Quote:
Originally Posted by ApK
The "it's all just photons" comment reminds of those people who think that a digital signal can't ever degrade or be effected by cables or connections because "it's all just ones and zeros.".
|
People who claim that a digital signal "can't ever degrade" are clearly wrong, but that's not the claim that is usually made. The point is that digital signals degrade in a completely different way from analogue signals. An analogue signal starts degrading as soon as there is any the addition of noise, and degrades progressively more with the addition of more noise. A digital signal will be immune to some amount of noise (up to the noise margin for that signal). Once that margin is reached, bit-errors will appear in the raw signal. However, depending on the rate and distribution of bit errors, and the error-correction coding scheme in use, the original signal may well still be able to be recovered with no errors. If the noise level gets sufficiently high, then the error rate will get too high for the correction mechanism to cope with, and errors will appear in the corrected output.
There are a few relevant points about this.
Firstly, if you're getting any noticeable level of uncorrectable bit errors in any sort of normal domestic installation, something has gone terribly wrong. Think about your computer and all the devices it talks to error-free over digital cables. You'd soon notice if all your apps were loaded with random bit errors - these things need to be 100% error free to function. If you are getting bit-errors, it'll generally be obvious (the effect won't be a subtle one) and there will usually be an obvious cause (e.g. a mobile phone next to a cable).
Secondly, even if there are bit errors, the visual/audible effect they will have on the picture or sound is very different from the artefacts you get from analogue degradation. I've had a sales assistant try to convince me to buy an expensive HDMI cable because it would give "more saturated reds" than the cheap cable I was buying. This is clearly garbage.
/JB