Bill Adair wrote: > The Perpetual Technologies devices (P-1A D/D & P-3A D/A) were very > successful a few years ago with their hardware based upsampling. Success == "sold a lot"? > I'm hoping to > achieve something similar by writing upsampling code that can operate in non-real > time on a PC chip. Are you aware of the Shannon Nyquist Sampling Theorem: http://en.wikipedia.org/wiki/Nyquist-Shannon_Sampling_Theorem Its corollary is that if you downsample and then upsample, the data destroyed during the downsampling can *never* be recreated. Erik -- +-----------------------------------------------------------+ Erik de Castro Lopo +-----------------------------------------------------------+ "We can forgive you for killing our children but we can't forgive you for making us kill yours." -- Golda Meir, one of the founders of the State of Israel.