The Windows host pegged the GPU 3D engine at ~97% during high-fps desktop streaming — measured (per-
process GPU-engine counters) as OUR process, not DWM. Cause: TWO VRAM->VRAM CopyResource per frame
(dupl->gpu_copy in the capturer, then gpu_copy->nvenc_pool in the encoder), and on Windows D3D11
routes copies to render-target textures through the 3D engine (the DMA copy engine sat idle at 7%),
so at 240 fps they saturate it and contend with a game's own rendering.
Eliminate the second copy: NVENC now registers the capturer's D3D11 texture directly (cached by raw
pointer, the cloned texture kept alive until unregister) and encode_pictures it IN PLACE — no
encoder-owned input pool, no per-frame copy. Safe because the host encode loop is synchronous
(capture -> submit -> poll, where lock_bitstream blocks until the encode finishes), so the capturer
never overwrites the texture mid-encode; documented in the module header in case that ever changes.
2 GPU copies/frame -> 1 (the remaining dupl->gpu_copy is unavoidable; that DXGI surface is transient).
Measured: SM/compute ~10-15% at ~217 fps 5K (was ~20% at only ~48 fps with two copies), 3687 frames
decoded clean. Windows-only; Linux/macOS unaffected.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
enricobuehler
5e665c2c3e