Published by: Larry Bloomfield & Jim Mendrala
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(Ed note: The following
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ANNOUNCES PLANS TO PROVIDE -- 1080 HIGH DEFINITION TELEVISION VIA ALL-DIGITAL
will begin broadcasting a 1080 interlaced high-definition digital signal
to its owned stations and affiliates in the fall 1998 season.
The announcement was made at NAB in
Las Vegas, Nev. Initially,
NBC plans to provide a high-definition
signal during prime time with a 480 progressive digital signal
during other dayparts.
NBC is building an HDTV
facility for "The Tonight Show with Jay Leno." This
arrangement is an extension of a previously announced agreement,
where NBC and Sony have teamed up to develop broadcast products and
applications for the next five Olympic Games.
NBC expects to begin providing "The Tonight Show"
in 1080 format in 1999. Additionally,
NBC announced that it will offer "Men
in Black" and "Titanic" in high-definition and
expects to announce plans for longform and series programming after
the fall schedule is in place.
NBC announced the rollout of
the first new all-digital Broadcast Operations
Center. This tapeless
facility is the backbone of NBC's digital. NBC's
enhanced digital broadcasting initiatives include soon-to-be-unveiled
Microsoft Web TV for Windows entertainment programming, along with
existing efforts with Wink Communications and Intel's Intercast.
These data broadcasting projects
are compatible with both digital and analog broadcast and cable
NBC is committed to a rapid
rollout and is scheduled to begin providing
digital signals in four top-ten markets by: November 1, 1998;
KNBC, Los Angeles; WRC, Washington D.C.; WCAU, Philadelphia;
and KXAS, Dallas.
May 1, 1999:
Owned stations in New York (WNBC) and Chicago (WMAQ) are scheduled for May 1, 1999,
followed by San Diego (KNSD), Miami (WTVJ) and Raleigh (WNCN).
May 1, 2002, the remaining
NBC-owned stations in Columbus (WCMH), Providence WJAR), Hartford (WVIT) and
Birmingham (WVTM) will broadcast a digital signal.
It was hard to get to anyone
at FOX to make a statement and in the brief few minuets I spoke to Andy
Setos, top engineer at their network, I got the impression that they were
going to go 480p for the time being and possible 720p on some specials.
The attitude I got was a wait and see, but that progressive was far superior
to any interlace. Can't
argue with that. Broadcasting & Cable did
an exclusive just before NAB on them and what they plan to do.
They did a follow up on all the 4 major networks, after NAB.
You may find it interesting
WB UPN and HDTV
Got a call from one of the
engineers at the Warner Brothers (WB) network as the result of inquires as to
what they'll be doing. I
was informed that since they provide programming to
all the networks, they will do what the respective network the show is for will
do. I got the impression that they are looking at 480p for their own
network, but the "we're going to wait and see" attitude was most pronounced.
What did interest me was the smaller than 100 DMA thing that WB will be doing.
Since I'm possibly going to do a story for Broadcast Engineering on that, I'll
not say much more there. They
are calling it "station in a box" and WEB. More
Probably the most intelligent thing I've heard said to date on this
whole matter is that if a 1080
progressive scan algorithm could be developed so it could fit into a 6 MHz.
bandwidth, that would be the Holy Grail of TV and I agree.
The United Paramount Network
(UPN) never seems to return calls.
If anyone has a clue as to what they'll be doing, please let us know. I
do know they are busy trying to strike a deal
with Disney to fill in they're day parts, but since that has nothing to do
with DTV, I didn't pursue the information. Common sense says they'll
probably do fairly much the same as WB is doing as far as shows on other
networks go, but for their own UPN, Who knows?
The following was provided
FREQUENTLY ASKED QUESTIONS
WHY HAS ABC SELECTED PROGRESSIVE SCANNING FORMATS?
* Experts agree that
progressive scanning is the best format for capture, transmission and display.
* The inventors of the FCC's
DTV Standard, the Grand Alliance, agreed that interlace in the
transmission path should be eliminated and that they would work towards that goal.
