The Research Of Prediction Alogrithm In H.264/AVC

By far, H.264/AVC is the newest video coding standard. Compared with the previous standards, it has a better efficient coding performance, which is based on the complexity of its design for internal structure. In the H.264/AVC coding framework, the prediction process is a very important component of the entire coding process, which takes up a lot of encoding time. In order to solve this problem, two fast prediction algorithms are proposed in this paper.Firstly,the principle of intra prediction and inter prediction in H.246/AVC video coding standard and the whole algorithm process of X264 encoder is analyzed deeply. And then, the mode decision alogrithm of intra prediction and motion estimation and compensation alogrithm of inter prediction is researched in this paper.Secondly, for intra prediction process, a fast intra prediction algorithm which is based on smoothness of the macroblock in the video image is proposed. Considering both smoothness characteristics of the macroblock and direction features of the intra prediction mode, three parameters which shows the smoothness of the marcblock is proposed . Comparing the parameters with the pre-set thresholds, it can determine the specific intra prediction mode. By setting different quantification parameters, experimental results show that the algorithm,which compares to the algorithm of X264 encoder, can reduce more than 30% encoding time while maintaining similar video quality.Finally, a fast motion estimation algorithm is proposed in this paper. By setting the search starting point, the judgement of early exit searching and determining search templete, it can optimize the motion estimation process. By using different motion estimation algorithm on the video sequences, the results show that the PSNR of the reconstructed video image has only a slight decline compared with the full search algorithm and the number of search points obviously drops.