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The Life And Death Of 720p... Or Was That 1080i?
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- Subject: The Life And Death Of 720p... Or Was That 1080i?
- From: Tom Tcimpidis <tgt at akamail.com>
- Date: Fri, 05 Mar 1999 12:16:09 -0800
- Organization: TGT Technologies / The MOG-UR'S EMS http://www.tgt.org
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This is important enough and germain enough to those on this list that I'm
taking the liberty of copying it to this group.
The Life And Death Of 720p... Or Was That 1080i?
How A Closed HD-CIF Can Kill Your Entire Future
by Michael SIlbergleid
HD-CIF stands for High Definition-Common Image Format. The idea is
simple--have everyone in the world agree on a single (hah!) common format
for program production and exchange. You can up-, down- and side-convert
all you want for broadcast, but you'll produce and deliver HD in this CIF.
The first HD-CIF actually consisted of two analog HD formats and the U.S.
did not support the HD-CIF because it was viewed as an interim standard
that would impede progress towards a single worldwide standard. Bully for
Now we're in the digital age and we have a digital HD-CIF (ITU
Recommendation BT-709-3, Part II). Not exactly a single
standard--1920x1080i/50 (fields), 1920x1080i/60 (fields), 1920x1080p/50
(frames) and 1920x1080p/60 (frames). Notice that no existing progressive
format (720p or 1080p/24) is part of the HD-CIF. The progressive formats
that are included in the HD-CIF (1080p/50 and 1080p/60) won't be around for
about three years (at least according to Sony). This means we are "stuck"
with interlace for at least three years, but more likely 10. Or in other
words--720p just bit the international big one.
Good question. It has a lot to do with NHK holding so many 1080i patents.
It has a lot to do with the choices that certain networks have made. It has
a lot to do with the egos of certain people at those networks who are more
interested in going down in history as the inventors of HDTV than the
future of television or of their network.
But it has nothing to do with technology.
Now to be fair, putting a standard together is no easy matter (just look at
the ATSC--we'll be done, maybe, in 2003). So the ITU Radiocommunication
Assembly passed a ruling recognizing the requirement that only one
technical standard should be recommended for each radiocommuniaction
application, and it directs all ITU-R Study Groups (including Study Group
11A--HDTV Programme Production and Exchange Formats) to act in this sense,
unless they can indicate good reasons to act otherwise, on a case-by-case
basis. We'll do just that.
This Is Not About P vs. I
This is about technology. Lets look at the benefits of 1080i/60 fields in a
broadcast stream--what we typically call 1080i/30 (frames): Each frame as
slightly over 2 million pixels. That means to encode 1080i/30 for ATSC
broadcast will take from 10-18 Mbps. Experts on encoding agree that 18 is
the more likely number for "real world" applications. This does not leave
you very much room for making money.
Opportunistic data is wonderful, but it's not a steady 24/7 revenue stream.
Leasing a small portion of your spectrum (let's say 2 Mbps) is. But if
you're broadcasting 1080i/30, there is no bandwidth left to lease.
So you decide that 720p might make a lot more sense since each frame has
slightly less than 1 million pixels. At 60 frames per second, experts say
that you'll need six-16 Mbps for ATSC encoding. That leaves you some
bandwidth leasing breathing space. Great, you'll just do all your HD
broadcasts in 720p (to hell with 1080i--that bandwidth hog) and make some
constant revenue. All the DTV sets will be able to receive 720p... they'll
just convert the signal to their native display format. The at-the-home
conversion to 1080i is fairly easy. And since all those flat panels are
already progressive, you figure you'll have great pictures. Maybe not.
At some point, that 1080i HD-CIF program you received will have to be
converted to 720p. This, unlike going from 720p to 1080i, is not easy. In
fact, it won't look as good as 720p material being converted to 1080i. It
might even look awful.
Of course, you might have gotten the program in 720p, except that 720p is
not an ITU-R HD-CIF.
Congratulations, your great business plan for data bandwidth leasing along
with high picture quality all at the same time, has been screwed. At least
for about 10 years until 1080p/60 comes along (and you know how expensive
that equipment is going to be).
What Can You Do?
Call your Congress-person. Call the NAB. Call the SMPTE. Call your network.
Call anyone you can think of. This is your business, and you should have a
say in what's going on in the world of specifications.
No advertising/marketing allowed on the main TIG. Contact rob at alegria.com
anonymous messaging now at http://www.alegria.com/HyperNews/get/ubique.html
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