A "large" (more than 12 cm or 4.72 inches) injection-molded optical disc containing digitized information that has been recorded with a laser device and must be read on a laser device known as a videodisc player. See
CD-DVD for a discussion of why videodisc technology is in the sunset of its use in the world. The most common sizes are eight and 12-inch discs. A 12-inch disc will hold 54,000 video frames of super VHS quality. Full-length movies usually require more than one disc since only 30 minutes of video with audio can be stored on each side of a 12-inch CAV disc. A CLV disc can hold up to 60 minutes per side of a 12-inch disc. CLV holds more video but is more limited than CAV in terms of searching for individual frames. Two audio tracks can accompany a video track, thereby enabling educational audio to accompany entertainment audio. Although a videodisc resembles a CD-ROM in appearance, there are major differences. Relative to a CD-ROM disc, the laser disc is "large" in varying sizes of eight or more inches. Whereas a CD-ROM player can hold computer files and computer graphics images in common file extensions (e.g., GIF, BMP, PCX, TIF, JPG, etc.) and can be treated as a computer storage disc somewhat analogous to a high-capacity floppy disc, a videodisc cannot hold computer files. Videodiscs are more like videotape in that they are recorded in video formats such as NTSC or PAL or SECAM. Videodisc players are generally connected to television sets and will play on-the-fly in a computer only if that computer has a video board for any video source such as television inputs and VCR inputs. Videodisc and videotape images can be "captured" and transformed into computer files only if the computer has video capture hardware and software. Videodiscs are currently used in some multimedia presentations but their future in hypermedia is uncertain. Videodisc players cannot be made portable as CD-ROM players. Recently options became available for desktop recording of videodiscs. For example, Panasonic (201-348-7837) offers the LQ-3031T model starting at $12,500. However, most videodiscs mastered in professional labs require inputs of professional-quality videotape (usually one-inch videotape) produced in a video workstation. A second drawback of videodiscs is that, unlike CD-ROM discs, videodiscs cannot be previewed prior to being mastered. There are two types of videodiscs known as CAV and CLV. The most common entertainment and educational videodiscs are CLV discs. There are currently four levels of interactivity for videodisc players. Level "one" is controlled with an inferred or wired remote control or bar code reader. Level "two" players have programmable memory. Level "three" is controlled by an external computer which greatly improves interactive controls with hypermedia software. Level "four" is a high speed computer interface videodisc player that accesses each side of the videodisc. Level four is more useful for using a videodisc as an external storage device for computer data. For a short discussion of levels of interactivity see
Lynch (1994) , p. 19. Sources of educational videodiscs are given in Appendix 6. Applications in accounting education and training are listed in Appendix 1. Alternative videodisc players are discussed by Waring (1994a).
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