DP/USB-C/Thunderbolt 3/4 to HDMI 2.1 4k@120hz RGB4:4:4 10b HDR with Apple Silicon M1/M2/M3 now possible !

[AironMan]

I'm having trouble getting 2560x1440 @ 120Hz HDR on M3 Max via HDMI—3840x2160 @ 120Hz HDR Works Fine.

At first I thought that there's an HDMI limitation involved but 4K 120Hz HDR works fine.

Lowering the refresh rate to 100Hz on 2560x1440 will show the HDR option.

I'm using a 2.1 HDMI cable with no adapters connected to a C2 OLED.

I'm on 14.6.1

This doesn't make sense to me at all. Am I missing something?

u can test in using BetterDisplay

 

[Rozzemak]

This update only breaks HiDPI+HDR not 4:4:4

Yea, it fixes HiDPI problem. My system is in HDR&hidpi mode:

 

[Skyllake]

I want to express my gratitude to everyone here, especially the thread owners and all contributors, for assisting me in finding the solution.

I am thrilled to announce that I have successfully achieved running both my gaming PC and MacBook Pro M1 at 4K@120Hz with HDR on my LG C2 42-inch display.

In my current setup, my MacBook is powered by a single USB-C connection to the display, allowing it to run at 4K@120Hz while simultaneously charging and sharing peripherals such as the keyboard, mouse, and webcam with my gaming PC.

With just a double press of my control key, I can effortlessly switch between the two devices, both operating at 4K@120Hz.

My objective was to find a streamlined single-cable solution for my MacBook Pro M1 to seamlessly integrate into my KVM setup with my gaming PC on my LG C2 42-inch display, while sharing all peripheral devices. I'm pleased to announce that I have achieved this goal. Now, I can easily transition between my Mac and work laptop by simply plugging and unplugging a single USB-C cable, while still enjoying the convenience of sharing all my devices with my gaming PC, and maintaining a 4K@120Hz HDR display. This community has played an invaluable role in helping me reach this milestone. Thank you all.
@AironMan

What KVM are you using? I have a very similar setup (C3 + Macbook pro M1 + Gaming PC) and I'm looking for a single cable solution like yours

 

[ihyder]

Hi mate, so I bought this relatively inexpensive KVM from AliExpress and it works perfectly fine for me.

Just found this amazing item on AliExpress. Check it out! AU$121.38 | HDMI 2.1 KVM Switch 4K 120Hz HDMI USB KVM Switch Dual Port USB HDMI 2.1 Switcher 2X1 2X2 4K 60Hz 8K 60Hz for 2 PCs 1 Monitor New

AU$121.38 | HDMI 2.1 KVM Switch 4K 120Hz HDMI USB KVM Switch Dual Port USB HDMI 2.1 Switcher 2X1 2X2 4K 60Hz 8K 60Hz for 2 PCs 1 Monitor New

AU$121.38 | HDMI 2.1 KVM Switch 4K 120Hz HDMI USB KVM Switch Dual Port USB HDMI 2.1 Switcher 2X1 2X2 4K 60Hz 8K 60Hz for 2 PCs 1 Monitor New

a.aliexpress.com

 

[Jashi]

I found (and its quite some time) how to enforce 4k 4:4:4/RGB & HDR & 120hz via usb-c dp->hdmi on my mbp m1 max after the breaking sonoma update. (LG C2)

It works in sonoma 14.1+ and I just upgraded to sequoia and it STILL works.

I never really figured out what I have to do, so I just fiddle with settings back and forth until I get 4:4:4/RGB 4L10/4L12 10b/12b on my c2.

You have to do this every macos update, but via the usage of better display and config protection, it will stay fixed until next update.

So what to do:

1) Use custom EDID, modified by the tutorial on first page. (I do this, it may no be required for you + I created my own for my C2)
2) Disable all config protections in better display.
3) Turn on HDR on some lower resolution and refresh rate. 1920x1080 100hz hdr works for me.
4) Enable HDR config protection
5) Disable HDR in macos control panel
6) Boom, your tv now should be in 10b/12b 4L10/4L12 // 444/RGB
7) Set your max refresh rate & resolution + enable all config protections - or at least refresh rate, resolution and hdr status.

I'm confident that this method will work on more panels than just LG C2.

