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 !

[joevt]

Thank you. When I bought it, I misread the USB 3 ports as being 2.0. Even when it was doing 4K 60hz, the color space was garbage. That explains it!

HBR3 x2 without DSC or chroma sub sampling can do 4K60 using 8bpc and CVT-RB timing.

4K60 HDMI timing would require working DSC or chroma sub sampling. In either case 10bpc should be possible (though some or all MST hubs don't support DSC decompression at 10bpc so the display would require DSC passthrough to get around that limit).

 

[freshtest]

Hi!

I've been using the original method and the VMM6100 for a while. I've been using it with an LG CX 48" with the native 4k resolution of

but 4k native doesn't make use of Mac's scaling to make everything look "retina", so I wanted to try HiDPI resolutions.

It also works fine with 1920x1080 HiDPI mode, and looks really sharp. But at 60hz.

When I try to use it with 1920x1080 HiDPI at 120hz, it looks like the normal LoDPI.

Examples:

1920x1080 HiDPI, 60hz: Looks sharp, as expected

1920x1080 LoDPI, 120hz: Doesn't look sharp, but that's expected as it's LoDPI

1920x1080 HiDPI, 120hz: Doesn't look sharp, it should look like the 60hz one, it changes a bit from the LoDPI but doens't look good:

All pictures taken at the same distance from the screen, with an iphone 15 pro.
Mac studio running Sonoma 14.1. Always using SDR as I don't use HDR that much.

Maybe an adapter with an VMM7100 would work?

 

[Rozzemak]

Hi!

I've been using the original method and the VMM6100 for a while. I've been using it with an LG CX 48" with the native 4k
...

Check chroma. You are surely not running in 4:4:4 or RGB mode in that HiDPI mode.
Mash green button while on your TV remote in 120hz mode a you will see 4:2:0 or 4:2:2 chroma.
Which produces these kind of artifacts.

 

[mcflury]

I can confirm, when HiDPI 4k@120hz is enabled HDR is gone since 14.1 !! Plz make also a bugreport on apple feedback assistant app. I will also contact CM support about this.

But i think this is an Apple bug.

I will update the OP with an warning to not update or use 14.1 till we know what's going on.

@stevemr123 @joevt hopefully u guys can help also with some informations?

FWIW, I had this problem on two different M1 MacBook Pros (14" on 14.1 and 16" on 14.2 public beta), and fixed them both by temporarily plugging in a different USB-C->HDMI2.1 cable (Uni UA116) to the same monitor (LG C2 42"). The other cable didn't offer more than 60Hz, but after plugging in the VMM7100 again, 2160P+120Hz+HDR was back.

There's probably a cheaper and more convenient way to clear whatever state that clears.

 

[Jashi]

FWIW, I had this problem on two different M1 MacBook Pros (14" on 14.1 and 16" on 14.2 public beta), and fixed them both by temporarily plugging in a different USB-C->HDMI2.1 cable (Uni UA116) to the same monitor (LG C2 42"). The other cable didn't offer more than 60Hz, but after plugging in the VMM7100 again, 2160P+120Hz+HDR was back.

There's probably a cheaper and more convenient way to clear whatever state that clears.

I hoped that plugging in a vmm6100 cm adapter and then unplugging it and plugging in the vmm7100 one would achieve the same effect. Unfortunately this does not work and HDR is still disabled on HiDpi resolutions above 1440p.

 

[chargerinthebox]

Not upgrading to 14.1 until HDR is fixed.

 

[acmac]

Hey Everyone,

I like many am still experiencing the external monitor wake bug (where the external monitor comes on, but the connection is lost and goes back into standby) when my m1 max 14" MBP wakes up from sleep (using a Cable Matters usb-c to hdmi w/ PD adapter). After updating to Sonoma 14.1.1, the issue still remains. The only workaround I've found that doesn't involve disconnecting and reconnecting the adapter, or turning the monitor on prior to waking the mac (or any other workaround) is to use "hibernatemode 25". This is acheived using "sudo pmset -c hibernatemode 25". The -c is to apply the setting only to AC power, but -a will apply to both battery and charger (or just battery would be -b).

"hibernatemode 25" is where the memory is stored to a sleep image and the memory is powered down (unlike with hibernatemode 3 where the memory stays powered). This may also power down USB ports, as it is essentially shutting down the mac.

