mindwarp~ mindwarp~ performs spectral envelope warping. mindwarp~ performs spectral envelope warping. It can be used to correct for the formant shifting effects of pitch-scaling. The warp factor is tuned to warp spectra to compensate for directly corresponding pitch-scaling values. For example, if you have pitch-scaled a signal by a factor of two, increasing its frequency content by an octave, by providing mindwarp~ with a warp factor of 2. and the pitch-scaled signal, mindwarp~ will restore the spectral formant of the signal to an estimation of the shape present in the original unscaled signal. Currently, warp factor values are restricted to the range [1/16 ... 16.]. mindwarp~ utilizes frequency shaping to perform its duty.

from the library : FFTease Format : External Environment : msp / PD freeware Max 3.x / 4.x http://www.sarc.qub.ac.uk/~elyon/LyonSoftware/MaxMSP/FFTease/