nomi-san/parsec-vdd

✨ Perfect virtual display for game streaming

ℹ About

This project provides a standalone solution for creating virtual displays on a Windows host using the Parsec Virtual Display Driver (VDD), independent of the Parsec app.

The Parsec VDD enables virtual displays on Windows 10+ systems, a feature available to Parsec Teams and Warp customers. With VDD, users can add up to three virtual displays to a host machine they connect to, ideal for setups where physical monitors may be unavailable or when additional displays are beneficial.

Built by Parsec, the VDD leverages the IddCx API (Indirect Display Driver) to generate virtual displays with support for high resolutions and refresh rates, including up to 4K and 240 Hz. This capability makes it a versatile tool for gaming, streaming, or remote work, allowing users to simulate multiple screens for an enhanced, flexible visual experience.

💡 Use cases

• Game streaming with Parsec, Sunshine / Moonlight, or Steam Remote Play — host at the exact streaming resolution and refresh rate without depending on a physical monitor's spec.
• Headless hosts and cloud VMs — Windows machines with no monitor attached (build servers, gaming VMs, cloud GPU instances). VDD gives them a real desktop session so capture tools, launchers, and benchmarks that refuse to run without an active display keep working.
• AR / XR workspaces — feed several virtual monitors into AR glasses or headset-based desktop projects (see Verto_XR below).
• Multi-monitor productivity — extend a laptop without docking; preview / test multi-display layouts without buying physical screens.
• Hyper-V / GPU-PV guests — the hypervisor's built-in Hyper-V monitor can't be disconnected, which prevents Parsec / Sunshine from falling back to their own virtual display. Adding VDD inside the guest gives the streaming host a controllable target.
• High-refresh capture & recording — record at the exact resolution and refresh rate the encoder wants (e.g. 1080p@240Hz, 4K@120Hz) without cropping or rescaling from a physical monitor's native mode.
• Privacy mode — pair a virtual display for the remote session with the physical monitor for local use, keeping the two desktops independent.

📺 ParsecDisplay App

ParsecDisplay is a virtual display manager for Parsec VDD, built with C# and WPF. It provides a tray-based interface to add and remove virtual displays, change their resolution, refresh rate, and orientation, capture screenshots, and more.

👉 Check out Releases to download it.

🚀 Using Core API

Design notes

Parsec VDD is designed to work with Parsec client-connection sessions. When the user connects to the host, the app starts controlling the driver — sending IO control codes and receiving results. Adding a virtual display returns an index, used later to unplug it; up to 16 displays can be added per adapter. The driver must be pinged periodically to keep added displays alive, otherwise all of them will be unplugged after about a second. There is no direct way to manipulate added displays — call the Win32 Display API to change their display mode (see the ParsecDisplay source).

flowchart LR
  A(app)
  B(vdd)

  A <--->|ioctl| B
  A ..->|ping| B

  B --- X(display1)
  B --- Y(display2)
  B --- Z(display3)

  winapi -->|manipulate| X

Using the code

For detailed instructions and usage examples, refer to the VDD_LIBRARY_USAGE.

• The core API is designed as a single C/C++ header that can be added to any project, 👉 core/parsec-vdd.h
• There is also a simple demo program, 👉 core/vdd-demo.cc

Picking a driver

You have to install the driver before any virtual displays can be created.

All of them also work on Windows Server 2019 or higher.

You can unzip (using 7z) the driver setup above to obtain the driver files and nefconw CLI.

vdd-0.45/
  |__ nefconw.exe
  |__ driver/
    |__ mm.cat
    |__ mm.dll
    |__ mm.inf

Command line method to install the driver using nefconw (admin required):

start /wait .\nefconw.exe --remove-device-node --hardware-id Root\Parsec\VDA --class-guid "4D36E968-E325-11CE-BFC1-08002BE10318"
start /wait .\nefconw.exe --create-device-node --class-name Display --class-guid "4D36E968-E325-11CE-BFC1-08002BE10318" --hardware-id Root\Parsec\VDA
start /wait .\nefconw.exe --install-driver --inf-path ".\driver\mm.inf"

In addition, you can run the driver setup in silent mode to install it quickly.

.\parsec-vdd-0.45.0.0.exe /S

😥 Known Limitations

This list shows the known limitations of Parsec VDD.

1. HDR support

Parsec VDD does not support HDR on its displays (see the EDID below). Theoretically, you can unlock support by editing the EDID to include HDR metadata and a 10-bit+ color depth. Unfortunately, you cannot flash its firmware the way you would a physical monitor — there is no registry setting to toggle either.

All IDDs have their own fixed EDID block inside the driver binary to initialize the monitor specs. So the solution is to modify this block in the driver DLL (mm.dll), then reinstall it with nefconw CLI (see above).

2. Custom resolutions

Before connecting, the virtual display looks in the HKLM\SOFTWARE\Parsec\vdd registry for additional preset resolutions. Currently this supports a maximum of 5 entries.

HKLM\SOFTWARE\Parsec\vdd:
  - key: [0 -> 5]
    value: { width, height, hz }

To unlock this limit, you need to patch the driver DLL the same way as above, but 5 is enough for personal use.

😑 Known Bugs

This is a list of known issues when working with standalone Parsec VDD.

1. Incompatible with Parsec Privacy Mode

If you have enabled "Privacy Mode" in Parsec Host settings, please disable it and clear the connected display configurations in the following Registry path.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers\Connectivity

This option causes your main display to turn off when virtual displays are added, making it difficult to turn the main display back on and disrupting the remote desktop session.

2. Windows 10 Connectivity registry quirk

Windows 10 caches display arrangements keyed by the combination of attached display IDs. When a middle display is unplugged, the remaining subset (e.g. DISP001_DISP003) is a new combo Windows hasn't seen — those displays fall back to default mode and arrangement.

The app works around this by always unplugging right-to-left (latest driver index first) during sleep, exit, and vdd remove all. See issue #23 for the full write-up.

3. Headless before user login

The app is a GUI process and requires an interactive user session (Vista+ session 0 isolation). On a freshly-booted headless host with no auto-login, nothing runs until the user signs in. Workarounds:

• Enable auto-login on the host.
• Or use a Task Scheduler entry that runs at logon with desktop interaction.
• Or use the service-based fork ParsecVDA-Always-Connected for fully headless single-display deployments.

🤔 Comparison with other IDDs

The table below shows a comparison with other popular Indirect Display Driver projects.

✅ - full support, 🆗 - limited support

Signed means the driver files have a valid digital signature. H-Cursor means hardware-cursor support — without it, you get a double cursor on some remote desktop apps. Tweakable is the ability to customize display modes. Visit MSDN IddCx versions to check the minimum supported Windows version.

🔗 Projects using Parsec VDD

Third-party libraries and apps built on top of the Parsec VDD driver:

• parsec-vdd-rust — Rust port of the core VDD API. Drop-in for Rust projects that need to add/remove virtual displays and keep them alive.
• Verto_XR — XR / AR-glasses desktop workspace that uses VDD as the source for its virtual monitors.
• ParsecVDA-Always-Connected — service-based fork that keeps a single virtual display alive across reboots and power events, aimed at headless hosts.

Open a PR if you'd like to add your project here.

📘 Parsec VDD Specs

Common preset display modes:

Check out docs/PARSEC_VDD_SPECS for the full list of preset display modes and driver specs.

🍻 Credits

• Thanks to Parsec for the driver
• The app's background was from old parsecgaming.com

Trusted code signing on Windows provided by SignPath.io, certificate by SignPath Foundation