pronunciation-finder/src/audio.js

An application for getting audio files with pronunciation from public dictionaries

const fs = require('fs');
const Audio = require('audio-2.0.0');
const lamejs = require('lamejs');

function encodeMono(channels, sampleRate, samples) {
  let buffers = [];
  const mp3enc = new lamejs.Mp3Encoder(channels, sampleRate, 128 / 2);
  let remaining = samples.length;
  const maxSamples = 1152;
  let length = 0;
  for (let i = 0; remaining >= maxSamples; i += maxSamples) {
    const mono = samples.subarray(i, i + maxSamples);
    const mp3buf = mp3enc.encodeBuffer(mono);
    if (mp3buf.length > 0) {
      length += mp3buf.length;
      buffers.push(Buffer.from(mp3buf));
    }
    remaining -= maxSamples;
  }
  const d = mp3enc.flush();
  if (d.length > 0) {
    length += d.length;
    buffers.push(Buffer.from(d));
  }
  return Buffer.concat(buffers, length);
}
module.exports.addGap = (file, gap) => {
  return new Promise((resolve, reject) =>
    Audio.load(file).then((audio) => {
      audio.pad(gap);
      console.log(`${file} gap size ${gap}`);
      const samples = audio.read({ format: 'int16' });
      const mp3Data = encodeMono(audio.channels, audio.sampleRate, samples);
      fs.writeFile(file, mp3Data, (err) => resolve(file));
    })
  );
};