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Okay first let me say this: I know that MANY people dont understand that cloning a monitor in windows means that BOTH monitors do have the same resolution. Now Im trying to do something that goes in this direction.

We have a big 4K TV sitting in the lobby and we need to monitor the content it is showing on a small tiny display with a resolution of 1080p. I know that windows wont mirror the 4K footage to the smaller screen.

What I would like to do is to mirror the 4K footage and scaling it down to 1080p and sending this to the small screen up in the office.

We do know that sampling the footage down will decrease the sharpness etc. This does not matter. We just need to see whats going on on the 4K screen on a very small 1080p display.

Our system has a GTX 970 build in. Is there a way with Nvidias system configuration?

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Recently I found a nice way to solve this. Im answering on my own question so everybody having the issue can read it. I now use a 4K screen getting the full 3840x2160 px output from my GTX 970 and a second 1080 px display displaying the same content. So I mirrored the 4K display with downscaling to a display with less resolution.

Having a NVIDIA graphics card there is no need for any additional software or even hardware.

HERE'S HOW: Just right click on the desktop and select NVIDIA Control Panel. Go to the 3D Settings and click Manage 3D Settings. Scroll down to DSR Factors and set the setting to 4.00x if you want to display 4K footage on a 1080 px display. Now you go to the windows display settings and set the resolution on the 1080 px display to 3840x2160 px. Of course this does not provide better quality on the 1080 px display. It might be worse but quality is not the reason why i have been doing this. Also I dont know if there is a equivalent solution for an AMD graphics card.

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I'm not entirely sure that this can be achieved with built in software, the "cloned" output expects to put out the exact same picture on multiple ports.

This means you either need

  1. to have it at 1080p and let the 4k screen do upscaling or, if you still need the 4k resolution,
  2. you need to downscale the image for the 1080p monitor.

For the downscaling solution something like a hardware 4k to 1080p converter box would do the trick. Something like this 4k to 1080 up/downscaler.

These kinds of bits of hardware should not be significantly expensive, but I think it is the only way it is going to work in practice.

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  • I hoped that there might be a downscaling solution provided by software. – Arjihad Nov 1 '18 at 16:42
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Windows can only duplicate a monitor by setting both monitors to the same resolution. The solution is to use a third-party product.

For example TeamViewer, which by default, will scale the transmitted screen to match your own screen. TeamViewer is free for personal use, otherwise using a subscription model.

For more information see the article TeamViewer and Ultra High Definition and 4K monitors.

There are alternatives to TeamViewer, but I don't know how well they work with monitors of different resolution : Ultra VNC and TigerVNC.

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  • Interesting. But this requires internet access right? Is there a wired solution? – Arjihad Nov 1 '18 at 16:45
  • Remote desktop is definitely a solution if you don't mind the viewing box being another PC. Teamviewer can be configured for local network only authentication using a single access password rather than the normal "one-time" passwords and internet authentication so it can definitely work. The only thing would be that you would fall foul of the "free for private use only" licence clause. There's almost no way they could detect the box if you block its internet access and limit it to a local network, but morally you would be in the wrong and in breach of the licence. – Mokubai Nov 1 '18 at 16:51
  • See the post Peer 2 Peer connection no internet available. As @Mokubai said : Using TeamViewer is based on an honor system. – harrymc Nov 1 '18 at 16:54
  • There are other Remote / Screen Sharing Tools available. All have the same security concern - if someone malicious notices the shared screen, they can work that vector into the source PC. Also, my experience is that long-term remote sessions require babysitting and can be embarrassing if they fail in the midst of a presentation or similar. – Christopher Hostage Nov 1 '18 at 19:50
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I have an NVIDIA GTX 1070ti Gaming 8G and I can confirm the DSR solution posted above absolutely works. I tried to use an external 4k->1080p scaler and it worked, but my card was not powerful enough to display two 4k signals at the same time with ultra resolution on my golf simulator game, TGC 2019. Without the scaler, my card kept downgrading the 4k to 1080p to match the monitor. Once I used the NVIDIA solution with DSR, I'm set, card can handle the 4k/1080p cloned signal and still perform! Very cool, thank you for posting!

I have two projectors and a touch screen monitor running off one card. The 4k projector and a 24" 1080p touch screen are duplicated/cloned, while the other 1080p projector is extended. The 4k projector gets a 4k signal and the others get a 1080p signal.

Note, it does take a little fiddling around in order to get it working properly. First you need to set up DSR per the instructions above, then right click on the display in the NVIDIA control panel (resolution setting) and clone one of the displays. Make sure the 4k display device is the clone source. Then select the DSR resolution that says 4k/1080p/4.x. Eventually both the 4k projector and the 1080p monitor will show 4k/1080p/4.x resolution. Note, I use the windows key+P to set the duplicated 4kprojector/monitor as primary, or the separate 1080p projector as primary.

