The session loop's pipeline deferral was designed around direct NVENC, whose
poll() BLOCKS in lock_bitstream; libavcodec's AMF wrapper is truly async
(EAGAIN until the ASIC finishes), so a single non-blocking receive quantized AU
retrieval to the submit cadence: +1–2 frame periods flat (~43 ms p50 at 720p60
on the Ryzen iGPU vs ~3.5 ms of actual encode). FfmpegWinEncoder now tracks
in-flight frames and, while an AU is owed, spin-polls with short sleeps bounded
to ~2 frame periods (an overloaded encoder degrades to next-tick pickup instead
of stalling capture). Also: quality=speed (latency-first, iGPU-class VCN),
explicit bf=0 (h264_amf defaults >0 on RDNA3+), AMF low-latency submission
mode (FFmpeg ≥6.1, ignored on older).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehler
8e8b536dae