Planning to create an audio phase-modulation effect. This is different from a delay effect, in which the delay is in absolute time and the phase mod is in relative time. Like this plugin, from the creators of setBfree and Whirl
But I am struggling to determine the wavelength/time shifting amount from a signal alone. Say, a sine wave with a varying rate is not at all being still enough for the delay time to be able to match the phase, or a complex audio signal with lots of harmonics has virtually the same effect.