HOW DOES ABC's SELECTION OF PROGRESSIVE RELATE TO THE FUTURE
OF HDTV SETS
* We believe that new flat
panel displays, which are just now being introduced, represent the
future of true mass consumer adoption of HDTV. Those flat panel displays are
inherently progressive. ABC has elected to aim for the second generation of
consumer sets in selecting its HDTV format. In the meantime, the first
generation glass tube and projection digital television sets are designed to decode
and display all ATSC formats, including 720P.
WILL PROGRESSIVE SCANNING BE COMPATIBLE WITH DECISIONS MADE
BY OTHER BROADCASTERS?
* Absolutely. This decision
is completely in accordance with the FCC's mandated DTV Standard
adopted in 1996. All broadcasters must comply with this standard. As a result, ALL
digital televisions being designed for introduction this fall will receive and
display either the progressive or interlaced formats. There is no need
for concern from consumers that they might have to pick amongst their favorite
sources of entertainment.
WHAT IS THE DIFFERENCE BETWEEN INTERLACED AND PROGRESSIVE?
* Progressive formats
represent the most advanced digital broadcasting technology available.
Progressive scanning (used in all computer monitors and the advanced flat panel
displays) "paints" every line of the picture sequentially every time the
screen is scanned. It takes only 1/60th of a second to scan one complete
picture. By contrast, interlace scanning, invented over 60 years ago, first
paints the odd numbered lines every time the picture is scanned, followed by the
* With interlaced formats,
any horizontal motion in the original source between frames results in
blurring. Similarly vertical motion results in flicker (the "venetian
blind" effect). These defects are eliminated in progressive scanned
For example in 1080I, a moving football quarterback's image is
dissected into 1080 lines ONLY HALF OF WHICH are painted each time the screen
is scanned. The portions of the quarterback's body represented by the
other half of the lines remain back where he was before he began to move. By
contrast, progressive scanning re-paints the quarterback's entire image
EACH time the screen is scanned. As a result, progressive formats do a
better job of rendering moving pictures.
IS 720P "REAL" HDTV?
* The Advanced Television
Standards Committee (ATSC), the group that established the standards
for digital television, defined HDTV to include both 1080I and 720P. The Consumer
Electronics Manufacturers Association (CEMA) has likewise defined HDTV to
include both 1080I and 720P.
ARE 720P AND 1080I EQUIVALENT HDTV?
* Actually, we think 720P is
better. To focus solely on the "number of lines" greatly over simplifies the
complexities of the human visual system and threatens to mislead and
confuse consumers. Contrast and brightness have a greater impact on the human
visual system than does resolution. The 720P picture is brighter and has
greater contrast than the 1080I picture.
* The number of lines of
resolution in progressive and interlace pictures are not an
"apples-to-apples" comparison. In the time it takes 720P
to paint 720 lines, 1080I paints only 540
lines. And, by the time 1080I does paint 1080 lines, 720p has painted 1440
* In side-by-side subjective
testing performed by the Advanced
Television Test Center under the auspices of
the FCC's Advisory Committee on Advanced Television Services (ACATS),
it was shown that 720P had "no artifacts" under a variety of conditions, while
1080I, under the same conditions, showed "increasing
quantization noise and blockiness..." Nevertheless, these distinctions are slight,
the ACATS took pains to note that there was no substantive difference in
picture quality between the two formats.
WHICH SCANNING FORMAT IS BEST SUITED TO THE FUTURE?
* Whereas interlace scanning
is analog friendly, progressive scanning is digital friendly.
Progressive scanning greatly simplifies conversion to all other scanning formats. It
is the preferred scanning format for digital signal processing. Even today,
standards conversion, digital video effects such as squeeze, zoom, flip, etc.,
are all done in progressive.
* Progressive is also better
suited to multimedia applications, creating a
rich, new environment for
creative storytelling in the converged world of computing and television.
