Let’s get creative with
as Bemidji did
Stop squinting! High-def is ready for primetime
Originally published in Current, April 12, 2004
Commentary by Bruce Jacobs
High-def: The time has come. Five years ago, things looked different. My essay in Current was headlined “High-def: too-high quality, too-high cost.”
Since then, a few important things have changed. There is lots of good news. Costs are lower all around. And a station can now broadcast both an HD program and two or more standard-definition programs simultaneously over the same channel and transmitter. Let’s call it the Bemidji solution (more on this later). If you’ve been holding back on HD, read on.
Then: In ’99 I suggested: “Balance the cost of quality against consumer benefit.” “Quality isn’t everything.” “Consumers weigh quality against price and convenience.”
Back then, high-def wasn’t all it was cracked up to be. Consumer displays sold as “HDTV” actually had resolutions not much better than SDTV. Many had such small screens that viewers couldn’t see HDTV resolution from the living room couch anyhow. The displays of the day were labeled “HDTV” only because they could make pictures when connected to an HDTV signal. But they were unworthy of the name.
Manufacturers couldn’t make HD sets with cathode ray tubes bright enough or large enough. Rear-screen projection displays were dim, heavy and unstable. One model of plasma display actually had HD resolution, but it had a $19,000 price and a dull, low-contrast picture.
To make matters worse, delivering HDTV over a DTV transmitter with high quality took up all the bits you could fit in a broadcast channel—disappointing public broadcasters, who hoped to provide multiple services to diverse audiences.
Cable delivery seemed far off, even in areas where the cable operators were progressive thinkers. HDTV cable boxes were available only in low-quantity, expensive custom runs.
So my article recommended that stations start producing in widescreen component digital SDTV rather than HD. “Use 480p and keep multicasting,” I suggested. “Become aware of what is really HDTV.” “Be selective about the use of HDTV.”
Now: Since ’99, display technology has improved dramatically, having matured significantly in just the past year:
With real HDTV quality available for less than $3,000, consumers have responded to the huge improvement in the “value equation.” Large numbers of them are buying HD displays of every size and type, with many creating home theaters by hanging affordable LCD and DLP in-front-of-the-screen projectors from the ceilings of spare rooms.
Programmers are responding by providing many more hours of HD and widescreen content over commercial television and all-HDTV channels on DBS and cable.
At stations, vastly improved digital encoding equipment puts out higher-quality
pictures using fewer megabits per second—in effect, smaller portions
of a broadcast channel.
It’s time to revisit my five-year-old recommendations and offer new ones:
Make widescreen 480i production your minimum. The popularity of DV cameras and editing equipment has made it cheap and easy to produce in digital widescreen SDTV in the interlaced 480-line standard. Analog NTSC field production equipment is becoming rare. Good riddance.
My 1999 suggestion that producers adopt the progressive-scanned, 480-line format (480p) for their SD standard now seems obsolete. The theoretical advantages of 480p claimed in scholarly papers didn’t work out in practice. While 480p offers about 30 percent more vertical resolution than the interlaced 480-line format (480i), its quality and bit efficiency aren’t enough better than 480i to be worth the effort.
Digital widescreen 480i pictures look good enough that they don’t
stand out alongside true HD programs that are carried on the PBS-HD feed.
PBS recently changed to a state-of-the-art upconverter for the PBS-HD feed
that shows digital widescreen content at its best. When the producer takes
care with production and the content is compelling, and especially if the
content is mostly interviews, the viewer many not be able to tell it’s
not really HD.
A lot of people buy HDTV sets after seeing only the widescreen pictures from a DVD, which falls short of true HD quality.
We should continue to push our standard quality level toward digital widescreen production if only for the benefit of having our new footage available in our archives for use in future widescreen productions. Producers are still turning out programs without widescreen masters even when they’re producing a widescreen image to be aired in a “letterbox” on ordinary 4:3 screens! And we still have many studio facilities that need switchers and routers converted to widescreen.
Don’t waste transmission capacity on HD detail that viewers will never see. Creative use of your station’s bitstream can give you both multicasting and HD at the same time. Though 480p didn’t prove to be the way to a better-than-SD picture, there’s another option with a lot more promise.
Consider what KAWE in Bemidji, Minn., is doing. The public TV station is configuring its state-of-the-art HDTV encoder to a resolution of 1280 x 1080 pixels (instead of the typical 1920 x 1080). Although this option isn’t listed in the Advanced Televi-sion Systems Committee’s list of DTV image formats, it’s perfectly “legal” within the MPEG2 compression standard and seems to work with the vast majority of set-top boxes.
Since all HDTV content is already reduced to 1400 x 1080 by the HDCAM format used in many cameras—and typical lenses on HD cameras don’t even capture that much detail—you don’t lose any discernable quality by reducing the number of pixels transmitted for HD. Besides, the increasingly popular LCD, DLP and plasma displays that viewers are buying are limited to 1280 x 720 anyhow. It makes no sense to use up extra bits to nonexistent detail that viewers can’t see.
The payoff of this approach is that you get to deliver true HDTV images along with two or more channels of SDTV programming. After compression, the images are better than achieved by many stations now airing HD plus only a single SD program. The Bemidji station is actually airing HD plus four SD streams through a single transmitter—an achievement unheard of with traditional encoder configurations.
Continue to examine supposed HD transmissions with a critical eye. You may experience this interesting phenomenon when you stand close to a good HDTV display during broadcast of a widescreen show on the PBS-HD channel. In various kinds of scenes, notice how it’s more or less obvious that the production is not HD. Now, move away from the display until suddenly this lack of HD is no longer obvious. Your brain will now switch from “picture evaluation” mode to “TV watching” mode. Depending on your eyesight, the size and quality of the display and the nature of the content, you may be no further away than typical couch distance. Viewers like you will be happy with these shows. Those with larger displays may not.
Be careful in evaluating new $5,000 “HDV” cameras. Models now on the market offer resolution not much better than digital widescreen.
Now that it requires less money and bandwidth, it’s time to air much more programming in HD. Fortunately, we don’t have to be so selective about producing in HDTV anymore. Improved encoders running in the Bemidji mode discussed above allow us to transmit stunning HD quality along with multiple SD streams. HDTV field cameras and editing equipment are becoming much more affordable and practical.
We are living with the outmoded notion that HD production means an exceptional leap in costs. There are high-profile programs airing nationally that were shot in HD and sometimes even edited in HD that are not aired in HD because someone held back on spending a slight additional amount to complete the job in HD.
While HD is still inappropriate for many daytime programs destined for multicasting,
we can now dramatically increase the quantity of primetime HD programming
The public is making the switch to HD and is coming to expect it. So should we.
Bruce Jacobs is chief technology officer of Twin Cities
PTV and former chairman of the PBS Engineering Committee.
Web page posted April 19, 2004
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