A high quality re-quantization/quantization method for MP3 and MPEG-4 AAC audio coding

MP3 is the popular audio coding standard. But now, a new higher quality audio coding standard Advanced Audio Coding (AAC) is proposed and widely used. The quantization/re-quantization is essential in both MP3 and AAC. This paper proposes a new high accuracy estimation algorithm for MP3 and MEPG-4 AAC audio coding. The algorithm can be applied not only for re-quantization process in decoder, but also for quantization in encoder. According to the floating-point behavior description, the proposed algorithm can achieve the lowest error result measured in quantization/re-quantization. Furthermore, in order to maintain the high quality with limited data precision, finite word length for fixed-point effects are investigated. Our algorithm has the low complexity advantages of multiplication-free and low memory requirements which will be more suitable in VLSI design for audio encoder/decoder.