|Home | Audio Magazine | Stereo Review magazine | Good Sound | Troubleshooting|
(source: Electronics World, Nov. 1971)
By WILLIAM SLATKIN/ Product News Manager, Ampex Corporation
One of the great developments of our times--but will it really spawn a home recording /playback market as large as many anticipate?
VIDEO-tape recording, which is attracting growing interest in fields ranging from home entertainment to information storage and retrieval, was born just 15 years ago. It was conceived to solve a vexing problem of the then youthful television broadcasting industry.
It not only solved the problem of time delay in network broadcasts, but it also dramatically improved television viewing with techniques such as "instant replay," it has spawned $730,000,000 worth of business in the last 15 years, and it created three entirely new markets: (1) institutional closed-circuit television; (2) home recording and playback; and (3) automated information processing.
According to Ampex, which invented video-tape recording and has collected well over half the $730,000,000, this figure will be equaled again in less than five years. In fact, $730,000,000 is projected as a likely annual sales figure for video-recording equipment by 1976!
In 1971, the broadcast industry continues to be the largest user of video recording, constituting about half the market, while institutional closed-circuit television users (in education, industry, government, and medicine) are expected to account for 43 %; home recording and playback, virtually nothing; and automated information processing, 7 %.
In five years the picture will change drastically. Broadcasting and CATV are expected to represent about 10 to 15 percent, with closed-circuit television, home use, and information systems each taking 25 to 30 percent of the total.
Broadcasting and CATV
In the early days of television, networks and stations had no practical way of recording programs and commercials for quality rebroadcast within a few hours. News programs originating in New York City at 6 p.m. Eastern time, appeared simultaneously throughout the country, before most residents of the Midwest and Western states were home from work. Moreover, because it was impossible to edit live broadcasts, viewers from coast-to-coast witnessed those many embarrassing moments, such as when an announcer coughed his way through a cigarette commercial.
The Ampex VII-1000 video-tape recorder, introduced at the National Association of Broadcasters convention in 1956, provided the solution to these problems. It successfully converted images to electronic impulses and recorded them on tape for immediate or delayed transmission.
Before the end of that year, people in California could watch "Douglas Edwards and the News" at 6 p.m. Pacific time, since CBS recorded the live program and replayed it each hour to a different section of the country.
If production errors were made while putting a show or commercial on tape, the recorder was stopped, the tape erased and rewound, and the scene re-done.
The video-tape recorder was rapidly adopted throughout the broadcast television industry in the United States and abroad, but remained an exclusive tool of the broadcast industry for nearly 10 years.
Before the end of the 1950's, the National Academy of Television Arts and Sciences recognized the importance of the video-tape recorder and awarded Ampex an "Emmy" for its development. The firm began manufacturing a line of color recorders and another manufacturer, RCA, entered the growing broadcast field with its video-tape recorder.
Quadraplex recording on two-inch-wide tape rapidly became the broadcast-industry standard and the capability whetted broadcasters' appetites for more sophisticated technologies. Their new requirements brought about the development of significant advances; among the most important of which were electronic editing, high-band recording, and the "instant replay" system.
In 1962, electronic editing became feasible so the videotape recorder could be used as a production /editing tool, as well as a delayed broadcast system. Until then, if a tape editor wanted to change the sequence in which segments occurred in a tape, or add or delete material in a program, he had to physically cut the tape and splice together the desired finished production.
Electronic editing, widely used today, places an electronic signal on the tape at the touch of a button. This signal tells the recorder to erase a scene, to transfer a segment of action to another recorder, or to cue in a new input from a TV camera, film chain, or another video-tape recorder.
At the moment the insertion or deletion takes place, the electronic editor automatically synchronizes the change so the editing point will not be visible during playback. The viewer sees a change in scenes without the slightest jitter.
Because of further refinements in this capability, electronic editing can be accomplished from a single console which controls a variety of production systems. Modern consoles employ a computer memory to store cues and editing instructions.
