The frame-driven capture loop set its rate-limit floor (`earliest`) relative to
`next`, which is re-based to the instant AFTER submit(). For an async encoder
(NVENC) submit() returns in ~0, so that anchor is ~frame-arrival and the loop
correctly waits for the next vsync — full framerate. But PyroWave's encode is
SYNCHRONOUS (~2 ms inline in submit()), so the anchor lands ~2 ms late every
frame: the loop misses the next arrival and samples one interval behind, making
the period `interval + encode`. That capped a 240 Hz source at ~158 fps (and a
360 Hz request at ~200) with the link and the encoder both idle — no drops.
Anchor the floor to this frame's arrival (`t_cap`) instead. The synchronous
encode now overlaps the interval rather than stacking onto it; the ≥0.9×interval
spacing from the last grab still caps the rate at ~1.11× target. No-op for async
NVENC (t_cap ≈ post-submit there), which is why H.26x already held full rate.
Measured on-glass (5120x1440@240, RTX 4090 host, macOS client): desktop now
holds 240 fps. Also reduces latency (samples fresher frames).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehler
dc20e4452e