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Dummy display for Apple Silicon Macs to achieve custom resolutions

333 points by PikachuEXE 5y ago

babaganoosh89 5y ago
For those asking why this is useful: Mac mini's without a monitor hooked up can only display at a certain aspect ratio while remote screen sharing. The typical solution is to use a dummy hdmi plug (~$10) plus an app like SwitchResX (~$20) to support custom screen resolutions. If OP's app works as described, then this is a free software solution to a $30 problem.
- gprasanth 5y ago
  Was looking for this exact thing a month ago [1]. Now, this. I've given up the idea of connecting to mini over screensharing and connected a couple of displays to it, happily. [1] - https://apple.stackexchange.com/q/428243/51800 https://apple.stackexchange.com/q/428243/51800
- daveidol 5y ago
  This doesn't sound like the core use case though based on the README - it sounds like it's used for enabling HiDPI (aka not-blurry) scaling on less-than-4K monitors. So, using native resolution but not necessarily 1:1 DPI.
- spockz 5y ago
  It is not just a monetary problem though. Sometimes you don’t have the required physical access or permissions to install additional hardware.
- roderickm 5y ago
  Your presentation has presenter notes but your MacBook has only one display? Create a dummy display for the full-screen presentation, share that into the remote meeting/projector, and preserve the primary display for presenter notes, logtails, chat, etc.
  - djrogers 5y ago
    Sounds like it'd be easier to just run your slideshow in a window and share that window. PowerPoint and Keynote can both do that. Bonus to sharing only a window - you never accidentally show something you didn't want to, like that email or messages notification...
    - bombcar 5y ago
      For those who don't know, in PowerPoint go to Setup Slide Show on the Slide Show tab and select "Browsed by an individual (window)" and then share that window. Great for Zoom et al.
      - Isthatablackgsd 5y ago
        I use OBS to handle the screen sharing because it is easily to misclick the wrong window that are not for public view. In OBS, it is binded to specific window titles and it is easily to edit out the black bar on the top of the PowerPoint that appeared in Zoom directly (without OBS). I have a few scenes set up this away and quicker to switch than doing it through Zoom itself.
- waydabber 5y ago
  Hi, I tested the Screen Sharing scenario with BetterDummy running on an Intel headless Mac Mini 2018 running Big Sur. Works splendidly, all resolutions are available and resolution change works on-the fly through Screen Sharing!
- g42gregory 5y ago
  Here is another reason this is useful: If you connect a Mac (mini, MacBook pro, air) to an external monitor, AND this monitor is not recognized as "retina" (eg. Apple $4599 XDR) AND you are not running at the monitor's highest resolution, the screen will be blurry. There are a lot of "ands" in the above sentence, but it's actually quite common situation. Retina monitors are expensive. For non-retina monitors, native highest resolution still renders objects too small for many people. On MacBook Pro/Air the solution is to mirror the screens. The MacOS thinks that it renders to the retina screen and sends appropriate re-scaling to the external monitor. But mirroring has its problems. For example, expect ratio will be the same as MacBook's internal screen. This may result in black bars on the monitor, depending on its aspect ratio. Also, in M1 MacBook Pro 2021, the aspect ratio is variable, due to the 72 pixels menu bar up top, going in and out. I am not sure what will happen when you mirror the screens there. Hopefully the above software solves this problem.
karmakaze 5y ago
I love this, it's so crazy that the resolutions I can display on my screen can include/exclude resolutions that it will display only when an external display is connected. SwitchResX is cool but also a bit complex. 'Display Menu' is simpler but also somewhat limited.
mvanaltvorst 5y ago
Wonder if this can be used to bypass ImmersedVR's display limitations
- greggh 5y ago
  That is the reason I was reading through the comments. Guess it's time to just go try it out.
  - waydabber 5y ago
    Hey, I have a Quest 2, I'll try this one out myself as well. :) Thanks for the idea!
  - waydabber 5y ago
    Immersed apparently uses the same technique as BetterDummy to create virtual displays. I don't know if without a subscription BetterDummy created additional virtual displays show up in Immersed (as I have Elite), but for sure, BetterDummy created displays show up in Immersed.
    - greggh 5y ago
      Thats awesome. Thanks for trying it out.
donkeyd 5y ago
I have absolutely no use for this. But I love that people make stuff like this. There's so much creativity and skill involved in this type of thing, that often seems to get completely overlooked. So, to people who build stuff like this and release it... Thank you for your service!
- Grustaf 5y ago
  What does it actually do? What is the point of a fake display that doesn't exist?
  - sundvor 5y ago
    I'm guessing to reap benefits of https://en.m.wikipedia.org/wiki/Supersampling https://en.m.wikipedia.org/wiki/Supersampling
    - rzzzt 5y ago
      On Windows, I use AMD's VSR (Virtual Super Resolution) to set 5k screen resolution on a physical 4k display, letting me set the UI scale factor to 200% and have reasonable font sizes with clean icons (125% and 150% looks fuzzy). Under Linux, it is an xrandr spell that achieves the same thing.
      - vladvasiliu 5y ago
        How does this work? Don't you have to scale the virtual 5k resolution down to 4k? Wouldn't that also generate fuzziness? If a stroke is 1px wide at 100%, 2px at 200% / 5k, how does that stay sharp when you scale it down to 80%? Or is the idea that whatever algorithm AMD uses is better than the one Windows uses?
        xuki 5y ago
        Say you have a 28" 4K display but you want to run 2560x1440 resolution to get you desired UI size. You can either run 2560x1440 scaled up to 4K, or 5120x2880 scaled down to 4K. The latter will look better.
dessant 5y ago
Cloud providers that offer Mac mini servers use a HDMI dummy plug to emulate the presence of a display, but macOS will usually not treat it as a HiDPI display. This project is great for creating 4k screenshots on such servers.
- touisteur 5y ago
  EDID dongles have made my remote life work (with HP RGS of all things...) far more nice than any alternative. Goes up to 4K (but low Hz... which is OK for the kind of dev work I do).
  - KayL 5y ago
    What app do you used for remote work? I've tried teamviewer / anydesk, but the text always blurry. (I have 4k screen and need to scale up the text size to 2560*1440. Then I found these app only take the 2560 screen to remote)
    - zamadatix 5y ago
      I settle on Parsec, if you can't tweak the quality to your liking in the gui you can pass custom encoder settings as well.
    - InvaderFizz 5y ago
      I find ConnectwiseScreenconnect works well, but there is a pretty noticeable delay. The best remote experience I have had with macOS is using the built in VNC, but not with a standard client. Using the Remotix client provides a great experience. It's $50. I have also heard that NoMachine for macOS works really well, but I have not tried it.
      - KayL 5y ago
        Just realize how simple is it with the built in VNC. But it just show a DOT for mouse cursor :s And I tried "chrome remote desktop", also good quailty text. But both causing cpu hogging.
yots 5y ago
Can anyone link to or explain the problem? I'm in the market for a new display and didn't quite get the README explanation.
- LeonM 5y ago
