Further exploration of the hi-pass artifacts armed with some brilliant online advice and a raw oscillator. Using the raw oscillator, we can see how interpolation errors in the stock osc~ create artifacts with discrete pitches, whereas those resulting from the raw oscillator are continuous.
(The audio in this video contains ultra-high pitches in the left channel only; mind the volume – though I think Vimeo's optimized some of them away)
The three classes of artifacts discovered in the last video map more-or-less on to three explanations:
1. "squishy" / "sparkly" sounds - result from hi-pass struggles (these do alias but are probably not caused by aliasing as I had thought)
2. high harmonics above the input frequency - result from interpolation errors in the wavetable used by the osc~ object
3. static whine at samplerate / 64 - result of denormals optimization by pure data (seems to be introducing a noisy sample every bin)
This video got a little longer than I thought it was going to.
