| With the rapid development of mobile Internet and improvement of living stan-dard, people's demands for the mobile Internet products also increase. As an impor-tant part of people's Daily life, the video decoder is particularly outstanding in this respect. Therefore, how to develop high-performance video decoder based on the mo-bile Internet terminals with limited resources becomes the focus of some research.Because of its low bit rate, high definition and high compression ratio, the video compression standard of H264 / AVC is widely applied in video decoders of the mo-bile Internet terminals. But its high performance depends on the increasingly compu-tational complexity and the resource consumption. The research emphasizes: referring to the JM model and taking MTK6253 made by MediaTek for the embedded hardware development platform, to optimize the procedure and the algorithm, to analyze the performance of the time-consuming modules based on the study of basic structure of decoder in the H.264/AVC Standard. The measures can ease the contradiction in re-source using between high-performance algorithm and the hardware development platform so as to develop high-performance video decoders on the mobile equipment with limited computing capability and storage capacity. Furthermore, this paper gives the result of comparison tests on the whole and the key realization.Firstly, this paper introduces the basic structure of the H.264/AVC codec, the key technologies, and emphatically analyses the mainly sub module. At the same time, by taking JM10.1 reference model as the research object, this paper discusses the time-consuming proportion of each module by experiment.Secondly, as for the time-consuming proportion of each module in the reference model, it can take some measures to optimize on the algorithm, especially for the al-gorithms of the CAVLC, the interpolation of subpixel compensation for interframe movement, and the deblocking filter. Meanwhile, testing on the properties for optimi-zation algorithm and analyzing the test results in this paper are to verify the correct-ness of the optimization algorithm finally.Thirdly, the optimization for the structure of video decoders is taken in this part, referring to the mobile Internet terminal: MTK6253, MediaTek Company's product of development platform. In addition, the H.264/AVC algorithm is optimized on proce-dures. In order to optimize the decoders for a better performance, it can make full use of the TCM in order to avoid the processing performance degradation caused by the decoders with limited resources accelerating all the processing procedures.By setting up the start address and the size of the procedures to accelerate specified programs for video decoding, it can achieve the goal of optimization. To solve the existing problem that audio and video can't sync on a processing platform, it can analyze the relation-ship and processing flow between audio and video in depth and put the playing time-stamp in the process.Lastly, this paper optimizes the video decoder of MTK6253 according to the measures of the algorithms, the structures and the procedures mentioned above. The way to get the Benchmark data of the test sequences is collecting the Trace informa-tion of the operating system. By comparing the benchmark data before and after opti-mization, it can verify the correctness and superiority of the optimization method. In addition, it can gives an objective evaluation on the performance and it can meet the user's actual needs better. |
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