Originally Posted by GGA
Any thoughts on why 4k 60p 4:2:0 is HDMI 2.2 supported but 24p 4:2:0 is not? It would seem a lot easier for the player to avoid any conversions and just output what is on the disc, 2k or 4k 4:2:0. The display converts whatever it receives to whatever it uses internally no matter what it receives, so why not save some conversions (which could be incorrect) and a lot of cable bandwidth.
Hi, The 4:2:0 2160p as you saw to HDMI specs, it's not supported as an output option.
There bandwidth limitations that input/output chips have, there specification of max bit-rate cables can transfer also.
2160p60 @ 4:2:2 will require a lot of bandwidth more that current allowed transmission limit, this is the reason which 2160p60 can be only 4:2:0 at this moment with current hardware/specs.
Content is compressed from RGB to YCbCr 4:2:0 for SDR Full-HD BD or HDR UHD BD delivery, to reduce bandwidth which means smaller file size in discs.
At the end, the signal has to converted back to RGB for the TV/Projector to drive it's sub-pixels.
The question now is what device you will trust to make the required conversions from YCbCr 4:2:0->4:2:2-> 4:4:4->RGB.
There is combination of source/display...some displays work better if they receive a specific colorspace, there players that have superior colorspace conversion pipeline/chips; better from those available inside to a display/projector.
When you do multiple and unwanted extra colorspace conversions; problems with luma/chroma roll-off or clipping can be introduced.
Also the most of the displays, when they receive RGB-Video signal, they converting it to YCbCr for proccesing and then RGB again for the panel.
You need some specific patterns to use, to evaluate these colorspace conversions. When you will have less colorspace conversions and higher-grade...(when you will find out which device to trust for these conversions) then you will have more detail in high-frequency resolution without problems.
For 1080p there patterns for that test in S&M disk. For 2160p colorspace evaluation we don't have tools available in disks right now, we will wait the upcoming S&M 2160p disk to feature similar patterns for this evaluation.
Take a look here: