声网视频 SDK 被广泛应用于多种实时互动场景中，例如视频会议、视频通话、音视频社交、在线教育等。为了让刚刚接触声网 SDK 的开发者，可以更顺畅地实现基础的视频通话功能，我们基于声网 Web SDK 4.x 版本梳理了本篇教程。
在本文末，会提供相应 Demo 、文档地址供大家参考使用。同时，欢迎点击此处注册声网账号体验。声网每个月会为开发者提供 10000 分钟的免费额度。
本文为「声网 SDK 教程」系列内容
01 Demo 体验
我们在 GitHub 上提供一个开源的基础视频通话示例项目，在开始开发之前你可以通过该示例项目体验音视频通话效果。Demo 与线上体验地址，可在文末获取。
02 动手实践
实践任务
从 Web 前端页面引入声网 SDK，发起视频通话。
开发环境
声网 SDK 的兼容性良好，对硬件设备和软件系统的要求不高，开发环境和测试环境满足以下条件即可：
Chrome
Firefox
Safari
Edge
以下是本文的开发环境和测试环境：
开发环境
MacBook Pro (13-inch, M1, 2020)
Visual Studio Code (1.67.1)
测试环境
Chrome (101.0.4951.64)
如果你此前还未接触过声网 SDK，那么你还需要做以下准备工作：
注册一个声网账号，进入后台创建 AppID、获取 Token；
下载声网官方最新的 视频 SDK。
项目设置
文件组织结构
实现视频通话之前，参考如下步骤设置你的项目：
如需创建新项目，可以在 Visual Studio Code 里 File > New Window，创建 Web 项目。完整的目录结构如下，根据个人经验会有所变化。
.
├── index.css # 用于设计 Web 应用的用户界面样式
├── index.html # 用于设计 Web 应用的用户界面
├── index.js # 通过 AgoraRTCClient 实现具体应用逻辑的代码。
└── vendor # 第三方前端插件，辅助页面布局和交互，本教程中是下载到本地使用，你也可以使用 CDN 的方式
├── bootstrap.bundle.min.js
├── bootstrap.min.css
└── jquery-3.4.1.min.js
集成声网 SDK
可以下载到本地使用，也可以直接使用声网的 CDN 引入， 本文推荐使用 CDN 方式集成声网 SDK。
在 index.html 中添加以下代码
<!DOCTYPE html>
...
<link rel="stylesheet" href="./vendor/bootstrap.min.css">
<link rel="stylesheet" href="./index.css">
...
<script src="./vendor/jquery-3.4.1.min.js"></script>
<script src="./vendor/bootstrap.bundle.min.js"></script>
<script src="https://download.agora.io/sdk/release/AgoraRTC_N.js"></script>
<script src="./index.js"></script>
...
最终完整代码为
可以直接复制运行。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Basic Video Call -- Agora</title>
<link rel="stylesheet" href="./vendor/bootstrap.min.css">
<link rel="stylesheet" href="./index.css">
</head>
<body>
<div class="container-fluid banner">
<p class="banner-text">Basic Video Call</p>
<a style="color: rgb(255, 255, 255);fill: rgb(255, 255, 255);fill-rule: evenodd; position: absolute; right: 10px; top: 4px;"
class="Header-link " href="https://github.com/AgoraIO-Community/AgoraWebSDK-NG/tree/master/Demo">
<svg class="octicon octicon-mark-github v-align-middle" height="32" viewBox="0 0 16 16" version="1.1" width="32" aria-hidden="true"><path fill-rule="evenodd" d="M8 0C3.58 0 0 3.58 0 8c0 3.54 2.29 6.53 5.47 7.59.4.07.55-.17.55-.38 0-.19-.01-.82-.01-1.49-2.01.37-2.53-.49-2.69-.94-.09-.23-.48-.94-.82-1.13-.28-.15-.68-.52-.01-.53.63-.01 1.08.58 1.23.82.72 1.21 1.87.87 2.33.66.07-.52.28-.87.51-1.07-1.78-.2-3.64-.89-3.64-3.95 0-.87.31-1.59.82-2.15-.08-.2-.36-1.02.08-2.12 0 0 .67-.21 2.2.82.64-.18 1.32-.27 2-.27.68 0 1.36.09 2 .27 1.53-1.04 2.2-.82 2.2-.82.44 1.1.16 1.92.08 2.12.51.56.82 1.27.82 2.15 0 3.07-1.87 3.75-3.65 3.95.29.25.54.73.54 1.48 0 1.07-.01 1.93-.01 2.2 0 .21.15.46.55.38A8.013 8.013 0 0016 8c0-4.42-3.58-8-8-8z"></path></svg>
</a>
</div> <div id="success-alert" class="alert alert-success alert-dismissible fade show" role="alert">
<strong>Congratulations!</strong><span> You can invite others join this channel by click </span><a href="" target="_blank">here</a>
<button type="button" class="close" data-dismiss="alert" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div>
<div id="success-alert-with-token" class="alert alert-success alert-dismissible fade show" role="alert">
<strong>Congratulations!</strong><span> Joined room successfully. </span>
<button type="button" class="close" data-dismiss="alert" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div>
<div id="success-alert-with-token" class="alert alert-success alert-dismissible fade show" role="alert">
