ASCII-Compatible Time-Code System for Motion-Picture Films Using Microcomputers

The American Standard Code for Information Interchange (ASCII) code is the computer industry's standard for information interchange. This paper recommends the serial 8-bit ASCII code, its standard transmission techniques, and its derivatives as methods for recording time-code data on tape and film. A similar approach has already been implemented for videotape, and a new time-code system is now needed to facilitate production encoding, post-production decoding, and control of mixing and editing equipment in the film industry as well. One proposed derivative of the ASCII code, the frequency-shift-keying (FSK) modulation scheme, can be used with unmodified conventional recording and motion picture equipment. The most sophisticated derivative, the asynchronous-pulse-width-modulation (APWM) code, meets all the performance requirements of a time code for tape and film. The derivatives can be easily converted from one to another, which offers the advantage of inexpensive interface. The proposed codes have been developed for use with minicomputers, microprocessors, and standard data terminals. An integrated-circuit Motorola M6800 microprocessor is presently being used to generate and read time codes recorded on film and tape. The combination of the ASCII code and the microprocessor has resulted in a system that is “intelligent” and versatile and yet has substantially fewer parts than other systems.

Print ISSN

0036-1682

Published

1976-01

Content type

Original Research

DOI

10.5594/J07601