PERIODIC-COMBINED-ENVELOPE-SEQUENCE GENERATION DEVICE, PERIODIC-COMBINED-ENVELOPE-SEQUENCE GENERATION METHOD, PERIODIC-COMBINED-ENVELOPE-SEQUENCE GENERATION PROGRAM, AND RECORDING MEDIUM

摘要

This invention provides an envelope sequence that exhibits high approximation precision in the vicinity of a peak due to the pitch period of an audio signal. Using, as an input audio signal, a time-domain digital audio signal divided into frames, i.e. prescribed time intervals, this periodic-combined-envelope-sequence generation device generates an envelope sequence, namely a periodic combined-envelope sequence. This periodic-combined-envelope-sequence generation device has, at least, a spectral-envelope-sequence calculation unit and a periodic-combined-envelope generation unit. The spectral-envelope-sequence calculation unit calculates a spectral-envelope sequence for the input audio signal on the basis of time-domain linear prediction performed on said input audio signal. On the basis of frequency-domain periodic components in the input audio signal, the periodic-combined-envelope generation unit obtains a periodic combined-envelope sequence by changing the shape of an amplitude spectral-envelope sequence.