METHOD FOR DETECTING PITCH USING RATIO OF THE MAXIMUM VALUE OF CORRELATION FUNCTION TO CANDIDATE VALUE THEREOF, AND APPARATUS THEREFOR

摘要

PURPOSE: A method for detecting a pitch using a ratio of the maximum value of a correlation function to a candidate value thereof, and an apparatus therefor are provided to reduce a multiple or submultiple pitch error with reducing an amount of calculation, thereby improving the quality of sound in an audio codec. CONSTITUTION: A correlation function calculator(501) calculates a normalized correlation function from perceptual weighting filtered audio signals. A maximum correlation function and lag detector(502) receives the normalized correlation function for detecting the maximum correlation function value and the lag thereof, and detecting candidate values of the maximum correlation function value and lags thereof. A pitch candidate deciding unit(503) decides a pitch candidate by using ratios of the maximum value of the correlation function to the candidate values thereof, and ratios of the lag having the maximum correlation function to the lags of the candidates. A pitch detector(504) detects a pitch from the pitch candidate and the lag having the maximum correlation function by using a pitch of a previous frame of the audio signal.