【作者】 郎平；

【导师】 黎福海；

【作者基本信息】 湖南大学 ， 电路与系统， 2008， 硕士

【摘要】 媒体播放器是一种大众娱乐消费类电子产品,一般定义为多媒体影音播放器。它除了看电影的基本功能外还支持音乐播放、浏览图片,甚至部分产品还具有上网等功能,能够满足人们随时播放视频的需要。随着当今社会人们的旅游、出差、户外活动的日益增加,对媒体播放器的需求量将迅速增加,而由于现在多媒体技术中采用的视频、音频编码方式和文件格式的多样性和复杂性,要求媒体播放器要具有很强的性能和功能,这就对其硬件和软件系统都提出了很高的要求。本文选择ARM核心的三星S3C2440微处理器,在此基础上进行了硬件扩展和软件系统的选择,设计了一个简单的媒体播放器系统。在该系统中,首先,以S3C2440为核心,设计了系统终端的硬件,给出了系统硬件的总体架构,设计了S3C2440处理器和外部电路的硬件接口以及总线连接,详细设计了存储器、LCD、电源管理模块的电路。其次,阐述了将嵌入式Linux移植到本系统的具体方法,分析了混合文件系统的构建,选择Cramfs+Yaffs作为本系统的文件系统,并给出了具体的实现方法。同时,从硬件、操作系统以及软件代码设计的层面上,研究如何降低系统的功耗,通过减少系统的耗能从而节约能源、提高速度以及减小尺寸。再次,分别使用libmad和ffmpeg实现MP3音频解码和MP4视频解码,并对音视频同步进行了深入的研究。同时选择挪威Trolltech公司的Qt/Embedded作为系统上层图形界面应用程序,并成功地完成了其到系统的移植。最后,由于解码后的图像是YUV格式,需要转化成RGB格式来播放,并且每帧图像在播放前都要经过YUV到RGB的转换,降低了整体解码速度,为了解决这个问题,本文使用完全查表法来转换色彩空间,每次转换只需要一次查表,从而大大降低了算法的时间复杂度,加快了解码速度,保证了系统的实时性。更多还原

【Abstract】 Media Player is a kind of electronic production for mass recreation and consumption. In addition to the basic function of movie playing, it also support playing music and scanning pictures. Furthermore, some of the productions have further functions, such as surfing the internet, so as to satisfy needs of playing videos at any time. As social travel, going on errands, outdoors activities increase nowadays, the demand of Media player increases dramatically. For the diversity and complexity of the video and audio coding mode and file format used in current multimedia technique,it is essential for Media player with powerful performance and functions, and so the high requirements are proposed for their hardware and software system.In this thesis, an ordinary Media player system is designed and implemented based on S3C2440 microprocessor with ARM core with which hardware is expended and software system is developed. In this system, using S3C2440 as its core,the system terminal hardware is designed, first the system hardware whole structure is presented, then not only the design of the interface and bus connecting between S3C2440 processor and exterior circuits is presented but also and the design of the circuits of memorizer, LCD and power supply management module in details.In the next place, the concrete method of transplanting embedded Linux to this system is stated, the construction of mixed file system is analyzed, Cramfs+Yaffs is chose as the file system of the system and the concrete implementing method is presented. Meanwhile, from the aspect of hardware and operating system and software code designing, how to reduce system power consumption is researched.Third, LIBMAD and FFMPEG are used to implement MP3 audio and MP4 video decoding and the synchronization between audio and video is further studied. Qt/Embedded of Norwegian TROLLTECH Company is employed as system upper graphical interfaces application program.Finally, Using complete checking table method, the image format transformation is realized, and so time complexity of algorithmic is decreased a lot, system efficiency is improved and real-time nature of the system is ensured.更多还原