enricobuehler
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HDR (10-bit BT.2020 PQ) works end-to-end with the Windows host — it captures an HDR desktop (WGC FP16 / Desktop-Duplication FP16 for the secure desktop) and encodes HEVC Main10 to HDR-capable clients (Windows, Android). Only the Linux host is blocked upstream (no 10-bit compositor capture). Corrected the roadmap (grid + shipped/blocked), Windows Host page, status, and CLAUDE.md. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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title, description
| title | description |
|---|---|
| Windows Host | Run the punktfunk streaming host on a Windows PC with an NVIDIA GPU. |
Status: implemented and shipping — NVIDIA-only, x64-only. punktfunk is Linux-first, but it also
runs as a native Windows host: a signed installer registers a LocalSystem service that streams
your Windows desktop or games to any punktfunk or Moonlight client, at the client's exact resolution
via a virtual display — including HDR10 (10-bit BT.2020 PQ) when your Windows desktop is in HDR
mode. It's newer and less battle-tested than the Linux host, and it is built specifically around
NVIDIA hardware. (The Linux host is 8-bit only — HDR there is blocked upstream.)
This page is about the Windows host (streaming from a Windows PC). To stream to a Windows PC, see the Windows client.
Requirements
- Windows 10/11, x64. ARM64 is not supported — both NVENC and the virtual-display driver are x64-only.
- An NVIDIA GPU + driver. The host encodes with NVENC (
nvEncodeAPI64.dll); there is no other encoder backend on Windows. - (Optional) ViGEmBus for virtual gamepads — a manual prerequisite for now (releases).
Install
Download the signed punktfunk-host-setup-<ver>.exe from the package registry and run it — it
installs the host into C:\Program Files\punktfunk, optionally installs the bundled SudoVDA
virtual-display driver, and registers + starts the service. Full steps (including the silent install
and the CLI punktfunk-host service install path) are in
Running as a Service → Windows; packaging internals live in
packaging/windows.
How it works
The host installs a LocalSystem SCM service that runs from Session 0 and launches a worker into
the interactive session (CreateProcessAsUserW). That lets it capture the secure desktop (UAC
prompts, the lock screen) and keep streaming across reboots with nobody logged in — the same model
Sunshine and Apollo use. Service registration, firewall rules, and the supervisor all live in
punktfunk-host service install; the installer just lays the exe down and calls it elevated.
One core, Windows backends
Most of punktfunk is platform-agnostic. punktfunk-core (protocol, FEC, crypto, session, transport,
the C ABI), the QUIC control plane, the GameStream wire logic, the management API, and the per-frame
pipeline orchestration are all shared with the Linux host. The Windows host is a set of
#[cfg(windows)] backends behind the same traits the Linux host uses:
| Subsystem | Linux backend | Windows backend |
|---|---|---|
| Capture | xdg ScreenCast portal → PipeWire (dmabuf) | Windows.Graphics.Capture (+ Desktop Duplication for the secure desktop) → D3D11 texture; FP16/10-bit when the desktop is HDR |
| Virtual display | KWin / Mutter / Sway / gamescope | SudoVDA signed IDD — create a WxH@Hz monitor per session, capture it, tear it down |
| Encode | ffmpeg-next NVENC (CUDA hwframes) |
NVENC with a D3D11 device (--features nvenc); HEVC Main10 / BT.2020 PQ for HDR |
| Input — mouse/keyboard | libei / wlr protocols | SendInput (Win32 VK + absolute mouse) |
| Input — gamepads | uinput Xbox 360 pad + rumble | ViGEm virtual pad + rumble back-channel |
| Audio capture | PipeWire sink-monitor | WASAPI loopback |
| Virtual mic | PipeWire Audio/Source |
WASAPI virtual mic |
The virtual display uses SudoVDA (the Sunshine Virtual Display Adapter) — a pre-built, signed Indirect Display Driver — so there is no kernel driver to author or WHQL-sign. The installer bundles and stages it; if it's absent, the host falls back to capturing an existing monitor (losing the per-client native-resolution output).
Limitations
- NVIDIA-only. NVENC is the only encoder backend — there is no AMD / Intel / software encode path on Windows.
- x64-only. No ARM64 build (no ARM64 NVIDIA driver, and SudoVDA is x64-only).
- Newer than the Linux host. The Linux host is the most battle-tested path; the Windows host is more recent, with the virtual-mic and gamepad backends the youngest pieces.