Fast Filterbank and Efficient Compaction Algorithms for Audio Coding Systems

• Main Authors: Din-Yuen Chan, 章定遠
• Other Authors: Jar-Ferr Yang
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/23203256746043096811

博士 === 國立成功大學 === 電機工程研究所 === 84 === In this thesis, for image appli-cation, we propose a fast and low-roundoff-noise imple- mentation of alias-free quadrature mirror filters (QMFs) for tree-structured subband coding. Using recursive for- mulas and the polyphase concept, a QMF implementation requires few multiplications and additions to compute the same outputs. Furthermore, the proposed algorithm can reduce roundoff error when finite-wordlength proces- sors are used to implement the encoder and decoder. For high- quality audio coding, the fast algorithms for implementation of cosine modulated multirate subband filtering are proposed. First, we skillfully use above recursive formula to efficiently reduce the computation of poly-phase subband filtering. Then, we further pro -pose an implementation of the fast cosine transform (FCT). This FCT coupled with the above recursive formula can reduce the original computation in ISO. MPEG standard to about 13.2% of multiplications. Since the time domain aliasing cancellation (TDAC) technique is a very significant technique for implementing multiband filter- banks, we propose two highly regular algorithms for realizing it. For completing the high-quality audio research, in the last part of our thesis, we unionize the implementation algorithms in previous chapters and a simple psychoacous- tic model for evolving an audio coding scheme. It can compress monophonic- channel signal at 64 Kbps with CD- quality. Consequently, the dominant goals of overall the fast, simplified and regular implementation algorithms in the thesis are developing the relative ICs of audio codecs.