| 摘要 |
PURPOSE:To obtain the variable length frame type vocoder of less total distortions by providing a means for optimizing the analysis order of the spectral envelope parameter expressing the representative analysis frame in a segment within a prescribed range. CONSTITUTION:An LPC analyzer 2 outputs the quantatization voice signal from an A/D converter 1 as the analysis frame of 10msec and extracts the K parameter of 8th order which is one of a linear prediction coefft. A frame selector 5 determines the 200msec component of the analysis frame as one segment and the number of the representative analysis frames as 4 and makes the segmental optimum function approximation so as to minimize the total quantity of the quantatization distortions and the representative distortions of the frames. Frame selectors 6, 7 determine the number of the representative analysis frames as 5, 6 respectively and decrease the number of the quantatization of the K parameter in conformity therewith. A representative frame number selector 8 compares the input total distortions from the selectors 5 to 7 and selects the quantatization parameter and repeat bit at which the total quantity thereof is min. |
