【作者】 林宇；

【导师】 刘云海；

【作者基本信息】 浙江大学 ， 信息与通信工程， 2008， 硕士

【摘要】 随着信息时代的来临,多媒体技术已经渗透到生活的每个角落。视频图像是多媒体信息的重要组成部分,但是数字化的视频信号的数据量之大是非常惊人的,这使得在开发多媒体应用系统时,对包含巨大数据量的视频图像数据的采集、存储、传输成为最大的瓶颈。因此,视频数据的高效压缩意义重大,是降低网络传输带宽、节省存储容量的关键技术。但视频压缩算法运算量大,实时处理对通用处理器的要求高,因而各种专用高速数字信号处理器(DSP)得到广泛应用。AVS标准作为数字音视频产业的共性基础标准,可以应用于高清晰度和标准清晰度数字电视广播、激光视盘机、移动多媒体通信、视频会议与视频监控、宽带网络流媒体、数字电影等产业群。与其他类似标准相比,AVS有两大优势:基于自主技术和部分开放技术构建的开放标准,妥善解决专利许可问题;中国日渐强大的产业化实力和市场提供了良好土壤。在这两大翅膀的助推下,AVS已成为全球范围内最有可能成为事实标准的第二代音视频编码标准。目前AVS标准组已经发布了企业版参考软件,不过其编码器部分时间效率低并且在关闭RDO的情况下图像质量也相对较差。因此进一步提高AVS编码器的时间效率以及图像质量是很有必要的。现在国内已经有很多企业希望将AVS标准应用于实际产品中(比如数字电视或监控领域应用),这就进一步要求AVS编码器在保证编码性能具有竞争力的同时,还必须可以实现实时编解码。在这种环境下,选择对AVS编码器进行性能上的优化以及提高时间效率是很有意义的。TI的DM642开发板专门针对多媒体应用,其特有的优化器可以让开发者以线性汇编代码的形式书写汇编程序,从而缩短开发周期。同时其软件流水操作将大大提高程序执行效率,并且它提供了许多数据打包指令,以便开发者实现对一块内存的访问。本课题研究在TI的DM642平台上实现AVS编码器,包括AVS编码器性能提升;根据DSP的结构特点、内存限制生成合理的C代码;C代码从PC平台到DSP平台的移植研究;在DSP平台上的代码优化研究。最终实现一个可产生能被AVS参考软件解码器正常解码的AVS码流的AVS编码器,并且实现CIF格式视频流的实时编码。更多还原

【Abstract】 With the advent of the information age, multi-media technology has infiltrated every corner of life. Video and image are important components of the multimedia information, however, the digitized video signals in the large volume of data is very alarming, which led, the huge volume of video and image data acquisition, storage,and transmission become the biggest bottleneck in the development of multimedia applications. Therefore, the video data compression efficiency is the key technologies to reduce the network bandwidth,and save storage capacity. But video compression algorithm has great complexity of computing,and real-time processing demands on general processors have become very strict, so the various dedicated high-speed digital signal processor (DSP) was widely used.As a common basis of the digital audio and video industry standard,AVS standard is widely used in high-definition and standard-definition digital television,laser disc,multimedia communications of mobile,video conferencing and surveillance,broadband network streaming media, and digital film industries. Compared with other similar standard,AVS has two main advantages: Based on the partial opening and autonomous technology,it has constructed an open standard, which properly resolves the licensing issues;China’s increasingly powerful industrial strength and the market provides a good soil. With these two wings, AVS is most likely to become the standard for the second-generation audio-video coding standard in the world. Currently AVS standard group has provided the reference software for enterprise,but the time efficiency of encoder is low and when the RDO function is closed,the image quality is relatively poor. Therefore,further improvement of AVS encoder’s time efficiency and image quality is very necessary. Now many enterprises of China hope that the AVS standard applied to the actual products (such as digital television or monitor areas),which would further request that the image quality of AVS encoder is competitive, and real-time encoding can be achieved. Under such circumstances,the performance optimization for AVS encoder and improvement of the time efficiency is of great significance. TI’s DM642 development board is specifically for multimedia applications,and its optimizer allows developers to compile code in the form of linear assembler,so as to shorten the development cycle. At the same time its software pipelining operations will greatly enhance the efficiency of the implementation process. It provides a lot of data packing instructions,in order to process more data with one memory visit.The research in TI’s DM642 platform to achieve AVS encoder,including the improvement of AVS encoder’s performance;With the structural characteristics of DSP and memory limit,to generate a reasonable C code;The transplantation of C code from PC platform to DSP platform; the Optimization of the code on DSP platform. Finally we can produce a AVS encoder which can generate the bit stream decoded by the decoder of AVS reference software successfully, and can achieve the real-time encoding with video of CIF format.更多还原