【作者】 王军；

【导师】 李桂苓；

【作者基本信息】 天津大学 ， 信号与信息处理， 2004， 硕士

【摘要】 目前，数字视频领域普遍采用运动图像专家组(MPEG)制定的MPEG-2编码标准。作为符合该标准的一种信号源，需能按不同码率传输流（TS）的相应频率，发送TS。为此，本文研制了程序分频器，它利用了传统锁相环路原理，以及频率合成器的理论，使用Altera公司开发的CPLD，同时使用VHDL硬件描述语言进行核心程序的设计。它可按数字电视系统需求，在（3～30）MHz频率范围内，以足够的精度，满足PCI总线MPEG-2码流发送卡传送TS的需求。程序分频器已用于PCI总线MPEG-2码流发送卡。与MPEG-2 TS输出、解码、显示系统联调，可满足SDTV（标准清晰度电视）和HDTV(高清晰度电视) TS对频率范围、步级精度、稳定度等的要求，解码、播放正常。MPEG-2 AAC（ ISO/IEC13818-7）是一种新型高效多声道Hi-Fi音频编码标准，在每声道64kbit/s时重建的音质优于MP3和杜比AC-3。后来，MPEG-2 AAC被纳入ISO/IEC14496-3，并对自身进行了扩展，成为MPEG-4 AAC标准，本文详细分析了MPEG AAC 的编码技术特点，同时对解码也进行了相应的研究，并利用现有的工具和相关软件以及流行的软件开发平台，实现了对AAC各个档次的编解码，并通过实验对从MPEG 层2到AAC码流的转换编码的效率进行了分析比较。更多还原

【Abstract】 At present,the MPEG-2 coding standard set down by Moving Pictures Expert Group is adopted largely in digital video field. As a signal source according with the standard, it should send TS(transfer stream) according to the frequency of the TS that have different bitrates correspondingly. Therefore, we develop the programmable divider which use traditional Phase Lock Loop principle and the frequency synthesizer theory. We utilize the CPLD which is developed by Altera and make use of the VHDL to make the design of kernel programme. According to digital TV system requirements, in the range from 3MHz to 30MHz, it can satisfy the desire of the PCI Bus MPEG-2 bitstream sending card with sufficient precision. Now the divider has been used to the PCI Bus MPEG-2 bitstream sending card. It suit well to the MPEG-2 TS output, decode and display system, meeting the demand on the range of frequency, step precision and stabilization of SDTV and HDTV TS. It can decode and play normally.MPEG-2 AAC（ ISO/IEC13818-7）is a high efficient coding standard of multi-channel Hi-Fi audio, which provides better reconstructed audio than MP3 and dolby AC-3 at 64kbit per channel. Later, MPEG-2 AAC is absorbed into ISO/IEC14496-3, expanding itself, and become the MPEG-4 AAC. This paper presents the features of this coding technology in detail, at the same time makes the research on its decoding process. It realizes the coding and decoding process of all the profiles of MPEG AAC utilizing the tools and software in existence and the prevailing software developing platform. At last, it makes the analyse of the efficiency of the transcoding from the bitstream of mpeg layer II to AAC.更多还原