The Windows host capped at ~60 fps with 35-40 ms latency on a GPU-heavy game:
the per-frame capture→encode path shared the 3D engine with the game and got
scheduled behind it. Rework to minimize 3D-engine work per frame:
- VideoConverter (D3D11 video processor): capture → NVENC-native NV12/P010 so
NVENC skips its internal RGB→YUV (a 3D/compute step). Wired into both DDA
(dxgi.rs) and WGC (wgc.rs). New PixelFormat::Nv12/P010 + NVENC YUV input.
- GPU scheduling hardening (Apollo-style): D3DKMTSetProcessSchedulingPriorityClass
HIGH, absolute SetGPUThreadPriority, SetMaximumFrameLatency(1).
- WGC SDR zero-copy (hold pool frames; no CopyResource). DDA keeps a fast
CopyResource to decouple its single-frame acquire/release from the async convert.
- Pipelined helper encode loop (PUNKTFUNK_ENCODE_DEPTH, default 1) + perf split
(cap_wait / encode / write).
Live on the RTX 4090: hard 60 fps ceiling removed (now scene-scaling 40-200+),
latency much reduced. Residual cap in GPU-pinned scenes is the irreducible RGB→YUV
convert (no fixed-function unit on NVIDIA — VideoProcessing engine reads 0%) waiting
behind an uncapped game under WDDM context time-slicing; Linux avoids it via
gamescope capping the game to the display refresh.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
enricobuehler
11c238e56f