Streaming

The Hyper-V console only shows the basic Hyper-V display, not what the GPU draws. To see the VM with the GPU, GpuVM installs a streaming server inside the VM and opens it with a client on the host.

Components

Component	Where	Role	Pinned version
Sunshine	VM	Captures the virtual display and encodes with NVENC.	v2026.914.233613
Virtual Display Driver	VM	A monitor drawn by the GPU.	25.7.23
nefcon	VM	Command-line driver installer; creates the virtual display device.	v1.14.0
VB-CABLE	VM	Virtual audio cable that Sunshine captures.	Pack45 (3.3.1.7)
Moonlight	Host	Shows the VM.	Installed separately

The installers are downloaded on the host when the VM is created, verified against the SHA-256 pinned in streaming/components.json and copied to the VM’s disk. The guest downloads nothing. They are kept in a cache folder (in %ProgramData%\GpuVM when installed).

nefcon is pinned to v1.14.0, the version the official VDD install script uses, even though v1.21.0 exists.

Sunshine

Sunshine runs inside the VM. Its username and password are generated when the VM is created; on the host they are stored encrypted with DPAPI. The password travels in plain text to the guest only for the install and is deleted afterwards.

Each time you start and open a VM, GpuVM reads Sunshine’s display list through its API, sets output_name to the virtual display and dd_configuration_option to ensure_only_display, and restarts Sunshine if that changed. This avoids capturing the Hyper-V display by mistake.

Virtual display

The Virtual Display Driver adds a monitor drawn by the GPU. It is installed with nefcon, and only the certificate that signed the driver is trusted.

• After the first boot the VM restarts once on its own to finish registering the virtual display and the audio.
• If the virtual display works, the Hyper-V display is turned off so Windows and Sunshine use the virtual one (disableHyperVVideo in the profile).
• If something fails, the VM is still reachable over Remote Desktop.

Caution

Don’t use Remote Desktop while streaming: it takes the console session away. GpuVM moves the session back to the GPU display on the next start and open if it has the guest password.

Moonlight

Moonlight on the host shows the VM. Pairing is automatic: Moonlight generates the PIN and GpuVM hands it to Sunshine through its API. The paired client is this PC’s name.

• To pair again: Volver a emparejar Moonlight in the app’s menu, or ./gpuvm.ps1 connect -Name <vm> -Pair.
• The resolution and FPS are set in the app’s Options, or per connection:

./gpuvm.ps1 connect -Name win11 -Resolution 2560x1440 -Fps 120 -BitrateKbps 40000 -Codec HEVC

Codecs: auto, H.264, HEVC, AV1. Moonlight opens the Desktop app of Sunshine by default.

Audio with VB-CABLE

Hyper-V Generation 2 VMs have no sound card, so GpuVM installs VB-CABLE, a virtual audio cable whose driver has a Microsoft WHQL signature (no Windows warning), and Sunshine captures its output (virtual_sink).

• The install is silent, as its distribution license allows as long as the origin is credited and the user can donate.
• The original package is left in C:\GpuVM\VB-CABLE inside the VM, with a LEEME.txt (read me) file.
• virtual_sink is set by the VM after its automatic restart, and checked again on every Encender y abrir (Start and open) when the VM’s Windows password is saved. The cable’s output is found by device type, not by name, because Windows translates it (CABLE Input in English, Altavoces in Spanish).

Credit

VB-CABLE is donationware by VB-Audio Software (vb-cable.com). If you use it, consider supporting VB-Audio.

Profile settings

The streaming section of the profile sets the defaults:

"streaming": {
  "provider": "sunshine",            // or "none" to create the VM without streaming
  "virtualDisplay": true,
  "disableHyperVVideo": true,
  "audio": "vbcable",                // or "none" to skip audio
  "sunshine": { },                   // extra keys for sunshine.conf
  "client": { "app": "Desktop", "resolution": "1920x1080", "fps": 60, "bitrateKbps": 0, "codec": "auto" }
}

client also accepts vsync, framePacing, performanceOverlay (true/false) and displayMode (fullscreen, windowed, borderless). They are only passed to Moonlight when the profile defines them.

Updating components

./gpuvm.ps1 components-update -WhatIf   # see whether newer versions exist

It looks up the latest GitHub release of each component and updates version, URL and SHA-256 in streaming/components.json. VB-CABLE isn’t published on GitHub and is updated by hand. A new version isn’t tested: validate it in a lab before creating VMs with it. The app can’t run this command.