groove~ loopinterp xfade period?
Taking this as an example patch (where the right-hand bit populates a buffer with rising harmonics in sine waves, and the left-hand part loops over part of that buffer):
I would have expected loopinterp to smooth over discontinuities at the loop point (testing a couple of different loop points that are designed to be discontinuous). But my ear can't detect any difference between loopinterp 0 and loopinterp 1.
I searched the forum and saw a few other threads from quite long ago where users were asking, "what does loopinterp actually do?" Two of those threads received no reply. One only said briefly that it was supposed to make the loop point smoother, especially for shorter loops, but this didn't include any information beyond what's on the reference page.
One curious omission from the reference page is an attribute for crossfade duration. I'm puzzling over how loopinterp is useful without being able to configure the fade time...? Or if that's by design, what is the actual fade time?
OK, so I went a step further and recorded loopinterp 0 and loopinterp 1 into separate files and lined them up in Audacity.
... and, well, OK, it is indeed very slightly interpolating, but not nearly enough to smooth it out.
So... anything else I'm missing?
hjh
to grab any loop points from cycle kind of waveform interpolation is no help at all.
You need crossfader and length of crossfade will depend how disrupted glued start / stop
signal is, and how smooth it needs to be.
some infos here
You need crossfader and length of crossfade
Yes, at minimum -- this is what I expected loopinterp to do (and based on other forum threads, I'm not the only one).
Anyway, I think I figured out where my confusion came from. The Pd "cyclone" external pack implements a "loopinterp" property on play~ as a crossfader, differing from MSP's play~. Since I was familiar with that object first, I carried this expectation over to the same attribute name in MSP. Of course MSP has no need to follow the interface of an independently written clone.
I do feel that the MSP documentation here pretty much assumes that you already know what it does: "The word loopinterp, followed by 1, enables interpolation about start and end points for a loop." Incoming user: "... uh... wha?"
How about: "The word loopinterp, followed by 1, causes the default cubic interpolation to evaluate across loop boundaries, as if the loop were continuous audio. It is meant for cyclical waveforms and does not perform any additional crossfading. Since the time-stretching attribute disables cubic interpolation, this attribute has no effect when time stretching is enabled."
hjh