FScPippiTranslationFFTProcess.scala

def snd       = AudioFileIn("in")
val dur       = 60.0
val sr        = snd.sampleRate
val framesIn  = snd.numFrames
val framesOut = (dur * sr).toInt

def mkPosBs(el: Double = 0.0, posSq: Seq[Double] = Nil, bsSq: Seq[Double] = Nil): (GE, GE) =
  if (el >= dur) (ValueDoubleSeq(posSq: _*), ValueDoubleSeq(bsSq: _*))
  else {
    val pos = el / dur
    val bs  = (pos * 2 * math.Pi).sin.linLin(-1, 1, 0.5, 3.0)
    mkPosBs(el + bs/2, posSq :+ pos, bsSq :+ bs)
  }

val (pos, bs) = mkPosBs()
 
var mix = Seq(0.5, 1, 1.5, 2, 4).foldLeft(0.0: GE) { (in, speed) =>
  val f       = speed.reciprocal
  val r       = Resample(snd, f)
  val frInR   = framesIn * f
  val posInFr = (pos * frInR).toInt
  val posOutFr= (pos * framesOut).toInt
  val winSz   = (bs * sr).toInt.nextPowerOfTwo // toInt
  val step    = posOutFr.differentiate
  val spans   = posInFr zip (posInFr + winSz)
  val slic    = Slices(r, spans)
  val fft     = Real1FFT(slic, winSz)
  val mag     = fft.complex.mag
  val phase   = fft.complex.phase
  val freq0   = pos * 5000 + 1000
  val magSz   = winSz/2
  val freqN   = RepeatWindow(freq0 / sr, 1, magSz)
  val lpf     = LPF(mag, freqN)
  val rec     = (lpf zip phase).complex.polToCar
  val ifft    = Real1IFFT(rec, winSz)
  val layer   = ifft * GenWindow.Hann(winSz)
  val lap     = OverlapAdd(layer, winSz, step).take(framesOut)
  in + LeakDC(lap)
}

val amp   = mix.abs.maximum
val norm  = BufferDisk(mix) / amp
AudioFileOut("out", norm, sampleRate = sr)