Abstract: Focusing on the problem of moving object detection and tracking on MPEG-4 compressed streams by a stationary camera, an algorithm for detecting the moving object using DC coefficients and motion vectors of the motion information in MPEG is presented. The algorithm is first to mark the moving regions based on the motion vectors, then get the moving macro blocks by obtaining the DC coefficient of each marked block in MPEG data and calculating the fourth-order detector of inter-frame difference, and finally obtain the moving object by region growth. The computational complexity of only computing DC coefficients and the detection error only through motion vectors are reduced by the method. The algorithm presented makes the real detecting and tracking of the moving object possible.

Key words: object tracking, DC coefficients, motion vectors, MPEG-4