【作者】 王晓兰；

【导师】 沈建华；

【作者基本信息】 华东师范大学 ， 计算机技术， 2008， 硕士

【摘要】 近年来随着多媒体应用的领域逐渐扩展,人们在对新的先进编码技术进行理论研究的同时,也加大了实用化的力度。H.264是新一代的视频标准,比以往的视频标准在相同的信噪比下的压缩效果有明显的提升,并适合于在网络中传播,但算法复杂度成倍增加。计算复杂度的升高,使得H.264视频压缩标准很难在现有的条件下应用到实际中去,因此,对H.264的实现和优化是很必要、很有意义的一项研究工作。同时嵌入式系统,尤其是便携式的手持终端设备,需要找到一个性能和功耗的平衡点,而ARM处理器的出现正适应了这一需求。本论文首先在详细研究H.264 Baseline Profile视频解码的算法原理和标准的基础上,测试并分析总结出未经优化的软件在ARM9EJ处理器上的性能瓶颈和优化思路;然后结合ARM9EJ系列处理器架构的特点,对程序的整体结构及各个功能模块展开优化,尽可能地提高处理器效率;最后在实际的硬件平台MX21(ARM926FA内核)平台上实现一个解码算法、并测试优化结果。测试表明,解码核心和回放系统经过优化以后,各种运动复杂度的QCIF视频序列基本实现了视频解码的需要,达到了所需的优化要求。现阶段的工作成果为今后的实际应用做了很好的铺垫,并且本论文所采用的研究方法对于其它平台上的应用也具有指导意义。更多还原

【Abstract】 With the extension in the field of multimedia applications in recent years, people begin to pay more attention to the field of how to apply advanced compression technologies to practical applications while doing researches of new thoeries. As a new video standard, H.264 raises the compression rate obviously than those used video standards. And it is more suitable for transmitting in the network, but its computation complexity is multiplied. For the increased computational complexity, it is difficult for H.264 video compression standard to be widly used to pratical applications in the current conditions. Therefore, the realization and optimization of the H.264 is very necessary and significant. As embedded systems, especially the portable handset terminals, they usually try to keep balance between performance and power consumption. ARM processors can fairly meet this requirement.On the basis of understanding the theories and standards of H.264 Video Baseline Profile, this thesis analyses the bottleneck on the non-optimized decoder software on ARM9EJ platform and summarizes the aspects that need optimizing. H.264 video decoder software is optimized to improve the efficiency of the CPU according to the architecture of ARM processor. The optimization work is mainly focusing on the overall structure and various functional modues. In the last part, the implementation of a simple H.264 video playback system on MX21(ARM926EJ core) platform is discussed. The test results show that the QCIFs with various motion complexities meet the basic needs after the decoder core and the playback system being fully optimized.The work done at this stage is a good preparation for the future practical application, and the methods used in this thesis are instructive for the applications on other platforms as well.更多还原