Interesting story about the interpolation noise from very high oversampled signal approximations. I tend to think ïf it doesn't concern an actual sinc function of significant width and accuracy then the up-sampling is wrong unless the signal is prepared for it.
I can imagine in sample processing machines and software that you could do effect processing in an oversampled domain which is arrived at by having knowledge of the sample signals and possibly their detune filters, and that it is possible to compute "sample sets" which allow oversampling by relatively simple or cheap DSP operations to anyway fulfill certain accuracy criteria, such as low noise, frequency accuracy, or effect accuracy (like the number of fractional sampling accuracy in a phaser effect for instance). The linear interpolation I've used a decade ago for chorussing on a moderately strong DSP of the time was ok bvecause of signal properties and the tunings of the chorus I programmed, of course there's a lot to be said for using more than zero order interpolations in general. I've looked at Taylor expansions for the sinc function and it's possible accuracies, for instance. In mechanical design, it was one of the early computer math issues to use all kinds of interpolation schemes for a variety of purposes, with some terminology I suppose from the early days of the industrial revolution. However, a good understanding of these should be based on an understanding of what they are for. Some interpolations are for minimal stress, some for minimal distance given a certain curvature, others are statistically neutral in some sense, etc. More interesting is to look at more dimensional curves and surfaces or try out these in functional analysis or computations, which is far outside the scope here, and not very useful in normal audio subjects. Unfortunately the averaging and continuity considerations of the various interpolation curves and their mathematical properties aren't very well correlated with audi signals, and certainly not necessarily with sampling issues. So think about what some suggested here: what is the filte rkernel that you're putting over your signal when using them, and what does the sampled nature add in terms of misery by the side ? T.V. _______________________________________________ dupswapdrop: music-dsp mailing list music-dsp@music.columbia.edu https://lists.columbia.edu/mailman/listinfo/music-dsp
