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Old July 2nd 04, 11:25 PM
Stephen Neal
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Roderick Stewart wrote:
In article , Mark Carver wrote:
IBC 1988; a Sony HDTV event held at Sussex uni, along with a special
show in Brighton's seafront Cinema ? Or the UK's last ever IBC in
1990, again Sony were showing their stuff in a giant tent on the
beach ?


Possibly both. I do remember one of the HDTV exhibitions being at a
separate location a short bus ride out of town.


I was at both as well ISTR.

The cameras at that
time would have been using Plumbicon tubes and the displays were
nearly all CRTs, some of them back projected.


Nope - the 1125/60 cameras were based on Saticons, not Plumbicons, ISTR,
only the BTS 1250/50 cameras were Plumbicon based? By 1992 there were
1250/50 CCD cameras on Centre Court or Court Number 1 at Wimbledon (and
broadcast in HDMAC via Olympus)

Having seen 1250/50 HDMAC off-air - and the same picture received in 625 on
a D or D2 MAC receiver I'm quite glad we didn't go that route. A picture
with 50/25/12.5 Hz refresh rates depending on the content of each macroblock
was quite disconcerting...

There were even some
cinema size projectors in a darkened hall, including a three lens
Eidophor which was showing electronic pictures brighter clearer and
steadier than anything I have ever seen in a cinema.


In 1990 there were double-stacked projectors using polarising filters for 3D
HD - very impressive - but not exactly compressed to a broadcast bit rate.


Even then, sixteen years ago, the technology must have been several
years old, because some of the major manufacturers had lists of
productions that had been made using it. Which means that we are now
just beginning to think about how we might implement something that
from the figures being bandied about is not quite as good as what was
available about twenty years ago.


The Japanese HiVision system was the main system on-display, with a bit of
Eureka 1250 (though not much Eureka kit). Both are comparable in resolution
terms with the current 1080/60i system in use in Japan in vertical scanlines
(ISTR that 1125 was around 1035/60i active?) However most of the kit
supporting this was either 1" digital or 1/2" analogue (and quite massively
bandwith reduced in the case of the 1/2" UniHi system) - and the Muse
transmission system (used in Japan) was quite a major compromise. The
cameras were hardly sensitive (the older and better did some stuff for BBC
R&D in both 1125/60i and 1250/50i in the early 90s - and the cameras/lenses
weren't a patch on the 625/50i stuff routinely used at that point) and the
recording technology not suitable for normal broadcast deployment at the
time (the Beeb were using 4xD1 3/4" DVTRs to record a single 1250/50 stream
when a single 1/2" DigiBeta was just becoming available)

The picture quality delivered by 1920x1080/50i now is likely to be better
than either the 1125/60i or 1250/50i analogue or digital systems demo-ed
then - and actually exists as a broadcast production system (i.e. cameras,
vision mixers, VTRs, DVEs etc. now actually exist to produce in
1080/50or60i - unlike the experimental stuff on show then)

It has taken until roughly this point for technology to produce HDTV
pictures, record them, compress them and transmit them at a level the
broadcasters can afford. Given that 1080/50i and 720/50p deliver a similar
vertical resolution (though 720/50p is likely to be more efficiently
compressed) I suspect the 1080/i vs 720/p debate will run and run over here
as it has in the US.

Steve