Apparatus and method for detecting a pitch for a voice signal in a voice codec

摘要

An apparatus and method for detecting a pitch of a voice signal in a codec. The pitch detection apparatus for use in a vocoder includes a bandwidth expansion unit for performing an inverse-filtering process and a bandwidth expansion process on an input voice signal, and generating a bandwidth-expanded residual signal; a pitch analyzer for calculating a time autocorrelation function and a spectral autocorrelation function of the bandwidth-expanded residual signal, mixing the time autocorrelation function and the spectral autocorrelation function, comparing an autocorrelation function calculated by dividing a pitch acquired from the mixed autocorrelation function by an integer multiple with another autocorrelation function acquired at a predetermined pitch, and determining a point or position having the highest value to be an open-loop pitch; a pitch smoothing unit for smoothing the open-loop pitch using an average pitch value when the detected open-loop pitch is outside of a predetermined range of a previous frame; and a pitch quantizer for quantizing the smoothened open-loop pitch into predetermined levels, and generating the quantized result.