What is frame rate? What will happen if I choose a smaller value?

Hi,

What is a frame rate meaning in |NV_ENC_INITIALIZE_PARAMS|? I notice that if I set a smaller number, then the compression ratio will be bigger(bigger bitrate).

If my camera is running at 20fps, but I set the frame rate for the encoder to 10, what will happen? Will I lose frames or just slower encoding speed?

Thanks!