【作者】 汪燮彬；

【导师】 刘云海；

【作者基本信息】 浙江大学 ， 信息与通信工程， 2006， 硕士

【摘要】 随着多媒体技术的发展,实时实现各种视音频标准的系统得到了广泛应用。数字处理器(DSP)由于其丰富灵活的指令集、特殊的内部结构、超强的数据吞吐能力及运算速度,使得以DSP处理器为核心的实现方法成为了一种有效的媒体处理途径。 Blackfin DSP处理器是ADI公司率先推出的新一代16/32 bit嵌入式处理器,它们特别适合满足当今嵌入式音频、视频和通信应用对计算能力和功耗的严格要求。考虑到软件开发中的三个事实:(1)针对相同类型的处理器,可以建立一套比较通用并且计算能力很强大的函数库;(2)软件开发者为了得到一定的性能要求必须认真仔细的利用处理器的结构和指令来优化这些函数库;(3)函数的优化是复杂且花时间的。为此我们打算建立一套基于Blackfin系列处理器的高度优化的多媒体处理库(MML),为音视频编码、图像处理、信号处理、语音压缩等提供大量的库函数,方便用户的调用和缩短多媒体系统开发时间。 本文首先对多媒体处理库中的视频和图像部分进行分层封装,并分析了各层主要函数,不同层次的函数可以满足不同应用系统的要求;其次介绍了多媒体处理库的实现平台Blackfin处理器和软件开发平台Visual DSP,这些是媒体处理库优化的基础;然后重点阐述了视频处理库中的H.264/MPEG-4部分的优化,主要从算法结构、存储器结构以及汇编代码优化三个部分来详细叙述了各个模块的优化方法,并给出了实验结果;接着利用该媒体处理库构建了一个具有实际应用价值的数字视频图像监控系统,并详细说明了各个模块(如采集模块、存储模块、GPRS通信模块)的软硬件的实现过程;最后对本文的工作进行了总结,并提出今后工作的方向。更多还原

【Abstract】 With the development of multimedia technology, real-time system of various video and audio coding standards has been widly applied. Digital signal processor, which is rich in instruction, has special core structure, powerful in throughput and computing, is widely used in the multimedia processing, and this solution is considered to be the most effective approach.Blackfin Processors embody a new breed of 16/32-bit embedded processor designed specifically to meet the computational demands and power constraints of today’s embedded audio, video, and communications applications. Considering three facts in software development:(1)we could build a set of common computationally intensive functions needed on the similar processor;(2)Developers would have to optimization the functions carefully to get adequate performance;(3)This optimization process was complicated and time-consuming. So we began to build a set of optimized multimedia processing libraries, consisted of Video/Audio CODEC, Image Processing, Signal Processing, Speech compression, and so on. Also the libraries are convenient for call and ensure that product developing time is minimized.In this paper, first, the video and image processing libraries in multimedia processing library were encapsulated in several level functions, and we analyzed the different level functions. Different level functions are suitable for different systems. Second, we introduced the hardware platform -Blackfin processor and the software platform-Visual DSP, they are both the basis of the optimization. Third, the optimization of multimedia processing library based on the BF53x series DSP, this part is the emphases of the paper, the optimization methods cover three aspects: the algorithm of the Video CODEC, the structure of memory and the assemble code for DSP. Then, we use the multimedia processing library to construct an application system: Digital Video Surveillance. Finally, there are conclusion and tasks in the future.更多还原