path: root/client/lib/spectrum.js

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 = 1024
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
    // }
    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)

  return audioBuffer
}

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,
  fadeInOut,
  cloneSpectrum,
  reverseSpectrum, shuffleSpectrum, invertSpectrum, rotateSpectrum,
  reorderBins,
  linearBins, logarithmicBins,
  concatBins,
  reverseBins, minBins, maxBins,
  rotatePhase,
}