How does NvOSD works?

HI guys,
I’m interested to know how NvOSD API draw rectangle and other shapes and text on frame. Does it use shader and GPU or CUDA resource for drawing OSD or use CPU method like opencv ?
Thanks so much

Please refer to the plugin document Gst-nvdsosd — DeepStream 6.1.1 Release documentation (nvidia.com), it can leverage dGPU or VIC(Jetson) to accelerate the drawing.