Video tape recorders
Jul 1, 2001 12:00 PM, BY JOHN LUFF
Videotape still stores the intellectual assets of several generations of television production.
Commercial videotape recording began in the late 1950s. Though audio recordings on acetate strips had been done for many years, the considerably higher bandwidth of the television signal required new engineering approaches. The first recorders sold to CBS by Ampex recorded using high-speed rotating heads. Though only monochrome, those first recordings changed forever the way television programs were produced and distributed.
The first recorders consisted of racks of vacuum tubes. The recordings and servos were entirely analog, and the timer was mechanical and accurate to a few seconds an hour on a good day. Editing was done by razor blade, with a microscope used to view the patterns of the tracks on the tape after “developing” the tape.
With the advent of electronic editing scarcely a decade later, VTRs had to be controlled with daunting precision. The erase current had to be turned on at the right moment, without erasing the outgoing scene, and the new recording had to be precisely timed to begin exactly where the erasure had cleaned a spot for it. A reel of tape for an hour weighed 20 pounds and the maximum recording was 90 minutes. Eventually the mechanics and electronics evolved to make the recordings more stable, repeatable and editable.
Over the last half century, the distance between tracks has steadily dropped (the size of the tape is as low as 1/16 of the quad tape of the 1950s), yet the precision of the tracks laid down on tape has improved dramatically. Recorders are essentially all digital, with analog recorders beginning to wane even in consumer products.
Prices have dropped to under $5000 for a simple recorder for professional use. These recorders produce a picture easily the equivalent of the recorders of 30 years ago, when an Ampex AVR-1 cost $120,000. Modern digital video recorders use a variety of picture recording data rates. That range of almost 15:1 yields a wide range of features and capabilities, including recording of multiple channels of audio and metadata. Professional models vary in price from $5000 to over $80,000.
There are a number of formats in production, but it is a fact that, in the end, the picture quality from any modern professional-grade VTR will be roughly similar for most uses. High-end post production demands high performance, and some applications require specific attributes to support editing and effects work. Features, after market support, price, VTR family support for future interchange, field maintainability, I/O and control options, and other factors will usually be more important than the basic picture quality.
For the last decade or so there has been constant conversation among industry experts about what the role of linear recording will be in the future. Optical disk and hard disk have improved substantially in performance and now can rival the ability of linear videotape to provide the sustained data rates necessary to make video recording practical. Generally it is assumed that a removable medium is required, but with the increase in hard disk capacity, it is not hard to see a post-production recorder for a studio that has a removable drive with perhaps 500GB of random access recording capability. Optical recordings have yet to economically achieve the sustained bandwidth necessary to support high-bandwidth professional recordings. However, with DVD RAM we may well see direct competition to linear tape as a field and studio recording medium in the next few years. Optical disk recordings hold the possibility of long shelf life with little if any deterioration.
Any recitation on the evolution of videotape also must recognize the importance of the introduction of consumer video recording. Before the VHS/Betamax wars a couple of decades ago only professionals could record video. As mass market consumer electronics manufacturing techniques were applied to video recording it became inevitable that companies like Panasonic and Sony would find ways to leverage the research they were doing into inexpensive professional recording as well.
Much of the same recording electronics that show up in the crossover camcorder are inside the “professional” studio VTR for multiples of the same price.
Can alternative mediums replace videotape? At some point in the future, some major breakthrough in the physics of recording may bring about the decline and marginalization of linear tape. However, videotape is still ubiquitous, inexpensive and stores the intellectual assets of several generations of television production. That is hard to replace.
John Luff is vice president of business development for AZCAR.
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