| The technology of digital audio and video coding is general foundations for the industries of digital audio and video, it has extensive applications in the high definition digital TV, 3G video communication, etc. The first generation of source coding MPEG-2 standard is widely used both at at home and abroad at present, with the progress of technology and the implementation of 3G in our country, the source coding technology of the second generation is coming. Compress technology of higher efficiency, better audio and video quality, lower cost is badly needed for digital audio and video industry. Our country has already possessed stronge foundation in the field of the audio and video at present, but we haven't master core technical standards, relevant enterprise had to be enslaved by foreign enterprises and organizations who hold standardized patents and technologies for a long time. Who using the three standards including MPEG-2, MPEG-4 and MPEG-4 AVC (are abbreviated as AVC, claims JVT, H. 264) needs to pay the high use fee for American lawyer's company MPEG LA. Therefore Audio Video coding Standard Workgroup of China that includes Institute of Computing Technology, Chinese Academy of Science and Tsinghua University, etc. was approved and established by the Science and Technology Department of Ministry of Information Industry on June 2002. At the end of 2003, the standard work group exhibits the digital audio and video coding technical standard AVS, through strict tests, the compress efficiency of AVS video coding efficiency reaches 2 times of the international universal standard MPEG-2 at present, equal to MPEG-4 AVC, AVS is superior to MPEG-4 AVC in realizing complexity and high-definition application and of the international leading level. Because of the needs for compress technology of mobile picture, the sixth part of AVS standard-Mobile video (AVS-M ) to meet figure store media , network flow media , multimedia communication, etc. is made. AVS-M to small picture show of 3G application and it is a video coding standard which faces mobile communication of new generation. The proposition of AVS-M video coding standard, not only change the situation that the source code technological MPEG-2 of first generation has been already out of date, but also make China have our own core technical standard and satisfy the demands badly of industry's development of digital audio and video of our country at the same time .Because AVS-M is the video coding standard which China puts forward and it is later than H.264, MPEG-4 and other new standards, AVS-M is still unripe , not perfect. Also there is no ripe portable AVS-M solution, the ultilization of AVS-M in the new mobile communication faces many difficulties. At the same time every foreign systematic manufacturer and chip supplier do not have AVS-M special-purpose video coding chip, which has limited the popularization and application of AVS-M too. This paper describes characteristics of AVS-M, propose and realize AVS-M video coding scheme based on the common use multimedia processor-TMS320DM642. The research of this paper can realize the application of AVS-M encoder based on microprocessor DSP platform, and apply AVS-M to other portable terminals besides PC, thus promote the popularization and application of the digital audio and video standard AVS-M in our country. This paper mainly works on the basis of research and improvement of AVS-M video coding algorithm, AVS-M encoder scheme proposed and realizing on TMS320DM642 DSP platform. Regard this design plan as the centre , this paper has studied various kinds of video compress standards at first, then characterizes of the coding scheme of AVS-M at present, proposes the corresponding improved algorithm, Which reduce the operation amount of AVS-M while guaranteeing quality of the picture. Finally we realize AVS-M video coding on the digital signal processor DM642 platform. Through verifying, the AVS-M encoder, while keeping very high picture quality comparing with higher compression (100:1) to QCIF form picture of the TV quality of the meeting, having realized the real-time code basically, the speed of encoder is up to 27 frames / second. The research contents and achievements of this paper are summarized as follows: (1) Through reading and studying several kinds of commonly used video coding standard, the thought of AVS-M is understood thoroughly. Many kinds of key technology of AVS-M standard including motion estimation and motion compensation is discussed carefully. Further research and optimization to motion estimation and integer transform make AVS-M coder coding faster. (2)This paper further study the AVS-M standard, realize the AVS-M encoder of with C language in VC++6. Experiments results demonstrate that prove the AVS-M encoder code function is correct. (3)This paper has realized the transplantation of AVS-M encoder procedure based on digital processor TMS320DM642 platform, and combine the gathered video data in real time with AVS-M encoder, has realized gather of video data and compression in real time finaly. The corresponding optimization for AVS-M encoder with software pipelining and instruction-level parallelism of DSP make the coding speed of encoder satisfied the requirement. Through verifying, the AVS-M... |
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