| 摘要 |
PROBLEM TO BE SOLVED: To provide a single non-hybrid type audio encoding system which operates excellently to both of a speech signal and music signal, using characteristics of human aural system. SOLUTION: A source signal to be encoded is divided into plural frequency bands, and concerning the frequencies lower than a given threshold frequency, the waveforms are encoded so as to store the phase information, however, concerning the frequencies higher than the threshold value, the waveform of each frequency band of these (high frequency side) is decomposed into a carrier signal and an envelope signal, and (not phase information of the carrier signal, but) only the envelope signal is encoded. Thereafter, a decoder decodes these encoded envelope signals and the decoded signals are use for modulating the corresponding carrier waveforms. The carrier waveform is, for example, a constant cosine carrier having a frequency corresponding to a center frequency of a frequency band. |
