【作者】 华锡锋；

【导师】 陆生礼；

【作者基本信息】 东南大学 ， 微电子与固体电子学， 2005， 硕士

【摘要】 在嵌入式系统中实现MP3播放常见的解决方法有两种:一是完全依赖于嵌入式微处理器或DSP的处理能力,通过MP3定点或浮点解码程序实现MP3解码过程;二是通过专用的解码硬件进行MP3解码。在第一种情况下,对嵌入式微处理器或DSP处理能力的要求比较高。如果要求微处理器能够处理包括播放MP3在内的多个进程,这就将进一步对微处理器的处理能力提出了更为苛刻的要求。在第二种情况中,虽然专用硬件可以实现较高的性能和较低的功耗,但是可扩展性较差,不具备通用的处理能力。本文所研究的课题主要是在国家专用集成电路系统工程中心研发的“16/32位RISC嵌入式微控制器Garfield”(以下简称Garfield)SOC芯片上,基于自主设计的操作系统ASIX OS实现一款能实时播放MP3音乐的MP3播放器。Garfield系统级芯片是以嵌入式ARM7TDMI微处理器为核心,内部包括ESRAM高速内存和MMA多媒体加速器等外围设备在内的系统级嵌入式处理器。该MP3播放器以Garfield为硬件平台,采用了GUI应用程序和后台服务程序通过EventFlag通信原语的模式实现,利用自主操作系统ASIXOS的特定通信和编程模式、特定的控件实现MP3播放器的特定功能,如开始播放、停止播放、暂停播放、播放时间显示。在设计过程中本文还着重解决了MP3解码库的性能优化和解码音质的分析与优化问题,首先对核心解码库进行了代码级的优化,对其中的部分代码使用了宏替换、循环展开、内联函数替换等优化方法。然后对MP3解码库做了基于ESRAM的优化,并给出了最后实验数据,得到在主频70MHZ条件下每一帧的解码时间为19.2ms的优化结果,在很大程度上提高了解码器的性能。目前Garfield SOC芯片已经进行了小规模量产。MP3播放器也已设计成掌上样机,效果得到了验证,达到了设计的目标。更多还原

【Abstract】 There are usually two methods to disign a MP3 player in an embeded system. First, we can totally rely on embedded CPU and DSP to realize the MP3 decoder through the program based on fix-point or float-point algorithm. Second, MP3 decoder can be implemented throuth pure hardware docoder. In the first situation, it depends on the high performance of CPU or DSP. If many tasks include MP3 decoder task is handled by CPU, higher performance is required. In the second situation, though specific hareware can get higher performance and lower power, it doesn’t have the usual ability of process.In this paper, the research focuses on the implementation of a MP3 player for a SOC chip Garfield on an operating system ASIXOS which are designed by Asic Center. This research relies on the the project "16/32 bit RISC embedded controller Garfield design". Garfield is usually used by PDA and other divices, which supply many peripheral of mobile devices with users. Garfield uses ARM7TDMI as the CPU core. Garfield intragetes MMA(Multimedia Accelerator) module and AC97 module for sound multimedia handler.The MP3 player uses eventflag communication mode and program mode of ASIXOS to realize the function of MP3. This paper focuses on MP3 decoder performance analysis and optimization.The optimization is based on the on-chip-memory, which greatly enchanced the performance of the MP3 player.In the first chapter, the history of MPEG standard and MP3 are introduced, then the structure of MP3 player are illustrated. In the third chapter, the method of optimization based on ESRAM is researched and the data of experiment are given. In the fourth chapter, the OS ASIX is firstly introduced, then, the design of high level application base on ASIX program is illustrated.By now, Garfiled has been taped out and produced through MPW(Multi-Project Wafer),and the prototype MP3 player has been designed. Now the MP3 player can run fluently on the prototype, which satisfies the requirements of the project.更多还原