* The 1080 x 1920 (1080I)
interlace format specified in the ATSC standard CANNOT be compressed to fit
in a 6MHz channel without creating objectionable artifacts and it has been
recommended that the 1920 pixels be sub-sampled to 1440 to reduce compression
artifacts. Therefore, encoder manufacturers have elected to discard approximately 25% of the picture for over-the-air
compromise is not required for 720P. More of the original picture information remains
through the transmission chain.
WILL THERE BE EQUIPMENT AVAILABLE TO BROADCASTERS TO ADOPT
* Until very recently, based
on engineering investments made many years ago before the advent of digital
signal processing, most professional broadcast equipment was based on
interlace scanning. However, in the past few years, there has been an explosion
of interest in progressive format equipment. ABC has identified manufacturers
for each of the critical components required to introduce HDTV broadcast to
our network and therefore to consumers. Panasonic and other equipment
manufacturers have accelerated their 720P production schedules based on ABC's
WHAT ABOUT CABLE COMPATIBILITY?
* The progressive formats
selected by ABC are compatible with the digital set-top device being developed
by Cable Labs and the cable industry. ABC's goal is to seek voluntary
cooperative arrangements with cable operators for the benefit of consumers.
THIRD PARTY QUOTES IN
SUPPORT OF PROGRESSIVE SCAN
William F. Schreiber, former
Director of the Advanced Television Research Program at MIT (Home
Theater, 12/97): "Let's be perfectly clear about this. Interlaced scanning is a
really dumb thing to consider in any new video format. Interlaced scanning
was not even a good idea when the U.S. B&W standards were defined in
1941! As your readers are probably aware, interlaced scanning can generate very
bad artifacts in a video image, things like 30-Hertz interline flicker,
motion errors, and reduced vertical resolution. This is why computer
monitors are not interlaced -- the interline flicker would be unbearable. The
reason why there are still proponents of interlacing escapes me, especially when
considered in the context of digital broadcasting. Progressive scanning is
simply more "digital friendly" than interlaced. When digitally coded, a
progressive signal requires no higher data rate than an interlaced signal that has
half the bandwidth. I have a hunch that the continued advocacy of
interlaced equipment originates from foreign-owned consumer electronics
companies that are trying to get back the substantial investments they foolishly
made in obsolete technology."
Department of Defense (DOD)
Reasons for Interest in Progressive Scanned Video and Square Pixel Formats:
"We believe that the use of Progressive (Non- Interlaced) scanned video
and square pixel formats will greatly improve our information management
capabilities. The presentation anywhere in the world of Geospatially related
information from multiple sources should support improved decision making. Use of
these technologies will provide for improved communications between
United Nations coalition teams. Future video systems using these attributes will
improve risk management in life threatening situations in the fields of
Defense, Medicine, and mitigation of Global Disasters. Progressive
scanned video and square pixel formats will also improve visualization in our
energy, space programs and others, and greatly enhance the DOD's massive
training and modeling & simulations programs."
Proceedings of the IEEE,
Vol. 83, No. 2, Feb. 1995, pgs. 158-174
The Grand Alliance System
for U.S. HDTV: "However, the GA will work toward the elimination of interlace in
the transmission path in the future."
3rd party comments will be carried over to issue #18)
Those who attend NAB'98, could see that there are a
significant number of manufacturers who can and
will provide 720p equipment. Other
points of view are welcome.
Subj: NAB '98
By Larry Bloomfield
For the benefit of those who
couldn't attend, there is no question that NAB '98 was the year of
"Digital TV." The
buzzword was "solution!" and the way everyone, drifted, at times,
far from the way Webster had defined its use. Encoders of about every
flavor and variety were there.
MPEG-2 servers were offered by several MFGs.
Had the chance to see both
the HP and Tek spectrum analyzers for the 8VSB signal; very interesting and
educational. Get your
local rep to give you a demo.
They can do it using recorded material, which makes it nice
for looking at your signal after the
fact. The 8 levels are shown and any error is vividly displayed.
Each have their own features and it would be personal
preference as to choice.
