An H.263/MPEG video encoder using DCT in a mobile communication terminal. The H.263/MPEG video encoder controls a quantization value using granularity analysis by motion estimation and efficiently controls bit rates. The H.263/MPEG video encoder performs DCT for an input image (N−1), quantizes the input image to output the input image as a video stream, decodes the quantized signal by means of inverse quantization (IQ) and inverse discrete cosine transform (IDCT), and performs motion estimation in comparison with a next input image (N). The H.263/MPEG video encoder includes a granularity analyzing section for analyzing granularity using a result of performing the motion estimation, a granularity control section for controlling a quantization value for the quantization according to an analysis result of the granularity analyzing section, and a frame rate control section for controlling a frame speed of an output of the video stream.