pcm流添加文件头

废话不多说，看代码

/**
 * addWavHeader
 */
 
export default function addWavHeader (samples: ArrayBuffer, sampleRate: number, sampleBits: number, channelCount: number) {

  const dataLength = samples.byteLength
  const buffer = new ArrayBuffer(44 + dataLength)
  const view = new DataView(buffer)
  function writeString (view: DataView, offset: number, str: string) {
    for (let i = 0; i < str.length; i++) {
      view.setUint8(offset + i, str.charCodeAt(i))
    }
  }
  let offset = 0
  /* 资源交换文件标识符 */
  writeString(view, offset, 'RIFF'); offset += 4
  /* 下个地址开始到文件尾总字节数,即文件大小-8 */
  view.setUint32(offset, /*32*/ 36 + dataLength, true); offset += 4
  /* WAV文件标志 */
  writeString(view, offset, 'WAVE'); offset += 4
  /* 波形格式标志 */
  writeString(view, offset, 'fmt '); offset += 4
  /* 过滤字节,一般为 0x10 = 16 */
  view.setUint32(offset, 16, true); offset += 4
  /* 格式类别 (PCM形式采样数据) */
  view.setUint16(offset, 1, true); offset += 2
  /* 通道数 */
  view.setUint16(offset, channelCount, true); offset += 2
  /* 采样率,每秒样本数,表示每个通道的播放速度 */
  view.setUint32(offset, sampleRate, true); offset += 4
  /* 波形数据传输率 (每秒平均字节数) 通道数×每秒数据位数×每样本数据位/8 */
  view.setUint32(offset, sampleRate * channelCount * (sampleBits / 8), true); offset +=4
  /* 快数据调整数 采样一次占用字节数 通道数×每样本的数据位数/8 */
  view.setUint16(offset, channelCount * (sampleBits / 8), true); offset += 2
  /* 每样本数据位数 */
  view.setUint16(offset, sampleBits, true); offset += 2
  /* 数据标识符 */
  writeString(view, offset, 'data'); offset += 4
  /* 采样数据总数,即数据总大小-44 */
  view.setUint32(offset, dataLength, true); offset += 4
  function floatTo32BitPCM (output: DataView, offset: number, input: ArrayBuffer) {
    const i32xs = new Int32Array(input)
    for (let i = 0; i < i32xs.length; i++, offset += 4) {
      output.setInt32(offset, i32xs[i], true)
    }
  }
  function floatTo16BitPCM (output: DataView, offset: number, input: ArrayBuffer){
    const i16xs = new Int16Array(input)
    for (let i = 0; i < i16xs.length; i++, offset+=2) {
      output.setInt16(offset, i16xs[i], true)
    }
  }
  function floatTo8BitPCM (output: DataView, offset: number, input: ArrayBuffer) {
    const i8xs = new Int8Array(input)
    for (let i = 0; i < i8xs.length; i++, offset++){
      output.setInt8(offset, i8xs[i])
    }
  }
  if (sampleBits === 16) {
    floatTo16BitPCM(view, 44, samples)
  } else if (sampleBits === 8) {
    floatTo8BitPCM(view, 44, samples)
  } else {
    floatTo32BitPCM(view, 44, samples)
  }
  return view.buffer
}