<strong>Congratulations!</strong><span> Joined room successfully. </span>
<button type="button" class="close" data-dismiss="alert" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div> <div class="container">
<form id="join-form">
<div class="row join-info-group">
<div class="col-sm">
<p class="join-info-text">AppID</p>
<input id="appid" type="text" placeholder="enter appid" required>
<p class="tips">If you don`t know what is your appid, checkout <a href="https://docs.agora.io/en/Agora%20Platform/terms?platform=All%20Platforms#a-nameappidaapp-id">this</a></p>
</div>
<div class="col-sm">
<p class="join-info-text">Token(optional)</p>
<input id="token" type="text" placeholder="enter token">
<p class="tips">If you don`t know what is your token, checkout <a href="https://docs.agora.io/en/Agora%20Platform/terms?platform=All%20Platforms#a-namekeyadynamic-key">this</a></p>
</div>
<div class="col-sm">
<p class="join-info-text">Channel</p>
<input id="channel" type="text" placeholder="enter channel name" required>
<p class="tips">If you don`t know what is your channel, checkout <a href="https://docs.agora.io/en/Agora%20Platform/terms?platform=All%20Platforms#channel">this</a></p>
</div>
</div> <div class="button-group">
<button id="join" type="submit" class="btn btn-primary btn-sm">Join</button>
<button id="leave" type="button" class="btn btn-primary btn-sm" disabled>Leave</button>
</div>
</form> <div class="row video-group">
<div class="col">
<p id="local-player-name" class="player-name"></p>
<div id="local-player" class="player"></div>
</div>
<div class="w-100"></div>
<div class="col">
<div id="remote-playerlist"></div>
</div>
</div>
</div> <script src="./vendor/jquery-3.4.1.min.js"></script>
<script src="./vendor/bootstrap.bundle.min.js"></script>
<script src="https://download.agora.io/sdk/release/AgoraRTC_N.js"></script>
<script src="./index.js"></script>
</body>
</html>
视频通话逻辑
实现视频通话逻辑
下图展示视频通话的 API 调用时序,注意图中的方法是对不同的对象调用的。
参考以下步骤实现音视频通话的逻辑：
1.调用 createClient 方法创建 AgoraRTCClient 对象。
2.调用 join 方法加入一个 RTC 频道，你需要在该方法中传入 App ID 、用户 ID、Token、频道名称。
3.先调用 createMicrophoneAudioTrack 通过麦克风采集的音频创建本地音频轨道对象，调用 createCameraVideoTrack 通过摄像头采集的视频创建本地视频轨道对象；然后调用 publish 方法，将这些本地音视频轨道对象当作参数即可将音视频发布到频道中。
4.当一个远端用户加入频道并发布音视频轨道时：
a.监听 client.on("user-published") 事件。当 SDK 触发该事件时，在这个事件回调函数的参数中你可以获取远端用户 AgoraRTCRemoteUser 对象 。
b.调用 subscribe 方法订阅远端用户 AgoraRTCRemoteUser 对象，获取远端用户的远端音频轨道 RemoteAudioTrack 和远端视频轨道 RemoteVideoTrack 对象。
c.调用 play 方法播放远端音视频轨道。
注：以下代码都将在 index.js 中添加**
初始化client
var client = AgoraRTC.createClient({ mode: "rtc", codec: "vp8" });
加入RTC 频道并创建本地音频轨道
// Join a channel and create local tracks. Best practice is to use Promise.all and run them concurrently.
[ options.uid, localTracks.audioTrack, localTracks.videoTrack ] = await Promise.all([
// Join the channel.
client.join(options.appid, options.channel, options.token || null, options.uid || null),
// Create tracks to the local microphone and camera.
AgoraRTC.createMicrophoneAudioTrack(),
AgoraRTC.createCameraVideoTrack()
]);
播放本地视频
// Play the local video track to the local browser and update the UI with the user ID.
localTracks.videoTrack.play("local-player");
发布本地音视频到频道中
// Publish the local video and audio tracks to the channel.
await client.publish(Object.values(localTracks));
监听远端用户音视频
// Add an event listener to play remote tracks when remote user publishes.
