节点文献
H.264视频解码优化及DSP实现
【作者】 唐玲娜；
【导师】 唐雪飞；
【作者基本信息】 电子科技大学 ， 计算机应用技术， 2009， 硕士
【摘要】 作为最新的视频压缩标准,H.264/AVC在压缩性能和网络传输质量上全面优于MPEG-4和H.263,将运动图像压缩技术又向前推进了一大步。目前H.264的影响力越来越显著,很多公司和研究机构都在研究基于H.264编解码算法标准的视频商业化产品。H.264/AVC采用了一系列全新的视频压缩技术,但是在某些算法的实现较为复杂,一般的处理器很难实现实时的视频编解码。但是随着数字信号处理器(DSP)的高速发展,为高效地实现音视频信号处理提供了可能性。其中ADI公司推出的低功耗、高性能Blackfin处理器的DSP系列芯片,是H.264标准DSP实现的理想平台。本论文主要是探讨H.264软件解码器的优化及在ADSP-BF561上的实现。目的是实现支持main profile的H.264视频解码,并且解码D1尺寸视频速度到达实时。论文首先介绍了H.264视频压缩标准的基本原理、方法,以及数字视频压缩标准的发展过程。接着介绍了H.264视频标准解码的关键技术。然后在PC平台下实现了基于FFMPEG的H.264 main profile解码器,分析了该解码器流程,确定软件解码方案。本文在PC平台上完成了对该解码器的初步优化的基础上,实现了H.264解码器的移植,最后以ADSP-BF561 EZ-KIT LITE评估板为解码系统的VisualDSP编译环境下,使用各种优化方法和技巧,完成对H.264解码器的优化。根据BF561的结构特点,论文主要从系统级和程序语言级对H.264的解码代码进行优化,使之能够达到实际应用的要求。软件优化分为语法的优化和算法的优化,着重介绍软件语法的优化,这是软件优化的通用方法,合理的运用这些方法,可以大大提高软件的执行效率。着重用线性汇编优化了H.264的耗时模块,根据BF561的高速缓存机制,启用CACHE,提高系统解码速度。并且,使用性能测试工具,用不同的测试序列对各个阶段的优化效果进行测试,确定较优的H.264视频解码器的优化方案,使解码器的性能有较大的提高。经过测试表明本文设计的基于FFMPEG的H.264解码器支持main profile解码并且具有较高的解码效率。
【Abstract】 H.264/AVC, as the latest video coding standard, has an excellent performance over both MPEG-4 and H.263 in the compression and the quality of transmission through the network. Nowadays, H.264 is used widely because of its high compression and better image quality; many companies are developing the products based on H.264. However, because of its complex algorithm, the application is limited. As the high speed development of the Digital Signal Processor (DSP), the implemention the H.264 algorithm on ADI high performance DSP is valuable.The main discussion in the paper is the optimization and implementation of H.264 decoder based on BF561.The aim of the paper is to realize the decoder system based on H.264 standard which support the main profile and real-time application in deocding the D1 vidoe.Firstly, the author introduces the basic thought and theory of H.264, and the key technology about decoding, then the developing theories of BF561. Secondly, the author realizes the H.264 decorder based on FFMPEG in the PC platform, analyzes the flow of the decoder based on FFMPEG, and decides the software decoding scheme. Thirdly, the author realizes the migration of decoder based on VisualDSP. Finally, the author completes the optimization of decoder by various methords and skills based on the PC platform and the VsiaulDSP which used the ADSP-BF561 EZ-KIT LITE evaluation board as the video coding system.According to the characteristic of BF561, the author optimizes the decoder based on the system and the programming-languge which emphasis on the software grammar optimization; the method can efficiently promote the efficiency. Secondly, optimizes the time-consuming module using linear assemble language. Thirdly, makes use of the mechanism of Cache in order to improve the decoding rate. At last, tests the effect of the optimizing in every phases by using several test sequences and decides the best scheme.According to the test, the decorder designed in this paper which based on FFMPEG and supports the main profile decoding, has higher decoding efficiency.