| 摘要 |
A coding and decoding apparatus for an acoustic signal obtained by extracting a series of sampled acoustic signal data as a series of frames. From data obtained over each of a predetermined number of discrete frequencies by implementing orthogonal transform processing to acoustic signal data using the same window function for first and second frames in sequential frames of the acoustic signal having a predetermined fixed time length, phase information for each of the discrete frequencies is obtained for every first and second frames. Then, quantities of changes in the phase information of each one of the discrete frequencies in the first frame with respect to the corresponding frequencies in the second frame are determined. On the assumption that the quantities of changes of phase information for each of the individual discrete frequencies are fixed on the time base, individual phase information is determined for the predetermined number of discrete frequencies in a frame at a third time position which is temporally displaced from the second frame by an integer multiple of a time difference between the first and second frames to predict phase information of the frame at the third time position. Thus, it is possible to efficiently encode an acoustic signal to facilitate its satisfactory recording or transmission or to easily provide a sound source for an electronic musical instrument which provides excellent performance.
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