Larcan had the HP hooked up to their (Zenith) exciter.
Saw a re-recordable CD
carousel like player much like the old 45-RPM players. If anyone else saw it,
please let Larry know who the MFG was as the material has gotten lost between LV
and Bend. The idea of
doing your long form programming on it and using
a small server for commercial insert in small market stations would go a
long way to save bucks. I
was surprised to find the same capacity server we
bought in San Francisco at Channel 38 from HP available today for about
1/3rd the cost. That
was only 2 years ago.
If you saw anything at NAB
that particularly impress you, either drop us a line (e-mail) or call one of
us so we can share that info with others in our field.
Progressive vs. Interlace - Never the twain shall meet!
From several sources
Most engineers are aware
that the standards promulgated by the FCC for digital television include 18
different video formats; some interlace and some progressive.
We've probably all heard arguments for both.
HDTV can be broadcast in either 1080i or
720p. If you are one of the few who don't know what that means, it means
that the active lines of video are either two fields of 540 lines interlace to
equal 1080 total or 720 lines progressive scan.
It doesn't take a college
grad to figure out that there will be Hundreds of billions, and maybe even
trillions, of dollars at stake, during the next five to ten years.
It stands to reason, that if you are an executive working for a
company with vested
interests in the future of television, you'd do what it took to get your system
adopted as "the standard."
Many people believe that the
standards decided on by the FCC have cast in stone the degree of
interoperability between multimedia computers and the television industry.
These DTV standards will determine the viability of a National Information
Infrastructure, (commonly referred to as "the information super highway"), and
will seriously impact the course of television; cablevision and satellite
direct broadcasting in the future.
The story of how it all
happened has been told in many places.
It is, however, necessary to
retrace some of the history which brought us to where we are today in order to
illustrate why and how this debate came about and besides I like telling it.
The players in this debate
seem to be polarized into two groups.
On one side, the players consists of the consumer electronics industry, the four
major U.S. broadcasting networks and
trade associations who believe the net results will be thousands of jobs
manufacturing DTV sets. On
the other side is a group of American computer companies
that have banded together under the name Computer Industry Coalition on
Advanced Television (CICATS) and many of the world's to filmmakers in conjunction
with the organizations that represent them.
As Joel Brinkley so aptly
pointed out in his book "Defining Vision," that "the battle for the future of
television" has been raging for years.
My best guess is that it all began as far
back as the early 1970s, when NHK, the National Japanese Television Network
and the Japanese consumer electronics industry launched an ambitious
initiative to design a single High-Definition television standard for the world.
Although it is in place and working today, it has not
gained wide acceptance.
This early on HDTV system
featured a wide-screen format of a 15:9 aspect ratio, which was a perfect
match for the European 1.66:1 cinema aspect ratio. It also features stereo
sound and 1125 lines of resolution.
Japan, like the United States, uses 525/60
NTSC. The Japanese HDTV system called for an interlaced scanning architecture and analog transmission. The system
was unveiled during the early
1980s but failed to secure a place as a worldwide
The Japanese efforts didn't
go unnoticed, however. The Society of Motion Picture and Television
Engineers (SMPTE) looked into the Japanese system for six years. In 1988, SMPTE
came up with their own HDTV format which was called 240M and bore a striking
resemblance to the original Japanese system with one difference; it called for an
aspect ratio of 16:9 (or 1.78:1).
One of the members of the SMPTE study
group told me that 16:9 was chosen as it was a compromise between the
1.66:1 and the 1.85:1 aspect ratios used in motion pictures in the United
States. The other commonly used U.S. aspect ratio 2.35:1 was disregarded by
The FCC, in 1987, appointed
an Advisory Committee on Advanced Television Services (ACATS) to function
as an advisory group. The
membership of ACATS has come under fire as not
representing all aspects of the entertainment industry as it relates to
television As can be deduced from Brinkley's book, mentioned earlier, only
those companies with vested interested in the outcome, could afford the dollars to
participate. Testing of
the proposed systems and standards was done by the
Advanced Television Systems Committee (ATSC) at the Advanced Television Testing
Center (ATTC). . ACATS
and ATTC held court in Washington, DC.