  I think it's explained quite well in the introduction text: > M1 macs tend to have issues with custom resolutions. Notoriously they don't allow sub-4K resolution displays to have HiDPI ("Retina") resolutions even though (for example) a 24" QHD 1440p display would greatly benefit from having an 1920x1080 HiDPI "Retina" mode. So, if you connect a non-4k display, the Mac will render in a way that won't look as sharp as the display could. If you are in the marked for a new display, just but a 4K model (unless you have good reasons not to) and you won't need this hack.
  - joosters 5y ago
    So, if you connect a non-4k display, the Mac will render in a way that won't look as sharp as the display could. That's not true. A display will happily utilise it's full hardware resolution. The problem, as I understand it, is you can't change the DPI of the monitor. You can configure a 2560x1440 display to use a lower resolution (e.g. 1920x1080 or 1600x900), but then the monitor itself will upscale this into a blurry full screen. Tricking MacOS to change the DPI would let you configure the display to use all 2560x1440 pixels, but drawing everything bigger, at full resolution.
    - LeonM 5y ago
      You are correct, but I was trying to explain it a bit in layman's terms, since the OP did not appear to understand the intro text in the README.md.
  - Grustaf 5y ago
    But this is a fake display, it doesn't actually show anything. I think the explanation only makes sense for people that already know what the issue is.
HMH 5y ago
Interesting, for those wondering how this could be useful apart from what's already mentioned in the Readme: Projects like my Weylus [1] or the similar Deskreen [2] would greatly benefit from this as both can mirror your screen to a tablet and like that one could use a dummy display and said tablet to create an additional screen. On a related note, does anyone know of similar software to create dummy displays on Linux? All I could find so far is some trickery which only works with Intel hardware on X11 [3]. [1]: https://github.com/H-M-H/Weylus https://github.com/H-M-H/Weylus [2]: https://github.com/pavlobu/deskreen https://github.com/pavlobu/deskreen [3]: https://github.com/H-M-H/Weylus#intel-gpu-on-xorg-with-intel-drivers https://github.com/H-M-H/Weylus#intel-gpu-on-xorg-with-intel...
- raihansaputra 5y ago
  Yes thought about this when reading the README. Sidecar has been better than 3rd party apps in this regard (maybe the same technique) but having no DPI control sucks. Thanks for the links, will try to see how it works.
  - waydabber 5y ago
    Hmm. Didn't think of that use, but tried it and works nicely. However BetterDummy does not have 4:3 (iPad) aspect ratio support as of 1.0.7, I'll add so SideCar would fill the iPad screen properly.
    - waydabber 5y ago
      I stand corrected, 4:3 (16:12) is already available in the app just wasn't thinking right lol. So Sidecar scaling is supported as of now.
      - raihansaputra 5y ago
        Thanks, trying it out now! One more thing; can is it possible to have this on Homebrew? Just to make sure it becomes a default app for me. EDIT: works well with Sidecar -> Mirroring the Dummy display! Lag/latency wise, feels at least the same with native Sidecar. And thanks for the humongous amount of res options, even though I don't need it right now. I have another usecase: I used to have an off-brand external display that doesn't register HiDPI res to Macs. Bought DisplayResX for that, but maybe this can help. Once again thank you!
yoyopa 5y ago
does this work on intel mac? i want to set my MBP screen to a resolution that fills my PC screen for VNC
- martinclayton 5y ago
  Works for me on an intel mac mini, needs MacOS 11 (Big Sur) or higher.
  - waydabber 5y ago
    Amazing, thanks for the report! Did not have a chance to test it on Intel but I did compile the app to be Intel and Big Sur+ compatible and the APIs used by the app should be available on these platforms as well.
    - martinclayton 5y ago
      Thank you! I now have it working just fine to access my two headless minis. Small vote of thanks via open collective sent too.
      - waydabber 5y ago
        Wow, thanks! :)
  - waydabber 5y ago
    I can confirm this, I had now the chance to test it as well. My findings: - Works just fine on an Intel Mac (tested one with Intel UHD 630). - Works well with Big Sur (tested on an Intel Mac). - Does seem to provide headless macs with a HiDPI virtual display with customizable resolution (tested via Screen Sharing, resolution switch on the fly worked, all resolutions are available without any real display connected - should work with VNC as well, but I did not test that).
KayL 5y ago
I wonder if any macOS app able to do scaling and adding black border around the screen like what "nvidia scale resolution" does in Windows. My monitor have light leakages issues. In Windows, I scale it down and use black tap covered all 4 edges. It looks like a normal screen. :) When I use it as macOS external, I have to guess the top menu position :p
ekianjo 5y ago
This kind of dongle is also useful for certain workstations that refuse to boot without a screen if you want to turn them into servers.
- waydabber 5y ago
  BetterDummy will not help with that, the app fully runs in user space as a normal app and can start after login.
bluesign 5y ago
"Does not utilize graphics hardware in vain so it is somewhat faster." Can anyone shed a light on this feature? Doesn't HiDPI require graphics hardware ?
- waydabber 5y ago
  There is some difference, but it is marginal indeed at least in terms of speed. Via the traitional route with a real dummy, the display hardware needs to produce two sets of displayport output streams (one of which is converted to HDMI via a DisplayPort-HDMI controller chip MCDP2900 to drive the Dummy) + sync up the two displays in terms of vertical sync (this does not always work well, this is why real HDMI dummy users experience mouse jittery sometimes) and also has to scale the full-res framebuffer to two independent display (but scaling is done super efficiently on M1). With BetterDummy all this is not needed obviously. For ppl who until now had to resort to mirroring the internal displays (as M1 MacBooks - before the new MBPs - support only the internal display + a single external display) the benefit is more obvious, they now can use clamshell mode and don't have to drive the full MacBook display hardware (with brightness turned down to zero) all the time.
  - bluesign 5y ago
    Thanks for the detailed answer. Btw any chance this can work on virtualized environment without real GPU. Last time I gave this a shot (virtual screen), couldn’t manage to get it work with hidpi.
    - waydabber 5y ago
      This is an interesting question, honestly I have no idea. It might be that these APIs are relying on the presence of a GPU for acceleration (as the private framework APIs used are made by apple for Sidecar and AirPlay primarily). If you test this, please let me know about the results at the project GitHub page (https://github.com/waydabber/BetterDummy https://github.com/waydabber/BetterDummy). Thank you!
terramex 5y ago
Is there a way to keep using internal screen? When I turn mirroring on, internal display starts mirroring virtual screen too. Readme says "Your internal screen will be available as an extended space on a MacBook" but I do not know how to do it.
- waydabber 5y ago
  Of course, you can configure everything as usual under System Preferences/Displays. If you have a 2+ display setup for example, you can create a Dummy, mirror it to one display but leave the other display unaffected. Or you can create 2 dummies, mirror each one to a separate display. Every display can serve as a Main or Extended display, as well as a Mirror for some other display. Therefore a mirrored set can be Main or Extended as well. A typical use case is to use your MacBook display as an Extended display alongside your external display which is a Mirror of a Dummy that is set as Main display (providing all the fine grained HiDPI resolution options). Hope this helps!
