The quest for home video
The concept of using discs for audio-visual purposes goes back to the early years of the 20th century, combining the then youthful development of motion pictures with the equally youthful gramophone disc. Despite the huge success of videocassettes, the disc was always the favoured format for delivering pre-recorded video to the consumer market.
A cassette is relatively cumbersome and, at least in its early days, had to be copied by transferring a signal from a master copy onto each copy tape in real time. Although technology has speeded up the process, and thereby reduced costs, videocassette copies are still made by passing blank tape from one spool to another past a recording head.
So a disc has a distinct advantage over a cassette in that it can be reproduced as a single piece in a process that does not involve spooling tape: it is either stamped into plastic or exposed and processed photographically. Of course, the replication process for a DVD disc is elaborate and exacting, working towards the finite molecular limits of the materials used. But the principle is the same.
Much more to come!