 Ampex VR1200B quadruplex recorder, late 1960s
Curiously enough, the beginnings of video recording go back to the beginnings
of television itself, and where television begins, John Logie Baird is sure not
to be far away.
In 1926, the very year that Baird first publicly demonstrated television, he
applied for a patent on a system for video recording, which he called
'Phonovision'. The patent (324049), granted in 1928, described a device called a
'Phonovisor', designed to replay Phonovision discs. Baird managed to record
images on disc, but he never publicly demonstrated playback, no doubt because
the quality of the 30-line images is even worse than they were when broadcast.
However, with the aid of modern digital processing technology, author Don
McLean, a researcher who is at pains to give Baird no less than the recognition
he deserves, has recovered the content from all the existing Phonovision and other 30-line disc recordings and made them available on his web site (www.tvdawn.com) and on CD-ROM.
Phonovision used what was essentially a modified standard 78-rpm cutting
lathe. It was possible to use this to record the 30-line images because the
bandwidth was in the audible range - in fact, Baird's 30-line transmissions were
made on medium wave (AM) where the frequency response hardly exceeded a few
kilohertz. Even so, Baird had to drop the frame rate from the broadcast 12.5
images per second down to just four to capture the images on disc (three frames
per disc rotation at 78-rpm), which caused loss of greys. There are some other
differences between Baird's recording system and his broadcast system, notably
the fact that the 7:3 aspect ratio portrait-style image is scanned with 30
vertical lines from right to left on the air, but left to right in Phonovision.
Due to the anti-intuitive 'flying spot' scanning system that Baird used,
where a scanning beam was emitted from a fixed 'camera' and light reflected from
the scene was captured by banks of photocells that could be moved or crossfaded
to change the 'lighting', Baird 30-line transmissions and recordings demonstrate
quite strange illumination.
The extant Phonovision discs have clearly visible radial striations across
the disc surface, which suggest that they contain sync information and show how
the frames were synchronised to disc rotation.
By around 1930 there was at least one commercially-available disc system
designed for home audio recording. This was the Silvatone system, sold by Cairns
& Morrison for £4 12s. A microphone was provided and six blank single-sided
aluminium discs that could be recorded upon, once only, with a steel needle - a
fibre needle was used to play them back. Each disc had a running time of about 4
minutes. An enterprising owner of this system in Ealing, West London, used it to
record 30-line television broadcasts off-air, using a medium wave receiver
connected to the audio input of the recorder and no synchronisation information.
One disc survives, of part of a programme - the first-ever television revue -
called 'Looking In', featuring dancing by the Paramount Astoria Girls and
broadcast on 21 April 1933.
In 1934, the first publicly available videodisc was released. Advertised in
Television magazine and sold through Selfridges, the disc, by the 'Major
Radiovision Company', was sold in quite large numbers. It was in fact a 10in,
double-sided 78-rpm test disc with 11 cartoon-like test images and one test
pattern, designed to help 'lookers in' to adjust their Televisors. Viewers would
hook up their record player to the Televisor's audio input and presumably
synchronise the images by hand, there being no sync signals on the disc. It has
been suggested that you would use the test disc to 'warm up' your Televisor
before broadcasts came on the air, then switch over to the medium wave receiver
and adjust the set to gain a synchronised image instead of starting from scratch
at the beginning of a broadcast.
Eleven additional private off-air disc recordings of television broadcasts
(The 'Marcus Games discs') from the period 1932-35 also exist and have been
restored by Mr McLean. Television programmes were not to be recorded directly
again for another twenty years.