  - terramex 5y ago
    Is this a macOS 12 feature? I am stuck on 11 for now and I do not see any Main/Extended setting.
    - waydabber 5y ago
      The app is compiled for Big Sur but I did not test it and received conflicting reports whether it works or not. Please try it and let me know! Thanks!
      - terramex 5y ago
        I tried again got it working this time. I turns out that in versions below 12 the way to set up mirroring of only 2 out of 3 displays is: "Press and hold the Option key and drag one display icon onto another display icon to mirror those two displays.". 10 years of using Mac every day and never knew it was possible. It is pretty buggy though, "Arrangement" tabs stops working and I cannot change relative screen positions anymore, so to get it kinda working I had to set my real and dummy displays to the same lower resolution before dragging one onto the other and then I could set my desired resolution on dummy screen and it got mirrored onto physical screen.
lxgr 5y ago
Dummy plugs are an ingenious solution, but the fact that we still depend on them is baffling. Does Apple seriously not recognize the need for these uses cases?
- waydabber 5y ago
  You can simply create two dummies and mirror each one to separate displays. Or you can use the 4K display as is (since it will natively have 1920x1080 HiDPI on M1) and create a dummy to use with the QHD display to get 1920x1080 HiDPI.
  - lxgr 5y ago
    I guess, but my point is: There is no reason macOS shouldn't allow doing all of this on the software level. Especially with the wholly Apple-made M series of chips, they control the entire video stack down to the transistor level. Dummy plugs should be syscalls, not physical things.
    - waydabber 5y ago
      Yep, sorry, I guess I was clicking the wrong link while trying to respond to something else. I agree with you, it is funny that we need dummies and workarounds (being hardware or software).
deleted 5y ago
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alin23 5y ago
Thanks for doing and sharing this! It has been really helpful to finally have virtual displays that respond to CGDisplay methods when developing Lunar (https://lunar.fyi https://lunar.fyi) It also helped in unearthing some bugs apparently. [0] [0] https://github.com/MonitorControl/MonitorControl/issues/752#issuecomment-956087718 https://github.com/MonitorControl/MonitorControl/issues/752#...
- waydabber 5y ago
  Yeah thanks @alin23 for creating extra work for me lol :), I'll be working on fixing that in MonitorControl (https://monitorcontrol.app https://monitorcontrol.app).
schrijver 5y ago
Related to this, looking for a way to have the HDMI output of a 2015 MBP be horizontally flipped (for teleprompting). SwitchResX is supposed to be able to do this but it hangs when I try to flipped resolutions. Might be an interesting feature for this software… Anyone have an idea how to achieve this on an Intel Mac?
- Terretta 5y ago
  A number of ways: https://telepromptermirror.com/mirror-flip-screen/ https://telepromptermirror.com/mirror-flip-screen/ Personally I gave up on the window flippers and use LunaDisplay w/ iPad. Why? The window flippers flip the window — but not the mouse or button click targets! So you need the whole screen to flip, not just the window.
  - schrijver 5y ago
    Tried out the WindowMirror utility and the click targets are indeed pretty confusing… but it might still come in handy when presenting. With the looks of it, I could use it to flip a windowed OBS projector view, and drag that to the external monitor that is my teleprompter. Wouldn’t need to click much in that scenario. Thanks!
xylophoner 5y ago
i’ve used SwitchResX for years to create/use custom resolutions. though i don’t have an M1 mac (on order now). maybe that’s another way of achieving this?
- waydabber 5y ago
  SwitchResX I think is different. It is superior in a way that it creates additional display modes which macOS then can use as a native resolutions on Intel. On M1 the problem is that it can only create scaled resolutions and even at that cannot create HiDPI resolutions if the display reports itself as sub-4K. This is due to an inherent limitation in the M1 driver implemented by Apple, not the fault of the SwitchResX developer. I was a SwitchResX user for many years on Intel macs and was dumbstruck when after replacing my Intel macs with M1 I found out that I cannot use my displays as I used to. BetterDummy simply navigates around the whole problem by creating Virtual Displays that are mirrored to the main display. This is in one regard inferior, since this is inherently a workaround but on the other hand can work on-the-fly and all possible resolutions are instantly available and accessible via System Preferences/Displays.
  - xylophoner 5y ago
    thx!
- neither_color 5y ago
  This is how I got hiDPI to work with a 1440P monitor https://github.com/bbhardin/A-Guide-to-MacOS-Scaled-Resolutions https://github.com/bbhardin/A-Guide-to-MacOS-Scaled-Resoluti...
httpsterio 5y ago
Does anyone know if it's possible to run a Mac app in a "greater" resolution than what the display supports? We have quite a few 2017 macbook airs running at 1440x900 and it doesn't have enough width to display an enterprise app we need to use. Basically would need some sort of VM or sandbox that could run the apps in 1920 width and scale down to fit 1440px.
- matthew-wegner 5y ago
  This can do exactly that. You would create a dummy display at 1920x1080 (or higher), then have your real display become a mirror of the dummy display. macOS will scale down to display on 1440x900.
growt 5y ago
Does this allow to create virtual resolutions wider than 6016 px? I have a Samsung 32:9 monitor and this seems to be a hard limit on a Mac so far. Would be great if I could go higher with this.
michael1999 5y ago
Nice to see this wrapped up as an app. If all you need is a cli, then https://github.com/jakehilborn/displayplacer https://github.com/jakehilborn/displayplacer works great too.
- waydabber 5y ago
  I don't think displayplacer is intended to create a virtual display, it seems to be a CLI to manipulate display modes and mirroring for existing display so these seem to be two different things entirely. I might be wrong of course.
  - michael1999 5y ago
    I agree. But the problem the OP had was forcing a video mode. The virtual display was a means to that end. I think displayplacer solves that problem more directly.
leokennis 5y ago
You maybe wouldn’t expect it, but in this regard Windows is far superior to macOS. It will output whatever resolution your monitor has, and then you can just set a “scaling factor” which will make the interface exactly the size you like while still being pixel perfect. Given how simple most UI is, especially these days (circles filled with gradients, roundrects) and given how many different screen sizes and resolutions are used even within Apple’s first party displays, it’s almost insane macOS isn’t resolution independent.
- fortran77 5y ago
  That was my first thought. All this crap Mac users have to go through if they want to go off the "happy path" even slightly with an aftermarket monitor. I worked for Apple more than two decades ago, but now I'm a happy Windows 11 user.
  - rootusrootus 5y ago
    I have an aftermarket monitor, runs at 4K, has a scaling factor applied so that I can make everything bigger. I don't feel like I had to go through any crap, either, it's the simplest of UIs.
    - hollerith 5y ago