PS: Sometimes, it does not really work, and you have to cycle trough resolutions and fiddle with HDR button. But eventually, it will set itself to 444/RGB HDR. Maybe the workaround procedure is not correct, but try to fiddle especially with changing resolution and HDR status in macos control panel while having HDR protection enabled in better display.

Are you saying you can get any resolution and refresh rate + HiDPI + HDR doing this? I tried but it seems that this does not change anything at all.

 

[Lucas016]

I found (and its quite some time) how to enforce 4k 4:4:4/RGB & HDR & 120hz via usb-c dp->hdmi on my mbp m1 max after the breaking sonoma update. (LG C2)

It works in sonoma 14.1+ and I just upgraded to sequoia and it STILL works.

I never really figured out what I have to do, so I just fiddle with settings back and forth until I get 4:4:4/RGB 4L10/4L12 10b/12b on my c2.

You have to do this every macos update, but via the usage of better display and config protection, it will stay fixed until next update.

So what to do:

1) Use custom EDID, modified by the tutorial on first page. (I do this, it may no be required for you + I created my own for my C2)
2) Disable all config protections in better display.
3) Turn on HDR on some lower resolution and refresh rate. 1920x1080 100hz hdr works for me.
4) Enable HDR config protection
5) Disable HDR in macos control panel
6) Boom, your tv now should be in 10b/12b 4L10/4L12 // 444/RGB
7) Set your max refresh rate & resolution + enable all config protections - or at least refresh rate, resolution and hdr status.

I'm confident that this method will work on more panels than just LG C2.

PS: Sometimes, it does not really work, and you have to cycle trough resolutions and fiddle with HDR button. But eventually, it will set itself to 444/RGB HDR. Maybe the workaround procedure is not correct, but try to fiddle especially with changing resolution and HDR status in macos control panel while having HDR protection enabled in better display.

Hey! would you be able to share your LG C2 picture settings? Or anything in specific that you changed? Also, when you click the green button 7 times, what does it appear? Mine is currently at RGB 10b 4L10 SDR, not sure if I am getting the full 4:4:4, BetterDisplay shows I can only get 4:4:4 through YCbCr. Is HDR a must in this case? HDR is disabled when you click the resolution before the last on system settings.

 

[ageorgios]

Hello,

I have bought this cable
CABLETIME Type C to HDMI 8K 60Hz Cable 4K 144Hz VMM7100 Chip HDR10+ HDCP 2.3 for Acer Dell Macbook Pro PS 5 C438 (aliexpress)
and firmware upgarde it
connected successfully to Macbook M1 Pro 16" with 4K 120Hz and my TV Samsung QCQ90 43" 120Hz 4K

but if I turn off the TV and turn on again, there is no signal

The macbook is configured to never sleep

I have to unplug-replug the cable to have it working

I have found that there is a solution with BetterDisplay that is like unplugging-plugging (Reset VMM7100 Adapter) but
1. Is paid software
2. When in clamshell mode the Mac first goes to sleep mode first (disconnects my remote desktop connection, streams of video for example) when reset is happening.

Is there any other way ?

 

[Mizarus]

For anyone who wants plug and play like me the the hdmi to usbc moshou cable on aliexpress already comes with the firmware and I am getting 4k 120hz on my LG C2 oled right out of the box no flash needed.

has anyone else seen or tried this? can you provide us with more info or proof?

 

[DjSzabi]

macOS Sequoia breaks HIDPI for the MacBook Pro M1 Pro. On Sonoma worked the 4K 120hz HDR HIDPI with BetterDisplay, but after upgrading to Sequoia I only get 4K 120hz HDR without HIDPI.On Sequoia HIDPI only works if 120hz is changed to 60hz. Will there be any fix for this?

(MacBook Pro M1 Pro + HD22Q Dock + BetterDisplay Pro)

 

[Jashi]

macOS Sequoia breaks HIDPI for the MacBook Pro M1 Pro. On Sonoma worked the 4K 120hz HDR HIDPI with BetterDisplay, but after upgrading to Sequoia I only get 4K 120hz HDR without HIDPI.On Sequoia HIDPI only works if 120hz is changed to 60hz. Will there be any fix for this?

(MacBook Pro M1 Pro + HD22Q Dock + BetterDisplay Pro)

On sonoma 14.1 and later 4K 120hz HDR HiDPI only works on resolutions 2432x1368 and below. Is that not possible anymore?

