Hall, 1985. ISBN 0-13-942053-3.
• Lardner, James. Fast Forward: Hollywood, the Japanese, and the VCR Wars. (Also as: Fast Forward: Hollywood, the Japanese, and the Onslaught of the VCR.) New York: W. W. Norton & Co Inc., 1987. ISBN 0-393-02389-3.
• Lenk, John D. Complete Guide to Laser/VideoDisc Player Troubleshooting and Repair. Englewood Cliffs, N.J.: Prentice-Hall, 1985. ISBN 0-13-160813-4.
• Schneider, Edward W., and Junius L. Brennion. (1980). The Instructional Media Library: VideoDiscs, (Volume 16). Englewood Cliffs, NJ: Educational Technology Publications. ISBN 0-87778-176-1. 1981.
• Sigel, Efrem, Mark Schubin and Paul F. Merrill. Video Discs: The Technology, the Applications and the Future. White Plains, N.Y. : Knowledge Industry Publications, 1980. ISBN 0-914236-56-3. ISBN 0-442-27784-9.
• Sobel, Robert. RCA. New York: Stein and Day/Publishers, 1986. ISBN 0-8128-3084-9.
• Sonnenfeldt, Richard. Mehr als ein Leben (More than One Life). ?, 2003. ISBN 3-502-18680-4. (In German.)
• Journals:
• The Videodisc Monitor
• Videodisc News
• Videodisc/Optical Disk Magazine
• Video Computing

External links

• Videodiscs in Education
• Interactive Videodisc: An Emerging Technology for Educators
• Delivery of Career Counseling Services: Videodisc & Multimedia Career Interventions