Zero-copy capture->encode on the GPU via the raw NVENC API (nvidia_video_codec_sdk sys + ENCODE_API; the safe wrapper is CUDA-only). Opens an NV_ENC_DEVICE_TYPE_DIRECTX session on the SAME ID3D11Device as the DXGI capturer (carried on the new FramePayload::D3d11), registers a pool of BGRA textures once, CopyResources each captured texture in and encode_picture; CBR/ULL, infinite GOP, P-only, forced-IDR for RFI. The DXGI capturer gains a D3D11 zero-copy output (selected, like the encoder, by PUNKTFUNK_ENCODER=nvenc) so capture+encode share textures.
OFF by default (the nvenc feature pulls the NVENC SDK + cudarc): the default Windows host links without it (openh264 path). cudarc builds toolkit-less via the SDK ci-check feature (dynamic-loading). At link time --features nvenc needs nvencodeapi.lib (NVENC SDK, or an import lib generated from the driver's nvEncodeAPI64.dll) on PUNKTFUNK_NVENC_LIB_DIR. Both default and --features nvenc builds validated to compile+link GPU-less on the VM (import lib generated from the driver DLL). Runtime needs a real NVIDIA GPU.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
