punktfunk/docs-site/content/docs/windows-host.md

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Windows Host	Run the punktfunk streaming host on a Windows PC — a first-class, all-vendor, virtual-display host.

Set up a punktfunk host on a Windows 10/11 PC and stream its desktop or games to any punktfunk or Moonlight client. A signed installer registers a Windows service that streams at the client's exact resolution and refresh via punktfunk's own virtual display — including HDR10 (10-bit BT.2020 PQ) when your Windows desktop is in HDR mode. The virtual display is created on the fly, so you need no second monitor and no dummy HDMI plug, and capture keeps working even on the secure desktop (UAC prompts, the lock screen).

New to this? Skim Requirements first.

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 or 11, x64. ARM64 is not built (no ARM64 NVIDIA driver, and the virtual-display driver is x64-only).

• A GPU for hardware encode — the host auto-detects the vendor:

  • NVIDIA → NVENC
  • AMD → AMF
  • Intel → QSV

  No discrete GPU? The host falls back to a software H.264 encoder (higher CPU use, lower quality — fine for light desktop use).

• No gamepad prerequisite. The virtual gamepad drivers are bundled in the installer — there is nothing else to download. (Earlier builds needed ViGEmBus; it is no longer used.)

Install

Download the signed punktfunk-host-setup-<ver>.exe from the package registry and run it. The installer:

• drops the host into C:\Program Files\punktfunk and registers + starts the PunktfunkHost service,
• installs the bundled virtual-display driver (pf-vdisplay) so the host can create per-client displays,
• installs the bundled virtual gamepad drivers (DualSense, DualShock 4, Xbox 360),
• registers the bundled HDR Vulkan layer so Vulkan games can enable HDR over the virtual display,
• sets up the web management console (see below).

For an unattended install, append /VERYSILENT. Upgrades and uninstall go through Add/Remove Programs; your config and pairings are kept across upgrades. Prefer the CLI, or want the full service/firewall details? See Running as a Service → Windows. Packaging internals live in packaging/windows.

Web console & pairing

The installer also sets up the web management console (status, paired devices, the PIN pairing flow): it bundles the console plus its own runtime and runs it as the PunktfunkWeb service on http://<this-PC>:3000, starting at boot. During setup you choose the console login password (pre-filled with a secure random default and shown again on the final page); change it later in %ProgramData%\punktfunk\web-password.

The host requires PIN pairing by default (secure on a LAN). To connect the first time, open the console from any browser on the LAN, log in, go to Devices → arm pairing, and enter the PIN on your client. The host's own management API stays loopback-only behind the console.

Configure

The service reads %ProgramData%\punktfunk\host.env. The defaults work out of the box; common knobs:

• PUNKTFUNK_ENCODER=auto — auto picks NVENC/AMF/QSV by GPU vendor. Force one with nvenc, amf, qsv, or sw (software).
• PUNKTFUNK_HOST_CMD — the service runs serve --gamestream by default (native punktfunk/1 plus the GameStream/Moonlight-compat planes). Set it to serve for a secure native-only host with no GameStream surface (GameStream pairs over plain HTTP and uses weaker legacy encryption — trusted LAN only).

Edit the file, then restart: punktfunk-host service stop / punktfunk-host service start. See the Configuration reference for every option.

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 (secure desktop), with a zero-copy path straight from the virtual-display driver; FP16/10-bit when the desktop is HDR
Virtual display	KWin / Mutter / Sway / gamescope	pf-vdisplay signed IDD — create a WxH@Hz monitor per session, capture it, tear it down
Encode	NVENC (CUDA) / VAAPI (AMD·Intel) / software	NVENC (NVIDIA) · AMF (AMD) · QSV (Intel) · software H.264; HEVC Main10 / BT.2020 PQ for HDR
Input — mouse/keyboard	libei / wlr protocols	SendInput (Win32 VK + absolute mouse)
Input — gamepads	uinput Xbox 360 + UHID DualSense/DS4	UMDF virtual pads — DualSense, DualShock 4, Xbox 360 (XUSB) + rumble
Audio capture	PipeWire sink-monitor	WASAPI loopback
Virtual mic	PipeWire Audio/Source	WASAPI virtual mic

The virtual display uses pf-vdisplay, punktfunk's own all-Rust Indirect Display Driver (IDD) — the host pushes finished frames straight into it, so you get a real virtual display with no physical monitor or dummy plug. The installer bundles and stages the (self-signed) driver; if it isn't installed, the host falls back to capturing an existing monitor, losing the per-client native-resolution output.

HDR

When your Windows desktop is in HDR mode, the host captures it as 10-bit, encodes HEVC Main10 / BT.2020 PQ, and the client auto-detects HDR from the stream. A small always-on Vulkan layer (bundled and registered by the installer) also lets Vulkan games enable HDR over the virtual display — something the NVIDIA/AMD drivers otherwise refuse on an indirect display. The layer is self-gating: it's a no-op on SDR and on real monitors. HDR is Windows-only (the Linux host is 8-bit, blocked upstream).

Notes & limits

• AMD / Intel encode is newer. The NVENC path is the most exercised; AMF (AMD) and QSV (Intel) are built and tested in CI but less battle-tested on real hardware. Software H.264 is the GPU-less fallback.
• x64-only. No ARM64 build — no ARM64 NVIDIA driver, and the virtual-display driver 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 AMD/Intel encode backends the youngest pieces.

Trouble? See Troubleshooting and Pairing.