VOICE DECODING DEVICE, VOICE DECODING METHOD, AND VOICE DECODING PROGRAM

摘要

PROBLEM TO BE SOLVED: To improve subjective quality of a decoding signal by reducing occurring pre-echo/post-echo without increasing remarkably a bit rate in a band extension technique in a frequency domain represented by an SBR.SOLUTION: With respect to a signal expressed in a frequency domain, linear prediction analysis is performed in a frequency direction by using a covariance method or an autocorrelation method to obtain a linear prediction coefficient. Filter strength is adjusted for the obtained linear prediction coefficient, and then a time envelope of the signal is transformed by filter processing the signal in the frequency direction with the coefficient after adjustment.