Pioneer Electronic Corporation

Pioneer Electronics Corporation

Takeki Ihara

A code book is a set of code vectors to be selected when linear predictive parameters are vector-quantized as for an input audio which is divided into frames, each of which is further divided into sub frames. A code book designing method is provided with: a calculating processes of calculating the linear predictive parameters of the input audio for the sub frames respectively; a quantizing process of calculating a plurality of quantization candidates which are candidates for the code vectors with respect to the linear predictive parameters of the input audio as for the sub frames positioned at a predetermined interval set in advance; an interpolating process of calculating interpolation values for the linear predictive parameters on the basis of the calculated quantization candidates as for the sub frames other than the sub frames positioned at the predetermined interval; and a determining process of determining the code vectors of the code book by selecting the code vectors from among the calculated quantization candidates on the basis of the calculated quantization candidates, the calculated interpolation values and the calculated linear predictive parameters, within a range of continuous sub frames in a predetermined number set in advance.

METHOD OF AND APPARATUS FOR DESIGNING CODE BOOK OF LINEAR PREDICTIVE PARAMETERS, METHOD OF AND APPARATUS FOR CODING LINEAR PREDICTIVE PARAMETERS, AND PROGRAM STORAGE DEVICE READABLE BY THE DESIGNING APPARATUS

A pitch coding method is provided for calculating and coding the pitch of each sub frame of a speech input that is divided into a plurality of frames which are separated into a plurality of sub frames. The method calculates the pitch of each of the sub frames included in one or more of the frames, and determines whether or not the speech input is a voiced sound accompanying the vibration of a vocal chord. If it is determined that a head sub frame of a first speech input is the voiced sound, the pitch of the head sub frame is coded. Otherwise, if a subsequent sub frame is determined to be the voiced sound, a standard pitch value is selected and coded for the head sub frame. The method also determines whether a frame preceding the subsequent sub frame is judged to be the voiced sound, and if so the difference between the pitch of the preceding frame and the pitch of the subsequent frames is calculated and coded. If the preceding frame is not the voiced sound, the difference between the selected standard pitch and the subsequent frame's pitch is calculated and coded.

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Tsurugashima, Japan

Takeki Ihara