• What are media centres?
• Key components of a media centre PC
• The case
• TV-out
• The TV tuner
• Input devices
• Software
• Media servers
• Media streamers

TV-out

If you plan on plugging your media centre into a TV screen, then a video card that supports TV output is essential.

Not all TV-outs are created equal, and it's actually very hard to find details of the quality of TV-outputs. Video card reviewers almost never test them. The good news is that TV-out has improved markedly in recent years, and the major NVIDIA and ATI-based cards will have acceptable TV-out capabilities, so buying a TV-out card is less of a lottery than it was a few years ago. (Matrox, incidentally, has traditionally had the best TV-out, but its cards are sorely lacking in other qualities). The worst cards will have reds that bleed on screen, high levels of flicker (which leads to eye strain headaches) and large parts of the screen that disappear into overscan areas, without the possibility of correction.

The key things to look for in a TV-out video card are support for Digital Visual Interface (DVI) or High Definition Multimedia Interface (HDMI) output (assuming your TV supports it), flicker filtering and overscan compensation/adjustment. Most modern TV-out video cards will also support S-Video, however this is a much older, analogue connection, and generally won't deliver anywhere near the performance of DVI or HDMI for high definition content.

Flicker filtering is used to compensate for the fact that your TV screen operates at different refresh rates to a monitor and is interlaced (meaning the TV draws every second line, then comes back and does the other half of the screen). Flicker is most noticeable on a static screen.

Overscan adjustment is used because you normally can't see the edges of your TV picture. On a computer monitor, every pixel is shown, but on a TV screen, the outer edges of the display are hidden by the casing. That is, the bezel casing of your TV screen can actually be hiding an inch or more of the actual screen around the edges. For TV, that doesn't matter so much, but it's a big problem for PCs. With the bottom inch of the display not in the visible screen area, for instance, you would totally "lose" your Windows Task Bar (it would still be there, but hidden by the casing around the TV).

Good TV-out cards will have drivers that will allow you to "squeeze" the display into the visible area of the TV screen. If you can, have a play with the card drivers before you buy to see if they have this feature.

There is an alternative to cards with TV-out: the scan converter. A scan converter is an external box that takes signals designed for computer monitors (VGA signals) and converts them to signals suitable for TV screens (PAL/NTSC signals) - or visa versa. Scan converters are very much a lottery, however - some do a decent job, but many are horrible, with poor colour conversion, high rates of flicker and serious screen positioning problems. If you are going to buy a scan converter, always see it in action before purchase.