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Subject: Dead Media Working Note 07.7
Dead Medium: Dead Video Discs: Telefunken Teldec Decca
TeD, TEAC system, Philips LaserVision, RCA SelectaVision
CED, JVC VHD/AHD
From: kadrey_AT_well.com (Richard Kadrey)
Source: "Video on disc" By Tim Frost,
http://prostudio.com/issues/viddisc.html
The TeD Video Disc was an 8" disc system produced by
a collaboration between Telefunken, Teldec and Decca. The
TeD disc was very much like old vinyl records, but with
nearly 300 groves per mm. It ran at 1500 rpm. The FM
modulated video and audio was picked up by a stylus system
in much the same way as an LP, but it never really made it
into the commercial world.
By the start of the 1980s, no less than three
entirely different video disc formats were being actively
touted on both sides of the Atlantic. Philips had launched
LaserVision, which had been seen and discussed as early as
1972, and was the first of four different Philips video
disc formats. RCA was going strong with CED, and JVC
brought up the rear with VHD/AHD.
Several other companies were working on video disc
formats. Some like TEAC, who produced a workable laser
record/write system, kept the systems purely for
industrial users, keeping themselves out of the major
hustles of the domestic market.
On the consumer side each of the systems had their
own supporters, although as far as the consumer was
concerned, there was little difference in quality or
functionality.
The RCA CED or SelectaVision Videodisc was the most
high profile of the three systems. CED stood for
Capacitance Electronic Disc. The information was recorded
using FM techniques creating pits and bumps on the disc
surface. On playback, a small diamond stylus attached to
an electrode ran over the disc as it rotated. As the
electrode rose and fell, the capacitance between the
electrode and the carbon loaded PVC of the disc's surface
varied. This was decoded into video and audio signals.
Technical quality was up to VHS levels at least, and
CED offered stereo sound. It also had good initial support
with pre-recorded material. When the whole system came to
grinding halt in 1984, there were a good 250 titles
available. The discs played an hour each side, so that a
full movie could be placed on a single disc.
The technology for the JVC VHD/AHD system was a half-
way house between CED and LaserDisc as we know it.
The disk itself resembled a LaserDisc, with the data
carrier imbedded beneath a clear flat plastic surface. The
video and audio information was recorded more or less in
the same way as CED, using an electrode in the player to
sense different capacitances created by micropits in the
substrate. Each disk side offered an hour of playing time
with full colour and stereo sound.
An audio-only version of the 10" disc held up to
three channels of PCM encoded audio. Thorn/EMI entered a
joint venture with JVC to press the VHD/AHD discs.
Philips LaserVision was the progenitor of the current
LaserDisc. From the start it was a 'silver disc' 12" in
diameter, with pits recorded into it and read by a laser,
using Philips CD technology. Offering an hour of play,
stereo sound, and random access to any part of the disc,
in practical terms it offered everything that LaserDisc
and Video CD could offer, but a whole decade earlier.
In a re-launch of the system, Philips and Sony
introduced CD Video. This introduced the 5" CD, carrying
20 minutes of audio and 6 minutes of video. It was
intended to capture a CD/Video singles market- another
forlorn hope.
But CD Video did accomplish the merging of CD and
LaserVision, so a single 'combi-player' could play both.
It also marked the end of LaserVision and the beginning of
LaserDisc. In the US this meant only a formal name change,
but in Europe the LaserDisc was redesigned to carry
digital sound. The new LaserDiscs would not play on the
old analog FM sound LaserVision players. After a pause in
production, European LaserDiscs were re-launched, with
growing success.
Dead
Media | 0.01-02.0 | 02.1-04.0
| 04.1-06.0 | 06.1-08.0 |
08.1-10.0 | 10.1-12.0 |