1 files changed, 278 insertions, 0 deletions
diff --git a/app/client/audio/lib/spectrum.js b/app/client/audio/lib/spectrum.js
new file mode 100644
index 0000000..f4a5444
--- /dev/null
+++ b/app/client/audio/lib/spectrum.js
@@ -0,0 +1,278 @@
+import Tone from 'tone'
+
+import { shuffle, quantize, mod } from '../util'
+
+import { windows as signalWindows } from 'signal-windows'
+import FFTJS from 'fft.js'
+
+const fft_size = 512
+const fft_overlap = fft_size / 4
+
+const fft = new FFTJS(fft_size)
+
+function toSpectrum(pcm, sr){
+  sr = sr || 44100
+  const ham = signalWindows.construct('ham', fft_size)
+  const pcm_in = new Array(fft_size)
+  const pcm_length = pcm.length
+  const pcm_q_length = Math.ceil(pcm_length / fft_size) * fft_size
+  let i, j, fft_out, data = [];
+  for (i = -fft_size; i < pcm_q_length; i += fft_overlap) {
+    for (j = 0; j < fft_size; j++) {
+      pcm_in[j] = pcm[i+j] * ham[j] || 0
+    }
+    fft_out = fft.createComplexArray()
+    fft.realTransform(fft_out, pcm_in)
+    fft.completeSpectrum(fft_out)
+    data.push(fft_out)
+  }
+  return {
+    data,
+    sr,
+    fft_size,
+    fft_overlap,
+  }
+}
+
+function fromSpectrum(spec){
+  const data = spec.data
+  const sr = spec.sr
+  const fft_size = spec.fft_size
+  const fft_overlap = spec.fft_overlap
+  const spec_len = data.length
+
+  const ham = signalWindows.construct('ham', fft_size)
+  const out = fft.createComplexArray()
+  const pcm_length = fft_overlap * spec_len
+
+  const audioBuffer = Tone.context.createBuffer(1, pcm_length, sr)
+  const pcm = audioBuffer.getChannelData(0);
+
+  let i, j, u, col
+
+  for (i = 0; i < spec_len; i++) {
+    col = data[i]
+    // for (j = fft_size; j < fft_size << 1; j++) {
+    //   col[j] = 0
+    // }
+    // if (i == 0) console.log(col)
+    fft.inverseTransform(out, col)
+    u = i * (fft_overlap)
+    for (j = 0; j < fft_size; j++) {
+      pcm[u+j] += out[j*2] * ham[j] || 0
+    }
+  }
+
+  fadeInOut(pcm, fft_size)
+  // console.log(pcm)
+  return audioBuffer
+}
+
+function fromImageData(imageData, sr, _r, _i) {
+  const pixels = imageData.data
+  const w = imageData.width
+  const h = imageData.height
+  let data = new Array(w)
+  let x, y, u, v, v2
+  for (y = 0; y < h; y++) {
+    let col = data[y] = new Float32Array(h * 4)
+    for (x = 0; x < w; x++) {
+      u = (x * (w) + y) * 4
+      v = x * 2
+      col[v] = (pixels[u] / 255 - 0.5) * _r
+      col[v+1] = (pixels[u+1] / 255 - 0.5) * _i
+      v2 = (h-y + h) * 2
+      col[v2] = col[v]
+      col[v2+1] = 0 // col[v+1]
+    }
+    col[h*2] = col[h*2+1] = col[h*2-1] = col[h*2-2] = 0
+  }
+  const spec = {
+    data,
+    sr,
+    fft_size, fft_overlap
+  }
+  return spec
+}
+
+function binToHz(spec, i){
+  return (i / spec.fft_size) * spec.sr
+}
+
+function fadeInOut(pcm, fade_size){
+  const pcm_length = pcm.length
+  let fade = 0, i
+  for (i = 0; i < fade_size; i++) {
+    fade = i / (fade_size)
+    fade *= fade
+    pcm[i] *= fade
+    pcm[pcm_length - i] *= fade
+  }
+}
+function rotatePhase(spec, theta){
+  let { data, fft_size } = spec
+  let i, j, col, len = data.length
+  for (i = 0; i < len; i++) {
+    col = data[i]
+    for (j = 0; j < fft_size; j++) {
+      col[j*2+1] += theta
+    }
+  }
+  return spec
+}
+
+function linearBins(spec, n){
+  n = n || 1
+
+  let bins = [], i, q_i
