Comment by jmagar | Hacker News Reader

Comment by jmagar | Hacker News Reader

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Let's just start with the simple fact cable quality does matter when working with HDMI. I'm not here to argue about the price of one manufacturer versus another, or their relative quality and worth. But I will point out that "cheap cables" and the expectation that for the same $9.99 you'd spend on a serial cable you could get a reliable HDMI cable is somewhat laughable.

HDMI is really bad design, and due to its DVI legacy they've pushed the up against the limits of what is possible. Right up against the limit.

1) it's twisted pair technology instead of coax 2) it's parallel instead of serial 3) it's very fast (10.2 Gbps)

If you just spent money on a new 7.1 AVR, and a Deep Color Blu-ray player then you'll be needing cables that have been manufactured and tested to a highest HDMI 1.3 standard. Resistance, skin effect, impedance, capacitance, cross talk and inductance all conspire to disrupt the data and since it's digital, you will be left staring at a black screen or hearing pops and audio dropouts. This kind of quality control is not cheap, and is much more than a simple continuity check on each line within the bundle.

I've tested some really expensive HDMI cables and seen what is possible with them. I've ignored the "Direction of Flow" arrows on some long lengths and had them fail, reversed the cables and had it work. There is real engineering that goes into these things, and that is what you are paying for.

So for short lengths (3-6') the cheapest HDMI cable might be good enough, and you will probably be happy. But I'd still be looking for the HDMI 1.3 logo on the package, at least then you can be sure it has been tested against the upper ends of the spec.

I've ignored the "Direction of Flow" arrows on some long lengths and had them fail, reversed the cables and had it work. There is real engineering that goes into these things

You're bullshitting us. At least, I hope you are, otherwise you are sadly misguided. There is no way in hell you can design a cable in such a way that it will pass signals in one direction, but not in the other.

Resistance, skin effect, impedance, capacitance, cross talk and inductance all conspire to disrupt the data

You're just repeating electrical engineering terms without understanding them. Impedance is the combined effect of resistance, capacitance and inductance. The skin effect is an effect that adds to the resistance.

They all don't 'disrupt' the data. In the simplest terms, the resistance influences the amount of power required to transfer a signal, due to losses in the cable. The capacitance influences the amount of time required to transfer a signal, because it may be viewed as the resistance to signal change. Inductance is the only one that may change the signal, but it only influences AC signals, which, at most, act as the carrier for a digital signal. It doesn't change the digital signal.

The fact that Infiniband cables are cheaper than these kind of HDMI cables should also be recognized as a large red neon sign screaming: you're being scammed.

There is no way in hell you can design a cable in such a way that it will pass signals in one direction, but not in the other.

Did someone just uninvent the diode?

I was coming at the problem from a sane angle and meant that there was no way in hell that you could design a cable in such a way if you were simply trying to design the best possible cable.

If you are suggesting that Monster seperates each of the wires in its cables into multiple parts and connects them with electronic components emulating a diode (you couldn't just put a diode in; that would screw up the cable), then yes, it could be done. It would be an insane way to actually let the directional arrows make sense, but granted, when taken literally, my original statement was wrong.

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