Fast intra-prediction mode decision in H.264 advanced video coding

H.264/AVC, the latest video coding standard, achieves better video compression rates since it supports new features such as a large number of intra- and inter-prediction candidate modes. H.264/AVC adopts rate-distortion optimization (RDO) technique to obtain the best intra- and inter-prediction, while maximizing visual quality and minimizing the required bit rate. However, the RDO reduces the encoding speed via the exhaustive evaluation of all candidate modes. In this paper, we decrease the encoding time by reducing the computational complexity of the prediction function and the number of candidate modes. First, we improve Pan's method, by eliminating the DC mode from the candidates. Second, a new method based on the statistical properties of references pixels and adjacent blocks is proposed. Since the two methods utilize different properties of a block, they are combined together to reduce the number of candidate modes in intra prediction. Subsequently, the RDO procedure uses the reduced subset of all candidate modes for extracting the final mode. Experimental results show that our algorithm, compared to the RDO and Pan's algorithms, reduces the total encoding time with negligible loss in PSNR and a slightly increased bitrate.