      I agree that it is simple (i.e., the Displays pane of System Preferences) but the result IMHO is unpleasantly blurry. These days, fonts, SVG images, CSS, etc, are stored as mathematical descriptions of curves that can be rendered at any scaling factor. Any use of a scaling algorithm, like MacOS does when the scaling factor is not an integer multiple of the display's true resolution, is an unnecessary source of blurriness. A HiDPI display make the blurriness less noticeable, but do not solve the basic problem, which is that the scaling algorithm reduces the "effective resolution" of the display. (I have never used a HiDPI display with a desktop OS, but another participant here on HN has and reported that he notices MacOS's blurriness relative to Windows even on a HiDPI display.)
- jpablo 5y ago
chmod775 5y ago
A hardware fix to a software annoyance. Nice.
- waydabber 5y ago
  It is actually a software alternative for a hardware fix to a software annoyance lol. :)
nottorp 5y ago
Ok silly question because I've never ran into this use case but it got me worried about using real monitors. I'm using 1920x1200 monitors. If I upgrade to a M1 Pro/Max Mac Mini (if those will ever be available) will I have any trouble using them at their native resolution? From what I understand, this trick is helpful for headless machines.
- waydabber 5y ago
  No, you won't have trouble using your Mac at native resolutions with an 1920x1200 display, you don't need BetterDummy for that! :)
- danw1979 5y ago
  The display output of the M1, according to the very clever devs working on Asahi Linux, is a bit funky under the hood. I've found display compatibility has not been straightforward, having owned an M1 mini for the last year...which is unfortunate for a computer without a built-in screen. Don't count on it supporting multiple external monitors. Expect compatibility issues, etc. Last week it kind of burned a flickering rectangle onto my Dell ultrasharp 4k, which I thought was toast, but it gradually cleared up. Like I said - weird.
  - nottorp 5y ago
    > Don't count on it supporting multiple external monitors. Expect compatibility issues, etc. Well, no way I'm buying a M1 due to the lack of RAM. Hopefully Apple will make a decent desktop for me next year and fix some silicon bugs while they're at it. Incidentally, my current x86 mac mini is wonky with the hdmi output as well. The monitor randomly goes black for a few seconds once in a while.
    - flatiron 5y ago
      ram is on the chip with the cpu now. so i don't see that changing in the near future with the laptop/mac mini versions of the M1 at least
sbr464 5y ago
Can anyone confirm if the new M1 Max (or Monterey) can output HiDPI at higher resolutions than the 1st gen M1 13" MacBook pro? Using a 6k Pro Display XDR on the M1 with 3k scaling is brutal. The interface is way too big. An iMac pro with an eGPU was able to accomplish this perfectly. --edit The Display Dummy app resolves this problem perfectly. In the Display Dummy menu, select 16:9 ratio, then go to displays in system preferences and choose 3840x2160. Curious if it will be able to work with dual Pro Display XDRs on M1.
- zamadatix 5y ago
  I'm away from my 13" M1 MacBook right now but there was a 3rd party app I used that lets me choose any resolution and scaling on the built in or external displays. I like having a lot of workspace and thankfully have good eyes so my usual setup is 2560x1600 no scaling for the built in and 3840x2160 no scaling for the external portable USB C monitor I carry around with it. There may well be a way to do it from the CLI as well but the app just sits as a tray icon in the menu bar which is great from a "I don't know what I just plugged in but I want to to just be <x>" perspective.
  - sbr464 5y ago
    Ideally 3840x2160 in HiDPI on the Pro Display XDR. I get this with an eGPU puck on an iMac pro with SwitchResX. Unfortunately the original M1 limited SwitchResX from using HiDPI at higher resolutions. It is limited to 3008x1692 at HiDPI (half of 6k). The higher resolutions are available but they aren't HiDPI and text looks noticeably worse. It's a known issue with several display tools like: https://github.com/xzhih/one-key-hidpi/issues/164 https://github.com/xzhih/one-key-hidpi/issues/164
  - dkonofalski 5y ago
    Can't you just go to System Preferences and click Alt + Scaled? That usually gives you all the resolutions that your monitor supports without having to use the "Larger/Smaller" visual options.
    - 5y ago
AndrewUnmuted 5y ago
I remember when Windows had to be subjected to lots of different downloaded freeware applications to "unlock" full customization of the OS. macOS is in these days at the moment. What does that say about its product arc?
ChrisMarshallNY 5y ago
The 11.6 (I believe) release of MacOS X finally allowed native support for 5120 X 1440 (my display). The thing that annoys me, is that I have a second display that I use, from time to time (when giving video classes, for instance), but it remains assigned to a different device, most times. However, I can't leave it plugged in. If I do, the OS insists that I have a second screen, even though it is not actually connected to the Mac. This means that I can lose my cursor and the graphics processors are rendering undisplayed pixels. I can use an app like SwitchResX[0], but I feel that I should not need it. The OS should detect more than just if an HDMI cable is plugged in. It needs to know whether or not the screen is actually "live," and rendering graphics. [0] https://www.madrau.com https://www.madrau.com
- kristjansson 5y ago
  Maybe you want a physical KVM in between the two sources and the monitor? I tried to get a similar setup working locally (2 monitors, a macOS source and a Debian source, supporting all four input/output combinations) and couldn't find a satisfying software solution. There were a few people using ddcutil/ddccontrol/ddctool on Linux hosts to script changes on source changes, but (a) it was difficult/impossible to get DDC to work consistently with DP and HDMI outputs with first party Nvidia drivers (b) I couldn't find anything comparable on the macOS side. Hardware KVMs weren't much better, but if you're willing to spend the money, and have enough DP sources on both sides, they aren't too bad. Funny how hard/expensive it is to replicate the convenience of a nice analogue KVM with a bunch of VGA/DVI/PS2 I/O, a knob, an not much else...
  - ChrisMarshallNY 5y ago
    Actually, belay that. I just tested with Monterey, and a new MBP, and it works the way that I expect. I need to use the built-in HDMI, but it works.
    - nitrogen 5y ago
      Does anybody know of software-defined ways to switch this behavior? I have the opposite problem sometimes -- I have an external display shared between two devices (of varying OSes), and sometimes I want it to remain a logical display on each device no matter which input is selected on the display. But other times I want the display to be removed when the device is not the active input.
deleted 5y ago
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aa_memon 5y ago
This is exactly what I’ve been looking for. Wanted to use my 2012 imac as a second monitor for my MacBook and in the absence of target display mode decided to use NoMachine but couldn’t get resolution + separate display without a physical dummy hdmi plug. Thank you
itwillnotbeasy 5y ago
This is my main problem with MacOs - text on non 4k displays is so blurry, Windows and Linux are doing much better job with rendering fonts. And Apple doesn't seem to care about it at all - they even removed subpixel aliasing in the recent system update (i guess it was High Sierra). So weird, given most of the high refresh rate monitors on the market is 1440p, so if you have a gaming pc you need to buy separate 4k monitor for your macbook, because no one seems to care about fixing this, WTF?
sbr464 5y ago
Great app. I can confirm it works well with the new M1 Max and Monterey. Currently using with dual Pro Display XDRs in clamshell mode (14" MacBook Pro). It allowed using HiDPI at a higher resolution (4k or 3840x2160) than the M1 chipset natively allows (3k or 3008x1692 HiDPI on the 6k XDRs).