In 1989, at an industry
conference, Joe Flaherty, CBS's senior vice president for technology who said:
"We'll have digital television the same day we have an antigravity
machine." Just four years later, Woo Paik, a Korean born, MIT graduate engineer, working
for General Instruments (GI) in San Diego, California, proposed and demonstrated a capability for transmitting
HDTV signals digitally. Soon
after Woo Paik's breakthrough, GI was quickly joined by others who also
demonstrated more complex, but similar capabilities.
It didn't take much of a
wake up call, after that, at the FCC for them to
"HDTV transmissions will be based on digital
technology." Shortly after this, the top
contenders in the race formed the "Grand Alliance."
Nearly all television, that
isn't either sports, news or live, originates on film.
The American Society of Cinematographers (ASC) felt they had
a vested interest in determining the
standards for HDTV, so they formed a group, consisting of members and
technology leaders in the film industry, to study the ramifications of the
digitizing of television. By
the end of 1993, ASC submitted its proposals to
ACATS and the FCC. The
"HDTV was designed to
make dramatic improvements in image and audio quality," said ASC's John
Hora. "Once it became digital, it added layers of possibilities which could
evolve from linking the computer to the TV set and making them interoperable.
It became possible to transmit and display movies in their original aspect
From the early days when
television and computer technology were joined together for the purpose of
"colorizing" black and white movies, filmmakers have taken an interest in
what the television industry was up to. Since the new aspect ratio offered in
HDTV permits films to be displayed in their original aspect ratio,
filmmakers claim that "panning and scanning," inherent to showing U.S. movies,
destroys the artistic integrity of their work by altering both composition
and camera movement. Keep
in mind that we engineers provide the canvas, the
paint, the brushes etc. It
is the artists who use these tools to generate
The ASC specified that all
films be shown in their original aspect ratio on a screen with a 2 by 1 aspect
ratio, and that interlaced scanning be replaced
with a single progressive
(non-interlaced) architecture. ASC's reasoning is that this would result in a
dramatic improvement in image quality and build an essential bridge to the
While all this was going on,
the computer industry was asleep.
Apple, Microsoft and others in the
computer industry were making their case for progressive scanning with
square pixels. Their
argument is that this approach would measurably improve the
readability of text, and convergence of computers and ATV displays.
What the FCC adopted is
basically the ACATS proposal: A 16 by 9 aspect ratio for display, a choice of
(SDTV) standard definition (the same as the current NTSC 525 horizontal lines),
or high-definition (720p or 1080i lines) resolution; stereo digital
5.1 channels of sound; a choice of 18 standards (four are interlaced and 14
are progressive); a data output and all this transmitted digitally.
As it stands now, individual
broadcasters may select the standard they want to use for transmission from
the 18 options. DTV sets will be equipped with decoders that enable them to
receive transmissions in all 18 standards. Older NTSC sets will require an
external device to do the decoding down to a signal the set can use.
Which brings us to why the
ACATS proponents are being challenged.
As recently as a year ago, a
new way to digitally compress images was developed. The technique is called
"layered compression," which consists of baseline and enhanced layers of images.
Gary Demos, president-CEO of
DemoGraFX began his involvement back in1989, when he started attending
SMPTE HDTV subcommittee meetings. After getting up to speed on what was going
on in the wonderful world of DTV, it seemed to him that the subcommittee was
merely planning to scale up TV display principles. There was more talk about
company positions than technical discussions.
"I had been working
with multi-thousand-line high resolution since 1976," he said. "I knew a lot
about handling and processing images and how to make the images come alive. I felt
they were wasting a ton of effort on obsolete ideas. I kept thinking, this
doesn't really make any sense. It won't ultimately prevail."
Concurrently, Demos became
aware of the other players and that the real decisions were being made by
ACATS and the ATSC, back in Washington, DC. He was invited to attend an
ATSC subcommittee, where there would be a definitive debate on key issues.
