【作者】 庄明渊；

【导师】 时龙兴；

【作者基本信息】 东南大学 ， 微电子学与固体电子学， 2005， 硕士

【摘要】 人类社会而今已经迈入数字时代,各种各样的数字技术产品在普通老百姓的日常生活中随处可见。包括音频上从广播接收到MP3、MIDI等音频播放的支持,以及视频上彩屏的出现、摄像功能在手持终端上的应用,越来越多的多媒体功能被集中到小小的手持终端产品中。本文的主要目的是选取一种合适的视频解码技术,在原有Garfield系统架构上实现实时的视频解码,并从软硬件优化和系统重新划分的角度得到最优的解码性能。本文首先介绍几种现在应用比较广泛和比较有发展前景的视频压缩算法,通过比较分析选择MPEG-4 Simple Profile作为在Garfield平台上实现的压缩算法;接着初步实现MPEG-4 Simple Profile在Garfield架构中的解码播放,并分析总结实现过程中出现的问题;然后在保持Garfield系统架构不变的情况下,对解码实现进行全面的优化,提高解码效率;最后从架构的角度对整个系统进行重新的规划和设计,提出最优化的软硬件设计。论文通过对各种视频压缩技术的比较选择最适用于移动数码终端产品的MPEG-4 Simple Profile作为视频解码算法,在Garfield结构上系统全速运行于80MHz,纯软件解码只能实现QCIF(176×144)每秒8-9帧的播放效率。经过从软硬件多方面优化后,在系统全速运行时实现QCIF每秒钟24帧左右的解码效率。为使系统能够达到CIF(352×288)每秒25帧(最差情况)的解码效率,本文从系统架构方面考虑重新对系统做出软硬件划分,由硬件加速器来完成整个8×8象素块的IDCT运算。实验结果表明当处理器选用ARM9系列,硬件加速单元在500周期内完成IDCT运算时,系统最差情况下可以达到CIF@25fps的解码效率。更多还原

【Abstract】 With the fast development of digital technology, more and more kinds of digital applications such as MP3s、mobile phones、digital cameras are used or accepted by people . Inevitably, the video technology based-on hand hold applications becomes very important.The purpose of this paper is to choose a suitable video decode technology and use this standard to achieve real-time video decode on the Garfield, and then optimize it through hardware and software. First this paper introduces several video compression standards and chooses MPEG-4 Simple Profile as our standard. Then we achieve MPEG-4 Simple Profile video decode on the Garfield and analyzes the problems we meet. and optimizes the performance from both hardware accelerator and software modification, but still keeps the Garfield system structure unchanged. At last this paper takes the system structure into account including re-dividing hardware and software cooperation in order to meet greater performance. Last chapter makes a summary of the whole paper and issues some points for the future work.After choosing MPEG-4 Simple Profile as system video decode standard , this paper achieves QCIF(176*144)@8-9fps without any optimization when system clock is 80MHz. Then QCIF(176*144)@24fps is achieved through both hardware and software optimization on the Garfield when system clock is 80MHz. In order to achieve CIF(352*288)@25fps , a special hardware accelerator which performs IDCT is used through system structure modification.更多还原