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Comment by interpol_p | Hacker News Reader

When wiring up my projector, I needed a 10 or 20 meter HDMI cable. The first one I got produced a snowy image on the screen — it wasn't like analogue static, but it was definitely a poor quality image. I replaced that cable with a more expensive one and the image looked correct. It surprised me that there would be a difference in HDMI cables, because I thought exactly the same way — a digital signal is a digital signal

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This is what happens with a damaged or underspecced cable.

The HDMI standard doesn't have a way of telling you that you really need an HDMI 2.2 cable and you actually have an HDMI 1.x cable. It just tries to send the signal, and if the analogue bandwidth of the cable is insufficient, then the error correction will be insufficient and you'll get no signal or snow and blocks.

This is somewhat of a good thing, since many short HDMI 1.x cables will work for standards that require HDMI 2.x.

That's not really what digital implies, but you figured out the important part: When digital signals fail, they do so in a very obvious fashion. A worse cable won’t give you “less saturated blacks” or something else that's subtle, it will give you random bit errors that manifest as snow. If the picture isn't obviously bad, then it is as good as any cable will give you.

This isn’t even true with other common ‘digital’ cables.

Not all ‘Ethernet’ cables are the same. Someone will give you 100mbit. Some will give you a gigabit. Some will give you even more. They’ve all got RJ45 on them.

“All HDMI cables are the same” is an almost-baseless corruption of a very valid critique of Monster et al.

RJ45 is just the plug. Ethernet cables are labeled with category 5, 5e, 6 etc.

8P8C is the plug.

RJ45 is a wiring pin-out standard for that plug [1]. It's also a standard for telephony, not networking -- it carries one phone line. A gross waste of pins if you ask me.

[1] Not quite. An RJ45S plug has a tab on the side that will not insert into an 8P8C jack.

Calculations change at 10+ meters. Most cables are not rated past 15.

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