The only annoyances are that it takes longer to wake from sleep (as it has to restore memory from the sleep image) and you HAVE to input your password after it wakes even after disabling requiring password after waking from sleep.

Since enabling this, my MBP has successfully woken my monitor and established a connection without issue, even after sleeping over night.

Every other pmset combination I've tried doesn't work and results in the same troublesome wake behavior. I also observed in console that when the MBP fails to establish a connection with the external monitor, there's a windowserver log that says "failed to get EDID 0x000XX" or something to that effect.

Hopefully Apple will address the external monitor issue as it appears to be a well-known issue, however, I'm not holding my breath.

For reference, my setup is a 14" MBP m1 max 32c and a Samsung Neo G9 QLED (mini-LED). I am using 144hz at 5120x1440.

Best of luck to you all!

 

[psyguy]

Wow, what a journey. After 1 bricked adapter, 2 adapter orders from Amazon had them send me the completely wrong items (one of them being an ointment for dogs with STDs???), and my thunderbolt 4 hub being delayed by 3 days... I finally got this setup to work.

1. 16" MacBook Pro M2 Pro
2. 42" LG C2
3. Cable Matters 201388-A
4. iVanky 8K 2.1 HDMI Switch
5. Dell WD22TB4
6. 3 Amazon Basics Ultra HDMI cables (2x3FT & 1x6FT)

One weird thing happens though, that I need to test more. When in clamshell mode, it goes into YCBCR 4:2:2 8b. Initially changing BetterDisplay and MacOS display settings didn't fix it back to RGB 10b. I opened the laptop, and that didn't fix it. I unplugged the hub, and that worked to get it back to RGB, but it went back to YCBCR once I closed the laptop. Fortunately, this time toggling HDR off and on did fix it.

Edit: The switch back to YCBCR 4:2:2 8b from RGB 10b keeps happening. I started noticing things looking bad when taking a break where the MBP went idle. The 'fix' isn't consistent. I don't have to open the lid back up, but I did have to unplug the TB4 dock about 2-3 times. The third time, I turned off HDR before unplugging, and that did it, I think.

 

[psyguy]

And it looks like this might be something wrong on the Caldigit side. If I plugged in the Anker typeC to HDMI converter to Mac directly, it ALWAYS reboots with RGB. But not if I plug it on TS4. Everytime after reboot, TS4 seems to negotiate different speed to Display.

Were you ever able to resolve this issue of degrading to YCBCR on your TB4 dock? I saw someone suggest a CalDigit firmware update. I have a Dell WD22TB4 myself and the firmware update didn't help unfortunately.

It does seem like the TB4 dock negotiates a new speed every time indeed after waking up. I noticed that I have to turn off HDR before unplugging it to get it to renegotiate a high enough bandwidth to get back to 120hz RGB 8b.

Does anyone else notice color space degradation after wake with a Thunderbolt dock?

 

[cfletch1]

Odd success here - Using a Cable Matters foldable USBC to 8k adapter (VM7100 chipset w firmware upgrade). Out of my Akitio Thunderdock3 Pro's Thunderbolt port it won't give me full resolution( limited to 4k, 60hz, 8 bit ycmrgb or whatever it is). But it will work straight from one of the 2021 M1's thunderbolt ports (4k, 120hz, 10 bit RGB). Might be limitation of the Akitio dock's bandwith. Not really noticing much difference between 60 to 120 though, tbh. More noticeable with the Windows machine.

 

[joevt]

Odd success here - Using a Cable Matters foldable USBC to 8k adapter (VM7100 chipset w firmware upgrade). Out of my Akitio Thunderdock3 Pro's Thunderbolt port it won't give me full resolution( limited to 4k, 60hz, 8 bit ycmrgb or whatever it is). But it will work straight from one of the 2021 M1's thunderbolt ports (4k, 120hz, 10 bit RGB). Might be limitation of the Akitio dock's bandwith. Not really noticing much difference between 60 to 120 though, tbh. More noticeable with the Windows machine.

Akitio Thunderdock3 Pro has Alpine Ridge Thunderbolt controller so it is limited to HBR2 bandwidth (66% of HBR3 bandwidth).
Are Alpine Ridge Thunderbolt controllers unable to output DSC at HBR2 bandwidth?

