Method and apparatus for time-warping a digitized waveform to have an approximately fixed period

Abstract

An input sequence of unwarped signal samples is stored in an input buffer ( ). A pitch and voicing analysis unit ( ), which analyzes voicing classification data from the input buffer ( ), provides a voicing classification variable indicating whether the voicing classification data is voiced or unvoiced and a preliminary estimate of the signal period in the interval spanned by the voicing classification data to a pitch pulse detection unit ( ). The pitch pulse detection unit ( ), also using analysis frame data from the input buffer ( ), provides a set of locations of unwarped pitch pulses contained in the interval spanned by the analysis frame data to a mapping optimization unit ( ). The mapping optimization unit ( ) provides a set of parameters describing a mapping from an unwarped time-scale to a warped time-scale, to a warped sampling instant calculation unit ( ). The warped sampling instant calculation unit ( ) provides a set of warped sampling instants to a warped sample value calculation unit ( ). The analysis frame data is also conveyed from the input buffer ( ) to the warped sample value calculation unit ( ), which provides a set of warped signal samples to an output buffer ( ).