mechtopia

The great HDMI Scam

It always annoys me when people are sold unnecessary electroncs. Often people are bamboozled into purchasing components that are way overspecified for the task in hand. One recent example that I have been noticing is as new high definition equipment is coming onto the market, people are being sold overpriced HDMI cables, and are being told that it improves the picture quality

In the early days of video cables, you’d need to link up using RGB, component, or VGA: all analogue formats, and it was important to preserve the signal quality by using good cables for long cable runs.

HDMI is a newer cable designed for consumer video, and supports high definition video. Basically the designers took DVI-D (a system for connecting computers to monitors), implemented content protection (HDCP), added audio channels and squeezed it all into a compact connector.

So what’s the point?

Well, HDMI is a purely digital connector. This means that whatever interference is picked up by the cable en route, the receiving device can separate out the digital signal, and reconstruct it, exactly as it was before it was sent down the line.

Will buying a more expensive cable make the picture quality better?

Well, do you think this web site would look better with an expensive ethernet cable? Do you think that if you had a gold plated modem lead, then online photos would look crisper?

Digital transmission changes the way in which failure occurs. If your cable was bad enough to break up the signal it would break up entirely, like Digital TV, or when you're on a GSM mobile phone, and you travel through a tunnel. It wouldn't slowly degrade like in an analogue system, where you'd experience hiss as the signal degraded. Even really cheap HDMI cables will carry a signal way above the threshold required for a perfect image.

My advice is, don't spend any more than £5 on a short HDMI cable (in the order of 1m) and no more than £30 on any cable under 10m without built in electronics (some really long cables will use repeaters, for example).

Posted at 12:20PM Sep 30, 2009 by ohp in Skepticism  |  Comments[1]