Originally Posted by Ratman
Thanks for derailing this thread.
You have now gone to the absurd. Bye!
Oh I see what you did there, you still provided no answers and chose to throw a final insult into the mix. Pretty clever really but definitely not an IQ 200 move.
OK, so lets get this thread back on track to where it was before Ratman started throwing it off course. I'll just paste the entire last comment in below. And Jong1 you seemed much less hostile than Ratman and Otto have been toward me so I hope you're the person with the answers:
That's interesting and makes sense. I would have hoped every cable had passed a performance quality inspection when it was manufactured though, but maybe not if the manufacturers are using the certification to prove the design and are then choosing to save money on performance inspection costs by simply not doing that performance testing because they think the certification means they'll never get quality problems? I know you'd never get away with that in the UK but maybe in Taiwan and China etc this lack of inspection is deemed ok and maybe even common practice to save money? That then makes sense why every cost saving effort I've known in Aerospace and Motorsport projects where the accountants have tried to save money by having parts manufactured in these cheaper countries has ultimately resulted in poor part quality resulting in huge production problems and typically several months of delays to projects before the decision was ultimately made to finally bring manufacture back to more local machine shops back in the UK.
When I work through the maths theory myself I keep reaching the answer that 17.92Gbps supports 4K 60Hz 12bit 4:4:4 so I'm not sure what's going on now because none of the cables, not even the 48Gbps cables give that performance..... thinking.....
I find it curious how every 18Gbps cable I've ever tried does not match up to the 27Gbps or 48Gbps cables though. I mean I've definitely purchased Premium Certified 18Gbps cables and those didn't work as good either.... so what's going on.....
There must be more than meets the eye going on inside a HDMI cable. I mean there's obviously sound information too but I'm sure this can only be a very small fraction of the data required compared to video information. Then there must be timing information to give the CPU on the TV end enough information to stitch everything perfectly back together again, but I'm not sure how much extra information this all takes up? Oh and it's digital too so the 17.92Gbps video information must be having to be sent at least twice...... WAIT, maybe that's it.....???
Maybe 18Gbps cables can only support a 9Gbps data "picture" but the information is sent down the cable twice... 9+9=18 ? That would actually make sense as a 4:2:0 picture requires exactly 50% of the data that a 4:4:4 picture requires!!! OK, so working through these numbers I get the following which seems to tie in nicely with the results being achieved with the cables I've tested:
4K 60Hz HDR12 4:2:0 picture = 17.92Gbps video data.
4K 60Hz HDR12 4:2:2 picture = 23.89Gbps video data.
4K 60Hz HDR12 4:4:4 picture = 35.83Gbps video data.
This would explain why all the 18Gbps cables I've tested are only achieving the 4:2:0 Chroma picture. And it would also explain why the 27Gbps and 48Gbps cables are achieving the 4:2:2 Chroma picture too. The only thing it doesn't explain is why the 48Gbps cables are not achieving a 4:4:4 Chroma picture, but I imagine this simply is a result of the actual female HDMI 2.0 port reaching it's maximum data capacity and so when the two devices are handshaking they're opting to choose the next best picture standard that does work which is the 4:2:2 Chroma one.
Jong1, Hi, nice to meet you. You seem like you're willing to try and provide answers, so I'm interested to know if you have enough of a background to be able to comment on the numbers I've questioned above? I mean it really seems to make sense to me but I'll happily be taught otherwise if you know what is going on and can provide some simple logical reasoning to support it