无法在“RTCPeerConnection”上执行“setRemoteDescription”：无法设置远程应答 sdp：在错误状态下调用：稳定

Question

我用websocket和js写了一个语音通话。运行代码后出现错误，问题出现在客户报价阶段。 这是我的 client.js 代码：

'use strict';
var loginPage = document.querySelector('#loginPage');
var usernameInput = document.querySelector('#usernameInput');
var loginBtn = document.querySelector('#loginBtn');

var callPage = document.querySelector('#callPage');
var callToUsernameInput = document.querySelector('#callToUsernameInput');
var callBtn = $('#callBtn');
var answerBtn = $('#answerBtn');

var hangUpBtn = $('#hangUpBtn');
var localAudio = document.querySelector('#localAudio');
var remoteAudio = document.querySelector('#remoteAudio');


let pc;
let sendTo = callBtn.val();
let localStream;


const mediaConst = {
    audio:true
};

const options = {
    offerToReceiveAudio : 1,
}
function getConn(){
    if (!pc){
        pc = new RTCPeerConnection();
    }
}

async function getCam(){
    let mediaStram;
    try{
        if (!pc){
            await getConn();
        }
        mediaStram = await navigator.mediaDevices.getUserMedia(mediaConst);
        localAudio.srcObject = mediaStram;
        localStream = mediaStram;
        localStream.getTracks().forEach(track => pc.addTrack(track,localStream));
    }catch (error){
        console.log(error);
    }
}

async function createOffer(sendTo){
    await sendIceCandidate(sendTo);
    await pc.createOffer(options);
    await pc.setLocalDescription(pc.localDescription);
    send('client-offer',pc.localDescription,sendTo);
}
async function createAnswer(sendTO , data){
    if (!pc){
        await getConn();
    }
    if (!localStream){
        await getCam();
    }
    await sendIceCandidate(sendTo);
    await pc.setRemoteDescription(data);
    await pc.createAnswer();
    await pc.setLocalDescription(pc.localDescription);
    send('client-answer',pc.localDescription,sendTo);
}
function sendIceCandidate(sendTo){
    pc.onicecandidate = e =>{
        if (e.candidate !== null){
            send('client-candidate' , e.candidate, sendTo);
        }
    }
    pc.ontrack = e =>{
        remoteAudio.srcObject = e.streams[0];
    }
}

$('#callBtn').on('click' , () =>{
    getCam();
    send('is-client-ready',null,sendTo);
})

conn.onopen = e =>{
    console.log('connected to socket');
}

conn.onmessage = async function(e){
    let message = JSON.parse(e.data);
    let by = message.by;
    let data = message.data;
    let type = message.type;

    switch (type){
        case 'client-candidate':
            if (pc.localDescription){
                await pc.addIceCandidate(new RTCIceCandidate(data));
            }
        break;
        case 'is-client-ready':
            if (!pc){
                await getConn();
            }
            if (pc.iceConnectionState === "connected"){
                send('client-already-oncall');
            }else{
                /*hangUpBtn.on('click', () =>{
                    send('leave' , null , sendTo);
                    location.reload(true);
                })*/
                answerBtn.on('click' , ()=>{
                    send('client-is-ready',null,sendTo)
                })
            }
        break;
        case 'client-answer':
            if(pc.localDescription){
                await pc.setRemoteDescription(data);
            }
        break;
        case 'client-offer':
            createAnswer(sendTo,data);
        break;
        case 'client-is-ready':
            createOffer(sendTo);
        break;
        case 'client-already-oncall':
            setTimeout('window.location.reload(true)',2000);
        break;
        case 'client-rejected':
            alert("client-reject-the-call");
        break;
    }
}

function send(type,data , sendTo){
    conn.send(JSON.stringify({
        sendTo:sendTo,
        type:type,
        data:data
    }));
}

这是错误： 未捕获（承诺中）DOMException：无法在“RTCPeerConnection”上执行“setRemoteDescription”：无法设置远程应答 sdp：在错误状态下调用：稳定 client.js 第 139 行

我试过这个：

async function createAnswer(sendTo, data) {
    if (!pc) {
        await getConn();
    }
    if (!localStream) {
        await getCam();
    }
    try {
        await pc.setRemoteDescription(new RTCSessionDescription(data));

        const answer = await pc.createAnswer();
        await pc.setLocalDescription(answer);

        send('client-answer', pc.localDescription, sendTo);
    } catch (error) {
        console.error('Error creating answer:', error);
    }
}

Answer 1

这里的问题可能是你的 pc 变量是全局变量