 

[acmac]

Sure. In my case I have these issues regardless of whether I'm in HDR mode or not. I've attached a compiled binary of the USBResetter tool which ought to be equivalent to hitting "reset board" in the VMMHIDtool. You can find the sources to this tool here:

GitHub - djrobx/USBResetter

Contribute to djrobx/USBResetter development by creating an account on GitHub.

github.com

In my Hammerspoon scripts I have:

    print("Waking screens.")
    hs.execute("/usr/local/bin/USBResetter", true)
    hs.execute("sleep 1")
    os.execute("sudo /usr/local/bin/python3.11 /Users/djrobx/.hammerspoon/broadlink_cli.py --type 0x5213 --host 192.168.0.11 --mac ec0baea04a28 --send 260056000001269213121312133713121312131213111312133713371312133713371337133713371312131213371312131213121337133713371337131213371337133713111312130005370001264913000c620001264913920d05")

The broadlink command is a USB IR emitter that sends the discrete power on code to my LG C2. The "Wake on lan" method that is commonly used is not consistent in my experience.

Important note: If USBResetter is working, and you just run it while the screens are on, you'll see them go black to "No signal". This is the same behavior you will see if using VMMHIDtool in parallels. Once you reset board, it seems like Mac OSX needs some event to wake the displays back up. Changing the refresh rate or resolution on a screen will do the trick. Or, even just powering the monitors on, as you see in the above script.

I've been going a week now or so without having to unplug the adapters. Would be nice if CableMatters could fix this firmware issue, but after months of trying different things, this is the best workaround I've been able to come up with.

I would encourage people who are seeing this problem to write to CableMatters. It would be awesome to get a solidly working dongle that didn't need hacks to wake up from sleep.

Hi djrobx, I tried running USBResetter even as root but it doesn't find my adapter. I'm using the CM 201428 which has the VMM7100 chip with the custom firmware. Any suggestions? I also noticed that the adapter itself doesn't show up anywhere is "System Information" (not under USB/thunderbolt connections, etc) but my display that is connected to my MBP through the adapter does show up under "displays".

Im trying this on a m1 max 14" MBP running Sonoma 14.1.1

 

[canttouchthis]

Hi all, first of all thanks for the guide, yes it worked quite well. At least I got 4k AT 120Hz, with a minor flaw. I don't know if this is related to this workaround but whenever I use usb-c on my MAC to connect to LG C2 42", resolution doesn't really fit. If I switch to traditional HDMI Port, it's just perfect, except being 60Hz.

Any idea what's missing here? Probably I'm missing a settings somewhere. attaching a photo sowing the edges of the monitor and how screen is not a fit, even I can't see the menu. this is almost same for all resolutions.

 

[Pressure]

Hi all, first of all thanks for the guide, yes it worked quite well. At least I got 4k AT 120Hz, with a minor flaw. I don't know if this is related to this workaround but whenever I use usb-c on my MAC to connect to LG C2 42", resolution doesn't really fit. If I switch to traditional HDMI Port, it's just perfect, except being 60Hz.

Any idea what's missing here? Probably I'm missing a settings somewhere. attaching a photo sowing the edges of the monitor and how screen is not a fit, even I can't see the menu. this is almost same for all resolutions.

Did you put the TV into PC mode on that HDMI input?

 

[freshtest]

A bit offtopic but, what mode do you use LG's display? CX's, C1's, C2's... Game mode for lower input lag? Filmmaker for color accuracy? I have a Spider X pro to calibrate nonetheless

 

[psyguy]

A bit offtopic but, what mode do you use LG's display? CX's, C1's, C2's... Game mode for lower input lag? Filmmaker for color accuracy? I have a Spider X pro to calibrate nonetheless

I'm using Game Optimizer in HDR Select mode. I don't remember exactly why, as it was after a bit of research from reddit and videos on the optimal color profile. I do know I Filmmaker is recommended for color accuracy, but it's quite warm to my eyes, and not as close to the MBP's own display. I do color accurate work and I haven't had any complaints.

