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 !

[waydabber]

@AironMan I'm on an M1 Pro. I saw the same lower res on first boot after updating.

What works for me is setting the refresh to 60hz in system preferences. Then start messing with Better Display settings. Set resolution to 4k, enable HiDPI, and then set refresh rate to 120. Try toggling config protections on and off. Takes a few tries but eventually 4K/120/HiDPI will stick. System preferences still shows 60Hz but it is actually 120, confirmed by BetterDisplay and LG C2. I've tested this a few times.

It seems to go back to lower resolution every time I reconnect the display, so quite a pain, but at least it can work.

You should be able to use Configuration Protection menu's Refresh Rate option to force an "unexposed" refresh rate on reconnect. I saw @AironMan's post about this not working properly. I should check why this is the case (it should work, at least that was the intention when doing the feature).

The "unexposed" refresh rates are not listed as valid display modes in the system's display mode list, that's why you don't see them in the normal Display Mode menu and under System Settings/Displays. The "unexposed" stuff uses some low level APIs to change the refresh rate (works very much like how the Color Mode menu does its stuff).

You can check the entire mode list using this command:

/Applications/BetterDisplay.app/Contents/MacOS/BetterDisplay get -n=lg -displayModeList

You can check the low level connection modes recognized by the system based on the EDID using this command:

/Applications/BetterDisplay.app/Contents/MacOS/BetterDisplay get -n=lg -connectionModeListAll

(note: if the 'lg' string is not in the display name, you need to substitute that accordingly - the match with -n= is case insensitive.)

You can switch connection modes manually with the `set -connectionMode=` command for the display using it's unique identifier.

When the connection mode is switcehed to a different refresh rate like this, vsync does adapt to this in macOS but the system generally thinks it's the old refresh rate, so System Settings will not provide the right information. When using a non-matching resolution, the desktop will be cut off.

For more information on how to change connection modes using CLI:

Add CLI option to set, get and list external display connection configuration (bit depth, RGB/YCbCr, subsampling, range) · Issue #3229 · waydabber/BetterDisplay

This is not the standard mode change but alters the negotiated connection mode itself. Works on Apple Silicon only with natively connected external displays.

github.com

For more info about BetterDisplay's CLI stuff in general:

Integration features, CLI

Unlock your displays on your Mac! Flexible HiDPI scaling, XDR/HDR extra brightness, virtual screens, DDC control, extra dimming, PIP/streaming, EDID override and lots more! - waydabber/BetterDisplay

github.com

 

[waydabber]

An important note to add: the app lists the "unexposed" refresh rates based on the physical pixel output resolution, not the framebuffer resolution - this disregards some of the limitations macOS puts on the display mode list for larger framebuffer resolutions. This might however mean that whatever Apple is trying to prevent by limiting framebuffer resolution for some refresh rates is just ignored when using some of these "unexposed" higher refresh rates. If there is an underlying justified hardware reason for that limitation, this might cause a crash or green screen or flickers or something. So one needs to use this feature with some caution.

 

[AironMan]

An important note to add: the app lists the "unexposed" refresh rates based on the physical pixel output resolution, not the framebuffer resolution - this disregards some of the limitations macOS puts on the display mode list for larger framebuffer resolutions. This might however mean that whatever Apple is trying to prevent by limiting framebuffer resolution for some refresh rates is just ignored when using some of these "unexposed" higher refresh rates. If there is an underlying justified hardware reason for that limitation, this might cause a crash or green screen or flickers or something. So one needs to use this feature with some caution.

But can u list this "unexposed combination" also on the Display Mode List ? That will be fine also for restore it with config protection

 

[shrik450]

After a day of use I think I was speaking too quickly - it's been just as bad as before. I assume the first few hours were a fluke. I've gone back to 60 because I cannot deal with this while working.

 

[tman2damax]

Greetings,

has anyone tested the new adapter from Belkin?

Here in Germany it is even listed in the official Apple Store.
It claims to support 8k60hz and 4k@120hz plug and play. Compatible with all recent MacBooks.

It is odd though that in other countries Apple lists the old adapter supporting only 4k60.
What do you guys think?

