Hi,
Please refer to the samples to map NvBuffer to cv::gpu::gpuMat in gstreamer or jetson_multimedia_api:
[gstreamer]
Nano not using GPU with gstreamer/python. Slow FPS, dropped frames - #8 by DaneLLL
[jetson_multiemdia_api]
LibArgus EGLStream to nvivafilter - #14 by DaneLLL
NVBuffer (FD) to opencv Mat - #6 by DaneLLL