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Convention Paper

Dynamic Allocation of Bits Based on Perceptual Entropy in Perceptual Audio Coding Systems

Authors: Eng, Kelvin H. C.; Foo, Say Wei; Huang, Dong-Yan

AES Convention 109 · Paper 5272 · September 2000

Abstract

An analysis-by-synthesis stage and additional noiseless compression (Huffman coding) tools are employed to implement the quantization and coding process in a perceptual audio transform coding system. The objective of the process is to keep the quantization noise below the masked threshold, given an available number of bits. An iterative method with two nested loops realizes the control of distortion and bit rate for the process. Preliminary analysis indicates that in some instances more than the required amount of bits, estimated by the perceptual entropy (PE), is allocated to subbands when these additional bits could be re-allocated to regions of a higher need. Moreover, quantization at a fixed bit rate neglected the bits not used in the coding process. A proposed third iteration loop addresses these two inadequacies by dynamically allocating bits according to the PE. Results indicate that there are improvements in the audio quality, particularly at low bit rates, but at a higher computational cost. Moreover with the proposed method, perceptually transparent coding is achieved at an estimated bit rate of 1.797 bits/sample-a significant improvement over past estimates of 2.1 bits/sample.:

Details

Published in
AES Convention 109
AES Convention
109
Paper number
5272
Publication date
September 6, 2000
Session subject
Low Bit-Rate Coding
Affiliation
National University of Singapore, Singapore ; Intitute of Microelectronics, Singapore (See document for exact affiliation information.)
Type
Convention Paper