NVIDIA HEVC Video Encoder Settings
You can select the settings of the NVIDIA H264 preset. Each Preset is a predefined group of encoding settings, designed to facilitate the user. You can also specify the Profile and Level in the corresponding fields. Further down in the Generic area, you can define GOP length.
•For PAL set the Max GOP length to 
•For NTSC set the Max GOP length to 
Rate Control area
The Rate Control area allows you to modify the input video encoding Mode.
Depending on the Mode, you can set different values.
For all modes in the drop-down list, except the Constant quantizer mode you can set the minimum Bit-rate speed in kbits/sec, and for Constant quantizer you can enter different values for the Frame QPs in the respective field.
For all Variable bit rate modes you will be able to specify the Maximum VBR Rate in kbits/sec.