Convert AudioBuffer's Float32Array to Wav file format

wav.js

/** @param sampleRate {number} */
/** @param channelBuffers {Float32Array[]} */
function audioBufferToWav(sampleRate, channelBuffers) {
  const totalSamples = channelBuffers[0].length * channelBuffers.length;

  const buffer = new ArrayBuffer(44 + totalSamples * 2);
  const view = new DataView(buffer);

  const writeString = (view, offset, string) => {
    for (let i = 0; i < string.length; i++) {
      view.setUint8(offset + i, string.charCodeAt(i));
    }
  };

  /* RIFF identifier */
  writeString(view, 0, "RIFF");
  /* RIFF chunk length */
  view.setUint32(4, 36 + totalSamples * 2, true);
  /* RIFF type */
  writeString(view, 8, "WAVE");
  /* format chunk identifier */
  writeString(view, 12, "fmt ");
  /* format chunk length */
  view.setUint32(16, 16, true);
  /* sample format (raw) */
  view.setUint16(20, 1, true);
  /* channel count */
  view.setUint16(22, channelBuffers.length, true);
  /* sample rate */
  view.setUint32(24, sampleRate, true);
  /* byte rate (sample rate * block align) */
  view.setUint32(28, sampleRate * 4, true);
  /* block align (channel count * bytes per sample) */
  view.setUint16(32, channelBuffers.length * 2, true);
  /* bits per sample */
  view.setUint16(34, 16, true);
  /* data chunk identifier */
  writeString(view, 36, "data");
  /* data chunk length */
  view.setUint32(40, totalSamples * 2, true);

  // floatTo16BitPCM
  let offset = 44;
  for (let i = 0; i < channelBuffers[0].length; i++) {
    for (let channel = 0; channel < channelBuffers.length; channel++) {
      const s = Math.max(-1, Math.min(1, channelBuffers[channel][i]));
      view.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7fff, true);
      offset += 2;
    }
  }

  return buffer;
}

Usage:

const channelBuffers = [];
for (let channel = 0; channel < audioBuffer.numberOfChannels; channel++) {
  channelBuffers.push(audioBuffer.getChannelData(channel));
}
const wavData = audioBufferToWav(audioBuffer.sampleRate, channelBuffers);
saveToFile(wavData);