Beginners' guide to video connections

Confused by all the home-video terminology that's thrown around in your local TV store? Join the club. Between all your HDMI, DVI, Toslink, S-Video and component cables, navigating your way though the wilderness of different audio and video connections is a daunting task, to say the least.

So here's a quick cheat sheet of the main video connections you need to know (the audio cheat sheet will come this Friday); take it with you the next time you go to your local Best Buy or Circuit City. I've grouped the various connections according to video quality, starting with the best first.

HD connections (best of the best):

HDMI: Short for "High-Definition Multimedia Interface," HDMI is the latest thing in home-theater interfaces. You'll recognize HDMI inputs by their thin, flat shape, and most HDTV sets sold today have at least one HDMI input (if not two or more). One of the advantages of HDMI is that it allows for an all-digital connection, meaning that the digital signals from your DVD, Blu-ray or HD DVD player don't need to be converted to analog (a process that will degrade the resulting picture, if ever so slightly). HDMI connections will also deliver both audio and digital signals, and the latest version of HDMI (1.3) supports Dolby TrueHD and DTS-HD Master Audio, a pair of "lossless" audio formats that you'll find on Blu-ray and HD DVD discs. Oh, and one more thing: HDMI also supports DRM, a little feature that's much loved by the movie industry and despised by home-theater advocates, who note that once HDMI-based copy-protection schemes are fully implemented (which won't happen for a few years, at least), they may lead to nightmarish compatibility problems.

DVI: The Digital Visual Interface, or DVI, is primarily used for computer displays and digital projectors, although you'll find DVI-D (the extra D stands for "digital") inputs on some older HDTVs. Unlike HDMI connections, DVI only delivers video. If you happen to have an older HD set with a DVI input, you can still try connecting it to an HDMI device using a DVI-to-HDMI cable. 

Component video: An analog connection as opposed to the digital HDMI and DVI interfaces, component video is perfectly capable of delivering high-def signals to your HDTV—my Xbox 360, for example, sends gorgeous 1080p video to my TV over component video. However, many manufacturers don't let their DVD, Blu-ray and HD DVD players send 1080p images over component, probably because component video doesn't support DRM copy protection. And while robotic TV salesmen will repeat endlessly that HDMI connections are the best, I urge you to take the Pepsi challenge with HDMI versus component—you may be able to tell the difference on a massive 70-inch display, but otherwise, good luck.  Anyway, a component video cable is actually a bundle of three cables that separates the video signal into three distinct components: the "Y" cable handles luminescence (or brightness), while the "Pb" and "Pr" cables divide up the color signals. If your HDTV has a component-video input (and I can virtually guarantee you that it does), you'll find a trio of RCA-type plugs marked "Y", "Pb" and "Pr"; when you connect the component-video cable, make sure you match those three plugs correctly, or else you'll get a black-and-white picture or no image at all.

Standard definition connections

S-Video: A step down from component video, S-Video (or "separate video") carries video signals (but no audio) to TVs using two distinct signals, compared to three for component video. S-Video connections came into vogue with the development of high-end VHS players, and while they do a decent job with standard-definition images, they're incompatible with HD. If you're connecting a DVD player to a 19- or 24-inch CRT TV, S-Video will probably do the trick, but if you're watching on a screen that's 32 inches or bigger, you should use the component-video inputs if you can. S-Video cables have little round plugs at the end with thin, oh-so-delicate pins inside; be careful when plugging the cable (it can be maddeningly difficult to do), lest you damage the pins and render the cable unusable.

Composite video: Even lower quality than S-Video, composite video cables send images to your TV using just one signal, so the picture will be less than pristine, although the single RCA-type plug couldn’t be easier to attach. While most big-screen HDTVs have composite video inputs, you better not let me catch you using it (unless you're just plugging in your vintage GameCube or something).

And, in a category all it's own…

Coaxial RF: These round, threaded inputs aren't straight-ahead video connectors per se; rather, they let you plug over-the-air antennas and cables to your TV, and coupled with an analog or digital tuner, they deliver anything from old-style VHF and UHF broadcast TV channels to full-on HDTV signals.