I tried with this cable forever ago and the new firmware just completely bricked the cable despite using the same VMM7100 chip, wasn't even able to flash back to the original I backed up. I contacted belkin support and they never even got back to me. I bet the same would happen with that adapter, belkin probably has some additional tweaks to the firmware that don't allow this trick to work on them. I'd just go with on the of the proven cable matters adapters/cables, zero issues with the this one.

 

[szeller]

After a day of use I think I was speaking too quickly - it's been just as bad as before. I assume the first few hours were a fluke. I've gone back to 60 because I cannot deal with this while working.

Found an approach that may work - In BetterDisplay, under the Color Mode menu select 8bit SDR RBG Full Range (I'm using the Chinese version so the English wording may not be accurate) You could lock this color mode setting by BetterDisplay. In addition, a good enough HDMI cable may help (I replaced my old HDMI cable with a Zestik 1m HDMI 2.1 cable)

BTW, if you select HDR output in MacOS, the signal show-out time after wake up/screen connection will be much quicker. You could have a try. But HDR mode is more eye-burning so I choose the turn it off.

I am still testing whether my method REALLY WORK so you could have a try too

 

[imhereforthe120hz]

I have an M1 Max 14", LG c2 55", cable matters gray adapter (https://www.amazon.com/dp/B08MSWMXT4?tag=mrforums-20) and upgraded using the official CM firmware and modified the EDID to specify DisplayPort.

I was able to get full 4k @ 120hz, 10 bit 4:4:4 (limited). When I toggled hiDPI the resolution was reduced a bit to 3008x1692 and the option for HDR went away.

Does HiDPI interfere with HDR? Is it implicitly enabled?

 

[kevinwinsper]

Really nice @dinosauradventure, when using "other unexposed frequencies" 120hz I can reproduce 4K HiDPI. So confirm that this will work!

Steps:

1. BetterDisplay: Disable config Protection and quit the hole app
2. MacOS: Display settings, set to 4k and 60hz
3. BetterDisplay: Open again and enable only HiDPI
View attachment 2444301

4. BetterDisplay: Use 120hz on BetterDisplay "other unexposed frequencies"
View attachment 2443615


Display Mode must look like this (nothing selected!)
View attachment 2444298


BUT: I warn u, apple will read this and "fix" this faster as u can see

It appears this workaround stopped working on 15.2 dev beta 1

 

[Zacharybinx34]

So I just orders 4 Cable matters 7100 USB-C to HDMI adapters, and they all come with firmware version: 7.02.123
But the firmware with this is Firmware version: 7.02.112. Is that right? We are downgrading the firmware?

I'm also using this on a Mac Studio M1 with 1080p monitors. Any reason to update this? I want it stable as possible!
Which firmware will do that for me?

 

[AironMan]

It appears this workaround stopped working on 15.2 dev beta 1

If yes, its cleary shown apple does watch this thread and wanna f... us up... This has to be gone public !

 

[jasonwoo]

How about Satechi USB4 Multiport w2.5G Ethernet, did anyone try? or by any chance who knows the chip modul, or has the same hacking method?

https://satechi.net/products/usb4-m...Mg==?queryID=c28c08697c8b5c45b628b6f82e421b0c

 

[svandive]

I am somewhat perplexed by the significant attention being paid to the HiDPI configuration. Currently, I am connected to a Mac Studio M1 Ultra via the Thunderbolt 4 port to an LG OLED48CXPUB television using the Cable Matters 201388-A adapter. The television is reporting that it is displaying 3840x2160P@120Hz RGB 10b 4L10 HDR10.

Given this setup, I am curious about the specific benefits of enabling HiDPI. I previously believed that HiDPI was designed to accommodate smaller 4K screens, such as 32” or 27”, by scaling the GUI to 2560x1440 (for example) while preserving the full 4K resolution (3840x2160). This would effectively double the pixel density, resulting in a higher resolution while still allowing the content to be readable. However, I am now uncertain if this understanding is accurate.

If I intend to maintain the native 3840x2160 resolution, does the HiDPI issue currently being observed with the Sequoia (15.x) release of MacOS not hold any relevance?

I guess also maybe my understanding is correct and the folks who are concerned are actually running smaller screens at 32" and 27" in which case loosing the HiDPI setting would be of great concern.

