pvsinit — Initialise a spectral (f) variable to zero.
fsig -- output pv stream set to zero.
isize -- size of the DFT frame.
iolap -- size of the analysis overlap, defaults to isize/4.
iwinsize -- size of the analysis window, defaults to isize.
iwintype -- type of analysis window, defaults to 1, Hanning.
iformat -- pvsdata format, defaults to 0:PVS_AMP_FREQ.