IN a system on chip (SoC) for adaptively adjusting a bit rate, the SoC includes a central processing unit (CPU) configured to compare a first reference bit rate with a bit rate of a previous frame and to output a first parameter, a spatial filter configured to adjust a cutoff frequency using the first parameter, to filter high-frequency components from a current frame using an adjusted cutoff frequency and to output a filtered current frame, and a video codec configured to adjust a bit rate of a current macroblock in the filtered current frame using a second parameter generated according to a result of comparing a second reference bit rate with a bit rate of a previous macroblock in the filtered current frame.