333 points by PikachuEXE 5y ago

For those asking why this is useful: Mac mini's without a monitor hooked up can only display at a certain aspect ratio while remote screen sharing. The typical solution is to use a dummy hdmi plug (~$10) plus an app like SwitchResX (~$20) to support custom screen resolutions. If OP's app works as described, then this is a free software solution to a $30 problem.

gprasanth 5y ago
Was looking for this exact thing a month ago [1]. Now, this. I've given up the idea of connecting to mini over screensharing and connected a couple of displays to it, happily. [1] - https://apple.stackexchange.com/q/428243/51800 https://apple.stackexchange.com/q/428243/51800
daveidol 5y ago
This doesn't sound like the core use case though based on the README - it sounds like it's used for enabling HiDPI (aka not-blurry) scaling on less-than-4K monitors. So, using native resolution but not necessarily 1:1 DPI.
spockz 5y ago
It is not just a monetary problem though. Sometimes you don’t have the required physical access or permissions to install additional hardware.
roderickm 5y ago
Your presentation has presenter notes but your MacBook has only one display? Create a dummy display for the full-screen presentation, share that into the remote meeting/projector, and preserve the primary display for presenter notes, logtails, chat, etc.
- djrogers 5y ago
  Sounds like it'd be easier to just run your slideshow in a window and share that window. PowerPoint and Keynote can both do that. Bonus to sharing only a window - you never accidentally show something you didn't want to, like that email or messages notification...
  - bombcar 5y ago
    For those who don't know, in PowerPoint go to Setup Slide Show on the Slide Show tab and select "Browsed by an individual (window)" and then share that window. Great for Zoom et al.
    - Isthatablackgsd 5y ago
      I use OBS to handle the screen sharing because it is easily to misclick the wrong window that are not for public view. In OBS, it is binded to specific window titles and it is easily to edit out the black bar on the top of the PowerPoint that appeared in Zoom directly (without OBS). I have a few scenes set up this away and quicker to switch than doing it through Zoom itself.
waydabber 5y ago
Hi, I tested the Screen Sharing scenario with BetterDummy running on an Intel headless Mac Mini 2018 running Big Sur. Works splendidly, all resolutions are available and resolution change works on-the fly through Screen Sharing!
g42gregory 5y ago
Here is another reason this is useful: If you connect a Mac (mini, MacBook pro, air) to an external monitor, AND this monitor is not recognized as "retina" (eg. Apple $4599 XDR) AND you are not running at the monitor's highest resolution, the screen will be blurry. There are a lot of "ands" in the above sentence, but it's actually quite common situation. Retina monitors are expensive. For non-retina monitors, native highest resolution still renders objects too small for many people. On MacBook Pro/Air the solution is to mirror the screens. The MacOS thinks that it renders to the retina screen and sends appropriate re-scaling to the external monitor. But mirroring has its problems. For example, expect ratio will be the same as MacBook's internal screen. This may result in black bars on the monitor, depending on its aspect ratio. Also, in M1 MacBook Pro 2021, the aspect ratio is variable, due to the 72 pixels menu bar up top, going in and out. I am not sure what will happen when you mirror the screens there. Hopefully the above software solves this problem.

karmakaze 5y ago

I love this, it's so crazy that the resolutions I can display on my screen can include/exclude resolutions that it will display only when an external display is connected. SwitchResX is cool but also a bit complex. 'Display Menu' is simpler but also somewhat limited.

mvanaltvorst 5y ago

Wonder if this can be used to bypass ImmersedVR's display limitations

greggh 5y ago
That is the reason I was reading through the comments. Guess it's time to just go try it out.
- waydabber 5y ago
  Hey, I have a Quest 2, I'll try this one out myself as well. :) Thanks for the idea!
- waydabber 5y ago
  Immersed apparently uses the same technique as BetterDummy to create virtual displays. I don't know if without a subscription BetterDummy created additional virtual displays show up in Immersed (as I have Elite), but for sure, BetterDummy created displays show up in Immersed.
  - greggh 5y ago
    Thats awesome. Thanks for trying it out.

donkeyd 5y ago

I have absolutely no use for this. But I love that people make stuff like this. There's so much creativity and skill involved in this type of thing, that often seems to get completely overlooked. So, to people who build stuff like this and release it... Thank you for your service!

Grustaf 5y ago
What does it actually do? What is the point of a fake display that doesn't exist?
- sundvor 5y ago
  I'm guessing to reap benefits of https://en.m.wikipedia.org/wiki/Supersampling https://en.m.wikipedia.org/wiki/Supersampling
  - rzzzt 5y ago
    On Windows, I use AMD's VSR (Virtual Super Resolution) to set 5k screen resolution on a physical 4k display, letting me set the UI scale factor to 200% and have reasonable font sizes with clean icons (125% and 150% looks fuzzy). Under Linux, it is an xrandr spell that achieves the same thing.
    - vladvasiliu 5y ago
      How does this work? Don't you have to scale the virtual 5k resolution down to 4k? Wouldn't that also generate fuzziness? If a stroke is 1px wide at 100%, 2px at 200% / 5k, how does that stay sharp when you scale it down to 80%? Or is the idea that whatever algorithm AMD uses is better than the one Windows uses?
      - xuki 5y ago
        Say you have a 28" 4K display but you want to run 2560x1440 resolution to get you desired UI size. You can either run 2560x1440 scaled up to 4K, or 5120x2880 scaled down to 4K. The latter will look better.

dessant 5y ago

Cloud providers that offer Mac mini servers use a HDMI dummy plug to emulate the presence of a display, but macOS will usually not treat it as a HiDPI display. This project is great for creating 4k screenshots on such servers.

touisteur 5y ago
EDID dongles have made my remote life work (with HP RGS of all things...) far more nice than any alternative. Goes up to 4K (but low Hz... which is OK for the kind of dev work I do).
- KayL 5y ago
  What app do you used for remote work? I've tried teamviewer / anydesk, but the text always blurry. (I have 4k screen and need to scale up the text size to 2560*1440. Then I found these app only take the 2560 screen to remote)
  - zamadatix 5y ago
    I settle on Parsec, if you can't tweak the quality to your liking in the gui you can pass custom encoder settings as well.
  - InvaderFizz 5y ago
    I find ConnectwiseScreenconnect works well, but there is a pretty noticeable delay. The best remote experience I have had with macOS is using the built in VNC, but not with a standard client. Using the Remotix client provides a great experience. It's $50. I have also heard that NoMachine for macOS works really well, but I have not tried it.
    - KayL 5y ago
      Just realize how simple is it with the built in VNC. But it just show a DOT for mouse cursor :s And I tried "chrome remote desktop", also good quailty text. But both causing cpu hogging.

yots 5y ago

Can anyone link to or explain the problem? I'm in the market for a new display and didn't quite get the README explanation.

