Sunday, July 30, 2006

HDTV Myths

Plasma TV sets start out bright and beautiful, but burn out to an early death. Every single high-definition television program looks equally crisp and gorgeous. The higher resolution of a 1080p high-def set means that your shows and DVDs will always look better than on a more ordinary 720p set.

Are these gospel truths about HDTV? Nope. Just a sampling of the many popular factoids, half-truths, and myths that can make choosing and enjoying a high-def television set complicated and confusing--and in some cases, needlessly expensive.


To help dispel these myths, we consulted an A-team of HDTV experts. The challenge: Identify and debunk troublesome, costly, and all-too-prevalent misconceptions about high-definition TV--from the basics of broadcasting to the arcane secrets of hardware. We lay out the facts you'll need to have at your disposal in order to make the right decisions. Armed with this information, you'll know just what to expect when you take the HDTV plunge. For more of these tips, see PCWorld.com.


"An HD set is all you need to get high-def programs."


In our dreams! To experience the vibrant images and the Dolby 5.1 sound of true high-definition TV, you need several things--and an HD-ready set (a display that can accept HD-format input and display it at a minimum of 720 lines of progressive-scan or noninterlaced video) is just one of them.


First, a show needs to be shot in high definition, and that may not be the case, even when a show claims that it is. For example, although TNT's digital channel presents Law & Order reruns in high definition, early episodes weren't shot in HD; as a result, in those episodes, you see a 4:3 standard-def show that is stretched and scaled up to high-def size. It doesn't look great.


Second, the program must be transmitted in high def by a station that you can receive either over the air or from your cable or satellite provider. ("Shown in high definition where available" doesn't mean it's available to you.)


Third, you need an HD receiver to process the signal. A set that has a built-in ATSC digital tuner can display over-the-air HD broadcasts with nothing more than a good antenna. ATSC, which stands for Advanced Television Standards Committee, is the group that defined the 18 formats of the coming digital TV system, only six of which are considered high definition. (And by the way, there is no such thing as an HD antenna--there are just antennas.) If your HDTV set comes with picture-in-picture, you won't get high-def-picture-in-high-def-picture unless your set comes with two ATSC tuners.


An HD-ready set lacks such a tuner, so you'll need either a set-top box with a tuner or an HD box from your cable or satellite service. Regardless of the box you get, you need to make sure that you're feeding its digital output into your HD-ready set.


Finally, you must tune your HDTV set to a high-definition channel showing actual HD content. Picking up the analog transmission from your local affiliate on your high-def cable box won't result in delivery of a show in HD.


"The higher the screen resolution, the better the image quality of an HDTV."


Most HDTV sets today are 720p displays, but a few vendors are beginning to offer 1080p sets--either LCDs or rear-projection, micro-display (LCD, LCoS, DLP) models. As yet, no 1080p plasmas are available (though some have been announced in very large sizes). These sets will clearly do the best job of handling 1080p content--when it arrives. But today's HDTV shows are shown in either 720p or 1080i format: Nobody broadcasts in 1080p because of bandwidth issues. Movies may someday be available in 1080p on optical media, but Hollywood hasn't settled on the next-generation hardware standard (Blu-ray or HD-DVD), much less chosen a content format.


Lack of 1080p content is one reason some vendors are holding off on introducing 1080p sets. But those that are selling 1080p sets point out that some HDTV is broadcast in 1080i, and that such content arguably looks better on a 1080p set because less scaling is involved. (On the other hand, 720p content has to be scaled up for a 1080p set.) Here again, though, the capabilities of the human eye come into play: You'll probably notice the superior resolution of 1080p only if you sit very close to the set--or have an extremely large set.


"You have to relinquish the fluid motion of a CRT screen when you move up to HDTV."


Not at all. You can purchase a high-definition CRT set--and you'll save a lot of money if you do, because they cost less than LCD and plasma-screen televisions of similar size. But in doing so you'll lose the sleek, flat-panel chic of a plasma or LCD set. If you want that slim profile, however, be aware that LCDs have trouble rendering fluid motion as a result of their somewhat pedestrian response times. Plasma and DLP screens aren't susceptible to this technological weakness.


"Burn-in will wreck your plasma HDTV within a year."


The plasma display has advanced since the days when most of us saw plasmas only at airports, where constantly switched-on screens showing formatted flight information suffered from burn-in--ghost images that linger on screen despite no longer being transmitted.


Today, vendors rate the life expectancy of high-quality plasma TVs at 60,000 hours. That works out to more than 20 years of use if you watch eight hours a day, 365 days a year; it's also about the same lifetime claimed for LCDs and CRTs (the latter are similarly prone to burn-in because, like plasma TVs, they depend on phosphor-based displays).

What changed? Phosphors and gas mixtures in the new plasma panels greatly reduce the risk of burn-in, and some sets use burn-in-prevention software. "If you're not worried about burn-in for your CRT, you shouldn't worry about it for your plasma TV," says the Society for Information Display's Larry Weber.

"Bright LCDs look beautiful everywhere, and they use much less power than plasma or CRT sets do."

It's true that LCDs are bright, which makes them a good choice if you watch TV in a brightly lit room. But if you're inclined to turn down the lights for your rendezvous with Entourage or Medium, you probably don't want the brightest set on the block, and plasmas and CRTs offer superior color capabilities without introducing the response-time (and associated motion artifacting) issues that have long plagued LCDs.

As for power consumption, a study by Japan's Green Purchasing Network--an organization dedicated to promoting environmentally friendly purchasing by consumers, business, and government--concluded that the power consumption of similar-size plasma, CRT, and traditional LCD displays in real-world viewing situations is practically the same. However, the coming generation of LCDs that use LED backlighting, while expected to deliver significantly better color, will consume roughly twice as much power as traditional LCDs of the same size.

"Standard-definition TV is unwatchable on HDTV."

This is a case of hyperbole, not outright fabrication. True, standard-def programming will never look as good as HD programming on an HDTV because of scaling issues. But vendors are toiling to better the SD experience on their HD sets, and the success of these efforts varies between vendors and sets. So if you're expecting to watch standard-definition TV on an HD set, make sure that you do your own taste tests.

These may not be the only myths you'll encounter in your quest for the perfect HDTV--and you can't trust everything you hear (or see) in a showroom. So careful research is essential before you pay for what's likely to be the most expensive TV set you've ever bought. And that is the gospel truth.
    

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