Method for coding/decoding, coding/decoding device, and videoconferencing apparatus using such device

摘要

The object of the invention is to provide a coding/decoding method in which degradation of sound quality perceptible by the listener does not occur at an low bit rate. A shift number calculation section of a decoding device divides a frequency domain into at least two sub-bands, and approximates each of normalized transform coefficients in the sub-band whose allocated bit value is less than a predetermined threshold using a quantized value of the transform coefficient in a predetermined sub-band other than the sub-band so as to obtain information concerning the approximation, and a multiplexer multiplexes the information and another signal and transmits them. A de-multiplexer of a decoding device separates the code of information concerning the approximation, and a shift number restore section restores the information based thereon. An approximation coefficient calculation section assigns, based on the information concerning the approximation, the transform coefficient values in the predetermined sub-band to the normalized transform coefficients whose allocated bit value is less than the predetermined threshold.