Three encode-time fixes from the 4K120 field analysis (sessions pinned ~107 of
120 fps, 14-15 ms reported encode):
- Ceiling truth: the codec-level bitrate clamp (binary search at session open)
now records its result in a process-lifetime advisory cache keyed by
GPU/config, so an ABR overshoot opens — or in-place reconfigures — straight
AT the ceiling instead of re-running the ~6-open search (and a full rebuild
+ IDR) on every overshoot. New `Encoder::applied_bitrate_bps()` exposes the
post-clamp rate so the session loop can stop pacing/acking a phantom
requested rate (consumed host-side in a follow-up).
- Clamp-search hygiene: only NVENC parameter/caps rejections steer the search
now (`NvCallError` keeps the raw status downcastable); a transient failure
(busy engine, session limit, OOM, driver skew) propagates instead of
shrinking into — and now caching — a bogus ceiling. The floor fallback also
records the split mode it actually opened with, so a later reconfigure
re-presents the real session params.
- Split-frame selection: one shared `resolve_split_mode` replaces the two
byte-identical direct-SDK copies; the force-2-way threshold moves to
`SPLIT_FORCE_PIXEL_RATE` (950 Mpix/s, shared with the libav path) because
4K120 = 995,328,000 px/s missed the old `> 1e9` gate by 0.47% and stayed on
AUTO — which never engages at 2160 px height, leaving the second NVENC
engine idle in exactly the mode the threshold existed for. The Linux
session-ready info! line now carries the final split mode (journals are
INFO+; this was undiagnosable from user logs).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehlerandClaude Fable 5
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