[Question]: Easiest way to make VDD activate only when no real monitors are detected

[St0RM53]

What is your question?

I just found about this project by luck (i knew and used usbmmidd_v2 before and searching about it again lead me here), and want to use it on my main home/workstation/gaming PC when i am accessing it remotely, specifically now with AnyDesk.

To skip the details, i don't know if it's worth implementing this function as a feature in the companion app, but what i am looking to achieve is for this virtual display driver to only activate when no other monitors are detected/connected to the system. This will prevent many of the regular issues i see people posting here, as one of the main uses is driving a headless system remotely much how i am doing.

I am assuming the simplest way is to write some script and have it as a task running in the background at an internal, where it enables the virtual monitor when it identifies no (real) monitors are detected, and disables VDD when one or more (real) monitors are detected.

Of course i am a noob in software programming so i could give it a try with some LLM bot and see if i can make it work.

Although i am writing it here in case you are also interested implementing such a feature.

Now some relevant background details:

There are multiple issues stemming from EDID/monitor detection, hot-plug detection, and multi-monitor setups in windows:

• Under windows in a multi-monitor setup, when a display is "disconnected" the windows of that monitor are transferred to the remaining active monitor. Upon reconnecting the disconnected monitor the windows do not return to their place. So you lose positioning and sizing. Microsoft knows about this and they implemented a solution back in 2021 ( https://devblogs.microsoft.com/directx/avoid-unexpected-app-rearrangement/ ) in a W10 insider build. I remember i tested it and it wasn't perfect. Since then this build continued to become W11 and this fix was never backported to W10 as far as i know.

• Monitor detection is regulated by the GPU driver that interfaces the hardware monitor detection (EDID, HPD aka hot-plug detect) to the software side (Windows DWM). GPU manufacturers (Nvidia/AMD) are mostly to blame here as they lock down EDID emulation behind their professional/workstation gpu's (Quadro/Radeon Pro), without even giving the option to force video output for existing monitors. Then you have the implementation of several monitor manufacturers not providing any option to disable hotplug detect. On HDMI output it's much easier to bypass/spoof than Displayport and there are existing cheap dummy passthrough plugs (with their own EDID, you can still use CRU to modify to liking). Still, this is really stupid when the GPU driver can prevent all of this hassle.

• Many remote desktop programs require the need of an active display output. Teamviewer used to provide their own virtual video driver a long time ago, but nowadays it uses windows safe mode output (normally stuck at 640x480 but you can change it through registry with this latest method: https://superuser.com/a/1684605/454548)
  Personally i've stopped using them since they've gone downhill in the last couple of years, and now using Anydesk which doesn't provide such fallback option. Without video output the program is totally useless.

I did rant about this issue several years ago: https://www.reddit.com/r/pcmasterrace/comments/lbz2zv/request_for_gpu_manufacturers_to_allow_display/

And had my try in developing a solution, which is a hardware passthrough that can manipulate Hot-plug detection for DisplayPort monitors, of which is still use to this day:

https://www.facebook.com/TechnoRageDevelopments/posts/pfbid02GgVK42nhfFfahiCK13oJNcrEnncXfprESLk3Xke587GWgyeHQLKv8h9z4nHAsqmnl

I did also make another variation that can theoretically emulate EDID directly, but even though i have the pcb's ready i didn't test them, neither wrote FW for this as i have no free time (and many other projects to finish)

The issue with this light ("LE") solution is that while it works perfectly fine it will not work when:

• You power-on or reboot the PC with monitor(s) powered off.
• GPU driver fully crashes due to OC or whatever, and monitor(s) are powered off.

In both cases EDID is never communicated to the GPU so no video output

Anyways, while this information is a bit outside the scope of this project, i think it's relevant and useful and it's also worth adding so you understand where i am coming from, plus it will also help more people to find about it when searching about such issues.

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[zjoasan]

Sorrry for late reply,

I'm the one that drafted most of the community ps1 scripts, and I even did a "enable VDD on login and disable at logout/power down". Since it's a software solution, if the computer hangs or completely lose power, you might be in a bit uncomfortable position as a regular non-headless user. But it's rather easy to fix, when it has rebooted and you physical monitor is black, wait just a bit longer then usual. Like 30 sec longer then you usual do for the login screen, instead of blindly enter password, use "Win+p" 2 times then press Enter. Nine times out of ten, you will get only second monitor or clone, either way you will have display on your physical screen.