Edit: Here's the guide I set up my colors from: https://www.reddit.com/r/OLED_Gaming/comments/mbpiwy

 

[psyguy]

Hi all, first of all thanks for the guide, yes it worked quite well. At least I got 4k AT 120Hz, with a minor flaw. I don't know if this is related to this workaround but whenever I use usb-c on my MAC to connect to LG C2 42", resolution doesn't really fit. If I switch to traditional HDMI Port, it's just perfect, except being 60Hz.

Any idea what's missing here? Probably I'm missing a settings somewhere. attaching a photo sowing the edges of the monitor and how screen is not a fit, even I can't see the menu. this is almost same for all resolutions.

This only happens to me when I'm not on HDMI PC mode. Unless it's the picture quality, this also seems to be evident by the artifacting/color banding I'm seeing here.

 

[Adubg]

Does the 13.1 update effect the Display port to HDMI (102101) or is this a USB-C to HDMI issue only?

 

[Donga120]

Hi, I hope someone can point me in the right direction here...

I have a Mac Studio M2 Max and wanted to use a 42" LG OLED. I decided to try it on my 55" OLED first and bought an expensive 8K@30 / 4K120 USB-C to HDMI 2.1 cable and it works at 1920x1080 @60hz which I assume is scaled up and I'm happy with the sharpness and scaling.

However, when I enable HDR, I get lots of banding and artifacts across the screen with colours etc. Any solution to this?


SDR

60.00Hz
FIXED
3840 x 2160P@60
RGB 8b 3L6 SDR

Running 120hz makes the display very blurry on this mode



HDR (enabled via BetterDisplay)

60.00Hz
FIXED
3840 x 2160P@60
YCBCR422 8b 4L6 HDR10


MacOS 14.2 Beta 3

 

[Pressure]

Hi, I hope someone can point me in the right direction here...

I have a Mac Studio M2 Max and wanted to use a 42" LG OLED. I decided to try it on my 55" OLED first and bought an expensive 8K@30 / 4K120 USB-C to HDMI 2.1 cable and it works at 1920x1080 @60hz which I assume is scaled up and I'm happy with the sharpness and scaling.

However, when I enable HDR, I get lots of banding and artifacts across the screen with colours etc. Any solution to this?


SDR

60.00Hz
FIXED
3840 x 2160P@60
RGB 8b 3L6 SDR

Running 120hz makes the display very blurry on this mode



HDR (enabled via BetterDisplay)

60.00Hz
FIXED
3840 x 2160P@60
YCBCR422 8b 4L6 HDR10


MacOS 14.2 Beta 3

Why don't you just use the HDMI port on the back of the Mac Studio?

 

[clutchm3]

So I have been using the Dell WD19TB and all has been well for the connection to displays. But there are ethernet speed issues with WD19TB and Macbook Pro M2 Max...speeds slower than when directly plugged into computer. Using ATT Fiber. Anyway to make it not get capped? Thank you!

 

[Donga120]

Why don't you just use the HDMI port on the back of the Mac Studio?

Will try that option...

 

[psyguy]

That is odd then because I mostly keep my Macbook docked and it has no problem waking when I turn on my computer. I am using the Dell WD19TB dock though so maybe that might be part of it.

I have only been using this solution for a week but it has been flawless for me after getting it working.

Did you update your dock firmware or are you able to check what firmware it's on? I got a WD22TB and figured I might as well update the firmware for it while I was on a PC. Found out today, a firmware update breaks wake functionality. I never tried it vanilla, so I'll never know unfortunately.

 

[clutchm3]

Did you update your dock firmware or are you able to check what firmware it's on? I got a WD23TB and figured I might as well update the firmware for it while I was on a PC. Found out today, a firmware update breaks wake functionality. I never tried it vanilla, so I'll never know unfortunately.

No way to downgrade? I was just about to check update firmware for my WD19TB dock to see if it would solve my ethernet speed issue above.

 

[psyguy]

Confirmed working on Dell WD22TB4. Both usb c -> hdmi and dp -> hdmi work on this dock.

What was updated in the firmware to allow for DP -> HDMI 2.1 to work on Mac?

Welp, have you managed to get 4K 120 RGB with the DP > HDMI? Otherwise, this doesn't work and has been a complete waste of time. USB C > HDMI works great, but needs workarounds for Wake and Color Profile resetting on the WD22TB4. Do you get any issues with Wake?