如何录制web/浏览器音频输出(非麦克风音频)

<button id="start">开始录制</button>
<button id="stop" disabled>停止录制</button>
<audio id="audioPlayback" controls></audio>

let mediaRecorder;
let audioChunks = [];

const startButton = document.getElementById('start');
const stopButton = document.getElementById('stop');
const audioPlayback = document.getElementById('audioPlayback');

startButton.addEventListener('click', startRecording);
stopButton.addEventListener('click', stopRecording);

async function startRecording() {
    const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
    mediaRecorder = new MediaRecorder(stream);

    mediaRecorder.ondataavailable = event => {
        audioChunks.push(event.data);
    };

    mediaRecorder.onstop = () => {
        const audioBlob = new Blob(audioChunks, { type: 'audio/wav' });
        const audioUrl = URL.createObjectURL(audioBlob);
        audioPlayback.src = audioUrl;
        audioChunks = [];
    };

    mediaRecorder.start();
    startButton.disabled = true;
    stopButton.disabled = false;
}

function stopRecording() {
    mediaRecorder.stop();
    startButton.disabled = false;
    stopButton.disabled = true;
}