Research On Video Compression Technology And Video Encoding Based On Mpsoc

With the development of video compression teconology, especially the emergment of H.264international standard, the performance of video encoding based on uniform block has been advanced. Int recent years, a hot spot in video domain is how to improve video compression performance further. In this dissertation, from the view point of non-uniform block model, we focus on the following fields:compression of the bi-directional predicted frame, the inter frame motion modeo and the discrete cosine transform.Image matching using multiresolution critical point filters (CPF) is based on elastic model, which is effective in expressing non-translational motion. The elastic model is sensitive to occlusion, and we propose an occlusion refine modeo to release the part-occlusion problem in the interpolated image. To solve the boundary correspondence convergent problem, we propose an unconstrained boundary extension (UBE) approach, which can improve the visual quality of interpolated image at image boundary.Image interpolation based on CPF matching is employed to compression of bi-directional predicted frame. By direct frame skip coding, the bit rate can be reduced by5-15%, while maintain comparative image quality at low and medium bitrate; At high bitrate, with a little loss of quality, direct frame skip coding can save about10-20%bit rate. To solve the model failure problem, we propose a frame skip coding method with local compensation (LC). With LC, the quality of skipped frame is enhanced, and the bit rate saving range from5%to20%at different bitrates, when compared to the traditional IBPBP coding structure.Traditional motion estimation utilized rectangle based block partition, which does not fit with the curved edges of motion objects. To further reduce the error data after motion estimation, we propose a hybrid block partition approach, in which the image is first partitioned by uniform block, and then the uniform block is partitioned by a poly-line. Experimental results show that the polyline based partition method can improve the compression performance by0.2-0.3dB, compared to the tree structure based partition. Furthermore, to enhance the efficiency of2D-DCT, we propose a new DCT method, which is called Reorder DCT (RDCT). When combined with the hybrid partition approach, RDCT can achieve PSNR gain of0.2-0.3dB from low to high bitrate.The improvement of compression efficiency also leads to the increasement of complexity. Multi-processors system on chip (MPSOC), a parallel computation system, is suitable for video compression. When applying MPSOC to video encoding, some problems need to be solved, which include memory optimization, schedule of multiple processors, and so on. In this dissertation, by implementing MPEG4encoder on the media MPSOC (MediaSOC3201A) designed by our lab, we research on the aspects of memory optimization and MPSOC schedule.To overcome the drawback of a single processor with limited program memory, we develop a program overlap technique based on master-slave interaction mode. Results show that it can save the program memory size by33.6%for the slave processor responsible for MPEG4encoding. To simplfy the scheduling between different processors, we propose an object oriented scheduling model, according to the coarse grain data flow graph (CGDFG). By using the object oriented scheduling model, the encoding efficiency of MPEG4encoder can be enhanced by33.19%.