FAQ: The finer points of HDTV

By Erica Ogg
Staff Writer, CNET News.com
September 5, 2006 4:00 AM PDT

More high-definition television programming than ever will be available on broadcast, cable and satellite TV this fall.

To experience the sharpest picture and sound, you'll need more than just a high-definition TV. Whether you're planning on buying or are just curious what all the HD hubbub is about, here are some answers to common HDTV questions:

What, exactly, is HDTV?
Several types of televisions can be considered "high definition." In general, HDTVs are set apart from standard-definition TVs by their high display resolutions and wide aspect ratios or rectangular displays.

HDTVs come in display resolutions of 720p (720 lines of detail) or 1080i (1,080 lines of detail). A standard TV has 480. The "p" refers to progressive scan, in which each of the picture frames that appear are drawn line by line from top to bottom on the screen, causing on-screen action to appear smoother. The "i," stands for interlaced, meaning that every second line of a picture is drawn in sequence.

HDTVs that display 1080p content are relatively new to the HD world, though they're said to be the best for TV viewing, since they combine the smooth image of progressive scan and sharpness of 1,080 lines of resolution.

Movies, commercials and TV shows filmed in HD have a ="http: www.cnet.com="" 4520-7874_1-5108580-4.html?tag="bnav"">wider aspect ratio (the ratio of a screen's height to its width) than their standard-definition counterparts. High-definition display width divided by its height is denoted as 16-9 compared with standard definition's 4-3 ratio. The net result is a rectangular, wide-screen format for HDTV panels and content.

Can I watch my favorite shows in HD?
Most likely, yes. ABC, CBS, NBC, Fox and PBS have nearly all of their prime-time fall lineups scheduled in both HD and standard definition. ESPN, HBO, TNT, Discovery and others come in high definition. TVGuide.com and the blog HD Beat now list the nightly TV offerings available in HD, including each show's resolution.

Most broadcasters are going with 1080i, according to the Digital Entertainment Group, which promotes HD entertainment.

What equipment do I need to get HDTV?
To see the mutilated corpses of CBS's "CSI" in stomach-turning detail or to count freckles on the faces of the "Grey's Anatomy" cast requires an "HD-ready" TV, an HDTV tuner and an antenna. An "HD-integrated" TV needs only the antenna.

Cable and satellite services offer HD programming, too. For HD cable, you need cable services and an HD-integrated TV or cable services, an HD cable box and an HD-ready TV. Satellite requires an HD satellite receiver, a satellite antenna and an HD-ready TV.

What's the difference between DLP, LCoS, plasma and LCD TVs?
Digital light processing (DLP) and liquid crystal on silicon (LCoS) are both microdisplay rear-projection TV technologies. DLP is a Texas Instruments-trademarked technology in which light is projected onto a series of tiny moving mirrors, with each mirror representing 1 pixel. LCoS is similar, but light is projected onto liquid crystal-coated silicon chips instead of mirrors. Both technologies offer very clear resolutions, but since they use rear projection, they are often bulkier than flat panels.

High-definition plasma and liquid crystal display (LCD) TVs are ultraslim flat panels. Most models can be hung on a wall.

Plasma TVs often have larger screen sizes, faster response times and wider viewing angles than LCD TVs. However, the technology is fragile, it can dim over time, and it buzzes at higher elevations.

LCD TVs are usually better for viewing in a lighted room. They don't weigh as much or consume as much energy as plasmas. However, it is generally accepted that the picture quality of these newfangled TVs can't compete with that of a standard cathode ray tube, or CRT, television.

Front-projection TVs are popular among videophiles for watching movies in a darkened room. A projector using the aforementioned DLP, LCoS or LCD technology can hang from the ceiling or sit on a table to throw up a picture on a separate screen.

Is a digital TV the same as HDTV?
No. A digital TV can show progressive-scan DVDs and usually HDTV. An enhanced-definition television (EDTV) is capable of receiving HD broadcasts, but it can't display them in true HD quality. HDTVs work with both standard- and high-definition signals, as well as with progressive-scan DVDs. Analog televisions cannot receive HDTV signals or show progressive-scan DVDs.

Will my new TV be obsolete by next year?
Not as long as you get the right connections. Make sure that your HDTV has an all-digital audio/video interface like High-Definition Multimedia Interface (HDMI) or Digital Visual Interface (DVI). For a full listing of TV inputs and outputs, visit CNET's HDTV World.