COMPRESSION AND EXPANSION APPARATUS AND METHOD FOR REDUCING QUANTIZATION NOISE BY USING HIGH SPECTRAL EXPANSION

摘要

To provide a compression and expansion method and system for reducing encoding noise.SOLUTION: In the system, a compression process 300 divides the first audio signal into a plurality of time segments by using a defined window shape, calculates a wideband gain for each time segment in the frequency domain by using a non-energy based average of the frequency domain representation of the first audio signal, and applies a separate gain value to amplify the segment of relatively low intensity to attenuate a segment of relatively high intensity. The compressed audio signal is then expanded to substantially return to the original dynamic range. The inverse gain value is applied to amplify a segment of relatively high intensity to weaken the segment of relatively low intensity. To obtain a frequency domain representation, a quadrature phase modulation (QMF filter) bank is used to analyze the first audio signal.SELECTED DRAWING: Figure 3A