jdg@ncrcae.UUCP (Jim Griggers) (01/10/85)
This article appeared in the January 7th issue of Electronic
Engineering Times. It is very interesting reading. I have a VHS vcr
now, but I might reconsider getting a Beta machine given the contents
of this article.
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H I - R E S V C R T E C H D E T A I L E D
by Richard Doherty
LAS VEGAS - A new home video cassette-recorder technology that effec-
tively doubles the picture quality obtainable on standard half-inch
Beta video, is being privately shown here at the winter Consumer Elec-
tronics Show.
The technology, called SuperBeta or SuperVideo, is being
developed by Sony Corp., Toshiba Corp. and the Sanyo Electric Corp.
Sony's consumer video group was expected to display SuperBeta
publicly, but changed its mind at the last minute. However, it is
expected that it will appear before the April meeting of the National
Association of Broadcasters.
Sony pioneered in-home VCR 10 years ago with its Betamax
recorder, and the current activity strengthens the Japanese commitment
to Beta and VHS. It also means that only three photographic companies
(Polaroid Corp., Eastman Kodak Co. and Fuji Photo and Film Ltd.) are
now offering the more compact, 8-mm video-cassette format that was the
rage at last winter's CES.
Also, many have cited the lack of an adequate consumer video
recorder as delaying interest in higher-quality broadcast television.
SuperBeta may thus be able to get the jump on proposed high-resolution
broadcasting by offering programming on prerecorded cassettes. Such
video cassettes would offer greater resolution than current laser
videodisks.
Present half-inch VCR's deliver, at best, about 250 lines of hor-
izontal resolution, with a signal-to-noise ratio (S/N) of about 40 to
46 dB. In contrast, Sony's new SuperVideo has over 400 lines of hor-
izontal resolution at an S/N ratio of 50 to 55 dB.
NEW METALFILM CASSETTE
This is done with new metalfilm cassette media, new higher-
bandwidth spinning recording heads (with attached low-noise amplif-
iers) and the use of so-called high-band recording signals.
The SuperBeta system uses a near-5-MHz video bandwidth for the
recording of chrominance (color) and luminance (brightness). By com-
parison, most consumer Beta recorders have a peak bandwidth of about 2
MHz, with slower VHS recorders having an even smaller bandwidth.
Proprietary analog bandpass tricks are used in both the latter systems
to record the NTSC (National Television System Committee) 3.58-MHz
color signal used in North America and Japan and to then deliver an
interlaced picture on conventional television.
In contrast, SuperVideo allows compressed, non-interlaced record-
ing of a full 525-line video frame in the same time that a current
256-1/2 line video frame is now broadcast (1/60 second). An 8-bit A/D
(analog-to-digital) converter doubles the SuperVideo signal (per
frame) to achieve 1,050 lines each 1/30 second. This delivered image
is essentially free from scanning lines and approaches 16-mm motion-
picture quality.
The precise bandpass shifting and companding for the chrominance
and luminance signals can be modified, allowing the system to work
with the PAL (phase alternation line) and SE-CAM (sequential couleur
a'memorie - sequential color with memory) color-broadcast systems used
abroad.
GOAL IS COMPATIBILITY
Supposedly, Sony, Toshiba and Sanyo want full compatibility with
existing half-inch cassettes before full production is begun.
As has been the case with past Beta technology, Sony will strive
to manufacture the specialized analog and digital componentry for
other VCR makers and to develop a technology that VHS makers would be
forced to license in some way. That is, if SuperVideo can even be
applied at all to VHS, since VHS uses an incompatible slower writing
speed with an attendant, reduced bandwidth.
Viewers of conventional TVs will benefit from SuperVideo, but not
as much as owners of the new, higher-bandwidth "digital" TV sets.
Sony and Toshiba are among a handful of Japanese TV manufacturers
who are expected to offer these so-called digital sets this year.
Recently, Sony demonstrated a color TV which could operate in standard
R-G-B, NTSC or a special doubled horizontal-frequency mode. Operating
at 31,500 Hz vs. the 15,750 Hz frequency used for standard NTSC video,
it can achieve a true interlaced screen display of 1,050 lines-- dou-
ble that of a prime-quality color TV.
Observers say that with an appropriate video source, such as a
computer-generated or SuperVideo signal, the resultant picture is vir-
tually line-free and without flicker.
DIFFERENT ASPECT RATIO
SuperVideo picture quality is on a par with, but not in the same
physical format as, that of the HDTV (high-definition TV) system pro-
posed by Japan's NHK telecommunications researchers and the Japan
Broadcasting Corp. In the latter, TV pictures are in a motion-picture
format, a 3-to-5 (vertical to horizontal) ratio, whereas SuperVideo
uses the standard 3-to-4 ratio of TV sets worldwide.
Sony has demonstrated its new technology on 15-inch and larger
screens, but it is best revealed on even larger CRT's and projection
TVs. Indeed, many projection TVs that use separate CRT sources for
each color are capable of more than 1,050-line resolution. All of the
SuperVideo developers are expected to show high-resolution digital-
TV receivers this week at the CES.
The development comes just two years after Sony introduced 80-dB,
high-bandwidth stereo recording at the CES. Beta HiFi has helped
boost Beta sales, which have leveled at between one-quarter and one-
third of the multi-billion-dollar VCR market.
Last year, the leading VHS manufacturers followed suit by
developing a 60- to 65-dB "depth-recording" VHS HiFi. Companding of
the audio signal boosts that dynamic range to above 80 dB. However,
many recording purists still prefer non-companded Beta HiFi.
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Comments? I would like to hear from someone that has attended this
year's CES and has seen the new digital TVs. Maybe I should wait until
next year to buy another VCR.
-Jim Griggers