【作者】 王军伟；

【导师】 裴东；

【作者基本信息】 西北师范大学 ， 电路与系统， 2011， 硕士

【摘要】 目前最新的视频编码标准H.264与以往视频编码标准相比具有无法比拟的优点,加之TI公司生产的高性能通用多媒体数字可编程处理器TMS320DM642超强的计算能力,很好地解决了H.264较高的算法复杂度对其在实时环境下应用的影响,是实现H.264编解码的理想平台。本文分别针对H.264关键算法与DSP平台的移植和优化这两个方面展开工作。首先对H.264中采用的关键技术进行了分析,在此基础上,对于帧内算法,利用宏块自身的纹理特征来达到只计算一种宏块模式的目的;同时,利用帧内预测模式的方向性,减少了候选模式,从而达到对Intra4×4模式的快速选择。大大降低了标准算法中全搜索算法的复杂性。另外,在研究了全搜索算法、非对称十字型多层次六边形格点搜索算法(UMHexagonS)、三步搜索法等算法的基础上,采用复合搜索模板、初始点自动预测和早停止策略,提出了新的快速运动估计算法,减少了运动估计时间,提高了编码速度。之后在DSP平台方面,依据TMSDM642与H.264编码器自身的结构特点,优化了片内存储器、合理分配存储空间、调整了的变量定义、头文件的改动,成功的实现了DSP平台的算法的移植;又利用编译器选项优化、数据打包技术、关键字等方法对H.264编码器代码进行了优化。经过H.264关键算法与DSP平台两方面的优化,编码器在编码效果没有大的损失的情况下,编码速度得到极大的提高。通过验证,解码后的视频图像与原始图像相比,图像的质量没有明显的降低。这些方法有效的降低了整个编码器的运行时间,为今后基于这个平台的软件开发提供了很好的借鉴。更多还原

【Abstract】 Nowadays the H.264 is advanced than any other former standards, at the same time TI company produces the high-performance general multimedia digital programmable processor TMS320DM642, with super computing power. It is a good solution to the higher algorithm complexity seriously influenced its application in real-time environment. It is to realize the H.264 encoding the ideal platform.The work of this paper is focused on the H.264 key algorithms and the DSP platform transplantation and optimize on the two aspects respectively.Firstly, the key technology used in the H.264 are analyzed, then for the intra-frame algorithm, the texture characteristic is adopted to judge the best intra-frame prediction mode before coding, which achieve the only purpose of a macro block mode during the coding process. Meanwhile, direction of intra prediction mode is adopted to achieve the purpose of a macro block mode. In addition, the study of the full search algorithm asymmetric cross-shaped multi-level hexagonal grid search algorithm (UMHexagonS),three-step search algorithm, the using of complex search patterns, the initial point of automatic forecasting and early stop strategy, a new fast motion estimation algorithm is proposed which to reduce the motion estimation time and improve the coding efficiency.Secondly, on the DSP platform, according to the structure of TMSDM642 and the H.264, this paper optimize on-chip memory, allocation of storage space to adjust the variable definitions and header file changes, Successful implementation of the DSP platform migration algorithm following Optimized using compiler options, data packaging technology, keyword, and other methods of the H.264 encoder is optimized.Through the optimization of the H.264 and the DSP, the encoder results in no major loss of coding circumstances, greatly increase encoding speed. Validated, the decoded video image, compared with the original image, the image quality is not significantly reduced.These method effectively reduce the running time of the encoder and provides a good reference for the future of software development based on this platform provides a good reference.更多还原