In that script you could add a "any other active monitors online"-statement before starting the VDD.

As I understood VDD(not a lot of experience with windows API), in order to circumventing GPU control of EDID and other stuff, VDD is a mutli-device driver. It creates a VDD adapter, that gets feed the "edid" we choose. With that info it sets up Virtual display(s) connected to that device, grabbing the swapchain from the gpu you chosen.

This is from time to time, "CPU timing sensitive" (that's perhaps my formulation), since there could be little actual load on the CPU but still the driver can feel laggy.

What do you think, enable and disable the driver at login and logout with "is other displays active"-terms? Or rethink the whole thing, and always boot with it off and read from registry if it should be enabled or not? Or any other solution you could come up with =)

Would love to hear you thoughts.

[St0RM53]

Thanks a lot for you reply. I only found some time yesterday to install and make this work out. Found a few issues along the way: #375

I also used ChatGPT and your community scripts as reference to write a working script that solves my problem:

monitor-check.ps1

 # Self-elevate the script if required
 if (-Not ([Security.Principal.WindowsPrincipal] [Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole] 'Administrator')) {
    if ([int](Get-CimInstance -Class Win32_OperatingSystem | Select-Object -ExpandProperty BuildNumber) -ge 6000) {
        $CommandLine = "-File `"" + $MyInvocation.MyCommand.Path + "`" " + $MyInvocation.UnboundArguments
        Start-Process -FilePath PowerShell.exe -Verb Runas -ArgumentList $CommandLine
        Exit
    }
 }
# Get all monitor devices
$monitors = Get-PnpDevice -Class Monitor -ErrorAction SilentlyContinue

$matchingMonitors = @()

foreach ($monitor in $monitors) {
    try {
        # Skip if monitor is not in 'OK' state
        if ($monitor.Status -ne 'OK') {
            continue
        }

        # Check hardware ID
        $hardwareIds = Get-PnpDeviceProperty -InstanceId $monitor.InstanceId `
                                             -KeyName 'DEVPKEY_Device_HardwareIds' `
                                             -ErrorAction SilentlyContinue

        if ($hardwareIds -and $hardwareIds.Data -match "GSM5B7F") {
            $matchingMonitors += $monitor
        }
    } catch {
        continue
    }
}

# Get the Virtual Display Driver
$virtualDisplay = Get-PnpDevice -ErrorAction SilentlyContinue | Where-Object {
    $_.FriendlyName -eq "Virtual Display Driver"
}

if ($matchingMonitors.Count -eq 0) {
    Write-Host "No active monitors with Hardware ID 'GSM5B7F' detected."

    if ($virtualDisplay) {
        if ($virtualDisplay.Status -eq "OK") {
            Write-Host "'Virtual Display Driver' is already enabled."
        } elseif ($virtualDisplay.Status -eq "Error") {
            Write-Host "'Virtual Display Driver' is disabled. Attempting to enable..."
            try {
                Enable-PnpDevice -InstanceId $virtualDisplay.InstanceId -Confirm:$false -ErrorAction SilentlyContinue
                Write-Host "'Virtual Display Driver' has been enabled."
            } catch {
                Write-Error "Failed to enable 'Virtual Display Driver'. Error: $_"
            }
        } else {
            Write-Host "Unknown status for 'Virtual Display Driver': $($virtualDisplay.Status)"
        }
    } else {
        Write-Error "'Virtual Display Driver' not found on this system."
    }
} else {
    Write-Host "Active monitor(s) with Hardware ID 'GSM5B7F' detected."

    if ($virtualDisplay) {
        if ($virtualDisplay.Status -eq "OK") {
            Write-Host "'Virtual Display Driver' is currently enabled. Attempting to disable..."
            try {
                Disable-PnpDevice -InstanceId $virtualDisplay.InstanceId -Confirm:$false -ErrorAction SilentlyContinue
                Write-Host "'Virtual Display Driver' has been disabled."
            } catch {
                Write-Error "Failed to disable 'Virtual Display Driver'. Error: $_"
            }
        } elseif ($virtualDisplay.Status -eq "Error") {
            Write-Host "'Virtual Display Driver' is already disabled."
        } else {
            Write-Host "Unknown status for 'Virtual Display Driver': $($virtualDisplay.Status)"
        }
    } else {
        Write-Error "'Virtual Display Driver' not found on this system."
    }
}

In short, the script checks for an active monitor with a specific hardware id (GSM5B7F in my case). I choose to use this identifier as many monitors don't have specific drivers that will give them a friendly name and use the default microsoft driver as VDD ("Generic PnP monitor")
If it finds one it will make sure that the VDD driver is disabled.
If it doesn't find one it will make sure that VDD driver is enabled.

