On 1/8/12, Miller Puckette <[email protected]> wrote: > Hi all -- > > Peter Brinkmann and Michael Goggins did some related work recently: > > http://nettoyeur.noisepages.com/2010/10/doppler-effects-without-equations/ > > but back in the dark ages Barry Vercoe made a Music 11 ugen called 'pipadv' > that added a signal into a delay line assuming the write location was > continuous and could be stably differentiated (so that for each point of the > delay line you could associate a fractional pposition in the incoming > signal. > He then interpolated to get fractional-indexed values of the incoming signal > to correspond with successive sample locations in the delay line, turning > the problem around backward.) > > I've thought about this for a few hours but so far my only conclusion is > that > it's very interesting :) > > Miller
The problems that I see are with orthogonality and reconstruction. A sample really just represents a sync that's centered on a point in time (in the easy case). Integer numbers of samples are orthogonal... but the fractionally-centered sample is not orthogonal to samples at all the integer indexes. Then, the reconstruction problem follows from it. When you want to read a value from a table, does it exactly retrieve the value that was recorded there? It seems like the interpolator needs to be modified continuously with the spacing of adjacent samples. All I know right now is, I can't spend my whole vacation on a math problem, even if it's good :) Chuck _______________________________________________ [email protected] mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