 

[DjSzabi]

On Sequoia it's not possible to use HDR with HiDPI only on 1280x720.

 

[Lucas016]

Does someone know what settings to disable and enable to prevent wake issues and signal issues using the adapter at 120hz?

 

[djork]

I just got the Cable Matters USB-C to 8K HDMI Cable (201392) and flashed the firmware using the update tool listed here via Parallels on my MacBook Pro 14-in 2021. I re-attached the cable and I get 4K @ 120Hz with 10bit RGB:

However, when I put the MacBook in clamshell mode, I lose the connection to the display. I've read through the sleep issues posts and tried the Reset VMM7100 HDMI Adapter option in BetterDisplay but can't seem to get it to work. Is there anything else I can try? I'm on Sonoma 14.6.1.

 

[Jashi]

On Sequoia it's not possible to use HDR with HiDPI only on 1280x720

Oh, that is painful.

 

[johnmf]

I bought the Cable Matters 48Gbps USB C to HDMI 2.1 Adapter, Support 8K 60Hz / 4K 240Hz HDR, Thunderbolt 4 to HDMI 2.1, HDMI 2.1 to USB C Adapter, and I upgraded the firmware connected successfully to Macbook M3 Pro Max 16" with 4K 120Hz and my TV Samsung QN90 55" 120Hz 4K. The problem I am having is that after about 2 to 3 minutes, the monitor goes blank like it stopped receiving a signal. I have tried different Thunderbolt ports both on the Mac and on the Caldigit TS4 dock, and the same problem. Thoughts?

 

[chargerinthebox]

any breakage on Sequoia? I'll be updating in the morning

 

[esfrost]

HDR is still not available unfortunately with Sequoia. I believe Apple really did put an end to this "feature". They really want you to upgrade your mac. I was really hoping to get HDR back with the new OS, but I guess it's not coming back.

 

[Rozzemak]

Hey! would you be able to share your LG C2 picture settings? Or anything in specific that you changed? Also, when you click the green button 7 times, what does it appear? Mine is currently at RGB 10b 4L10 SDR, not sure if I am getting the full 4:4:4, BetterDisplay shows I can only get 4:4:4 through YCbCr. Is HDR a must in this case? HDR is disabled when you click the resolution before the last on system settings.

HiDPi 444/RGB 120 HDR mode works for me on M1 Max. I shared green button statistics even how I got it to work.

 

[chargerinthebox]

Nothing has changed in Sequoia. It's the same as Sonoma, you can get 4k HiDPI HDR @ 120 hz below a certain scaling:

 

[chargerinthebox]

Okay, nvm. The screen goes black if I enable HDR at this res. :/

 

[chargerinthebox]

Okay, I can confirm that I can do 4k 120hz HiDPI like in Sonoma but under no scaling option, can I enable HDR at 120 hz, not even if I turn the scaling down to 720p. I have to switch to 60 hz to enable HDR.

 

[DjSzabi]

Okay, I can confirm that I can do 4k 120hz HiDPI like in Sonoma but under no scaling option, can I enable HDR at 120 hz, not even if I turn the scaling down to 720p. I have to switch to 60 hz to enable HDR.

No workaround found until now. I think it is because it is on apple end that breaks 4K 120hz HDR HiDPI.

 

[chargerinthebox]

No workaround found until now. I think it is because it is on apple end that breaks 4K 120hz HDR HiDPI.

Yeah it looks more like a bug on their end now.

 

[Jashi]

Just updated and I am currently still on 4k 120hz 2432x1368 HiDPI HDR. What I find strange is that there is a brightness slider that I can use on my C2 from the settings. I never had that option before. Kind of scared to change the resolution, as I doubt I will be able to go back since it seems to not work for anyone in this thread.

Edit: Forgot to mention I am using an M1 pro macbook.

 

[waydabber]

@Jashi - That brightness slider is there to remap the peak SDR brightness (up to 500 nits max) when the display is in HDR mode (so it's a software brightness control). This helps with the overly dark HDR screen with some displays. Windows had this slider for ages, it's great that Apple added this in Sequoia! BetterDisplay uses this new control as well in HDR mode (and adds HDR brightness upscaling beyond the max 500 nits SDR if more brightness is needed).

@Rozzemak - if you see "RGB", then you are running 4:4:4, no worries (only YCbCr has chroma subsampling).