Component, composite, S-Video--how can anyone make sense of video connections for the home theatre? Home-theatre expert Kevin Miller will give you a clear picture of why they should matter to you.
Every television is armed with some sort of video input--even if it's just a radio-frequency (RF) jack that you plug your rabbit-ear antennae into. These days, you'll almost always find a composite-video jack (usually colour-coded yellow) and S-Video support, too. The latest development is called component video. You'll find this connector, usually as a set of three RCA plugs (colour-coded red, blue, and green), on everything from new mid-priced TVs to the most expensive HDTV's. It delivers the best picture yet in terms of resolution and colour accuracy. Now, let's clear up some of this clutter and explain what you'll find on the back of your TV.
In order to transmit a colour TV show to your home, a station must combine the audio and the composite video channels, which it broadcasts as an RF signal. Then your TV has to separate the sound and the picture so that you can view your show. However, you'll get cleaner pictures and sound if you don't combine the signals. And that's why you find separate audio and composite-video cables on most VCRs, satellite boxes, and video game consoles.
Composite video
 Composite-video cable |  |
Although the composite-vido system was developed for colour-TV signals, it doesn't give you a very sharp picture. Composite video was created as a backward-compatible solution for television's transition from black and white to colour. It was a fairly clever solution to the problem of how to continue to send the same black-and-white picture to all the old sets and layer colour information on top--a composite of those two picture components. The black-and-white sets ignored the colour component, while the newer sets separated out the colour information and displayed it with the black-and-white picture. This made for a smooth TV transition in the 1950s with low-resolution colour TVs. Today, though, sophisticated high-resolution displays show all of the compression artifacts and cross-colour (or moiré) blurring that comes with a composite video connection. It's simply impossible to perfectly separate the colour and picture information of a composite-video signal. So, if your TV picture isn't sharp enough or the colours blur together, the likely culprit is a composite output signal.
S-Video
 S-Video | |
S-Video, which was introduced in the 1980s, solved some of the problems that came with composite video. It provides better colour separation and a much cleaner signal. S-Video does so by keeping separate the colour and picture parts of a composite-video signal.
You'll find S-Video ports on most TVs for sale today, but not many people are really taking advantage of them yet. Why is that? Well, take a look at Direct Broadcast Satellite, for example. It starts broadcasting in the composite-video domain and the inherent artifacts still show up. Changing the connector between the receiver box and the TV can't improve a bad source. You will, however, see a noticeable difference if you use an S-Video connection between a high-quality source such as a DVD player or video game console and your TV.
Component video
 Component video | |
Component video improves the picture quality even more by not only separating the colour from the black-and-white portions of the picture but by further splitting the colour information into two colour-difference signals. When the picture signal is split up in this way, you get an unfiltered, uninterrupted image, with better resolution and greatly improved colour saturation. And this is why component video is the predominant method of hook up from HDTV set-top decoders to HDTV's. (For a very technical explanation of colour television and component video, see Tektronix's Web site.)
This separation is most frequently labelled Y, Cb, and Cr for DVD players and other standard video sources. HDTV sources can display a wider colour palette, and their component video connectors are labelled Y, Pb, and Pr to differentiate them. However, we've found that many manufacturers mislabel their component-video connectors. For example, some analog Sony TVs have jacks labelled Y, Pb, and Pr, but they cannot accept HDTV signals. The most common connection from DVD players is three RCA-type jacks.
Best pictures around
DVD and HDTV sources are the best examples of the high-bandwidth, low-noise, and deeply saturated colour that component video is capable of producing. The bigger the size of the screen and the higher the resolution of the display, the more evident the enhanced picture quality using component video. On small direct-view analog TVs, for example, you'll be hard-pressed to see a difference between an S-Video and a component-video connection from a DVD player. On higher-resolution, HDTV-capable direct-view and rear-projection TVs, though, the distinction becomes much more obvious.
On higher-end HDTV-ready sets, progressive-scan DVD players deliver the best possible DVD picture. As you may have guessed, progressive-scan DVD is delivered via component-video outputs from a progressive-scan-capable DVD player. Progressive scan adds even more resolution and detail to the picture, as well as the enhanced colour resolution inherent in a component video signal.
Advanced user tip
If you are in the market for a home-theatre system, make sure to get a TV with component-video inputs--either a new-generation, HDTV-capable set or just a big-screen analog set. Virtually all HDTV-capable sets have component-video inputs. Many of today's HDTV-compatible sets have only one high-bandwidth (broadband, 480p, or 1,080i compatible) component input for the HDTV set-top box. A set with two broadband component-video inputs gives you greater flexibility, as it will allow you to simultaneously hook up a progressive-scan DVD player and an HDTV set-top box, thus eliminating the need for an expensive component-video switcher.
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