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Help: 4k 60hz RGB 444 10bit
Today, 04:06 PM (Last edited: Today, 04:17 PM by Moogerfoogers)
Post: #1
Help: 4k 60hz RGB 444 10bit
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.

   
   
   
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Today, 06:37 PM
Post: #2
RE: Help: 4k 60hz RGB 444 10bit
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.
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