In This Posting, I wrote that Polynomial Smoothing / Fitting / Approximation can be used in conjunction with a Sinc Filter, to convert Sample-Rates. I should note that sometimes, Polynomial functions can be used by themselves.
This could be an explanation for how early CD Players eventually replaced the sinc filter, with “Mathematical Sound Shaping” (M.A.S.H.). The sinc filters were much maligned for their lack of immediacy. In their place, M.A.S.H. suffered from some level of distortion at frequencies near the Nyquist Frequency.
Further, experiments I have yet to carry out with ‘
QTractor‘, may show, that it will convert
44.1 kHz -> 48 kHz
using the exact same method as
48 kHz -> 44.1 kHz
Assuming that is, I set the Global filtering method to a (slower) non-default setting.