HDMI 2.0 Bandwidth

[Twinstar]

Hey there,

 

I just watched LTTs newest video about Cloud Gaming and this lead me to one big question about the data rate / bandwith.

 

Tell my, why does HDMI 2.0 require 14,4 GBit/s for 4K 60hz, why do the creators of the HDMI standard even bother, when obviously 50 Mbit/s is sufficient for 4k 60hz?

 

best regards from Germany!

[Mira Yurizaki]

Because cloud gaming heavily compresses the video.

[Mira Yurizaki]

In any case, if you want a more thoughtful answer, a raw uncompressed 24-bit color UHD 60Hz signal requires about 11.94 Gbps ( 3840 * 2160 * 24 bits * 60 Hz ). Add in things like sound and generic data and you'll need more.

 

Also I would argue a 50Mbps 4K video stream is likely okay quality. Even UHD Blu-Ray operates at 85 Mbps

[RasmusDC]

and you can "trick" cheaper HDMI solutions to run 60hz 2160p by degrading colors like running YUV 422 insted of YUV444 but text looks like shit.

 

TV 4K streams are even less than 50mbit, but seriously a 4K stream on tv is worse than a 1080p bluray in picture quality..

 

on that Shadow setup, you will se degredation in picture quality, especially in darker gradients where blockyness will be a large part of it, since it tries to save bandwith by killing gradients.

 

in theory simple airplay is also a transcode stream sent to a tv it also looks okay, whereas Google chromecast runs natively on a device.

[Twinstar]

Hey thanks for the replys,

So Shadow compresses the shit out of the Video, which deteriorated the whole quality. Like you rent a 3000$ GPU (Quadro K6000) which can output a true 12bit HDR signal and all the goodness. Than you shove it down the drain. Nice.

But people still use 720p for Gaming nowadays and mobile Gaming is on the rise, so i guess they will be just fine.

I tried the whole chroma subsampling thingy myself, back as 4K 60hz was not a standard and yeah my TV did not want to accept it and @ my friends house the picture looked like shit. So 4k 30hz was the way to go *shiver*.

 

 

[Glenwing]

On 12/10/2018 at 4:33 PM, Twinstar said:

Hey there,

 

I just watched LTTs newest video about Cloud Gaming and this lead me to one big question about the data rate / bandwith.

 

Tell my, why does HDMI 2.0 require 14,4 GBit/s for 4K 60hz, why do the creators of the HDMI standard even bother, when obviously 50 Mbit/s is sufficient for 4k 60hz?

 

best regards from Germany!

Video is transmitted from the source to the display uncompressed. Uncompressed 4K video requires about 14.4 Gbit/s (actually closer to 18 Gbit/s of physical transmission spec, using the encoding methods that HDMI uses). Compressing it to 50 Mbit/s would require processing and latency.