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TechWaTch
Video Recording Becomes Real: Stand up and Cheer
By Walter Salm
tem — a technology that dramatical- ly lowered the background hissing noise that was an unavoidable part of every tape recording. Then a relat- ed noise suppression system was de- veloped for FM broadcast stations and for a while also for automobile stereo receivers. The advent of digi- tal meant even better quality, and now the Dolby license logo appears on movies and recordings as a hall- mark of quality audio reproduction. Dolby Laboratories continues to be an extremely active technology com- pany in several locations throughout Silicon Valley and other major tech- nology and entertainment centers worldwide. Yet what is probably among Ray
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Dolby’s most significant contributions to today’s technology goes largely un- known by people who are too young to have lived through the pre-video era. To backtrack a little, in the late 1940s, commercial television was
ay Dolby is perhaps best known for his revolutionary audio noise-suppression sys-
starting to enter living rooms across the USA. Networks began to reach across the continent, linking New York with Los Angeles and other West Coast metropolitan centers. The connections were made with a ponder- ous combination of coaxial cable and strings of microwave relay towers lo- cated every 30 miles. There were no satellites, no fiber optics or lasers. None of them had yet been invented. Virtually all locally produced TV
shows were telecast live in those days, and they were live of necessity; there was no really easy way to record video. There was a serious time zone problem, since network productions that originated in New York could on- ly be viewed live in Los Angeles three hours earlier. In an effort to equalize the time zone differences, network TV stations on the West Coast would record the live signal for later trans- mission. The problem was that the on- ly recording technology available, called “kinescope”, recorded images from a TV screen onto 35mm or 16mm movie film, which then had to be
chemically processed in a hurry and readied for rebroadcast, all within three hours. The resulting image quality was frequently awful, yet giv- en enough time and finesse, it was possible to get fairly decent quality kinescope recordings. For starters, there was a major problem synchro- nizing television’s 30 images per sec- ond with the movie camera’s 24 frames per second. Very often, kine- scopes were third or fourth generation copies, and not well handled. In addi- tion, the process was very expensive, with the time-zone delays reportedly costing as much as $4,000 (in 1950 dollars) to record a 30-minute show in black and white. The TV studio kine- scope recordings were eating up more movie film than the movie industry it- self — undoubtedly a great boon for Eastman Kodak, but a very high price to pay for what was often less-than- desirable reproduction. So what about magnetic tape
recording? Audio tape recording was still in its infancy, and used a cellulose acetate base that was coated on one side with iron oxide. Mylar base tape was still years away. Cellulose acetate was extremely brittle and deteriorated rapidly over time in storage, even in climate-controlled atmospheres. Tape breakages were frequent, and audio tape had to run at 15 ips (inches per second), the optimum speed for high- fidelity audio reproduction, with lots of pre-Dolby hiss. Many experi- menters and commercial laboratories got to work trying to record video on mag tape, but the quarter-inch audio tape that they were using had to run at a breathtaking 300 to 400 ips. Tape that would accommodate 30 minutes of audio would be good for only 60 sec- onds of video, and poor, shaky video at that. And at that speed, if the tape broke, which it did frequently, the re- sult would be a shower of confetti-size pieces of demolished tape, and there went the recording. One major proponent of video
tape recording was David Sarnoff, chairman of radio/TV manufacturing giant RCA in Camden, New Jersey. He would pound the lectern at meet- ings, promising that video recording was just around the corner. But his R&D people were no closer to practi- cal video recording than the many other labs in the field who were all struggling with quarter-inch tape that they ran at 300 to 400 ips. Mul- tiplexed signals were also tried, but these were likewise unsuccessful.
Startup Company It remained for a small, rela-
tively unknown Silicon Valley start- up company called Ampex to come up with the solution. Ampex had al- ready developed state-of-the-art au- dio tape recording equipment, but
early on realized that using the 300- 400 ips speed for video was far from practical. Believing that 2-inch-wide tape held the answer, Ampex engi- neers worked with several approach- es. The idea of a rotating head had been first suggested by Marvin Cam- ras of Armour research. Then the Ampex people saw a demonstration of a rotating head system at BCE (Bing Crosby Enterprises) in Holly- wood, a starting, toe-in-the-water sort of thing. BCE had worked close- ly with Ampex on the development of audio tape recording technology, and BCE’s Jack Mullin showed off a mod- ified rotating head recording system to Ampex engineers. They went back to Redwood City to do some more tin- kering. Engineers there were largely stumped, just like everyone else. Enter serendipity, in this case a
brilliant teenager, Ray Dolby, who while still in high school, was sent to Ampex by his school because they had requested a projectionist. The teen - aged Dolby developed an immediate affinity with Ampex founder and pres- ident 60-year-old Alexander Poniatoff, a relationship that ultimately had a big payoff for the company. He started working with Charlie Ginsburg on the TVR (Television Recorde r) project. Thus he became the second member of what was eventually a team of six working on TVR at Ampex. It was during this period that
Ginsburg and Dolby had to deal with issues of tape being shredded by the rotating head. This was largely alle- viated by installing female track- forming rotating guideposts, ma- chined by Shelby Henderson, and the team finally had something to show to Poniatoff. It was a short snippet from a Western film, but the Ampex CEO couldn’t tell which image was the horse and which was the cowboy. So Ginsburg and Dolby went back to the lab and within two weeks had a much improved image — still not very good, but they were light years ahead of anyone else. High school graduation meant
that Dolby could spend his summer working full time at Ampex, and was awarded his first patent for a syn- chronization technique for Ampex audio recorders. In the Fall he en- rolled in San Jose State College to study electrical engineering.
More Improvement Needed The improved video system was
still plagued with reproduction diffi- culties. Dolby was lying in bed one night (in March 1952) when an idea occurred to him, that the basic geome- try of the system was wrong. He drove to Ginsburg’s house in the middle of the night and they worked on sketch- es for a different rotating head system
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May, 2016
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