Phase Distortion Synthesis

phasedist.io

// https://en.wikipedia.org/wiki/Phase_distortion_synthesis

// NB. completely untested

Range

pi := 3.14159265
tau := 2 * pi

FreqCtr := Object clone do(
	factor := nil

	new := method(srate,
		rv := self clone
		rv factor = tau / srate
		self)

	sample := method(freq, i,
		freq * i * factor)
)

PeriodicLUT := Object clone do(
	data := Sequence clone
	factor ::= 1

	init := method(
		self data := Sequence clone)

	new := method(function, size, period,
		self clone setFactor(period / size) populate(function, size))

	populate := method(f, size,
		0 to(size) foreach(i,
			self data atPut(i, f call(i))))

	at := method(n,
		n := (n * self factor) % data size
		data at(n floor) + data at(n ceil) / 2)
)

PhaseDist := Object clone do(
	base := nil
	res := nil
	lut ::= PeriodicLUT new(block(x, (x * tau/1024) sin), 1024, tau)
	operator ::= method(i, self lut at(i))

	new := method(srate, baseFreq, resFreq,
		rv := self clone

		self res := FreqCtr new(srate, resFreq)
		self base := FreqCtr new(srate, baseFreq))

	sample := method(freq, i,
		bsamp := base sample(freq, i)
		val := res sample(freq, i % bsamp)
		operator(val) * (1 - bsamp))
)