Research On Reducing Block Artifacts In Video Coding And Driver Program In DSP System

Block artifact is a major causation of reducing the quality of picture in video coding, especially when the bit rate is low. Supported by the national high technology research and development program of China (863 Program) "Joint Source-Channel Coding"(No.2002AA119010), the work introduced in this dissertation has researched the algorithm of reducing the block artifact in video coding. And under the support from Key Science and Technology Item Foundation of China National Education Ministry for the project "Key Technologies in Modern Distance Learning: Interactive Real-time Education Software Tools" (No.2000175), this dissertation also researched the boot and control algorithm of the video coder used in DSP system.Video coding is now changing its international standard at its zero hour. The new emerging H.264 exceeds original MPEG-4 in great part because of its better quality in many aspects, and become the first choice of the video coding standard in future generation. At the same time, China is applying herself of establishing the first national audio and video coding standard (AVS for short).An overview of the relative international standards is given in this dissertation firstly. Then analyses the main technologies in H.264 and AVS, including quantization and transform coding, motion estimation and compensation, and entropy coding. Then analyses the causation of the block artifacts, which reduce the visual quality of video coding, and gives a summary of the research in detecting and reducing block artifacts. After comparing these algorithms, designs and improves a filter algorithm to reduce block artifacts based on the content in AVS, which uses smooth filter of different granularities depending on different block artifact strengths. It reduces the block artifacts effectively and protects the true details in the picture, which improve the visual quality of decoded pictures. The video coding test based on standardized HDTV sequences shows the biggish enhancement in objective and subjective quality of our algorithm.After that an approach for the video codec used in the tele-monitor is given. The principle of development of DSP system based on the DSP chip trimedia PNX1300 is discussed. Then discusses the key technology to design a boot program based on the PNX1300. Shows the pSOS operating system, as well as the multi-task management method of the multimedia process system based on the pSOS operating system. And then designs a control program of multimedia system using the multi-task management method. Lastly the thesis draws a conclusion and points out future research directions.