GPU Clean Output Plugin (GPU-Clean-Output)

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GPU-Clean-Output is an advanced, high-performance OBS Studio output plugin for Windows 10/11. It streams clean-feed video (Program or Preview) directly to physical HDMI/DisplayPort monitors configured as Specialized Displays ("Remove display from desktop") using DirectX 11 and WinRT Windows.Devices.Display.Core.

By bypassing the Windows Desktop Window Manager (DWM) compositor entirely, GPU-Clean-Output achieves zero-copy, hardware-exclusive direct scanout with broadcast-grade ultra-low latency.

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🌟 Key Features

• Hardware Direct Scanout (DWM Bypass): Outputs directly to dedicated displays without going through DWM window compositing, eliminating OS windowing overhead and frame-jitter.
• WinRT DisplayCore Integration: Takes exclusive hardware ownership of monitors marked as "Specialized Display" in Windows.
• GPU Zero-Copy Pipeline: Passes OBS frame textures directly to DXGI swap chains on the GPU, avoiding CPU memory copies.
• Multi-Output Support: Configure up to 4 independent display output slots simultaneously.
• Flexible Video Routing: Choose Program (PGM) or Preview (PVW) feed individually for each output slot (ideal for broadcast Studio Mode setup).
• Ultra-Low Latency Engine: Dedicated background worker threads with hybrid spin-wait mechanisms for sub-millisecond frame submission response.
• Hot-Plug & Self-Recovery: Automatic connection monitoring and recovery upon DXGI device resets or display topology changes.

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💻 Requirements & Prerequisites

• Operating System: Windows 10 (Version 1903 / Build 18362 or higher) or Windows 11 (64-bit).
  • ⚠️ Edition Requirement: Microsoft's "Specialized Displays" ("Remove display from desktop") feature is ONLY supported on Windows Enterprise, Windows Pro for Workstations, and Windows IoT Enterprise (Windows 10 / Windows 11).
  • ❌ Unsupported Editions: Standard Windows Pro and standard Windows Home editions are NOT supported (they lack the specialized display detachment setting).
• OBS Studio: OBS Studio v28.0.0 or higher (64-bit).
• Hardware: NVIDIA, AMD, or Intel GPU supporting DirectX 11.
• Development / Build Tools:
  • Visual Studio 2019 / 2022 (with Desktop development with C++ workload).
  • CMake 3.16 or newer.
  • Windows 10/11 SDK.

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🔨 How to Build

Follow these steps to build gpu-clean-output.dll from source:

1. Clone the Repository

git clone https://github.com/your-username/GPU-Clean-Output.git
cd GPU-Clean-Output

2. Configure with CMake

Open PowerShell or Developer Command Prompt for VS 2022 and create the build directory:

mkdir build
cd build

If you have OBS Studio dependencies installed or extracted locally, specify the path via OBS_SDK_DIR:

cmake -G "Visual Studio 17 2022" -A x64 -DOBS_SDK_DIR="C:/path/to/obs-studio-deps" ..

(If libobs is already installed in standard CMake search paths, running cmake -G "Visual Studio 17 2022" -A x64 .. will auto-detect it.)

3. Compile the Plugin

Build the Release binary using CMake:

cmake --build . --config Release

Upon successful compilation, the plugin DLL will be located at: build/Release/gpu-clean-output.dll (or build/gpu-clean-output.dll).

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📦 How to Install .dll File

1. Close OBS Studio if it is currently running.
2. Locate the compiled gpu-clean-output.dll file.
3. Copy gpu-clean-output.dll into your OBS Studio plugins directory:
   • Standard Installation (64-bit): C:\Program Files\obs-studio\obs-plugins\64bit\
   • Portable OBS Studio Installation: <OBS_DIRECTORY>\obs-plugins\64bit\
4. Launch OBS Studio.
5. Verify installation by checking the OBS top menu bar: Tools -> GPU Clean Output (Specialized Display).

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🖥️ How to Trigger Screen Exclusivity (Specialized Display & Direct Scanout)

To trigger hardware-exclusive direct scanout, you must first configure the target monitor in Windows and then activate the plugin in OBS Studio.

Step 1: Configure Windows "Specialized Display" Mode

Mark your external broadcast/monitor display as a Specialized Display to remove it from desktop DWM control:

1. Connect your target HDMI/DisplayPort monitor to your PC.
2. Open Windows Settings (Win + I).
3. Navigate to System -> Display -> Advanced display settings (or Advanced display in Windows 11).
4. In the display dropdown at the top, select your target monitor.
5. Find the "Remove display from desktop" option (or Specialized display toggle) and turn it ON.
6. Windows will immediately detach this monitor from the desktop space (it will no longer display the Windows desktop background or cursor).

⚠️ Important Edition Notice: If the "Remove display from desktop" toggle is missing in Advanced Display settings, check your Windows edition. This setting requires Windows Enterprise, Windows Pro for Workstations, or Windows IoT Enterprise. Standard Windows Pro and Windows Home editions do not support this feature.

ℹ️ Note: The monitor will appear black or go to sleep until GPU-Clean-Output takes ownership and begins streaming.

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Step 2: Activate Direct Output in OBS Studio

1. Open OBS Studio.
2. Go to the top menu bar and click Tools -> GPU Clean Output (Specialized Display).
3. In the plugin configuration window:
   • Check Enable Direct Output (啟動硬體直輸出) to turn on master output.
   • Target Specialized Display 1: Select your display target from the dropdown list (e.g. Auto-Detect First Specialized Display or the specific hardware ID of your monitor).
   • Source Output 1: Select either Program (PGM 主畫面) or Preview (PVW 預覽畫面).
   • (Optional) Configure Output Slots 2 to 4 if you have multiple specialized displays connected.
4. Click OK / close the dialog.

The targeted physical display will instantly wake up and receive the ultra-low latency clean feed direct from the GPU!

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🛠️ Architecture & Technical Summary

[ OBS Render Engine ] ---> (Zero-Copy GPU Texture) ---> [ Direct3D 11 Renderer ]
                                                                 |
                                                     DXGI SwapChain Present
                                                                 v
[ WinRT DisplayTarget ] <--- (DisplayCore API) <--- [ Exclusive Physical Display ]

• API Layer: WinRT Windows.Devices.Display.Core::DisplayManager for hardware target acquisition, locking, and display state management.
• Rendering Engine: Dedicated D3D11 device bound to the specific physical GPU adapter (LUID) connected to the output target.
• Render Pipeline: Sub-millisecond queue flushing with zero-copy texture sharing.

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📄 License

This project is licensed under the GPL-2.0 License - see the LICENSE file for details.