client.on("user-published", handleUserPublished);
client.on("user-unpublished", handleUserUnpublished); function handleUserPublished(user, mediaType) {
const id = user.uid;
remoteUsers[id] = user;
subscribe(user, mediaType);
} function handleUserUnpublished(user, mediaType) {
if (mediaType === 'video') {
const id = user.uid;
delete remoteUsers[id];
$(`#player-wrapper-${id}`).remove();
}
} async function subscribe(user, mediaType) {
const uid = user.uid;
// subscribe to a remote user
await client.subscribe(user, mediaType);
console.log("subscribe success");
if (mediaType === 'video') {
const player = $(`
<div id="player-wrapper-${uid}">
<p class="player-name">remoteUser(${uid})</p>
<div id="player-${uid}" class="player"></div>
</div>
`);
$("#remote-playerlist").append(player);
user.videoTrack.play(`player-${uid}`);
} if (mediaType === 'audio') {
user.audioTrack.play();
}
}
离开频道
async function leave() {
for (trackName in localTracks) {
var track = localTracks[trackName];
if(track) {
track.stop();
track.close();
localTracks[trackName] = undefined;
}
}
// Remove remote users and player views.
remoteUsers = {};
$("#remote-playerlist").html("");
// leave the channel
await client.leave();
}
最终完整的代码
// create Agora client
var client = AgoraRTC.createClient({ mode: "rtc", codec: "vp8" }); var localTracks = {
videoTrack: null,
audioTrack: null
};
var remoteUsers = {};
// Agora client options
var options = {
appid: null,
channel: null,
uid: null,
token: null
}; // the demo can auto join channel with params in url
$(() => {
var urlParams = new URL(location.href).searchParams;
options.appid = urlParams.get("appid");
options.channel = urlParams.get("channel");
options.token = urlParams.get("token");
if (options.appid && options.channel) {
$("#appid").val(options.appid);
$("#token").val(options.token);
$("#channel").val(options.channel);
$("#join-form").submit();
}
}) $("#join-form").submit(async function (e) {
e.preventDefault();
$("#join").attr("disabled", true);
try {
options.appid = $("#appid").val();
options.token = $("#token").val();
options.channel = $("#channel").val();
await join();
if(options.token) {
$("#success-alert-with-token").css("display", "block");
} else {
$("#success-alert a").attr("href", `index.html?appid=${options.appid}&channel=${options.channel}&token=${options.token}`);
$("#success-alert").css("display", "block");
}
} catch (error) {
console.error(error);
} finally {
$("#leave").attr("disabled", false);
}
}) $("#leave").click(function (e) {
leave();
}) async function join() { // add event listener to play remote tracks when remote user publishs.
client.on("user-published", handleUserPublished);
client.on("user-unpublished", handleUserUnpublished); // join a channel and create local tracks, we can use Promise.all to run them concurrently
[ options.uid, localTracks.audioTrack, localTracks.videoTrack ] = await Promise.all([
// join the channel
client.join(options.appid, options.channel, options.token || null),
// create local tracks, using microphone and camera
AgoraRTC.createMicrophoneAudioTrack(),
AgoraRTC.createCameraVideoTrack()
]); // play local video track
localTracks.videoTrack.play("local-player");
$("#local-player-name").text(`localVideo(${options.uid})`); // publish local tracks to channel
await client.publish(Object.values(localTracks));
console.log("publish success");
} async function leave() {
for (trackName in localTracks) {
var track = localTracks[trackName];
if(track) {
track.stop();
track.close();
localTracks[trackName] = undefined;
}
} // remove remote users and player views
remoteUsers = {};
$("#remote-playerlist").html(""); // leave the channel
await client.leave(); $("#local-player-name").text("");
$("#join").attr("disabled", false);
$("#leave").attr("disabled", true);
console.log("client leaves channel success");
} async function subscribe(user, mediaType) {
const uid = user.uid;
// subscribe to a remote user
await client.subscribe(user, mediaType);
console.log("subscribe success");
if (mediaType === 'video') {
const player = $(`
<div id="player-wrapper-${uid}">
<p class="player-name">remoteUser(${uid})</p>
<div id="player-${uid}" class="player"></div>
</div>
`);
$("#remote-playerlist").append(player);
user.videoTrack.play(`player-${uid}`);
}
if (mediaType === 'audio') {
user.audioTrack.play();
}
} function handleUserPublished(user, mediaType) {
const id = user.uid;
remoteUsers[id] = user;
subscribe(user, mediaType);
} function handleUserUnpublished(user) {
const id = user.uid;
delete remoteUsers[id];
$(`#player-wrapper-${id}`).remove();
}
运行效果
在浏览器开两个tab运行网页，使用两个用户加入同一个频道，如果能看见两个自己，说明你成功了。
03 完整代码下载
访问声网文档中心，根据下图所示路径，下载对应 SDK 压缩包。压缩包中包含完整代码。
参考链接
1.Github 源码
https://github.com/AgoraIO/API-Examples-Web/tree/main/Demo/basicVideoCall
2.线上体验Demo
https://webdemo.agora.io/basicVideoCall/index.html
3.声网文档中心
https://docs.agora.io/cn/Video/downloads?platform=Web
