An efficient lossless coding algorithm and its application to audio coding

This paper proposes a tonal component coding algorithm for a codec that emp loys a transform followed by Huffman coding, such as MPEG-2 Audio AAC (adva nced audio coding) [1]. After the input audio signal is mapped onto the frequency domain, the propo sed algorithm removes local maxima components that degrade the coding effic iency. As a result of this withdrawal, the flatness of the spectrum increas es and the efficiency of Huffman coding is improved. The removed components are encoded separately as side information. When the frequency resolution of the time/frequency mapping is high, this a lgorithm works more effectively since local maximum samples appear more fre quently with such a mapping. Simulation results show that this algorithm ac hieves as much as an 11% bit reduction per frame and improves the coding ef ficiency in 41% of all audio frames. (C) 1999 Scripta Technica, Electron Co mm Jpn Pt 3, 82(4): 71-78, 1999.