 

[AironMan]

I am somewhat perplexed by the significant attention being paid to the HiDPI configuration. Currently, I am connected to a Mac Studio M1 Ultra via the Thunderbolt 4 port to an LG OLED48CXPUB television using the Cable Matters 201388-A adapter. The television is reporting that it is displaying 3840x2160P@120Hz RGB 10b 4L10 HDR10.

Given this setup, I am curious about the specific benefits of enabling HiDPI. I previously believed that HiDPI was designed to accommodate smaller 4K screens, such as 32” or 27”, by scaling the GUI to 2560x1440 (for example) while preserving the full 4K resolution (3840x2160). This would effectively double the pixel density, resulting in a higher resolution while still allowing the content to be readable. However, I am now uncertain if this understanding is accurate.

If I intend to maintain the native 3840x2160 resolution, does the HiDPI issue currently being observed with the Sequoia (15.x) release of MacOS not hold any relevance?

I guess also maybe my understanding is correct and the folks who are concerned are actually running smaller screens at 32" and 27" in which case loosing the HiDPI setting would be of great concern.

Iam on a 42 inch 4k OLED. The Problem is, Apple does not have good font smoothing. So without HiDPI, fonts does not good if the pixel density is not very high. On a 4k 42 inch the pixel density is about 105. I think about 220 the text will look good also in native resolution.

Does someone test this ?:

defaults write -g CGFontRenderingFontSmoothingDisabled -bool NO

 

[acrylicus]

I have a 42" C4 and a 14" MBP M3 through a CalDigit TS4.
I am running Sequoia - 15.0.1 (24A348)

I have a secondary monitor that is a 1920x1080@144hz

• I connect to the LG C4 from the TS4 dock via this cable which has the VMM7100 chipset
• I connect to the secondary monitor over a DP>HDMI cable from the dock

After flashing the firmware of the cable it worked for a while, then stopped working. Now I can only achieve 60hz and for some reason I can't set my resolution to 160% scaling as I did before. Its made things worse and worst of all its very inconsistent, I have had it work maybe once more after hours of retrying and I have no idea what "fixed it".

Any help would be appreciated!

Firmware Info​

BetterDisplay Configuration​

After loading the EDID into AW EDID Editor I can see the Displayport setting correctly​

 

[AironMan]

I have a 42" C4 and a 14" MBP M3 through a CalDigit TS4.
I am running Sequoia - 15.0.1 (24A348)

I have a secondary monitor that is a 1920x1080@144hz

• I connect to the LG C4 from the TS4 dock via this cable which has the VMM7100 chipset
• I connect to the secondary monitor over a DP>HDMI cable from the dock

After flashing the firmware of the cable it worked for a while, then stopped working. Now I can only achieve 60hz and for some reason I can't set my resolution to 160% scaling as I did before. Its made things worse and worst of all its very inconsistent, I have had it work maybe once more after hours of retrying and I have no idea what "fixed it".

Any help would be appreciated!

Firmware Info​

View attachment 2446444

BetterDisplay Configuration​

View attachment 2446445
View attachment 2446446
View attachment 2446450
View attachment 2446447
View attachment 2446449

After loading the EDID into AW EDID Editor I can see the Displayport setting correctly​

View attachment 2446448

This Cable is not listed as supported. Plz use cables that are listed in the OP

 

[acrylicus]

This Cable is not listed as supported. Plz use cables that are listed in the OP

I've just placed an order for this https://www.amazon.es/gp/product/B08MSWMXT4/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Which is the one listed in the original post.

I'm not convinced it will make a difference as its the same chipset, but we shall try none the less!

 

[waydabber]

It appears this workaround stopped working on 15.2 dev beta 1

The workaround should work fine on 15.2 beta with BetterDisplay. Just tested with my old M1 Pro 14" MBP and a 4K high refresh rate display.

This is what I tried:

1. Check the max. HiDPI resolution in the canonical resolution list for 120Hz which is 3072x1728.
2. Switched to 60Hz and choose a higher resolution, namely 3456x1944 HiDPI.
3. Switched to "unexposed" 120Hz, 144Hz and 144Hz variable modes.
4. Tested all using the app's own vsync checker (hold OPTION while opening the Refresh Rate menu) on the display's OSD and UFO speed test to see if these are legit.
5. Everything checks out OK (see all details on the screenshot below + the screenshot resolution shows it's a HiDPI rendered desktop).

