Research On Fast Mode Decision Algorithms Of Video Coding

Along with the development of network and multimedia technology, video application has become more and more important to people's life and work, The development of technology provides people with a better experience and the high demand for experience also led to the development of technology. Video encoding technology is developing with technology blends and user needs, and gradually formed to the standard of H.265 and H.264 as the leading one. Although it improves the efficiency of encoding with the use of techniques such as inter frame prediction, multi reference frame, block matching, and multiple segmentation methods, the encoding complexity is increasing sharply. Traversing the full mode greatly increases the encoding time with the use of multi prediction model in inter frame encoding, which limits its application range, especially in the field of video surveillance, video phone, video conference, live broadcast and so on.In order to reduce the inter frame encoding complexity and to shorten the encoding time,this paper studies the part of inter frame mode decision. First this paper introduces the related mode decision process, including motion search criteria and model selection cost function,describes the traversal mode process in inter frame encoding, and introduces the JM reference model and the JM mode selection algorithms. Then studies the P frame fast mode decision algorithms, and designs the P frame fast mode decision scheme based on temporal-spatial correlation by using the prejudgment method based on space-time adjacent blocks, the mode combination strategy of motion consistency, the intra mode decision method based on spatial-temporal analysis. Next, studies the B frame fast mode decision algorithm, using the prejudgment method based on adjacent blocks, the method based on image texture analysis in the horizontal and vertical direction of the image and the method of determining prediction direction based on the B frame adjacent blocks. Finally combines with P, B frame mode decision method, designs the final scheme of inter frame fast mode decision.The proposed methods are implemented in the JM reference model, and tested on a number of sequences and QPs. The experimental results show that the proposed P frame fast mode decision scheme can reduce about 55%-65% of encoding time compared with JM, and the proposed inter frame fast mode decision scheme can reduce about 42%-68% of encoding time compared with JM, while PSNR and bitrate are almost the same. It is proved that the proposed P frame fast mode decision scheme and the proposed inter frame fast mode decision scheme are effective.