Help: 4k 60hz RGB 444 10bit

[Moogerfoogers]

New member here. Hopeful & glad I found this forum. I’ve been struggling to get 4k 60hz RGB 444 10bit working with my 2018 MacBook Pro running Windows 11 natively (no bootcamp partition at all) when connected to my LG C3 OLED tv. I’m desperate for some help. My MBP has an AMD Vega 20 Pro. I am able to get 4k 60hz RGB 444 10bit with my regular computer monitors connected via USB-C to Displayport adapters. So I know my gpu is able to output that resolution/color/bit depth. I have purchased over $500 in cables & adapters the past 2 wks trying to get this to work when connected to my LG C3, but the best I can get is 8bit. AMD Adrenalin shows the option for 8,10,12 bit RGB 444 but after selecting 10 or 12 the screen blacks out and reverts to 8bit. I am currently using a USB-C to HDMI 2.1 adapter from Cable Matters (201388-A) with the 7100 chip and updated firmware along with a cable matters 6ft HDMI 2.1 cable connected directly to one of my MBP thunderbolt 3 ports and to the TV’s HDMI port. Is there anything I can possibly do to get my LG C3 output 4k 60hz RGB 444 10bit by editing the EDID with CRU? Im very new to CRU & do not understand the majority of what can be edited. Looking for some guidance help to possibly get my LG working at 4k 60hz RGB 444 10bits… This is the 3rd forum I’ve tried reaching out for help with not a single reply from anyone in the previous attempts. Hopefully someone here will be gracious enough to help me out. Thank you advance.

   
   
   

[ToastyX]

The likely problem is either the MacBook Pro or the adapter is limited to 4-lane HBR2 or 2-lane HBR3, which limits the pixel clock to 720 MHz at 8 bpc and 576 MHz at 10 bpc. They should both be capable of 4-lane HBR3 as far as I know, so there might be a compatibility issue with the adapter or a bug in AMD's graphics driver. The computer monitors probably work because monitors with DisplayPort normally use the CVT-RB standard for 3840x2160 @ 60 Hz, which makes the pixel clock 533.25 MHz, while TVs use the CTA-861 standard, which makes it 594 MHz, which puts it over the 576 MHz limit. If the LG C3 can handle PC timings, you can try editing the detailed resolution for 3840x2160 @ 60 Hz and setting the timing to "Automatic PC" or "CVT-RB" to bring down the pixel clock to 533.28 MHz. Keep in mind this might limit the audio formats you can use because audio is transmitted during the blanking periods, and CVT-RB has less horizontal blanking than CTA-861.

[Moogerfoogers]

Appreciate the reply @ToastyX. I tried both PC automatic & CVT-RB & it changed the pixel clock to 533.28, but with no success. However, I am able to get 10bit when I reduce the refresh rate to 30hz at 4k RGB 444. But that's refresh rate is too low for my liking. The VRR information I'm seeing on the tv shows 8b 3L6 HDR10 if that means anything? There's also an application that can be used gain access to service menus and such on the LG called ColorControl - https://www.patreon.com/posts/77041300 - could maybe something like this application be used to possibly get the 10bt RGB444 4k60 working? I'm sorry if I'm beating a dead horse here. Just really want it to work

Also what I found if this helps -

MacBook Pro 2018 - “ The new 15-inch MacBook Pro with Touch Bar models support DisplayPort at High-Bit Rate 3 (HBR3), a signal standard of both DisplayPort 1.3 and DisplayPort 1.4”

Cable Matters 201388- A - “Resolved Issues: This firmware update resolves-
Doesn't support the DDC/CI function with Dell Monitors
Only supports up to 2Lane HBR3 at the upstream end on some VMM7100 4Lane HBR3 Products”

[ToastyX]

With the pixel clock still at 533.28 MHz, try deleting 3840x2160 @ 60 Hz from the TV resolutions data block just in case it's using that, and delete the 4:2:0 capability map as well. If that doesn't help, maybe there is an issue with HDR or FreeSync. You can try deleting each data block from "Video capability" downward and see if that has any effect.

The TV is not the issue here, so something like ColorControl wouldn't help. This is some compatibility issue with the MacBook Pro and the adapter. Something isn't being supported correctly.

[Moogerfoogers]

Alas… Tried all the suggestions, but still unable to get 10bit. Appreciate your help. The MBP and the adapter both do 4 lane HBR3 so idk what else I can do. That link I showed you in the previous post dealing with the LG “color control”. Might that be able to do something?

EDIT: I see you mentioned Color Control won’t do anything. Sorry I missed that bit.