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import Tone from 'tone'
import output from './output'
const signalWindows = require('signal-windows').windows
const FFTJS = require('fft.js')
const fft_size = 2 << 10
const fft_overlap = fft_size / 4
const half_fft_size = fft_size / 2
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, v, _r, _i, col
for (i = 0; i < spec_len; i++) {
col = data[i]
fft.inverseTransform(out, col)
u = i * (fft_overlap)
// for (j = fft_size * 1/4; j < fft_size * 3/4; j++) {
// pcm[u+j] = out[j*2] / ham[j] || 0
// }
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 fadeOut(pcm){
}
export default {
toSpectrum,
fromSpectrum
}
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