From what I can tell, DSR is like a proxy for resolution. It tells the computer and the games/applications that your display can accepts 4k signals, so I can set 4k in the game. Then on the HDMI/display port outputs it uses EDID to gather the metadata detailing the capabilities of the display (4k, 1080p, etc), and down-converts the 4k signal to 1080p when necessary. I also believe the 4k signal is being maintained for a device capable of displaying that resolution. Reason being is when I check this signal on my 4k projector it shows 3840 x 2160, and when checking the same on the 1080p it shows 1920x1080. Secondly, there is a slider to adjust DSR sharpness in the NVIDIA control panel. When I move that from 0%-100% the sharpness changes on the 1080p monitor, but not on the 4k projector, which tells me DSR is working on the monitor, but passing the 4k signal straight to the projector. No extra hardware required. Here is an explanation of the down-scaling from NVIDIA: https://www.geforce.com/hardware/technology/dsr/technology

This works 100%, what an awesome feature from NVIDIA!

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You could also use a hardware device such as this to reduce the strain on your graphics card/monitor doing the scaling.

See HDMI Splitter 4K 60Hz 1X2 Multi-Resolution Output (MRO) by J-Tech Digital HDMI 2.0: https://www.amazon.com/Splitter-Multi-Resolution-J-Tech-Digital-downscale/dp/B0839PRQ2V

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The solution proposed above for NVIDIA cards is awesome. I will include this post in case someone is using an AMD card or needs an alternative solution.


Sorry for resurrecting a couple old threads, but there's that sort of classic old meme of people finding solutions to something and then never posting them.

I was trying to solve this problem recently. I came up with a solution that utilizes streaming from one screen to the other, and in the interest of sharing knowledge I've decided to resurrect some of these old posts and threads in various places to share one possible solution to this problem.

This is an especially great solution for gamers that might want to play something with adaptive sync features (GSYNC, FreeSync) or want to play at your monitor's native resolution and downscale it for the screen you wish to mirror.

Best of all, this solution uses free and open source software.


TL;DR

  • While not a native solution, OBS has a Fullscreen Projector option if you right click on the Base Canvas that can stream one display. I found the latency unnoticeable.

BACKGROUND

  • I like to mirror things from my computer monitor to my TV screen. Other people I live with like to see me do various things such as play games on the big screen, and I like to play on my monitor for the adaptive sync features. But my monitor isn't big enough for everyone to view.

  • The problem I encountered is that by downscaling my monitor to my TV screen using Window's or NVIDIA's built in "Mirror" feature, I wasn't able to use the GSYNC feature on my monitor which introduced screen tearing and gave me headaches. Not great.

  • After countless online searches, it was hard for me to come up with any answer other than "It just can't be done, your other display always has to be downgraded to your other display's settings." or "Oh, you can do that but you need to get _________ expensive multi-monitor software to do that" such as UltraMon.

  • Turns out that's not exactly true with a bit of creative problem solving. It occurred to me that while it may not be possible to have a truly "native" solution to the problem of mirroring different screens, I could stream one display to the other display with some down-scaling. And as long as the latency wasn't noticeable, then it should suit my needs perfectly.

  • This made me think that OBS might be the right piece of software to do the trick.

  • At first I was thinking maybe I would capture my screen and stream it to a VLC server and run a VLC instance on the other screen. Turns out you don't even need to do that, OBS has the functionality to project one screen to another built right in.

REQUIREMENTS

  • OBS: Open Broadcaster Software, a free and open source screen capture and streaming software.
  • I tested this on a Windows 10 machine however OBS is also available on Mac OS and Linux.
  • A PC powerful enough to capture, down-scale, and copy the source rendering over to a secondary monitor using OBS. I think most modern PCs should be able to handle this but I'm not sure.

SOLUTION

  1. In Windows Display Settings or your Graphics Card Control Panel, set your monitor to Extend mode, NOT Duplicate or Mirror mode.
  2. Install OBS if you do not have it already.
  3. Open OBS. If this is your first time using the software, it will probably prompt you for some settings related to streaming or recording. Either option is fine.
  4. If you don't get prompted for anything, go to Settings->Video.
  5. Set your Base (Canvas) Resolution to whatever the resolution of the secondary screen would be. The Base Canvas is the thing the preview screen that you see inside OBS.
  6. In my testing, I don't think Output Resolution in Settings->Video will affect anything for the purpose we are using it for although I think it will affect recording/streaming.
  7. Under Sources, you will need to set a source to capture. You could for example go to "Display Capture" or you could do "Window Capture" or "Game Capture". I won't go into much detail here since there's a lot of different sources you could potentially display and it's all documented on OBS documentation. The OBS documentation can be found here: https://obsproject.com/wiki/
  8. Once you have that configured correctly, you should be able to see the Scene Item with a red border in or around the Base Canvas within OBS showing the window that is being captured. You may need to resize the capture window so that it fits correctly into the preview canvas. One easy way to do this is to right click on the Scene Item->Transform->Fit to screen.
  9. If you right click on the Base Canvas, there will be an option that says "Fullscreen Projector (Preview)". It will then have another drop-down to select the monitor you would like to project to.
  10. You should now see the screen cast to the other monitor.

In my testing, and on my (fairly powerful) desktop PC, the output has had low enough latency to not be detectable to the eye.

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