This way when you are active on the PC you don't have extra desktops, nor lose any performance, nor having games interfere with the regular desktop setup (plus the VDD driver is disabled so i am assuming no issues with anti-cheat engines as well).

Then i created a task in task scheduler to periodically perform this check:
It expects the script to be located in the community scripts folder, default: C:\VirtualDisplayDriver\ControlApp\Community Scripts\

As a note, ESET detected this as a suspicious application (PowerShell/Runner.F) probably because i setup it to keep running forever.

I've also used the conhost --headless method to prevent the powershell window from showing up. There are multiple methods to do this, but this is the best from my testing.

VDD monitor check.xml

<?xml version="1.0" encoding="UTF-16"?>
<Task version="1.4" xmlns="http://schemas.microsoft.com/windows/2004/02/mit/task">
  <RegistrationInfo>
    <Date>2025-06-13T04:12:50.0828886</Date>
    <Author>TNF-PC\TnF</Author>
    <URI>\VDD monitor check</URI>
  </RegistrationInfo>
  <Triggers>
    <BootTrigger>
      <Repetition>
        <Interval>PT5M</Interval>
        <StopAtDurationEnd>false</StopAtDurationEnd>
      </Repetition>
      <Enabled>true</Enabled>
      <Delay>PT1M</Delay>
    </BootTrigger>
  </Triggers>
  <Principals>
    <Principal id="Author">
      <UserId>S-1-5-21-3870882956-894697989-2234603847-1001</UserId>
      <LogonType>InteractiveToken</LogonType>
      <RunLevel>HighestAvailable</RunLevel>
    </Principal>
  </Principals>
  <Settings>
    <MultipleInstancesPolicy>IgnoreNew</MultipleInstancesPolicy>
    <DisallowStartIfOnBatteries>false</DisallowStartIfOnBatteries>
    <StopIfGoingOnBatteries>false</StopIfGoingOnBatteries>
    <AllowHardTerminate>true</AllowHardTerminate>
    <StartWhenAvailable>true</StartWhenAvailable>
    <RunOnlyIfNetworkAvailable>false</RunOnlyIfNetworkAvailable>
    <IdleSettings>
      <StopOnIdleEnd>true</StopOnIdleEnd>
      <RestartOnIdle>false</RestartOnIdle>
    </IdleSettings>
    <AllowStartOnDemand>true</AllowStartOnDemand>
    <Enabled>true</Enabled>
    <Hidden>false</Hidden>
    <RunOnlyIfIdle>false</RunOnlyIfIdle>
    <DisallowStartOnRemoteAppSession>false</DisallowStartOnRemoteAppSession>
    <UseUnifiedSchedulingEngine>true</UseUnifiedSchedulingEngine>
    <WakeToRun>false</WakeToRun>
    <ExecutionTimeLimit>PT0S</ExecutionTimeLimit>
    <Priority>7</Priority>
  </Settings>
  <Actions Context="Author">
    <Exec>
      <Command>conhost</Command>
      <Arguments>--headless powershell.exe -File "C:\VirtualDisplayDriver\ControlApp\Community Scripts\monitor-check.ps1"</Arguments>
    </Exec>
  </Actions>
</Task>

I've tested it with Anydesk from another PC, and it works as expected. Time will tell if i find issues with it. From now on it will be running 24h on my main PC.

Still this is not the ideal solution to my problem.
The ideal solution is for GPU manufacturers to allow force video output/EDID emulation that is already possible but locked behind their professional/workstation models/drivers.

The other solution is to build and code my advanced version of HPDKiller that should be able to do full EDID emulator passthrough in hardware, but it's not a priority at the moment.

If you want you can share/add this as a community script, although it will need to be modified by the user to set his specific monitor hardware id, for it to work.