Near the end of WWII, British radio monitoring stations had been bemused to
hear Hitler making speeches in several different cities sufficiently close
together in time that he could hardly have made the journey himself, and they
suspected recordings were being used, but they were audio recordings of a much
higher quality than was generally believed possible from the disc recording
systems of the time. As the Allies pushed across Germany, they discovered
several sound recording machines using paper tape coated with a black iron oxide
- magnetic tape - but their recording quality was limited. However, American
soldiers were informed that a radio station in Frankfurt had rather different
Magnetophon machines with an extra piece of electronics on them. On examination,
it turned out that these were AC-biased machines that offered far higher quality
than the previous DC-biased recorders ('biasing' is a method of making the tape
work with lower distortion). It's generally believed that two of these machines,
and tape to use on them, were brought to the US after the war by Jack Mullin. He
demonstrated the recording system to singer Bing Crosby who, impressed, helped
with funding and led to the setting up of the Ampex Corporation and the launch
of its first audio recorder, the Model 200, which was first used on the air in
1948.
At this time, as it had been since the BBC's 405-line Television Service
opened in 1936, apart from films, all television was live (and the expense of
film made it unusual for the production of television programmes in the UK). If
a programme was to be repeated, it required a second performance. There was a
way of recording television images, but only by shooting a television monitor
with a specially-modified synchronised, usually 35mm, film camera. The results
from the 'kinescope', as this system was called, were considered by and large
acceptable (although there were significant problems with the image quality) and
the process reliable, but by the 1950s in the United States, where time-shifting
across the continent was a way of life - a live network show broadcast to New
York had to go out three hours later on the West coast - the 35mm kinescopes of
the networks and their 16mm backups ate up more film in a year than the entire
Hollywood film industry: NBC is estimated to have used over a million feet a
month, and the costs were astronomical, including requiring extremely rapid
processing turnarounds.
There was obviously a market for an alternative recording medium, and
magnetic tape showed promise. But unlike the narrow-bandwidth Baird
transmissions, a 405- or 525-line video signal needed much wider bandwidth than
audio - as much as around four megahertz. To record higher frequencies required
a higher tape-to-head speed - much higher. And while some systems tried to
achieve this goal by simply running the tape faster, this initially meant that
lower frequencies (which contribute to the rendering of greyscales) were not
recorded as well. An early attempt at overcoming these obstacles was the BBC's
VERA (Vision Electronic Recording Apparatus), designed by a team led by Dr Peter
Axon, which, starting in 1952, offered broadcast-quality capability by 1958 when
it was used on the air. VERA spun tape at 16 feet per second, offering just 15
minutes of recording time on a 21-inch reel. High frequencies (100 kHz-3MHz) were recorded on one track with AM, while low frequencies were frequency modulated on another. The unit included a number of other innovations such as a
closed-loop drive mechanism locked to external sync. Another example of this
'longitudinal' recording approach was the machine that Jack Mullin produced for
Crosby Enterprises, which multiplexed the signal across ten tracks on half-inch
tape running at 120 in/s. The technology was subsequently acquired by 3M, who
applied the concept to data instrumentation recording.
However, it became evident that longitudinal recording was not the way to go.
Instead of running tape at high speed, the idea was put forward of moving the
tape head past the tape at high speeds, putting the head on a disc or drum and
spinning it across the tape while moving the tape forward, to create a
transverse recording pattern. This needed multiple heads so that one head met
the tape just before another left so a continuous signal could be reassembled -
two or four were needed. The first attempt at this kind of recording used heads
on a vertical disc spun alongside the tape, producing a pattern of adjacent arcs
('arctuate' recording). A better approach was developed by a 6-man team at
Ampex, including the now-famous Ray Dolby, in the form of what ultimately became
known as the 'quad' or quadruplex recorder, where four heads on a drum at right angles to the tape were spun against it to produce almost straight transverse paths on the tape.
By the mid-1950s, the Ampex team was still bedevilled by problems, and
switched from AM to FM recording with immediate improvements. Results were shown
to management in early 1955 and although the resolution was still only 1.5MHz or
so, the team under Charles Ginsburg was given the go-ahead. A year later, in
February 1956, a demonstration was held using what was their Mark III machine,
and the team received a standing ovation. It was shown to major broadcasters and
a Mark IV was built to show at the upcoming Chicago broadcaster's convention.
