(An) efficient assignment of the intra frames for H.264

Abstract

Video sequences often have many shot transitions and fast motion. The coding efficiency of those sequences is generally low, and buffer overflow or severe degradation can occurs. The most crucial reason of these problems is that encoder uses fixed arrangement GOP (Group Of Picture). Although encoding with a fixed assignment of picture type may reduce computational complexity, it does not help to compress efficiently and does not utilize shot features. Therefore, video can be compressed further by taking advantage of scene transitions and this enables the effective placement of reference frames. To utilize these advantages, adaptive GOP algorithm is required. Our proposed algorithm for constructing this adaptive GOP structure is composed as follows. First, a criterion of correlation measure is proposed to estimate the scene change. And next, the new decision method for assignment of intra frame is proposed. Finally, intra QP rule for avoiding buffer overflow and fluctuation of image quality is also proposed. Our proposed algorithm has a drawback of just one-second initial delay so that it is not proper for real-time mobile communication, but streaming service with short initial delay is sufficiently possible.