LeonM 5y ago
I think it's explained quite well in the introduction text: > M1 macs tend to have issues with custom resolutions. Notoriously they don't allow sub-4K resolution displays to have HiDPI ("Retina") resolutions even though (for example) a 24" QHD 1440p display would greatly benefit from having an 1920x1080 HiDPI "Retina" mode. So, if you connect a non-4k display, the Mac will render in a way that won't look as sharp as the display could. If you are in the marked for a new display, just but a 4K model (unless you have good reasons not to) and you won't need this hack.
- joosters 5y ago
  So, if you connect a non-4k display, the Mac will render in a way that won't look as sharp as the display could. That's not true. A display will happily utilise it's full hardware resolution. The problem, as I understand it, is you can't change the DPI of the monitor. You can configure a 2560x1440 display to use a lower resolution (e.g. 1920x1080 or 1600x900), but then the monitor itself will upscale this into a blurry full screen. Tricking MacOS to change the DPI would let you configure the display to use all 2560x1440 pixels, but drawing everything bigger, at full resolution.
  - LeonM 5y ago
    You are correct, but I was trying to explain it a bit in layman's terms, since the OP did not appear to understand the intro text in the README.md.
- Grustaf 5y ago
  But this is a fake display, it doesn't actually show anything. I think the explanation only makes sense for people that already know what the issue is.

HMH 5y ago

Interesting, for those wondering how this could be useful apart from what's already mentioned in the Readme: Projects like my Weylus [1] or the similar Deskreen [2] would greatly benefit from this as both can mirror your screen to a tablet and like that one could use a dummy display and said tablet to create an additional screen. On a related note, does anyone know of similar software to create dummy displays on Linux? All I could find so far is some trickery which only works with Intel hardware on X11 [3]. [1]: https://github.com/H-M-H/Weylus https://github.com/H-M-H/Weylus [2]: https://github.com/pavlobu/deskreen https://github.com/pavlobu/deskreen [3]: https://github.com/H-M-H/Weylus#intel-gpu-on-xorg-with-intel-drivers https://github.com/H-M-H/Weylus#intel-gpu-on-xorg-with-intel...

raihansaputra 5y ago
Yes thought about this when reading the README. Sidecar has been better than 3rd party apps in this regard (maybe the same technique) but having no DPI control sucks. Thanks for the links, will try to see how it works.
- waydabber 5y ago
  Hmm. Didn't think of that use, but tried it and works nicely. However BetterDummy does not have 4:3 (iPad) aspect ratio support as of 1.0.7, I'll add so SideCar would fill the iPad screen properly.
  - waydabber 5y ago
    I stand corrected, 4:3 (16:12) is already available in the app just wasn't thinking right lol. So Sidecar scaling is supported as of now.
    - raihansaputra 5y ago
      Thanks, trying it out now! One more thing; can is it possible to have this on Homebrew? Just to make sure it becomes a default app for me. EDIT: works well with Sidecar -> Mirroring the Dummy display! Lag/latency wise, feels at least the same with native Sidecar. And thanks for the humongous amount of res options, even though I don't need it right now. I have another usecase: I used to have an off-brand external display that doesn't register HiDPI res to Macs. Bought DisplayResX for that, but maybe this can help. Once again thank you!

yoyopa 5y ago

does this work on intel mac? i want to set my MBP screen to a resolution that fills my PC screen for VNC

martinclayton 5y ago
Works for me on an intel mac mini, needs MacOS 11 (Big Sur) or higher.
- waydabber 5y ago
  Amazing, thanks for the report! Did not have a chance to test it on Intel but I did compile the app to be Intel and Big Sur+ compatible and the APIs used by the app should be available on these platforms as well.
  - martinclayton 5y ago
    Thank you! I now have it working just fine to access my two headless minis. Small vote of thanks via open collective sent too.
    - waydabber 5y ago
      Wow, thanks! :)
- waydabber 5y ago
  I can confirm this, I had now the chance to test it as well. My findings: - Works just fine on an Intel Mac (tested one with Intel UHD 630). - Works well with Big Sur (tested on an Intel Mac). - Does seem to provide headless macs with a HiDPI virtual display with customizable resolution (tested via Screen Sharing, resolution switch on the fly worked, all resolutions are available without any real display connected - should work with VNC as well, but I did not test that).

KayL 5y ago

I wonder if any macOS app able to do scaling and adding black border around the screen like what "nvidia scale resolution" does in Windows. My monitor have light leakages issues. In Windows, I scale it down and use black tap covered all 4 edges. It looks like a normal screen. :) When I use it as macOS external, I have to guess the top menu position :p

ekianjo 5y ago

This kind of dongle is also useful for certain workstations that refuse to boot without a screen if you want to turn them into servers.

waydabber 5y ago
BetterDummy will not help with that, the app fully runs in user space as a normal app and can start after login.

bluesign 5y ago

"Does not utilize graphics hardware in vain so it is somewhat faster." Can anyone shed a light on this feature? Doesn't HiDPI require graphics hardware ?

waydabber 5y ago
There is some difference, but it is marginal indeed at least in terms of speed. Via the traitional route with a real dummy, the display hardware needs to produce two sets of displayport output streams (one of which is converted to HDMI via a DisplayPort-HDMI controller chip MCDP2900 to drive the Dummy) + sync up the two displays in terms of vertical sync (this does not always work well, this is why real HDMI dummy users experience mouse jittery sometimes) and also has to scale the full-res framebuffer to two independent display (but scaling is done super efficiently on M1). With BetterDummy all this is not needed obviously. For ppl who until now had to resort to mirroring the internal displays (as M1 MacBooks - before the new MBPs - support only the internal display + a single external display) the benefit is more obvious, they now can use clamshell mode and don't have to drive the full MacBook display hardware (with brightness turned down to zero) all the time.
- bluesign 5y ago
  Thanks for the detailed answer. Btw any chance this can work on virtualized environment without real GPU. Last time I gave this a shot (virtual screen), couldn’t manage to get it work with hidpi.
  - waydabber 5y ago
    This is an interesting question, honestly I have no idea. It might be that these APIs are relying on the presence of a GPU for acceleration (as the private framework APIs used are made by apple for Sidecar and AirPlay primarily). If you test this, please let me know about the results at the project GitHub page (https://github.com/waydabber/BetterDummy https://github.com/waydabber/BetterDummy). Thank you!

terramex 5y ago

Is there a way to keep using internal screen? When I turn mirroring on, internal display starts mirroring virtual screen too. Readme says "Your internal screen will be available as an extended space on a MacBook" but I do not know how to do it.

