feat(host): default the Windows AMF encode input to zero-copy D3D11

On-glass A/B on the Ryzen 7000 iGPU (1080p120 HDR P010, hevc_amf,
PUNKTFUNK_PERF stage split): the system-memory readback costs the encode
thread 2.7-2.9 ms p50 (6.6 ms p99) per frame in submit; the zero-copy D3D11
pool path does the same work in 0.26 ms p50 (0.5 ms p99) — and on an iGPU the
readback also burns the shared memory bandwidth the game needs. The docs-site
already promised "on by default ... D3D11 on Windows" since the Linux flip
(2f9e61d was Linux-only); the Windows code now delivers it.

PUNKTFUNK_ZEROCOPY becomes a tri-state override: unset defers to a per-vendor
default in zerocopy_enabled(vendor) — ON for AMF (validated above; open
failures still fall back to system-memory readback), OFF for QSV until it is
validated on Intel glass (the fallback only catches *setup* errors; a QSV
derive that opens but maps wrong would corrupt silently, so probe-never-assume
applies). Explicit values force either way: 0|false|off|no = readback,
anything else = zero-copy, so the old presence-style =1 keeps working.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
2026-07-06 14:36:43 +02:00
parent 06d594bc2a
commit 8fb126482e
3 changed files with 41 additions and 27 deletions
+1 -1
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@@ -36,7 +36,7 @@ On Linux the host **rewrites `WAYLAND_DISPLAY` / `XDG_CURRENT_DESKTOP` / `XDG_RU
|---|---|---|
| `PUNKTFUNK_COMPOSITOR` | `kwin` · `mutter` · `gamescope` · `wlroots` (aliases: `kde`/`plasma`, `gnome`, `sway`/`hyprland`) | Which backend creates the virtual display. **Leave unset to auto-detect;** set only to force one. |
| `PUNKTFUNK_VIDEO_SOURCE` | `virtual` · `portal` | `virtual` creates a per-client display at the client's exact mode (the normal choice). `portal` captures an existing monitor instead. |
| `PUNKTFUNK_ZEROCOPY` | `1` · `0` *(default on)* | GPU zero-copy capture→encode (dmabuf → CUDA → NVENC, or D3D11 on Windows). **On by default** — no need to set it; it falls back to a CPU path automatically. Set `0` to force the CPU path. |
| `PUNKTFUNK_ZEROCOPY` | `1` · `0` *(default on)* | GPU zero-copy capture→encode (dmabuf → CUDA → NVENC, or D3D11 on Windows). **On by default** — no need to set it; it falls back to a CPU path automatically. Set `0` to force the CPU path. One exception: Windows **Intel/QSV** keeps the CPU path by default until zero-copy is validated on Intel hardware — set `1` to try it there. |
| `PUNKTFUNK_INPUT_BACKEND` | `libei` · `gamescope` · `wlr` · `uinput` | How input is injected. `libei` for GNOME/KDE, `gamescope` for Bazzite/gamescope, `wlr` for Sway/wlroots. Auto-detected with the compositor. |
| `PUNKTFUNK_ENCODER` | `auto` · `nvenc` · `vaapi` (Linux) · `amf` · `qsv` (Windows) · `software` | Encoder backend. `auto` (default) detects the GPU vendor: NVIDIA→NVENC, AMD→VAAPI/AMF, Intel→VAAPI/QSV. `software` (aliases `sw`/`openh264`) is the GPU-less H.264 path on both platforms — on Windows `auto` falls back to it when no GPU is found; on Linux it is **explicit-only** (`auto` never picks it). |
| `PUNKTFUNK_RENDER_NODE` | path | Linux DRM render node for zero-copy (default `/dev/dri/renderD128`). Set on multi-GPU boxes to pick the right GPU. |