April 2004

HDTV: Not Quite Ready for Prime Time

It seems that you can’t mention TV these days without the topic of high-definition television (HDTV) coming up. When you walk into an electronics store, for example, the sales floor is usually covered with high-definition (HD) televisions, while satellite and cable providers are offering more and more channels with a lot of sports and movie programming in hi-def. All of the major networks are now producing shows in HD; for example, The Tonight Show with Jay Leno and the Super Bowl.

So what, exactly, is HDTV? Everyone talks about how great it is, how "filmlike" and realistic the picture looks -- and you may even have seen some impressive-looking demos yourself at your local dealer. But you might not know exactly how HDTV differs from regular television. This month we’ll take a closer look at what HDTV is and isn’t, and what you’ll need to enjoy HD programming in your home.

What is HDTV?

High-definition television is generally thought of as video that is displayed at a resolution of at least 720p (progressive scan) or 1080i (interlaced scan) horizontal lines. An interlaced scan is the conventional method of displaying video, in which each frame consists of two fields of alternating lines that are refreshed with each pass. Progressive-scan video refreshes every line of a complete frame all at once, and thus requires twice the scanning frequency as interlaced video.

To enjoy true HDTV in your home you’ll need an HD television, an HD video source, and a video connection capable of transmitting the high-resolution, high-bandwidth video signal.

What isn’t HDTV?

DVD is not an HD source. A standard DVD player can output video only at 480p, so it’s not considered HD. True HD DVD systems (called Blu-ray and HD-DVD) will soon be released, perhaps even as early as this year, but they’re not available yet.

Digital cable and satellite boxes are typically not HD sources, unless you get the more expensive HD-capable models and you subscribe to the HD channels, which also usually cost more.

Regular over-the-air TV broadcasts, analog cable, and VHS VCRs are not HD. It’s safe to say that most video sources that are readily available to consumers are not HD.

First things first: You’ll need an HD television

High-definition televisions come in all shapes and forms. Whether it’s one of the new LCD or plasma flat-panel displays, a rear-projection television (RPTV), a front projector, or even the good old direct-view CRT, there are HD versions of all of these types of devices. Some HDTVs accept only a 1080i signal or only a 720p signal; others accept both. HD direct-view CRTs can currently be bought for $1000 or even less, while high-end front projectors can cost tens of thousands of dollars; there is an HD television for just about every budget.

Then you’ll need something to watch

If you have an HDTV, you’ll need some HD programming to enjoy the benefits of your new display’s higher resolution. As mentioned, most commonly available video sources are not in HD. But even if you live in an area in which many HDTV broadcasts are available over the air, you’ll still need a set-top box to receive these signals, as most HDTVs don’t have built-in HD tuners -- which is why they’re referred to as "HD-capable" or "HD-ready." Technically, only a television with a built-in HD tuner can be referred to as a true HDTV set.

Most people, however, will opt to receive HD digital cable or satellite signals. To do this, you’ll need a different set-top box (available from your cable or satellite provider) to decode these signals, and you’ll have to subscribe to their HD services, which are usually available on only a limited number of that provider’s channels.

The only recorded HD medium currently available to consumers is called D-VHS -- a digital HD version of the ubiquitous VHS tape format. Prerecorded D-VHS movies are available in a copy-protected format called D-Theater, usually recorded at 1080i, though D-VHS also supports 720p. Both are noticeably superior to the DVD format’s maximum resolution of 480p.

Making the right connection

Some of the less expensive HDTVs have only analog video inputs, such as component video; the more expensive ones will usually have a digital video input. While connecting an HD source to an HDTV with an analog connection will result in a very good picture, you’ll need a digital video connection to get the most out of your HD video system.

There are basically three digital video connections currently used by the consumer-electronics industry. FireWire (or IEEE1394), more commonly seen in computer hardware, transmits both digital audio and video, albeit in a compressed format. DVI transmits uncompressed video, but lacks any capacity to carry audio signals. HDMI, the latest digital audio/video connection to be introduced, passes uncompressed video signals that are compatible with DVI, and adds the ability to transmit uncompressed digital audio data. The HDMI interface appears to be gaining widespread acceptance among major electronics manufacturers; hopefully, it will become the universal standard for digital A/V connections.

The future of HDTV

In the not too distant future, all new televisions, video broadcasts, and recorded video sources will be in high definition. However, that doesn’t mean you’ll have to get rid of your old TV, VCR, and DVD player. The new HDTVs should continue to have analog inputs to which you’ll be able to connect non-HD video sources such as your VCR; and set-top digital HD tuners, such as satellite and cable boxes, should still have analog outputs so that you’ll be able to watch HD broadcasts in standard definition on your regular TV.

HD programming is still relatively rare, but if you’re inclined to set up an HD video system in your home, you’ll find the results well worthwhile. HDTV can be breathtaking -- it is, as they say, very filmlike. Once you’ve experienced HDTV, everything else, including DVDs, will look soft, lack detail, and will look like . . . well, like TV.

...Roger Kanno
roger@hometheatersound.com

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