如何使用WebRTC将视频流到RTMP？

// 获取视频流
navigator.mediaDevices.getUserMedia({ video: true, audio: false })
  .then(stream => {
    const videoTrack = stream.getVideoTracks()[0];
    
    // 创建一个RTCPeerConnection对象
    const peerConnection = new RTCPeerConnection();
    
    // 添加视频轨道到peerConnection
    peerConnection.addTrack(videoTrack, stream);
    
    // 当有ICE候选时处理
    peerConnection.onicecandidate = event => {
      if (event.candidate) {
        // 发送ICE候选到服务器
        sendToServer({ type: 'candidate', candidate: event.candidate });
      }
    };
    
    // 创建一个offer并设置本地描述
    peerConnection.createOffer()
      .then(offer => peerConnection.setLocalDescription(offer))
      .then(() => {
        // 发送offer到服务器
        sendToServer({ type: 'offer', sdp: peerConnection.localDescription });
      });
    
    // 接收来自服务器的消息
    socket.onmessage = event => {
      const message = JSON.parse(event.data);
      if (message.type === 'answer') {
        peerConnection.setRemoteDescription(new RTCSessionDescription(message.sdp));
      }
    };
  })
  .catch(error => console.error('Error accessing media devices.', error));

function sendToServer(message) {
  // 假设socket是已经建立的WebSocket连接
  socket.send(JSON.stringify(message));
}