GstVCam

Windows 11 Media Foundation virtual camera backed by a GStreamer pipeline (NV12 -> appsink).

What It Is

• VCamSampleSource (DLL): the Media Foundation virtual camera source loaded by Windows Frame Server.

At runtime, the source reads pipeline settings from registry and pushes frames from GStreamer appsink into the virtual camera stream.

Requirements

• Windows 11 (virtual camera API support)
• Visual Studio C++ build tools
• GStreamer MSVC x64 runtime installed, typically:
  • C:\Program Files\gstreamer\1.0\msvc_x86_64
• GStreamer bin in System PATH:
  • C:\Program Files\gstreamer\1.0\msvc_x86_64\bin

Build

• Build x64 (Debug or Release) from VCamSample.sln.

Register / Unregister

Run as Administrator from the folder containing VCamSampleSource.dll:

regsvr32 VCamSampleSource.dll

Remove:

regsvr32 /u VCamSampleSource.dll

Pipeline Configuration

Registry key:

• HKLM\SOFTWARE\VCamSample\GStreamer

Values used:

• Pipeline (REG_SZ)
• Width (DWORD)
• Height (DWORD)
• FpsNumerator (DWORD)
• FpsDenominator (DWORD)
• LogEndpoint (REG_SZ, example: tcp://192.168.120.1:5555)

Example pipeline:

videotestsrc is-live=true ! videoconvert ! video/x-raw,format=NV12,width=1280,height=960,framerate=30/1 ! appsink name=vcamsink

Logging

• File log: C:\gstvcam_trace.txt
• Includes source startup, pipeline state, bus errors/warnings, and frame fallback messages.

TCP kick lifecycle

• The source opens a TCP connection to LogEndpoint before GStreamer pipeline startup.
• If TCP connect fails, stream start fails (pipeline is not started).
• The source closes the TCP connection immediately after pipeline stop/shutdown.
• TCP is used for lifecycle coordination only; logs are not forwarded to this socket.

Troubleshooting

• The specified module could not be found on regsvr32 usually means missing dependency DLLs (often GStreamer runtime not resolvable).
• Ensure architecture matches (x64 DLL with x64 GStreamer).
• Ensure output DLL path is accessible by Frame Server service accounts.