waydabber 5y ago
Of course, you can configure everything as usual under System Preferences/Displays. If you have a 2+ display setup for example, you can create a Dummy, mirror it to one display but leave the other display unaffected. Or you can create 2 dummies, mirror each one to a separate display. Every display can serve as a Main or Extended display, as well as a Mirror for some other display. Therefore a mirrored set can be Main or Extended as well. A typical use case is to use your MacBook display as an Extended display alongside your external display which is a Mirror of a Dummy that is set as Main display (providing all the fine grained HiDPI resolution options). Hope this helps!
- terramex 5y ago
  Is this a macOS 12 feature? I am stuck on 11 for now and I do not see any Main/Extended setting.
  - waydabber 5y ago
    The app is compiled for Big Sur but I did not test it and received conflicting reports whether it works or not. Please try it and let me know! Thanks!
    - terramex 5y ago
      I tried again got it working this time. I turns out that in versions below 12 the way to set up mirroring of only 2 out of 3 displays is: "Press and hold the Option key and drag one display icon onto another display icon to mirror those two displays.". 10 years of using Mac every day and never knew it was possible. It is pretty buggy though, "Arrangement" tabs stops working and I cannot change relative screen positions anymore, so to get it kinda working I had to set my real and dummy displays to the same lower resolution before dragging one onto the other and then I could set my desired resolution on dummy screen and it got mirrored onto physical screen.

lxgr 5y ago

Dummy plugs are an ingenious solution, but the fact that we still depend on them is baffling. Does Apple seriously not recognize the need for these uses cases?

waydabber 5y ago
You can simply create two dummies and mirror each one to separate displays. Or you can use the 4K display as is (since it will natively have 1920x1080 HiDPI on M1) and create a dummy to use with the QHD display to get 1920x1080 HiDPI.
- lxgr 5y ago
  I guess, but my point is: There is no reason macOS shouldn't allow doing all of this on the software level. Especially with the wholly Apple-made M series of chips, they control the entire video stack down to the transistor level. Dummy plugs should be syscalls, not physical things.
  - waydabber 5y ago
    Yep, sorry, I guess I was clicking the wrong link while trying to respond to something else. I agree with you, it is funny that we need dummies and workarounds (being hardware or software).

deleted 5y ago

[deleted]

alin23 5y ago

Thanks for doing and sharing this! It has been really helpful to finally have virtual displays that respond to CGDisplay methods when developing Lunar (https://lunar.fyi https://lunar.fyi) It also helped in unearthing some bugs apparently. [0] [0] https://github.com/MonitorControl/MonitorControl/issues/752#issuecomment-956087718 https://github.com/MonitorControl/MonitorControl/issues/752#...

waydabber 5y ago
Yeah thanks @alin23 for creating extra work for me lol :), I'll be working on fixing that in MonitorControl (https://monitorcontrol.app https://monitorcontrol.app).

schrijver 5y ago

Related to this, looking for a way to have the HDMI output of a 2015 MBP be horizontally flipped (for teleprompting). SwitchResX is supposed to be able to do this but it hangs when I try to flipped resolutions. Might be an interesting feature for this software… Anyone have an idea how to achieve this on an Intel Mac?

Terretta 5y ago
A number of ways: https://telepromptermirror.com/mirror-flip-screen/ https://telepromptermirror.com/mirror-flip-screen/ Personally I gave up on the window flippers and use LunaDisplay w/ iPad. Why? The window flippers flip the window — but not the mouse or button click targets! So you need the whole screen to flip, not just the window.
- schrijver 5y ago
  Tried out the WindowMirror utility and the click targets are indeed pretty confusing… but it might still come in handy when presenting. With the looks of it, I could use it to flip a windowed OBS projector view, and drag that to the external monitor that is my teleprompter. Wouldn’t need to click much in that scenario. Thanks!

xylophoner 5y ago

i’ve used SwitchResX for years to create/use custom resolutions. though i don’t have an M1 mac (on order now). maybe that’s another way of achieving this?

waydabber 5y ago
SwitchResX I think is different. It is superior in a way that it creates additional display modes which macOS then can use as a native resolutions on Intel. On M1 the problem is that it can only create scaled resolutions and even at that cannot create HiDPI resolutions if the display reports itself as sub-4K. This is due to an inherent limitation in the M1 driver implemented by Apple, not the fault of the SwitchResX developer. I was a SwitchResX user for many years on Intel macs and was dumbstruck when after replacing my Intel macs with M1 I found out that I cannot use my displays as I used to. BetterDummy simply navigates around the whole problem by creating Virtual Displays that are mirrored to the main display. This is in one regard inferior, since this is inherently a workaround but on the other hand can work on-the-fly and all possible resolutions are instantly available and accessible via System Preferences/Displays.
- xylophoner 5y ago
  thx!
neither_color 5y ago
This is how I got hiDPI to work with a 1440P monitor https://github.com/bbhardin/A-Guide-to-MacOS-Scaled-Resolutions https://github.com/bbhardin/A-Guide-to-MacOS-Scaled-Resoluti...

httpsterio 5y ago

Does anyone know if it's possible to run a Mac app in a "greater" resolution than what the display supports? We have quite a few 2017 macbook airs running at 1440x900 and it doesn't have enough width to display an enterprise app we need to use. Basically would need some sort of VM or sandbox that could run the apps in 1920 width and scale down to fit 1440px.

matthew-wegner 5y ago
This can do exactly that. You would create a dummy display at 1920x1080 (or higher), then have your real display become a mirror of the dummy display. macOS will scale down to display on 1440x900.

growt 5y ago

Does this allow to create virtual resolutions wider than 6016 px? I have a Samsung 32:9 monitor and this seems to be a hard limit on a Mac so far. Would be great if I could go higher with this.

michael1999 5y ago

Nice to see this wrapped up as an app. If all you need is a cli, then https://github.com/jakehilborn/displayplacer https://github.com/jakehilborn/displayplacer works great too.

waydabber 5y ago
I don't think displayplacer is intended to create a virtual display, it seems to be a CLI to manipulate display modes and mirroring for existing display so these seem to be two different things entirely. I might be wrong of course.
- michael1999 5y ago
  I agree. But the problem the OP had was forcing a video mode. The virtual display was a means to that end. I think displayplacer solves that problem more directly.

leokennis 5y ago

You maybe wouldn’t expect it, but in this regard Windows is far superior to macOS. It will output whatever resolution your monitor has, and then you can just set a “scaling factor” which will make the interface exactly the size you like while still being pixel perfect. Given how simple most UI is, especially these days (circles filled with gradients, roundrects) and given how many different screen sizes and resolutions are used even within Apple’s first party displays, it’s almost insane macOS isn’t resolution independent.

fortran77 5y ago
That was my first thought. All this crap Mac users have to go through if they want to go off the "happy path" even slightly with an aftermarket monitor. I worked for Apple more than two decades ago, but now I'm a happy Windows 11 user.
- rootusrootus 5y ago
  I have an aftermarket monitor, runs at 4K, has a scaling factor applied so that I can make everything bigger. I don't feel like I had to go through any crap, either, it's the simplest of UIs.
  - hollerith 5y ago
    I agree that it is simple (i.e., the Displays pane of System Preferences) but the result IMHO is unpleasantly blurry. These days, fonts, SVG images, CSS, etc, are stored as mathematical descriptions of curves that can be rendered at any scaling factor. Any use of a scaling algorithm, like MacOS does when the scaling factor is not an integer multiple of the display's true resolution, is an unnecessary source of blurriness. A HiDPI display make the blurriness less noticeable, but do not solve the basic problem, which is that the scaling algorithm reduces the "effective resolution" of the display. (I have never used a HiDPI display with a desktop OS, but another participant here on HN has and reported that he notices MacOS's blurriness relative to Windows even on a HiDPI display.)
jpablo 5y ago

chmod775 5y ago

A hardware fix to a software annoyance. Nice.