High-band recording, developed in 1964, significantly advanced video-tape recording technology by substantial improvement in the signal-handling characteristics of the record /reproduce electronics.
The advancements in later designs (VR-2000) were significant enough to produce a noticeable improvement in the quality of color recordings. "Second-generation" equipment also made possible, for the first time, the production of several successive duplicates of a taped program through many generations without degradation of picture quality.
Another significant development in video recording for the broadcast industry was the video disc recorder--the "instant replay" device so familiar to armchair sports enthusiasts. The HS-100, introduced by Ampex in 1967, was first used in televising the 1967 U.S. Ski Championships from Vail, Colorado. Disc recording was developed because video-tape recorders, like audio recorders, do not provide a practical and totally accurate means of finding and replaying specific segments of recorded pictures and sound, and because slow-motion and stop-action effects are nearly impossible to obtain on a video-tape recorder.
The video disc technique uses a magnetically plated disc as the recording medium with the video record /playback heads placed in a movable carriage. During the recording operation, the head moves across the rotating disc, electronically placing video information in magnetic tracks on the disc, much as the rotating heads in a video-tape recorders place images on the tape.
When a particular segment of action is to be played back, the operator presses a button to command the head to return to a particular video frame and begin a replay.
By altering the speed at which the head moves across the disc either in record, playback, or both, speed of the segment being played is correspondingly altered. If the head is "frozen" over a single track, the HS-100 replays a single frame and the monitor exhibits a stop-action picture.
Scores of these machines are used throughout the world for "instant-replay" coverage of sporting events while a modified version, introduced in 1968, uses the disc technology along with a computer memory for the production of television programs and commercials. When used with electronic editing, it produces the fast, slow, and stop-action effects seen on many of the most popular comedy /variety shows.
Although sales of video equipment to commercial and educational television broadcasters and CATV operators will soon be surpassed by the three newer markets, broadcasting will remain the major source of technological innovations in the video-recording field. New developments, such as high-speed video-tape duplication, which will eventually serve all industries concerned with video-tape recording, are emerging first in the broadcast market.
Institutional Closed-Circuit TV
The largest of the three new markets for video-recording technology is currently closed-circuit television (CCTV) used in education, industry, government, and medicine for various training and communications applications. Various closed-circuit video-tape recording systems, offered by Ampex, Sony, and several other manufacturers, first appeared on the market in 1962.
While broadcast video-tape recorders weighed about 1200 pounds, were priced at approximately $60,000 and up, and used only two-inch-wide tape, the first closed-circuit video-tape recorders weighed between 50 and 100 pounds and were priced from about $10,000. Some used inch-wide tape.
A major technical difference between broadcast and CCTV recorders is the recording technique. Broadcast systems use four record /playback heads mounted on a drum which is rotated rapidly across the tape at virtually a 90-degree angle to the path of the tape. In this manner, the relative tape-to-head speed reaches approximately 1500 inches per second. At this speed, frequencies of more than 5 MHz may be obtained. This frequency is required to produce TV pictures with the quality necessary for commercial broadcasting.
Closed-circuit recorders use the helical recording format.
The tape is wrapped diagonally around the drum, which contains one or two record /playback heads. The rotating drum records across the moving tape in a diagonal curve.
In this manner, relative tape-to-head speeds of from 650 to 1000 inches per second are produced, creating frequencies up to 3.2 MHz. Although this bandwidth is ordinarily unsuitable for broadcast television, it produces pictures of high enough quality for the demanding requirements of the institutional market.
Within eight years after their introduction, at least 75,000 closed-circuit recording systems were being used throughout the world in a variety of applications.
