oldRuico/js/wav-audio-encoder.js

(function(self) {
  var min = Math.min,
      max = Math.max;

  var setString = function(view, offset, str) {
    var len = str.length;
    for (var i = 0; i < len; ++i)
      view.setUint8(offset + i, str.charCodeAt(i));
  };

  var Encoder = function(sampleRate, numChannels) {
    this.sampleRate = sampleRate;
    this.numChannels = numChannels;
    this.numSamples = 0;
    this.dataViews = [];
  };

  Encoder.prototype.encode = function(buffer) {
    var len = 1024;
    this.dataViews.push(buffer);
    this.numSamples += len;
  };

  Encoder.prototype.finish = function(mimeType) {
    var dataSize = this.numChannels * this.numSamples * 2,
        view = new DataView(new ArrayBuffer(44));
    setString(view, 0, 'RIFF');
    view.setUint32(4, 36 + dataSize, true);
    setString(view, 8, 'WAVE');
    setString(view, 12, 'fmt ');
    view.setUint32(16, 16, true);
    view.setUint16(20, 1, true);
    view.setUint16(22, this.numChannels, true);
    view.setUint32(24, this.sampleRate, true);
    view.setUint32(28, this.sampleRate * 4, true);
    view.setUint16(32, this.numChannels * 2, true);
    view.setUint16(34, 16, true);
    setString(view, 36, 'data');
    view.setUint32(40, dataSize, true);
    this.dataViews.unshift(view);
    var blob = new Blob(this.dataViews, { type: 'audio/wav' });
    this.cleanup();
    return blob;
  };

  Encoder.prototype.cancel = Encoder.prototype.cleanup = function() {
    delete this.dataViews;
  };

  self.WavAudioEncoder = Encoder;
})(self);