waydabber 5y ago
It is actually a software alternative for a hardware fix to a software annoyance lol. :)

nottorp 5y ago

Ok silly question because I've never ran into this use case but it got me worried about using real monitors. I'm using 1920x1200 monitors. If I upgrade to a M1 Pro/Max Mac Mini (if those will ever be available) will I have any trouble using them at their native resolution? From what I understand, this trick is helpful for headless machines.

waydabber 5y ago
No, you won't have trouble using your Mac at native resolutions with an 1920x1200 display, you don't need BetterDummy for that! :)
danw1979 5y ago
The display output of the M1, according to the very clever devs working on Asahi Linux, is a bit funky under the hood. I've found display compatibility has not been straightforward, having owned an M1 mini for the last year...which is unfortunate for a computer without a built-in screen. Don't count on it supporting multiple external monitors. Expect compatibility issues, etc. Last week it kind of burned a flickering rectangle onto my Dell ultrasharp 4k, which I thought was toast, but it gradually cleared up. Like I said - weird.
- nottorp 5y ago
  > Don't count on it supporting multiple external monitors. Expect compatibility issues, etc. Well, no way I'm buying a M1 due to the lack of RAM. Hopefully Apple will make a decent desktop for me next year and fix some silicon bugs while they're at it. Incidentally, my current x86 mac mini is wonky with the hdmi output as well. The monitor randomly goes black for a few seconds once in a while.
  - flatiron 5y ago
    ram is on the chip with the cpu now. so i don't see that changing in the near future with the laptop/mac mini versions of the M1 at least

sbr464 5y ago

Can anyone confirm if the new M1 Max (or Monterey) can output HiDPI at higher resolutions than the 1st gen M1 13" MacBook pro? Using a 6k Pro Display XDR on the M1 with 3k scaling is brutal. The interface is way too big. An iMac pro with an eGPU was able to accomplish this perfectly. --edit The Display Dummy app resolves this problem perfectly. In the Display Dummy menu, select 16:9 ratio, then go to displays in system preferences and choose 3840x2160. Curious if it will be able to work with dual Pro Display XDRs on M1.

zamadatix 5y ago
I'm away from my 13" M1 MacBook right now but there was a 3rd party app I used that lets me choose any resolution and scaling on the built in or external displays. I like having a lot of workspace and thankfully have good eyes so my usual setup is 2560x1600 no scaling for the built in and 3840x2160 no scaling for the external portable USB C monitor I carry around with it. There may well be a way to do it from the CLI as well but the app just sits as a tray icon in the menu bar which is great from a "I don't know what I just plugged in but I want to to just be <x>" perspective.
- sbr464 5y ago
  Ideally 3840x2160 in HiDPI on the Pro Display XDR. I get this with an eGPU puck on an iMac pro with SwitchResX. Unfortunately the original M1 limited SwitchResX from using HiDPI at higher resolutions. It is limited to 3008x1692 at HiDPI (half of 6k). The higher resolutions are available but they aren't HiDPI and text looks noticeably worse. It's a known issue with several display tools like: https://github.com/xzhih/one-key-hidpi/issues/164 https://github.com/xzhih/one-key-hidpi/issues/164
- dkonofalski 5y ago
  Can't you just go to System Preferences and click Alt + Scaled? That usually gives you all the resolutions that your monitor supports without having to use the "Larger/Smaller" visual options.
  - 5y ago

AndrewUnmuted 5y ago

I remember when Windows had to be subjected to lots of different downloaded freeware applications to "unlock" full customization of the OS. macOS is in these days at the moment. What does that say about its product arc?

ChrisMarshallNY 5y ago

The 11.6 (I believe) release of MacOS X finally allowed native support for 5120 X 1440 (my display). The thing that annoys me, is that I have a second display that I use, from time to time (when giving video classes, for instance), but it remains assigned to a different device, most times. However, I can't leave it plugged in. If I do, the OS insists that I have a second screen, even though it is not actually connected to the Mac. This means that I can lose my cursor and the graphics processors are rendering undisplayed pixels. I can use an app like SwitchResX[0], but I feel that I should not need it. The OS should detect more than just if an HDMI cable is plugged in. It needs to know whether or not the screen is actually "live," and rendering graphics. [0] https://www.madrau.com https://www.madrau.com

kristjansson 5y ago
Maybe you want a physical KVM in between the two sources and the monitor? I tried to get a similar setup working locally (2 monitors, a macOS source and a Debian source, supporting all four input/output combinations) and couldn't find a satisfying software solution. There were a few people using ddcutil/ddccontrol/ddctool on Linux hosts to script changes on source changes, but (a) it was difficult/impossible to get DDC to work consistently with DP and HDMI outputs with first party Nvidia drivers (b) I couldn't find anything comparable on the macOS side. Hardware KVMs weren't much better, but if you're willing to spend the money, and have enough DP sources on both sides, they aren't too bad. Funny how hard/expensive it is to replicate the convenience of a nice analogue KVM with a bunch of VGA/DVI/PS2 I/O, a knob, an not much else...
- ChrisMarshallNY 5y ago
  Actually, belay that. I just tested with Monterey, and a new MBP, and it works the way that I expect. I need to use the built-in HDMI, but it works.
  - nitrogen 5y ago
    Does anybody know of software-defined ways to switch this behavior? I have the opposite problem sometimes -- I have an external display shared between two devices (of varying OSes), and sometimes I want it to remain a logical display on each device no matter which input is selected on the display. But other times I want the display to be removed when the device is not the active input.

deleted 5y ago

[deleted]

aa_memon 5y ago

This is exactly what I’ve been looking for. Wanted to use my 2012 imac as a second monitor for my MacBook and in the absence of target display mode decided to use NoMachine but couldn’t get resolution + separate display without a physical dummy hdmi plug. Thank you

itwillnotbeasy 5y ago

This is my main problem with MacOs - text on non 4k displays is so blurry, Windows and Linux are doing much better job with rendering fonts. And Apple doesn't seem to care about it at all - they even removed subpixel aliasing in the recent system update (i guess it was High Sierra). So weird, given most of the high refresh rate monitors on the market is 1440p, so if you have a gaming pc you need to buy separate 4k monitor for your macbook, because no one seems to care about fixing this, WTF?

sbr464 5y ago

Great app. I can confirm it works well with the new M1 Max and Monterey. Currently using with dual Pro Display XDRs in clamshell mode (14" MacBook Pro). It allowed using HiDPI at a higher resolution (4k or 3840x2160) than the M1 chipset natively allows (3k or 3008x1692 HiDPI on the 6k XDRs).