DDCSharp

A .NET library for controlling displays via DDC/CI, including brightness, contrast, input source, and other display settings through a simple API

Lightweight C# (.NET 8) library for enumerating physical monitors and performing DDC/CI (MCCS VCP) VCP feature reads / writes (e.g. brightness, input source) with an extensible provider model.

Projects

• DDCSharp.Core – Provider & transport abstractions plus capability / VCP feature models.
• DDCSharp.Windows – Windows implementation using dxva2.dll (Win32 APIs) to enumerate and control monitors.

NuGet Packages

Package	NuGet	Description
DDCSharp.Core		Core abstractions + capability models
DDCSharp.Windows		Windows provider implementation

Install via Package Manager:

PM> Install-Package DDCSharp.Core
PM> Install-Package DDCSharp.Windows

Or with dotnet CLI:

dotnet add package DDCSharp.Core
dotnet add package DDCSharp.Windows

Key Concepts

• IDisplay – Abstraction of a physical monitor (read / write VCP features, refresh capabilities).
• IDisplayProvider – Produces IDisplay instances (platform / virtual). Multiple providers can be registered.
• DisplayService – Thread‑safe static registry to add / clear providers and obtain all displays.
• Capabilities Parsing – Windows provider fetches the MCCS capability string, extracts sections (type, model, mccs_ver, vcp) and builds a list of Capability entries (feature + supported values list if present).

Supported (subset) Features

Brightness, Contrast, Input Source, Sharpness, Color Gains, Color Presets, Power Mode, Speaker Volume, Audio Mute, Orientation, Frequencies, Panel/Tech info, Usage Time, etc. (See VCPFeature enum for details.)

Quick Start (Windows)

using DDCSharp.Core;
using DDCSharp.Core.Abstractions;
using DDCSharp.Core.Capabilities;
using DDCSharp.Windows;

// Register the Windows provider once at startup
WindowsDisplayProvider.Register();

// Enumerate displays
foreach (var display in DisplayService.GetDisplays())
{
    Console.WriteLine($"Description: {display.Description}  Model: {display.Model}  MCCS: {display.MCCSVersion}");

    // Read brightness
    if (display.TryGetVcpFeature(VCPFeature.Brightness, out var type, out var current, out var max))
    {
        Console.WriteLine($"Brightness: {current}/{max}");
    }

    // Set brightness (0..max range – caller responsibility)
    display.TrySetBrightness(50);

    // List supported input sources
    var sources = display.GetSupportedInputSources();
    Console.WriteLine("Inputs: " + string.Join(", ", sources));

    // Change input if supported
    if (sources.Contains(InputSource.HDMI1))
    {
        display.TrySetInputSource(InputSource.HDMI1);
    }
}

Thread Safety

• Provider registration is synchronized (DisplayService).
• Each WindowsDisplay synchronizes native calls per display instance.

Extending (Custom Provider)

Implement IDisplayProvider and produce objects implementing IDisplay.

public sealed class MyProvider : IDisplayProvider
{
    public IEnumerable<IDisplay> GetDisplays()
    {
        // Open native handles, wrap them in your IDisplay implementation
        yield break;
    }
}

DisplayService.RegisterProvider(new MyProvider());

IDisplay must expose metadata, capabilities, attempt VCP gets/sets, and dispose native resources.

Capability Refresh

Call display.RefreshCapabilities() to re-fetch the MCCS capability string (e.g., after OSD adjustments or hot‑plug events).

Error Handling

• Provider enumeration exceptions are swallowed so one provider cannot block others.
• VCP read/write methods return bool indicating success.

Platform Notes

• Windows: uses dxva2.dll (GetVCPFeatureAndVCPFeatureReply, SetVCPFeature, capability string APIs) + EnumDisplayMonitors.
• Other platforms: supply a custom provider (e.g., DDC via I2C, USB HID, network bridge, mock/testing provider).

Disclaimer

Writing values to unsupported VCP features may fail silently. Some monitors expose incomplete or vendor-specific capability strings. Use at your own risk.