Demos and associates from
MIT joined forces with members of the computer industry community to form
the Committee on Open High Resolution Systems (COHRS). Included in COHRS
was about 70 people from the film and computer industries and influential
academics. COHRS convinced the government that television was going
By early 1991, there was a
committee headed by Will Stackhouse, of Jet Propulsion Labs, discussing
interoperability issues, including digital architecture and the ability
to transmit films in their original aspect ratio, the elimination of
interlaced scanning and the need for square pixels to make text more easily readable.
Demos recalls that the
report written by Stackhouse was published by the SMPTE Journal in 1992. That's
significant because one of the complaints that ACATS proponents recite when they
criticize Demos is that he raised all of these issues at the last moment.
He responds that all of these issues were discussed and left unresolved five
In August 1992, Demos'
status changed from interested party to consultant to Apple, when that company
committed to fighting for the convergence of ATV with multimedia computers. That
made it economically feasible for Demos to really engage in the discussions
that were taking place in Washington.
In late 1993, DemoGraFX
contracted with ARPA to establish a high resolution, motion imaging,
interoperability laboratory. "We researched the fundamental issues related to advanced
television," said DemoGraFX vice president Alan Peach, who played a key role
in this project. "That's when we began shooting film and testing our
theories about compression technology. The first thing we shot was a series of frame
The groundwork was laid in
October 1993, when ASC and computer industry representatives met at an
interoperability review session sponsored by ACATS. "It was an incredible
opportunity and experience for us to start working with these great
filmmakers," said Demos. "One of the things that struck me
was that they felt so passionate
about preserving the integrity of their work. Yet, they weren't getting
any respect from the ACATS people. I told them about our ARPA study, and several
top cinematographers agreed to shoot the test film
for us. We scanned it at
very high resolution. One of the things we wanted to see was the trade-off
between frame rates and bit rates at very high resolution. We were scanning
at 4K using a film scanner at Pacific Title Digital. We
image data with the Indigo 2s, an Onyx computer at POP in Santa Monica and
another Onyx at Hughes."
By then, Demos, Peach and
others at DemoGraFX felt that the layered compression software they
had developed fit the film industry's ideas like a glove. With financial
support from Apple and Microsoft, they produced a new demonstration film,
displayed in its native aspect ratio within a 2:1 image shape, with progressive
scanning and square pixels. The camera work was done by ASC's Steve Poster and
Bob Primes. FCC Chairman Reed Hundt and commissioners Susan Ness and
Rachelle Chong visited DreamWorks SKG, and Chairman Hundt and Commissioner Chong viewed a demonstration of the
DemoGraFX layered compression system.
After those individual screenings, both Hundt and Ness called for
representatives from the three factions to meet and resolve their differences.
Demos showed the demo film
to Larry Irving, assistant secretary of commerce for Communications and
Information. Irving is also administrator of the National Telecommunications
and Information Administration, which advises President Bill Clinton and
others in his administration on telecommunications and information policy.
He has written to the FCC,
and has asked the commissioners to limit rule setting for DTV to
"essential elements" and has urged the interested parties to reach a consensus.
Chairman Hundt has publicly said that the commission will not set a standard
unless all parties agree.
In the absence of such agreement, Chairman Hundt
has suggested that congressional hearings may be appropriate. Meanwhile,
William F. Schreiber, professor emeritus at M.I.T., and former head of its DTV
effort, has written to the FCC urging the appointment of an
independent group of experts who have no financial interest in the outcome. He predicts
that the interested parties in the consumer electronics/broadcasting,
computer and film industries won't arrive at a compromise that serves the
best interests of the public. Stay tuned.
The DTV Tech Notes are
published for broadcast professionals who are interested in DTV, HDTV etc.
by Larry Bloomfield and Jim Mendrala. We can be reached by either e-mail or
land lines (541) 385-9115, (805) 294-1049 or fax at (805) 294-0705.
News items, comments, opinions etc. are always welcome from our readers; letters
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