The machine was unveiled on 14 April 1956 at a CBS affiliates meeting the day
before the show opened. Manager William Lodge delivered the annual report, his
speech visible live around the room on a number of video monitors. As soon as it
had finished, the Ampex team rewound and replayed the tape they had just made
back via the same monitors, to the astonishment of attendees. The word spread
and the Ampex booth at the Convention was crowded. Many orders were taken - but
the prototype machines then had to be developed into production products that
could be sold to meet those orders.
The first on-air use of the machines was on CBS on 30 November 1956, when the
news was recorded on the west coast for rebroadcast, but for the first month the
network ran kinescopes as a backup. Initial problems were ironed out and
production of the new VR-1000 began the following year. Also that year, RCA's
TRT-1A was unveiled, using the same recording system, RCA referring to the
process as 'quadruplex' recording for the first time because of the four heads.
The first machines cost around $50,000 and tape was $300 per one-hour reel -
much cheaper than kinescope recording and not nearly as fraught. Colour
recording followed in the early 1960s.
By the late 1950s, VTRs were being used regularly for time-shifting purposes,
but as far as the recording of programmes on videotape was concerned, the
problem was the lack of a simple editing capability. Although the first totally
video-recorded show went out on CBS in 1958, programmes were primarily 'recorded
as live'. Physical editing and splicing was possible, but only by 'developing'
the magnetic pattern on the tape and cutting between TV frames. Early recorders
added edit pulses to the control track on the tape to make these points more
obvious. Even so, half a second of audio was lost at the edit point, requiring
laying the audio back from a second machine. One technique was to edit a film
copy made with a kinescope and then conform the video recording to it - early
off-line editing. Editing with timecode was introduced in 1967 while the first
computerised editing systems began to appear in the early 1970s.
Meanwhile, another recording technique had been invented, this time wrapping
the tape most of the way around a large drum, the drum containing heads that
rotated against the tape to produce a helical scan - an approach that eventually
became dominant. This technique led to the first consumer video recorders, such
as the Philips semi-pro EL3400 open reel recorder (1964) and the development of
smaller and lighter recorders, such as the Sony 'Portapak', that could be used
in the field. Then came the first cassette-based recorders with the introduction
of Sony's popular 3/4in U-Matic recorder in 1971 (designed for home use but
finding its true niche in the corporate and educational fields, and ultimately
some broadcast applications), and the Philips N1500 consumer 'VCR' or
videocassette recorder, introduced in 1973, which was capable of extremely good
quality recordings on a one-hour VC60 cassette. Later versions reduced the tape
speed and thus increased the recording time. Sony's consumer Betamax format
arrived in 1975 and the technically inferior JVC VHS system a year later. But Sony was trapped in a court battle with Hollywood that gave VHS an unassailable edge.
At the broadcast end of the chain, quad machines persisted until around 1978,
with the introduction, once more by Ampex, of Type C, 1in open reel recorders.
Broadcast-quality camcorders became possible in the early 1980s, with CCD
imaging devices and recording systems that instead of recording colour
subcarriers (which were badly handled by helical scan systems) recorded
full-bandwidth luminance (the black and white signal) on one track plus two
bandwidth-limited FM colour difference signals on another, allowing tiny
helical-scan recorders.
The next fundamental revolution was the introduction of D1 digital video
recorders in 1986-87. High prices kept these out of all but the most well-heeled
facilities until more affordable digital systems began to appear in the
mid-1990s. Today, there is a proliferation of digital TV technologies, and the
ability to store and edit digital video on modern computer-based systems has led
to the introduction of video servers and other non-tape-based methods of working
on and distributing television programmes.
Sources include:
http://www.tvdawn.com/
http://www.tvhandbook.com/History/History_recording.htm
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