Patent ID: 6963646
Filing Date: 2005-11-08
Classification: G10L,H04H

Abstract:
1. A sound signal encoding apparatus for encoding two different sound signals, comprising: sound signals dividing means for dividing each of said two different sound signals into a plurality of sound signal sections along a time axis for each of said sound signals to be taken for receiving therein, said sound signals consisting of a first channel signal and a second channel signal; first sound signal sections analyzing means for analyzing each of said divided sound signal sections based on the sound signal characteristics inherent in said sound signal; sampling rate selecting means for selecting one arbitrary sampling rate for each of said analyzed sound signal sections from among predetermined sampling rates; sound signal sampling means for sampling each of said analyzed sound signal sections at said sampling rate selected by said sampling rate selecting means; second sound signal sections analyzing means for analyzing each of said divided sound signal sections based on a psycho acoustic model obtained by taking advantage of human's hearing characteristics; frequency components calculating means for calculating frequency components with two different information consisting of first and second signals for each of said sound signal sections sampled at said selected sampling rate, said above first signal being indicative of intensities, and said above second signal being indicative of frequencies; quantization bit numbers allocating means for allocating quantization bit numbers for each of said calculated frequency components for each of said sound signal sections; compression level calculating means for calculating a compression level for each of said sound signal sections; compression level judging means for judging whether or not said calculated compression level for each of said sound signal sections exceeds a predetermined threshold compression value; first frequency components compressing means for compressing said frequency components for each of said sound signal sections with two different information consisting of first and second signals, said above first signal being indicative of said intensities and said above second signal being indicative of ratio of one of said frequency components for said first channel signal and said frequency components for said second channel signal to the other of said frequency components for said first channel signal and said frequency components for said second channel signal; second frequency components compressing means for compressing said frequency components for each of said sound signal sections with two different information consisting of first and second signals, said above first signal being indicative of the addition of each of said frequency components for said first channel signal and each of said frequency components for said second channel signal, and said above second signal being indicative of the difference between each of said frequency components for said first channel signal and each of said frequency components for said second channel signal; frequency components quantizing means for quantizing each of said frequency components for each of said sound signal sections at predetermined quantization bit numbers under two different states consisting of a first state in which said frequency components for each of said sound signal sections are compressed by said first frequency components compressing means when said compression level judging means is operative to judge that said compression level for each of said sound signal sections exceeds said predetermined threshold compression value and a second state in which said frequency components for each of said sound signal sections are not compressed by said first frequency components compressing means when said compression level judging means is operative to judge that said compression level for each of said sound signal sections does not exceed said predetermined threshold compression value; and frequency components encoding means for encoding said quantized frequency components for each of said sound signal sections to a multiplexed bit stream with a predetermined bit rate under two different states consisting of said first state in which said frequency components for each of said sound signal sections are compressed by said first frequency components compressing means when said compression level judging means is operative to judge that said compression level for each of said sound signal sections exceeds said predetermined threshold compression value and said second state in which said frequency components for each of said sound signal sections are not compressed by said first frequency components compressing means when said compression level judging means is operative to judge that said compression level for each of said sound signal sections does not exceed said predetermined threshold compression value, said multiplexed bit stream with said predetermined bit rate being constituted by said sound signals for each of said sound signal sections and general information needed for said sound signals to be encoded and decoded.