用recorderWorker.js和recorder.js录制声音

Question

我正在使用recorderWorker.js和recorder.js，我从这个代码得到的最终输出是44.1 8khz，2声道(立体声) wav file.But我的要求是8 8khz，1声道wav文件。如何在recorderWorker.js的帮助下实现这一点？

请帮助我解决这个问题。

recorderWorker.js的代码是

var recLength = 0,
 recBuffers = [],
  sampleRate;
this.onmessage = function(e){
  switch(e.data.command){
 case 'init':
  init(e.data.config);
  break;
case 'record':
  record(e.data.buffer);
  break;
case 'exportWAV':
  exportWAV(e.data.type);
  break;
case 'getBuffer':
  getBuffer();
  break;
case 'clear':
  clear();
  break;
  }
};

function init(config){
  sampleRate = config.sampleRate;
}

function record(inputBuffer){
  var bufferL = inputBuffer[0];
  var bufferR = inputBuffer[1];
  var interleaved = interleave(bufferL, bufferR);
  recBuffers.push(interleaved);
  recLength += interleaved.length;
}

function exportWAV(type){
  var buffer = mergeBuffers(recBuffers, recLength);
  var dataview = encodeWAV(buffer);
   var audioBlob = new Blob([dataview], { type: type });
  this.postMessage(audioBlob);
}

function getBuffer() {
  var buffer = mergeBuffers(recBuffers, recLength)
  this.postMessage(buffer);
   }

function clear(){
  recLength = 0;
  recBuffers = [];
}

function mergeBuffers(recBuffers, recLength){
  var result = new Float32Array(recLength);
  var offset = 0;
  for (var i = 0; i < recBuffers.length; i++){
    result.set(recBuffers[i], offset);
    offset += recBuffers[i].length;
  }
  return result;
}
 function interleave(inputL, inputR){
  var length = inputL.length + inputR.length;
  var result = new Float32Array(length);

   var index = 0,
    inputIndex = 0;

  while (index < length){
    result[index++] = inputL[inputIndex];
    result[index++] = inputR[inputIndex];
    inputIndex++;
  }
  return result;
}

function floatTo16BitPCM(output, offset, input){
  for (var i = 0; i < input.length; i++, offset+=2){
    var s = Math.max(-1, Math.min(1, input[i]));
    output.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7FFF, true);
  }
}

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

function encodeWAV(samples){
  var buffer = new ArrayBuffer(44 + samples.length * 2);
  var view = new DataView(buffer);

  /* RIFF identifier */
  writeString(view, 0, 'RIFF');
  /* file length */
  view.setUint32(4, 32 + samples.length * 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, 2, 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, 4, true);
 /* bits per sample */
  view.setUint16(34, 16, true);
  /* data chunk identifier */
  writeString(view, 36, 'data');
  /* data chunk length */
  view.setUint32(40, samples.length * 2, true);

  floatTo16BitPCM(view, 44, samples);

      return view;
}

Answer 1

您不需要修改Recorder.JS库-此功能已经提供。构造函数接受配置对象作为第二个参数，如下所示：

var audioContext = new AudioContext();
var microphone = audioContext.createMediaStreamSource(stream);
recorder = new Recorder(microphone, { numChannels: 1, sampleRate: 8000 });