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FEATURE
MAINTAINING STANDARDS...
We should think ourselves
lucky there are only three incompatible colour TV systems in use today. Colour
television came about during the cold war, a period of relative peace and
stability for all that, and the distribution of the PAL, NTSC and SECAM systems throughout the world followed largely
geopolitical lines. Until the late seventies it really didn’t matter too much
which colour TV system a country was using, or their immediate neighbours for
that matter. Demand for television sets could normally be met by indigenous
manufacturers, then came video recorders, television satellites and cheap
travel then suddenly TV became a global medium, and standards began to matter.
Multi-standard operation
came first to television, where it’s a relatively simple matter build in
adaptability to display 525 or 625-line pictures and switchable colour
processing circuits but the really significant development was multi-standard
video recorders and they followed quite quickly once the VHS format gained
significant toeholds around the world during the early 1980s. The first
generation of multi standard machines could record and replay PAL, NTSC or
SECAM tapes, but not convert from one standard to another.
By the mid 1980s television
manufacture had become a global business, dominated by the Japanese and there
followed a rationalisation of designs and key colour processing mircrochips
that varied only slightly from one TV market to another. This had an interesting
side effect and some PAL VCRs -- notably machines made by Hitachi -- were
capable of replaying a passable 525-line NTSC picture (in black and white) on a
PAL TV because of the in-built flexibility in the VCR and TVs video processing
circuitry. By 1989 Mitsubishi and Panasonic had figured out a few simple tweaks
to make NTSC replay in colour and partial NTSC conversion quickly became a
commonplace feature.
Initially it caused a bit
of a stir, and major US movie distributors were concerned about the prospect of
a damaging cross-Atlantic traffic in American films but it never happened. The
same trick was also used on Laserdisc players, and a small but significant US
import market in laserdiscs has developed and survives to this day.
The next major development
was true digital standards conversion but to date only one VCR of note has come
onto the market, the truly amazing Panasonic NV-W1 VCR which
can transcode video to or
from any video standard, and the quality is excellent; good enough for numerous
small businesses to have grown up around it, offering to convert home movies
for people with friends or relative abroad. Unfortunately it’s quite expensive
at around #2000, and not very widely distributed, and can be difficult to find
nowadays. Aiwa briefly launched a couple of low-cost VCRs with digital
standards conversion two years ago but performance was poor, and they soon
disappeared.
Little has changed since
the Panasonic W1, though it’s clear that the coming of digital video will
simplify matters considerably. In theory any digitally encoded video recording,
whether on tape or disc, can be replayed on any machine, anywhere in the world.
The coded information -- basically numbers -- should be the same wherever the
disc or tape is mastered, the conversion to local TV standards takes place
inside the player or VCR. The reality is somewhat different, as we have already
seen with some CDi releases; there are considerable variations in PAL and NTSC
originated recordings that show up on replay. Some -- like reduced picture
height -- are merely annoying, others like deliberately or accidentally
introduced coding differences can make discs from one country unplayable in
another. We’ve come a long way in twenty years, but not so far that we will be
able to watch anything we like, unless the powers that be permit it.
BOX COPY -- STANDARD DIFFERENCES
Here in the UK we use the PAL colour TV system, and in
particular the PAL-I standard, the ‘I’ defining -- amongst other things -- the
difference in frequency between the sound and vision signals when they are
broadcast. A PAL TV picture is made up of 625 lines, with a field repetition
rate of 50Hz (i.e. the picture is shown 50 times a second). PAL stands for phase alternate line, which
describes the way the system corrects errors that can occur during colour
signal transmission and processing. The NTSC colour system is used in North
America, the Philippines, Bahamas and
Japan. NTSC stands for National Television Standards Committee, (aka
jokingly known as Never The Same Colour by witty TV engineers), the NTSC is the
US body who regulate technical standards for broadcasting. An NTSC colour
picture is made up of 525 lines, with a field repetition rate of 60Hz; this was
the first colour TV system to go into commercial operation in the mid 1950s and
is technically less refined than PAL, which was developed several years later
in what used to be West Germany; recent improvements in colour processing
circuitry have narrowed the quality gap. The third system is SECAM or Sequential
Coleur a’ Memoire, (sequential colour with memory), it is closely related to
PAL (though sufficiently different so as not to infringe any patents), and is
used in France and throughout much of what remains of the Soviet bloc. Like PAL
the picture is made up of 625 lines, with a field repetition rate of 50Hz.
---end---
1994 0309
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