Regarding overhead of H.264 and VP9, using Intel's QuickSync or AMD's VCE would make sense in a production version, in order to have a fast implementation. That

Regarding overhead of H.264 and VP9, using Intel's QuickSync or AMD's VCE would make sense in a production version, in order to have a fast implementation. That's VAAPI (and maybe VDPAU) on Linux and BSD. The encoders' output will look good enough for video streaming.