前端获取麦克风录音数据

const getPcmBuffer = (bytes, simpleBits = 16)=> {
  // pcm buffer 数据
  let offset = 0
  const dataLength = bytes.length * (simpleBits / 8)
  const buffer = new ArrayBuffer(dataLength)
  const data = new DataView(buffer)
  for (let i = 0; i < bytes.length; i += 1, offset += 2) {
    const s = Math.max(-1, Math.min(1, bytes[i]))
    // 16位直接乘就行了
    data.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7fff, true)
  }
  // return [data]
  return new Blob([data])
}



const context = new AudioContext({ sampleRate: 8000, sampleBits: 16 })
      navigator.getUserMedia =
        navigator.getUserMedia ||
        navigator.webkitGetUserMedia ||
        navigator.mozGetUserMedia ||
        navigator.msGetUserMedia
      if (navigator.getUserMedia) {
        navigator.getUserMedia(
          // constraints
          {
            audio: {
              channelCount: 1,
            },
          },
          // successCallback
          (mediaStream) => {
            const sourceNode = context.createMediaStreamSource(mediaStream)
            const scriptNode = context.createScriptProcessor(512, 1, 1)
            sourceNode.connect(scriptNode)
            scriptNode.connect(context.destination)
            // 监听录音的过程
            scriptNode.onaudioprocess = (event) => {
              if (ws.readyState === 1) { // websocket 推送数据
                ws.send(getPcmBuffer(event.inputBuffer.getChannelData(0)))
              }
            }
          },
          // errorCallback
          (err) => {
            console.log(`The following error occured: ${err}`)
          },
        )
      }