webrtc：createAnswer 适用于 chrome，但使用 firefox 引发错误答案

【问题标题】：webrtc: createAnswer works on chrome but fires an error with firefoxwebrtc：createAnswer 适用于 chrome，但使用 firefox 引发错误
【发布时间】：2014-05-30 05:04:29
【问题描述】：

function createPeerConnection() {
  try {
    pc = new RTCPeerConnection(null, pc_constraints);
    pc.onicecandidate = handleIceCandidate;
    pc.onaddstream = handleRemoteStreamAdded;
    pc.onremovestream = handleRemoteStreamRemoved;
    console.log('Created RTCPeerConnnection');
  } catch (e) {
    console.log('Failed to create PeerConnection, exception: ' + e.message);
    alert('Cannot create RTCPeerConnection object.');
      return;
  }

  try {
      // Reliable Data Channels not yet supported in Chrome
      sendChannel = pc.createDataChannel("sendDataChannel",
        {reliable: false});
      sendChannel.onmessage = handleMessage;
      trace('Created send data channel');
    } catch (e) {
      alert('Failed to create data channel. ' +
            'You need Chrome M25 or later with RtpDataChannel enabled');
      trace('createDataChannel() failed with exception: ' + e.message);
    }
    sendChannel.onopen = handleSendChannelStateChange;
    sendChannel.onclose = handleSendChannelStateChange;
    pc.ondatachannel = gotReceiveChannel;
}

    function doAnswer() {
      console.log('Sending answer to peer.');
      pc.createAnswer(setLocalAndSendMessage, null, sdpConstraints);
    }

我收到错误：

TypeError: Argument 2 of mozRTCPeerConnection.createAnswer is not an object.

【问题讨论】：

这两个浏览器都是 FireFox 吗？您的 SDP 限制是什么？
当您提供类似createAnswer 定义要求的失败回调时，它是否有效？

标签： webrtc

【解决方案1】：

以下代码应该可以在 Firefox 中运行：

function doAnswer() {
  console.log('Sending answer to peer.');

  pc.createAnswer(setLocalAndSendMessage, handleCreateAnswerError, sdpConstraints);
}

function setLocalAndSendMessage(sessionDescription) {
  sessionDescription.sdp = preferOpus(sessionDescription.sdp);
  pc.setLocalDescription(sessionDescription);

  console.log('setLocalAndSendMessage sending message' , sessionDescription);

  sendMessage(sessionDescription);
}

function handleCreateAnswerError(error) {
  console.log('createAnswer() error: ', e);
}

在 Firefox 中失败的原因可以在 documentation for createAnswer 中找到。问题是 Firefox 不允许您为错误处理程序传递 null。所有这些要求是您自己编写，然后将其传递给createAnswer。不要传递 null，您实际上应该传递一个函数（对象）来处理错误。

抱歉回复晚了，迟到总比没有好！

【讨论】：

【解决方案2】：

这个怎么样？它是@xsockets 的家伙使用的......

pc.createAnswer(setLocalAndSendMessage,function (ex) { self.onerror(ex); }, sdpConstraints);

【讨论】：