Dynamic Gop Structure Determination for Real-Time MPEG-4 Advanced Simple Profile Video Encoder

MPEG-4 advanced simple profile video provides I, P, and B-type frames in each GOP (group of pictures). To maximize the coding efficiency, it is important to determine the distribution of the three frame types, also called the GOP structure. In this paper, the GOP structure is determined dynamically in real time by using the information, such as Sad (sum of absolute difference) and Mad (mean of absolute difference), generated in the encoding process and little amount of computation is used. The algorithm first determines whether the current frame is an intra-picture or an inter-picture. If it is an inter-picture, one has to decide whether it is a P_picture or a B_picture. No more than 4 consecutive B_pictures can be employed to reduce the video buffer size. The proposed method is tested over a wide range of video sequences at different data rate conditions and produces consistent improvement compared to fixed GOP methods