| 摘要 |
PROBLEM TO BE SOLVED: To solve such a problem that the cycle of pitches does not always exist over all bands and when the cycle locally exists, encoding quality is bad. SOLUTION: The sampling input signal of 16kHz is liminated to be within bands of 10 Hz-7 kHz and 50 Hz-5.5 kHz respectively by band pass filters(BPF) 41-1 and 41-2 concerning an adaptive code book vector from an adaptive code book 16, an adaptive code book 14 is searched by minimizing the distortion of the adaptive code book vector passed through the filter 41-1 with the input signal as a target, and the adaptive code book 16 is searched by minimizing the distortion of the adaptive code book vector passed through the filter 41-2 with the input signal passed through a filter 51 of the same characteristics as the filter 41-2 as a target. Then, the distortion of the vector is such a searched result relative to the input signal is found, a vector corresponding to the smaller distortion out of this distortion and the distortion of the searched result is defined as a cyclic code Cp and a band code CF1 showing the filter 41-1 or 41-2, through which such a vector a passed, is encoded and outputted. |