So all in all, while for some reason macOS Sequoia does not list certain resolutions at higher refresh rates due to a software limitation, the hardware can still produce all the HiDPI resolutions with all the high refresh rates just fine. The trick is to first select the resolution using a lower refresh rate and then switch to an "unexposed" refresh rate using the app.

I understand that some reported that config protection for this mixed mode does not work properly in 3.1.2 - I'd probably need some more details on how to reproduce that as it seems to work fine here so I was not able to reproduce the issue yet.

 

[AironMan]

Yes look like the trick is so enable 60hz with HiDPI and then switch back to "unexposed frequencies" 120hz. Then its save the resolution also on Display Modes so it can handle better the restore config protection. Before we select the Resolution with macOS Settings, I think that was the problem here.

EDIT: Just testet, config protection does not set correctly the setting again. Looks like it will restore 3840x2160 120hz in normal Mode not in "unexposed frequencies" mode. U see, when using the trick, in Display Mode stays on 4k@60hz HiDPI. But when the config protection was in action it is on 4k@120hz native, because HiDPI is not present when it's not in "unexposed frequencies" Mode.

 

[svandive]

Yes look like the trick is so enable 60hz with HiDPI and then switch back to NTSC 120hz. Then its save the resolution also on Display Modes so it can handle better the restore config protection. Before we select the Resolution with macOS Settings, I think that was the problem here.

View attachment 2446579
View attachment 2446580

EDIT: Just testet, config protection does not set correctly the setting again. Looks like it will restore 3840x2160 120hz in normal Mode not in NTSC mode. U see, when using the trick, in Display Mode stays on 4k@60hz HiDPI. But when the config protection was in action it is on 4k@120hz native, because HiDPI is not present when its not in NTSC Mode.

View attachment 2446588

View attachment 2446589

I want to confirm with this configuration, you do loose access to HDR, is that correct?

 

[waydabber]

@AironMan - just a minor note: 'NTSC' is not the right term here - by NTSC refresh rate the app refers to those funny x/1.001 refresh rates (29.97 and 59.94 etc), these could be used when working with legacy NTSC (US video standard) video devices. The 120Hz, 144Hz etc is just simply "unexposed" refresh rate - meaning that for the given resolutions these refresh rate options are not enumerated by macOS in the display mode list, but are apparently still accessible with some low level hacking.

Regarding the config protection issue - I will need to do a test again. I did not test it with 3840x2160 HiDPI but with a different 3456x1944 resolution. It is possible that since 3840x2160 is available with 120Hz but as LoDPI, config protection is satisfied with that instead of forcing HiDPI. Do you have this config protection issue if you try a slightly lower HiDPI resolution (note: I am not sure how useful it is to have the native resolution as HiDPI, I don't think it improves clarity much - beyond zooming and screenshots of course - as simply there are no extra pixels to show high resolution content, so all you achieve is a kind of supersampling effect).

Update: just re checked config protection with the mixed 3840x2160 HiDPI 120Hz mode on M1 Pro and indeed it does not seem to work as expected. I will look into this issue and hopefully improve the situation in a future update. Meanwhile as a workaround you can script the required changes (set the mode to 3840x2160 HiDPI 60Hz using the app's CLI and then switch the refresh rate to 120Hz using the app's CLI) to quickly restore the preferred configuration.

 

[AironMan]

@AironMan - just a minor note: 'NTSC' is not the right term here - by NTSC refresh rate the app refers to those funny x/1.001 refresh rates (29.97 and 59.94 etc), these could be used when working with legacy NTSC (US video standard) video devices. The 120Hz, 144Hz etc is just simply "unexposed" refresh rate - meaning that for the given resolutions these refresh rate options are not enumerated by macOS in the display mode list, but are apparently still accessible with some low level hacking.

Regarding the config protection issue - I will need to do a test again. I did not test it with 3840x2160 HiDPI but with a different 3456x1944 resolution. It is possible that since 3840x2160 is available with 120Hz but as LoDPI, config protection is satisfied with that instead of forcing HiDPI. Do you have this config protection issue if you try a slightly lower HiDPI resolution (note: I am not sure how useful it is to have the native resolution as HiDPI, I don't think it improves clarity much - beyond zooming and screenshots of course - as simply there are no extra pixels to show high resolution content, so all you achieve is a kind of supersampling effect).

