基于AC-3数字音频解码的递归IMDCT的FPGA实现  

Recursive IMDCT Implementation on FPGA Based on AC-3 Digital Audio Decoding

作　　者：徐华结[1,2] 郭立[1] 李琳[1] 吴思[1] 

机构地区：[1]中国科学技术大学电子科学与技术系 [2]池州学院电子工程系,安徽池州247000

出　　处：《微电子学与计算机》2007年第12期167-170,共4页Microelectronics & Computer

基　　金：安徽省教育厅自然科学基金项目(2006KJ084B)

摘　　要：数字音频AC-3采用了逆改进离散余弦变换(IMDCT)进行时频变换,为节约硬件资源并提高其运算速度,提出了基于FPGA实现的一种面向AC-3。MPEG等解码的对称的奇偶共用的IMDCT递归运算结构。考虑数字音频AC-3的解码特点,通过一定的数学推导,得到改进离散余弦逆变换的递归特性和奇偶对称性,并结合硬件系统结构的模块化和规则性,对256个频谱系数中的128个分别采用两个硬件递归结构进行运算,再进行简单复制得到256个PCM样本值。最后在XilinxFPGA上编程实验表明,奇偶序列频谱数据在运算上能够同步,减少了所需的运算单元和寄存器资源,因而在提高了IMDCT运算速度的同时降低了硬件复杂度,为数字音频AC-3解码器的硬件实现奠定了基础。Inverse MDCT（IMDCT）is implemented on Digital Audio AC-3 for time-frequency transform. In order to improve the operation speed and save hardware resource, a symmetry shared on odd and even index of spectra coefficient and recursive Inverse MDCT（IMDCT）architecture is proposed based on FPGA realization, which is used in AC-3,MPEG and so on. Considering thepeculiarity of digital audio AC-3 and the odd-even symmetry and recursive property getting from mathematic deducing, and according with modularization and regularity of the hardware system architecture, two hardware recursive structure are used to calculate 128 of 256 points spectra coefficient, then 256 points PCM value are received by duplicating. Finally, experiment on Xilinx FPGA indicates that the synchro calculation on odd or even index spectra data can be realized. It reduce the operation cell and save resource of register, so that, while the calculation speed is improved, the hardware complexity is reduced greatly, and this has established the foundation of digital audio AC-3 decoder realization.

关 键 词：逆改进离散余弦变换(IMDCT) 共用递归结构 AC-3 MPEG 

分 类 号：TP393.11[自动化与计算机技术—计算机应用技术]