Speech coder/decoder

A speech coder comprising a speech coding means for determining an input speech signal excitation signal expressed in the form of a plurality of pulses such as to minimize the distortion, with respect to the input speech signal, of a reproduced speech signal obtained by exciting a linear prediction synthesis filter, which is prescribed by linear prediction coefficients of the input speech signal, on the basis of the excitation signal, and a control circuit for receiving a designated bit rate and a coding delay as control data and generating control parameters on the basis of the control data, the speech coding means serving to code the input speech signal on the basis of the control parameters.

A speech coder comprising a speech coding means for determining an input speech signal excitation signal expressed in the form of a plurality of pulses such as to minimize the distortion, with respect to the input speech signal, of a reproduced speech signal obtained by exciting a linear prediction synthesis filter, which is prescribed by linear prediction coefficients of the input speech signal, on the basis of the excitation signal, and a control circuit for receiving a designated bit rate, a coding delay and a computational effort extent as control data and generating control parameters on the basis of the control data, the speech coding means serving to code the input speech signal on the basis of the control parameters.

A speech decoder for restoring a reproduced speech signal from received coded speech data, the coded speech data including a speech signal excitation signal, linear prediction synthesis filter coefficients and control data, comprising a control circuit for generating control parameters on the basis of the control data, and speech decoding means for restoring a reproduced speech signal by restoring the excitation signal and the linear prediction synthesis filter coefficient by decoding from the coded speech data on the basis of the control parameters and exciting a linear prediction synthesis filter, which is prescribed by the linear prediction synthesis filter coefficient, on the basis of the excitation signal.

A speech decoder for restoring a reproduced speech signal from received coded speech data, the coded speech data including a speech signal excitation signal, linear prediction synthesis filter coefficients, bit rate and coding delay, comprising a control circuit for generating control parameters on the basis of the bit rate and coding delay, and speech decoding means for restoring a reproduced speech signal by restoring the excitation signal and the linear prediction synthesis filter coefficient by decoding from the coded speech data on the basis of the control parameters and exciting a linear prediction synthesis filter, which is prescribed by the linear prediction synthesis filter coefficient, on the basis of the excitation signal.

A speech decoder for restoring a reproduced speech signal from received coded speech data, the coded speech data including a speech signal excitation signal, linear prediction synthesis filter coefficients, a bit rate and a coding delay, the excitation signal being expressed in the form of a multi-pulse constituted by a plurality of pulses, the speech decoder comprising a control circuit for generating control parameters on the basis of the bit rate and the coding delay, a parameter setting circuit for setting parameters necessary for coding the multi-pulse as setting parameters on the basis of predetermine ones of the control parameters, and speech decoding means for restoring a reproduced speech signal by restoring the excitation signal and the linear prediction synthesis filter coefficient by decoding from the coded speech data on the basis of the control parameters and the setting parameters and exciting a linear prediction synthesis filter, which is prescribed by the linear prediction synthesis filter coefficient, on the basis of the excitation signal.

A speech coding method comprising of computing frame length from bit rate and coding delay, selecting control parameters from a table in which a plurality of control parameters for controlling an operation of CELP coding on the basis of the bit rate, computing pulse number of multi-pulse excitation signal, pulse position candidates of each pulse and candidate positions thereof from the sub-frame length and bit number of multi-pulse signal.

A speech coding method comprising dividing an input speech signal into frames on the basis of a given frame length, generating control parameters of frame length, sub-frame length and bit distribution that are necessary for coding, from given bit rate and coding delay data, and setting parameters necessary for generating a multi-pulse signal from the given bit rate and coding delay.