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Expensive HDMI cables make no difference - the absolute proof

Published 
25 May 2012
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Comprehensive, proper testing answers the question once and for all

PROOF THAT IMAGE QUALITY CAN'T BE IMPROVED BY A CABLE

This method of testing not only determines the number of errors transmitted by a particular cable, it will also indicate if colours change at all when switching between cables - an idea frequently used to explain why certain cables are “better” than others in high-end home cinema reviews. Basically, if the cable does anything at all, the captured frame will be different from the frame screencaptured on the PC.

We looked at a range of cables, from the bargain basement cables that come bundled with Blu-ray players and TVs, to incredibly expensive high-end ones with huge feature lists covering the packaging. There was a vast difference in terms of price, ranging from £5 to an eye-watering £150, which could easily confuse anyone looking for a new cable.

HDMI cables table

The list of cables that we used for our testing

ABSOLUTELY NO DIFFERENCE

After methodically testing each cable, our comprehensive results revealed the truth. We couldn’t find a single error in any of the frames of video we captured using our tests, regardless of the cable we used. Even allowing for a single error per billion bits, none of our captured frames contained as much as a single pixel out of order by a single colour shade.

HDMI tested: ImageMagick compare

This image is the ImageMagick Compare-created image. If there were any errors, the pixels would be highlighted in red

The MD5 hash values backed up our findings – the captured frames were identical to the original ones. As verification, the MD5 hash of the ImageMagick Compare files were also identical. For reference, here are the MD5 hash values generated.

HDMI hash comparison

The MD5 hash proves that the captured files are all identical

We had to force an error by reversing a uni-directional cable, which generated several incorrect pixels. Because our capture card doesn’t apply any error correction, these pixels simply failed to render.

Comparing our captured images to one another also proves that individual cables have no impact on colour reproduction. Because each capture was identical, with no differentiation between the colours of individual pixels, there can be no question that the final picture displayed on a TV is unaffected by your choice of HDMI cable. With no active circuitry inside them, HDMI cables don’t know what format the data it transmits will get re-encoded into when it reaches its destination, so there’s no way it could adjust colour values, improve skin tone or create better black response.

More expensive cables may have been engineered to eliminate timing jitter or reduce binary errors, but we didn't get any errors with our Lindy 10m cable, which costs less than the Atlas 1m cable. What's clear from our tests is that we got no errors on any of the cables, and more expensive cables did not improve image quality at all. Given our results, we'd definitely buy cheaper HDMI-certified cables.

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