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Re: ATV / DTV Standards



In a message dated 98-07-13 17:41:22 EDT, Martin writes:

<< I read them and understand them very well... and I still think they did a
very poor job.  The problem I have with all this stuff is that I don't see any
foresight.  How important will NTSC or PAL "compatibility", of any degree, be
in 10, 20, 30 or 50 years?   Zip.  Zero. Insignificant. >>

The FCC, for one, certainly hopes that aside from old archival footage, DTV
compatibility with NTSC will be a non-issue after 2006!  But you can't sell
incompatible TV sets for a new format until there are programs to watch, and
you can't convince broadcasters, producers, and post houses to invest in new
facilities for audiences that don't exist because nobody has a TV set that
works in the new format.  The only way out of this "chicken and egg" dilema is
a bridge between where we are and where we're going.  So compatibility with
NTSC is 100% vital now, because we'd never get to DTV without it.

<< What would happen with the millions of poor soles that wouldn't be able to
watch 24fps material on their 29.97 or 25fps sets?  Simple, Sony, Matsushita,
Sharp, Philips, etc.  would come out with cute little $150 to $250+ boxes that
you could buy to "convert" your set. >>

It was realized that about one million new HDTV receivers per year was about
the most the consumer electronics industry could be expected to suppy, at
least for the first few years.  At that rate, it would take them about 300
years to replace all the existing NTSC sets in the U.S.  Consequently, set-top
converter boxes that allow existing sets to be re-used are included in the
plans.  But it was considered essential that these boxes be as simple and
inexpensive as possible, which precludes installing the VLSI version of a Rank
Digiscan IV inside each one!

<< As to the issues surrounding the post-production stage conversion from
29.97fps interlaced to 24fps non-interlaced..... I urge you not to
underestimate the capabilities
of the thousands of bright design engineers working for the many companies
supplying our industry.  >>

One of the big falacies of digital video is that once it's in bits, you can
just spit them out any old way you want and the pictures will still look
great.  Unfortunately, that's just not the way it works.  You've probably
heard of NTSC referred to as "Never Twice the Same Color."  What this refers
to is the mathematical impossibility of fully decoding a NTSC composite color
signal to its original components.  There are many conversions in digital
video that are just as impractical to solve, regardless of the brilliance of
the engineers or the companies they work for.  Due to the temporal problems
involved, I suspect that 29.97 -> 24 would be a pretty nasty one.

<< At the transmission-end stations would then expect to see a tape that would
follow a single standard.  You wouldn't have the silly battles we have now
with one guy going 480P while the other insists on 1080i.  >>

Table 1 of ATSC document A-53 lists the acceptable video input formats, which
include our dear old friend, 601 digital video, along with higher resolutions
that have been either recorded on compressed or uncompressed formats which are
expected to be developed.  The transmission aspect of DTV depends only on
having signals that are amenable to MPEG-2 compression, not on the number of
lines used in a camera or telecine. So the guy who does 480p can get out just
as well as the guy who uses 1080i.  Whether or not you see a big difference in
your home depends on the TV set you buy.

<< My basic thought is that ATV/DTV should have as it's goal to deliver
"digital film" as opposed to some techno-soup of formats.  In this fashion you
could think of delivery choices such as 35mm or 16mm resolution analogs
depending on budget, etc. >>

Interestingly enough, in their introductory statements, the ATSC said that the
whole purpose of the system was to give television viewers film-quality images
at home.  But not everybody thinks film is good enough for their purposes.  If
you ask videophiles, they'll tell you that the motion rendition of 24 FPS film
may be good for story-telling, but they want faster frame rates for viewing
sports.  Computer companies will take issue with you as well for other
reasons.  So the political issues had to be dealt with as well as the
technical ones if the standard was to stay out of court for the next 20 years.

<< Wanna read something intelligent and well thought out?  How about the Space
Shuttle technical and piloting manuals? >>

Let's just hope DTV fares better than the Challenger did!

Best regards,
Christopher Bacon

---
Thanks to Queue Systems and Lipsner Smith for support in 1998.
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