Update: just re checked config protection with the mixed 3840x2160 HiDPI 120Hz mode on M1 Pro and indeed it does not seem to work as expected. I will look into this issue and hopefully improve the situation in a future update. Meanwhile as a workaround you can script the required changes (set the mode to 3840x2160 HiDPI 60Hz using the app's CLI and then switch the refresh rate to 120Hz using the app's CLI) to quickly restore the preferred configuration.

Perfect thanks! I use to name it NTSC because its in that config section for NTSC, but can also go with unexposed frequencies

And native + HiDPI: When 4K and HiDPI are enabled, the fonts look significantly better. Apple doesn’t handle font smoothing well when the pixel density is low. On a 42-inch 4K display, the density is about 104 PPI, which results in choppy fonts. When u are about 220 PPI u will not see any difference.

 

[acrylicus]

I have a 42" C4 and a 14" MBP M3 through a CalDigit TS4.
I am running Sequoia - 15.0.1 (24A348)

I have a secondary monitor that is a 1920x1080@144hz

• I connect to the LG C4 from the TS4 dock via this cable which has the VMM7100 chipset
• I connect to the secondary monitor over a DP>HDMI cable from the dock

After flashing the firmware of the cable it worked for a while, then stopped working. Now I can only achieve 60hz and for some reason I can't set my resolution to 160% scaling as I did before. Its made things worse and worst of all its very inconsistent, I have had it work maybe once more after hours of retrying and I have no idea what "fixed it".

Any help would be appreciated!

Firmware Info​

View attachment 2446444

BetterDisplay Configuration​

View attachment 2446445
View attachment 2446446
View attachment 2446450
View attachment 2446447
View attachment 2446449

After loading the EDID into AW EDID Editor I can see the Displayport setting correctly​

View attachment 2446448

Hi - I am now running the exact adapter from the OP and have flashed it the same as before.

I am still getting 60hz only (though interestingly I am getting an option for HDR now).

 

[LoneFireBlossom]

Really nice @dinosauradventure, when using "other unexposed frequencies" 120hz I can reproduce 4K HiDPI. So confirm that this will work!

Steps:

1. BetterDisplay: Select 4k HiDPI @ 60hz

View attachment 2446583

2. BetterDisplay: Use 120hz on BetterDisplay "other unexposed frequencies"

View attachment 2443615

Info: BD config protection does not work correctly for now. It's better to disable it and then change every time to "unexposed frequencies" 120hz manually.


BUT: I warn u, apple will read this and "fix" this faster as u can see

M1 MAX MacBook Pro & LG G4 55''
I don't see 120Hz option in hiden option of BetterDisplay, so I choose 119.88Hz. I think maybe it's same😂

 

[LoneFireBlossom]

M1 MAX MacBook Pro & LG G4 55''
I don't see 120Hz option in hiden option of BetterDisplay, so I choose 119.88Hz. I think maybe it's same😂
View attachment 2447163

Although the display output can reach 4K@119.88Hz, 12-bit RGB Full Range HDR (using BetterDisplay settings), the cable is running in 4L12 mode in this setup. As long as the cable is working in 4L12 mode, when connecting a Mac to the TV and then connecting the TV to the soundbar through HDMI eARC, the sound from the soundbar intermittently cuts out.

However, if I switch BetterDisplay back to the previous 4L6 output, i.e., 4K@60Hz, 12-bit RGB Full Range HDR, the soundbar works fine with this setup, and the issue doesn’t occur.

Has anyone else experienced this problem?
M1 MAX MacBook Pro macOS 15.1 & LG G4 55''

 

[waydabber]

M1 MAX MacBook Pro & LG G4 55''
I don't see 120Hz option in hiden option of BetterDisplay, so I choose 119.88Hz. I think maybe it's same😂
View attachment 2447163

BetterDisplay normally shows options in the "unexposed" list that are not available for the normal display modes. However if you hold SHIFT while you open the Refresh Rate menu, it will only show "unexposed" (low level switch) refresh rates - meaning that for each option the app will switch refresh rates using a low-level method, not via normal mode change.

You can discern the difference in the icon as well (the waveform icon will show a low level refresh rate switch). This is how this looks for example on a built-in XDR display: