GB203 has two NVENC engines. A single HEVC p1 session tops out ~1 Gpix/s, so 5120x1440@240
(1.77 Gpix/s) is encoder-bound on one engine; split-frame encode runs it across both (~1.8x,
latency-neutral, output is standard HEVC the client decodes normally). NVENC's AUTO split
won't engage below ~2112px height, so force split_encode_mode=2 when the pixel rate exceeds
~1 Gpix/s (HEVC/AV1 only — not H.264). Below that (e.g. 5K@120) stay single-engine to avoid
the ~2% BD-rate cost. Override with LUMEN_SPLIT_ENCODE. Verified: engages at 240, not at 120.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
enricobuehler
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