A virtual frame rate control algorithm for efficient MPEG-2 video encoding

This paper presents a virtual frame rate control algorithm and a bit allocation algorithm at frame level for efficient MPEG-2 video encoding. The proposed frame rate control scheme is composed of three steps. At the first step, the scan format of an input video sequence is converted into a progressive scan format before video encoding. At the second step, an average motion activity of the frames within a previous temporal window of a pre-defined size is examined, and a proper frame rate of a current temporal window is adaptively determined based on the computed average motion activity. At the final step, the frames located at particular positions in a current temporal window are virtually skipped according to the determined frame rate. We can skip the selected frames by deliberately fixing the coding types of all the macroblocks in those frames to ´skipped MB.´ We also propose a modified version of MPEG-2 TM5 bit allocation algorithm suitable for virtual frame rate control. Experimental results show that the proposed algorithm noticeably improves the coding efficiency in comparison with conventional MPEG-2 video encoding.