+  for (q_i = 0; q_i < n; q_i++) {
+    bins[q_i] = []
+  }
+  const step = Math.floor(spec.fft_size / n)
+  const len_quantize_n = quantize(spec.fft_size, n)
+  for (i = 0; i < len_quantize_n; i++) {
+    q_i = Math.floor(i/step)
+    bins[q_i] = bins[q_i] || []
+    bins[q_i].push(i)
+  }
+  // leftover bins get put at end
+  for (; i < spec.fft_size; i++) {
+    bins[q_i].push(i)
+  }
+  return bins
+}
+function logarithmicBins(spec){
+  let bins = [], i, j, q_i
+  let binCount = Math.log2(spec.fft_size) - 1
+  for (i = 0, q_i = 0, j = 0; i < binCount; i++) {
+    j += 1 << i
+    bins[i] = []
+    for (; q_i < j; q_i++) {
+      bins[i].push(q_i)
+    }
+  }
+  return bins
+}
+function concatBins(bins){
+  return bins.reduce((acc, cv) => acc.concat(cv), [])
+}
+function reverseBins(bins){
+  return bins.map( bin => bin.reverse() )
+}
+function minBins(bins){
+  return bins.map( bin => {
+    const b = bin[0]
+    return bin.map(() => b)
+  })
+}
+function maxBins(bins){
+  return bins.map( bin => {
+    const b = bin[bin.length-1]
+    return bin.map(() => b)
+  })
+}
+function rotateSpectrum(spec, n){
+  const { fft_size } = spec
+  if (n && n < 1) {
+    n -= 0.5
+    n *= fft_size
+  }
+  n = Math.floor(n)
+  let order = new Array(fft_size), i
+  for (i = 0; i < fft_size; i++) {
+    order[i] = mod(i + n, fft_size/2)
+  }
+  return reorderBins(spec, order)
+}
+function cloneSpectrum(spec){
+  const {
+    data,
+    fft_size,
+    sr, fft_overlap
+  } = spec
+  const spec_len = data.length
+
+  let new_data = new Array(spec_len)
+  let i
+  for (i = 0; i < spec_len; i++) {
+    new_data[i] = data[i].concat()
+    new_data[i][2] = 0
+  }
+
+  return {
+    data: new_data,
+    fft_size,
+    sr, fft_overlap,
+  }
+}
+function reverseSpectrum(spec){
+  let new_spec = cloneSpectrum(spec)
+  new_spec.data = new_spec.data.reverse()
+  return new_spec
+}
+function shuffleSpectrum(spec){
+  const { fft_size } = spec
+  let order = new Array(fft_size), i
+  for (i = 0; i < fft_size; i++) {
+    order[i] = i
+  }
+  shuffle(order)
+  return reorderBins(spec, order)
+}
+function invertSpectrum(spec){
+  const { fft_size } = spec
+  let order = new Array(fft_size), i
+  for (i = 0; i < fft_size; i++) {
+    order[i] = fft_size - i - 1
+  }
+  return reorderBins(spec, order)
+}
+function reorderBins(spec, order){
+  let new_spec = cloneSpectrum(spec)
+  const {
+    data,
+    sr,
+    fft_size,
+    fft_overlap,
+  } = spec
+  const spec_len = data.length
+  const { data: new_data } = new_spec
+
+  let i, j, col, new_col
+  for (j = order.length; j < fft_size; j++) {
+    order[j] = j
+  }
+
+  for (i = 0; i < spec_len; i++) {
+    col = data[i]
+    new_col = new_data[i] = data[i].concat()
+    col[0] = 0
+    col[2] = 0
+    col[4] = 0
+    for (j = 0; j < fft_size/2; j++) {
+      new_col[j*2] = col[order[j]*2]
+      new_col[j*2+1] = col[order[j]*2+1]
+    }
+    for (; j < fft_size; j++) {
+      new_col[j*2] = 0
+      new_col[j*2+1] = 0
+    }
+  }
+
+  return {
+    data: new_data,
+    sr, fft_size, fft_overlap,
+  }
+}
+
+export default {
+  toSpectrum, fromSpectrum, fromImageData, binToHz,
+  fadeInOut,
+  cloneSpectrum,
+  reverseSpectrum, shuffleSpectrum, invertSpectrum, rotateSpectrum,
+  reorderBins,
+  linearBins, logarithmicBins,
+  concatBins,
+  reverseBins, minBins, maxBins,
+  rotatePhase,
+}