Since the introduction of closed-circuit video-tape recording equipment, the prices of cameras and video-tape recorders have generally declined and new generations of systems have become available, offering sophisticated production-editing capabilities. Complementing the one-inch systems, a standard for half-inch video-tape recorders (the Type 1 standard) has emerged, to permit broad interchange of recorded programming. This half-inch standard plus the imminent availability of cartridge-loading recorders and players will greatly expand the closed-circuit market for video-recording equipment.
Home Recording and Playback
No aspect of video recording has attracted such wide interest as the anticipated home market. Many forecasts of future sales in the hundreds of millions of dollars have been made, although no true home recording or playback system is presently available.
Unlike the institutional CCTV market, which has grown steadily over the last seven years, this is a brand-new field in which there are many questions yet to be answered.
Among the current problems is a lack of system compatibility. No unit will accept and play a cartridge from any other manufacturer's unit.
In addition, there are many unanswered questions related to the programming, or "software." Among the most perplexing are: What kind of programming will the con sumer buy or rent? Can programming be produced and distributed economically enough to attract wide consumer support? Who will produce and distribute programs for this market? Although interest in home systems arose because of the potential seen in closed-circuit video-tape recorders for this market, several new technologies have emerged to vie for a share of the video cartridge business.
The EVR system, developed by CBS, is the only cartridge playback unit currently available on the market, with the present model designed for institutional use and the home version planned for the future. It uses ordinary although small, fine-grain photographic film. When plugged into the antenna terminals of a television set, EVR converts the optic information off the film to impulses that can be interpreted and recreated by a TV picture tube.
The RCA SelectaVision system, demonstrated in experimental models, effects an optic–to-electronic conversion, in this case from images imprinted by a laser on holographic tape.
Unique among the emerging technologies is the Teldec television disc to be produced jointly by Decca and Telefunken. Instead of a cartridge, the Teldec System plays a plastic foil platter, about the size of a long-playing record.
Although limited to about 10-15 minutes of playback time, prerecorded programs on disc will be available for a fraction of a dollar, considerably cheaper than program cartridges ($10-$20 and up for 30 minutes playing time). In addition to these systems, a number of manufacturers are working on home video-cassette units using helical video-tape recording techniques, but a variety of cassette and cartridge configurations.
Video-tape units will have the important advantage of providing the record capability, while owners of EVR, SelectaVision, Teldec, and other non-tape systems will not be able to use their equipment to record off-the-air or from camera.
While a number of industry spokesmen are heralding the imminence of the cartridge video market, there are enough unanswered questions--not the least of which concerns the availability of consumer-priced hardware-to suggest it may need a few more years of experimentation.
Even so, Ampex estimates sales of equipment for home use could reach $200 to $300 million by 1976, with most of the growth coming in the fourth and fifth years. For the longer term, it remains a market of great potential.
Automated Information Storage
From its inception, video recording's ability to store visual data faithfully and compactly and reproduce it immediately and electronically suggested its application in storing documents.
Ampex undertook development of a system (Video-file) for this purpose in the mid1960's. Prerequisites were the development of precise single-frame electronic editing capability, computer control equipment, and TV cameras and monitors with unprecedented reliability and picture resolution. The concept was announced in 1964 and the first commercial system was delivered in 1968. Following this long gestation period, the Video-file system has become a significant factor in the video-recording industry.
Video-file systems are not small. They are sophisticated, large-scale systems for automating large, active files. The first system, priced at $750,000, was installed at Southern Pacific Company in San Francisco in 1968 to automate the processing of hundreds of thousands of freight waybills each day. The system uses video tape to store images of documents, and computer address and search techniques to enable clerks to file and retrieve the documents in seconds. It operates virtually around the clock.
Video discs, like those used on "instant-replay" recorders are also part of the system. Document images called from the tape files are duplicated on disc recorders so office personnel are presented each required document for study in much the same way that single images are provided during stop-action "instant replays."
The discs also provide access to the images for several people at the same time without disturbing the original recording. As long as there are enough disc systems to go around, each person may view his own "copy" of a document, and no entry is ever "out of file."
Prev. | Next