JavaScript写通过麦克风输入语音，并将语音以16000k 16bit单声道pcm格式以formdata形式传输到后端的代码

我可以提供一段示例代码：navigator.mediaDevices.getUserMedia({ audio: true })
.then(stream => {
const mediaRecorder = new MediaRecorder(stream);
const audioChunks = [];
mediaRecorder.addEventListener("dataavailable", event => {
audioChunks.push(event.data);
});
mediaRecorder.start();

//当录音完毕，将录音数据以formdata形式传输
mediaRecorder.addEventListener("stop", () => {
const audioBlob = new Blob(audioChunks, { type : 'audio/x-m4a;codecs=opus' });
const fd = new FormData();
fd.append('fname', 'test.pcm');
fd.append('data', audioBlob);
// send the audio data to backend
});

// 停止录音
setTimeout(() => {
mediaRecorder.stop();
}, 16000);
});