Virtual Camera .NET Push API¶

The VisioForge.DotNet.VirtualCamera NuGet package sends video frames and audio samples from your .NET application straight to the VisioForge Virtual Camera and Virtual Audio Card. Zoom, OBS Studio and browsers see the camera as an ordinary webcam, and DirectShow applications also see the Virtual Audio Card as a microphone. No DirectShow graph is needed on your side.

The package has no dependency on the rest of the VisioForge SDK. It targets .NET Framework 4.7.2, .NET 8 and .NET 10 on Windows. Its types live in the VisioForge.VirtualCamera namespace, so it can be referenced next to VisioForge.DotNet.Core, which carries the same writers in VisioForge.Core.VirtualCamera.Push. A file that also imports VisioForge.Core.VirtualCamera.Push qualifies VirtualVideoWriter and VirtualAudioWriter, and one that imports VisioForge.Core qualifies BaseContext; a using alias works as well.

Install¶

<PackageReference Include="VisioForge.DotNet.VirtualCamera" Version="[2026.11.6]" />
<!-- The virtual camera and virtual audio card filters -->
<PackageReference Include="VisioForge.DotNet.Core.Redist.VirtualCamera.x64" Version="[2026.11.6]" />

Redist.VirtualCamera.x64 fits whatever your application's architecture: the consumer application loads the filter, and Zoom, OBS and browsers are 64-bit (see below for other consumers). Each Redist.VirtualCamera package brings the Redist.Shared package of its architecture, with the VisioForge_MFP*.dll and VisioForge_MFPX*.dll its filters load (and vcomp140.dll on x64). An application that is not x64 and calls PushFrameBgra or PushFrameBgr24 also references Redist.Shared of its own architecture (.x86 or .arm64) for the color conversion.

Register the Filters¶

The source filters must be COM-registered once on the machine, with administrator rights. The redist package copies them to the application folder:

using System;
using System.Diagnostics;
using System.IO;

var dir = AppContext.BaseDirectory;
var args = $"/s \"{Path.Combine(dir, "VisioForge_Virtual_Camera_x64.ax")}\" " +
           $"\"{Path.Combine(dir, "VisioForge_Virtual_Audio_Card_x64.ax")}\"";

// One UAC prompt for both filters.
var info = new ProcessStartInfo(Path.Combine(Environment.SystemDirectory, "regsvr32.exe"), args)
{
    UseShellExecute = true,
    Verb = "runas",
};

using (var process = Process.Start(info))
{
    process.WaitForExit();
    if (process.ExitCode != 0)
    {
        throw new InvalidOperationException($"regsvr32 failed with exit code {process.ExitCode}.");
    }
}

The consumer application loads the filter build that matches its own bitness, whatever the bitness of the application that pushes the frames. The x64 filters above serve 64-bit Zoom, OBS and browsers. For 32-bit consumers, also register VisioForge_Virtual_Camera.ax and VisioForge_Virtual_Audio_Card.ax from the .x86 redist; for ARM64-native consumers, VisioForge_Virtual_Camera_arm64.ax and VisioForge_Virtual_Audio_Card_arm64.ax from the arm64 subfolder that the .arm64 redist creates in the application folder.

An installer can register the same files instead; see Filter Registration.

Push Video¶

using VisioForge.VirtualCamera;

const int width = 1280, height = 720;

// The last argument is your Virtual Camera SDK license key; null shows the TRIAL banner.
using (var video = new VirtualVideoWriter(width, height, 30, "VideoStream1", null, "YOUR-LICENSE-KEY"))
{
    video.Start();

    // Every 1/30 s: a BGRA frame, top row first, stride in bytes.
    video.PushFrameBgra(bgraPixels, width * 4);

    video.Stop();
}

VirtualVideoWriter takes frames in three layouts:

The width must be even. PushFrameBgra and PushFrameBgr24 convert to YUY2 natively in VisioForge_MFPX64.dll (VisioForge_MFPX.dll on x86, VisioForge_MFPX_ARM64.dll on ARM64). Each push returns false when no buffer is free, so a slow consumer drops a frame rather than blocking your thread.

Push Audio¶

// 48 kHz stereo 16-bit PCM for the "VisioForge Virtual Audio Card" microphone.
using (var audio = new VirtualAudioWriter(48000, 2, 16, "AudioStream1", null))
{
    audio.Start();

    audio.PushSamples(pcmBytes); // a whole number of 4-byte sample frames

    audio.Stop();
}

Timestamps come from the number of bytes pushed, so push audio at the rate it is played.

Logging¶

The writers take a BaseContext for their warnings and errors; null sends them to System.Diagnostics.Trace. To route them elsewhere, derive from BaseContext and override Error and Warning.

Licensing¶

Without a license key the virtual camera draws a TRIAL strip across the picture. Pass the key you received with your Virtual Camera SDK purchase to the VirtualVideoWriter constructor; the key in HKEY_LOCAL_MACHINE\SOFTWARE\VisioForge\Virtual Camera SDK\License works as well.

Demo¶

The Virtual Camera Push Demo (WPF, C#) in the SDK samples repository draws a moving picture with WPF, pushes it with PushFrameBgra, sends a 440 Hz tone to the virtual microphone and registers the filters from a button.

See Also¶

• Virtual Camera SDK
• Examples