Method for compensating pitch in a AMDF pitch search unit

摘要

PURPOSE: A method for correcting a pitch in an AMDF(Absolute Magnitude Difference Function) pitch searching device is provided to investigate auto-correlation in an input voice signal by using pitch information obtained in the current frame, thereby correctly correcting doubling and halving of a pitch value in voice signals having big pitch variation. CONSTITUTION: A hamming window is applied to input voice signals to set an AMD for searching an AMDF pitch(S101). A pitch is searched by using the AMDF in the AMD(S102). An MAMD(Modified Absolute Magnitude Difference) existing in the AMD and from which auto-correlation of input signals is eliminated is calculated in multiple positions of the searched pitch(S103). The calculated MAMD is re-searched to obtain a pitch(S104). Whether the pitch obtained through the re-search is zero is checked(S105). If so, the searched pitch is set as a current pitch(S106), and if not, the searched pitch value and the pitch value obtained through re-search are compared(S107). If the searched pitch value is larger, the occurrence of a pitch doubling phenomenon is decided and the searched pitch value is divided by two to set the divided value as a current pitch(S108). And if the searched pitch value is not larger in the step of S107, the occurrence of a pitch halving phenomenon is decided and the searched pitch is multiplied by two to set the multiplied value as a current pitch(S109).