我一直在研究音频识别演示,而api需要我传递一个8000或16000的采样率的.wav文件,所以我必须对它进行下采样.我尝试了2种算法如下.虽然它们都没有按我的意愿解决问题,但结果存在一些差异,我希望这会使它更加清晰.

这是我的第一次尝试,当sampleRate％outputSampleRate = 0时它工作正常,但是当outputSampleRate = 8000或1600时,结果音频文件是静默的(这意味着输出数组的每个元素的值为0)：

function interleave(inputL){
  var compression = sampleRate / outputSampleRate;
  var length = inputL.length / compression;
  var result = new Float32Array(length);

  var index = 0,
  inputIndex = 0;

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

所以这是我的第二次尝试,它来自一家大公司,它也不起作用.更重要的是,当我设置sampleRate％outputSampleRate = 0时,它仍然输出一个静默文件：

function interleave(e){
  var t = e.length;
  var n = new Float32Array(t),
    r = 0,
    i;
  for (i = 0; i < e.length; i++){
    n[r] = e[i];
    r += e[i].length;
  }
  sampleRate += 0.0;
  outputSampleRate += 0.0;
  var s = 0,
  o = sampleRate / outputSampleRate,
  u = Math.ceil(t * outputSampleRate / sampleRate),
  a = new Float32Array(u);
  for (i = 0; i < u; i++) {
    a[i] = n[Math.floor(s)];
    s += o;
  }

  return a
}

如果我的设置错误,这里是encodeWAV函数：

function encodeWAV(samples){
  var sampleBits = 16;
  var dataLength = samples.length*(sampleBits/8);

  var buffer = new ArrayBuffer(44 + dataLength);
  var view = new DataView(buffer);

  var offset = 0;

  /* RIFF identifier */
  writeString(view, offset, 'RIFF'); offset += 4;
  /* file length */
  view.setUint32(offset, 32 + dataLength, true); offset += 4;
  /* RIFF type */
  writeString(view, offset, 'WAVE'); offset += 4;
  /* format chunk identifier */
  writeString(view, offset, 'fmt '); offset += 4;
  /* format chunk length */
  view.setUint32(offset, 16, true); offset += 4;
  /* sample format (raw) */
  view.setUint16(offset, 1, true); offset += 2;
  /* channel count */
  view.setUint16(offset, outputChannels, true); offset += 2;
  /* sample rate */
  view.setUint32(offset, outputSampleRate, true); offset += 4;
  /* byte rate (sample rate * block align) */
  view.setUint32(offset, outputSampleRate*outputChannels*(sampleBits/8), true); offset += 4;
  /* block align (channel count * bytes per sample) */
  view.setUint16(offset, outputChannels*(sampleBits/8), true); offset += 2;
  /* bits per sample */
  view.setUint16(offset, sampleBits, true); offset += 2;
  /* data chunk identifier */
  writeString(view, offset, 'data'); offset += 4;
  /* data chunk length */
  view.setUint32(offset, dataLength, true); offset += 4;

  floatTo16BitPCM(view, offset, samples);

  return view;
}

它困扰了我很长一段时间,请让我知道我错过了什么…

—————————–解决之后—————— ————–

我很高兴它现在运行良好,这是正确版本的函数interleave()：

    function interleave(e){
      var t = e.length;
      sampleRate += 0.0;
      outputSampleRate += 0.0;
      var s = 0,
      o = sampleRate / outputSampleRate,
      u = Math.ceil(t * outputSampleRate / sampleRate),
      a = new Float32Array(u);
      for (i = 0; i < u; i++) {
        a[i] = e[Math.floor(s)];
        s += o;
      }

      return a;
    }

所以你可以看到它传递给它的变量不是正确的类型〜
再次感谢亲爱的@jaket和其他朋友〜虽然我想到了myslf,但他们让我更了解原始的东西~~~