Efficient Fast Intra Mode Decision and Classified Block Type Algorithms for H.264/AVC Encoder

H.264, MPEG-4 Part 10, is the latest digital video coding standard that achieves very high data compression by using several new coding features. One of the key features is the intra prediction based on the rate distortion optimization (RDO) procedure, which requires a true encoding of the intra block by trying all intra prediction modes. The computational burden of intra prediction with the RDO procedure is extremely high for real time applications. In this paper, we propose a classified block type (CBT) algorithm that selects the appropriate intra block size and further our proposed subblock based direction detection (SDD) algorithm processes the selected block that reduces a number of candidate mode required for RDO which significantly reduces the encoder complexity. Experimental results show that the proposed fast mode decision algorithm reduces the encoding time by about 68%, with negligible loss of video quality.