Rokchip MPP h264 encoder settings

[Oto Dušek]

Hello, I am trying to use hw h264 encoder on RK3399. Everything works perfectly, but I would like to understand options available for encoder. There is two modes of bitrate control: CBR (constant bitrate) and VBR (variable bitrate). I would like to understand what is the difference betweem those modes. If I set bps_target, bps_min and bps_max to same value in VBR mode, it must be same as CBR. So why the CBR mode is there? One more question. In VBR mode if I change quality (MPP_ENC_RC_QUALITY_*), how it affect resulting video. There is qp parameters. So why is there quality parameter?

Thanks