search
HomeWeb Front-endH5 TutorialDetailed explanation of WebRTC new features of HTML5

1. Overview

WebRTC is the abbreviation of "Web Real Time Communication". It is mainly used to allow browsers to obtain and exchange videos in real time. ##, Audio and data.

WebRTC is divided into three APIs.

  • MediaStream (also known as getUserMedia)

  • RTCPeerConnection

  • RTCDataChannel

getUserMedia is mainly used to obtain video and audio information, and the latter two APIs are used for data exchange between browsers.

2. getUserMedia

2.1

Introduction

First, check whether the browser supports the getUserMedia method.

navigator.getUserMedia || 
    (navigator.getUserMedia = navigator.mozGetUserMedia ||  navigator.webkitGetUserMedia || navigator.msGetUserMedia);

if (navigator.getUserMedia) {
    //do something
} else {
    console.log('your browser not support getUserMedia');
}

Chrome21, Opera 18 and Firefox 17 support this method. Currently IE does not support it. msGetUserMedia in the above code is only to ensure future compatibility.

The getUserMedia method accepts three parameters.

getUserMedia(streams, success, error);

The meaning is as follows:

Usage is as follows:

navigator.getUserMedia({
    video: true,
    audio: true}, onSuccess, onError);

The above code is used to obtain real-time information from the camera and microphone.

If the web page uses getUserMedia, the browser will ask the user whether to allow the provision of information. If the user refuses, the callback function onError is called.

When an error occurs, the parameter of the callback

function is an Error object, which has a code parameter with the following values:

  • PERMISSION_DENIED: User Refusal to provide information.

  • NOT_SUPPORTED_ERROR: The browser does not support the specified media type.

  • MANDATORY_UNSATISHIED_ERROR: No media stream was received for the specified media type.

2.2 Displaying camera images

To display images captured by the user's camera on a web page, you need to first place a video element on the web page. The image is displayed in this element.

<video id="webcam"></video>

Then, use code to get this element.

function onSuccess(stream) {    
var video = document.getElementById(&#39;webcam&#39;);    
//more code}

Finally, bind the src

attribute of this element to the data stream, and the image captured by the camera can be displayed.

function onSuccess(stream) {    
var video = document.getElementById(&#39;webcam&#39;);    
if (window.URL) {
        video.src = window.URL.createObjectURL(stream);
    } else {
        video.src = stream;
    }

    video.autoplay = true;    //or video.play();}

Its main purpose is to allow users to take photos of themselves using the camera.

2.3 Capturing microphone sound

Capturing sound through the browser is relatively complicated and requires the use of Web Audio API.

function onSuccess(stream) {    
//创建一个音频环境对像
    audioContext = window.AudioContext || window.webkitAudioContext;
    context = new audioContext();    
    //将声音输入这个对像
    audioInput = context.createMediaStreamSources(stream);    
    //设置音量节点
    volume = context.createGain();
    audioInput.connect(volume);    
    //创建缓存,用来缓存声音
    var bufferSize = 2048;    
    // 创建声音的缓存节点,createJavaScriptNode方法的
    // 第二个和第三个参数指的是输入和输出都是双声道。
    recorder = context.createJavaScriptNode(bufferSize, 2, 2);    
    // 录音过程的回调函数,基本上是将左右两声道的声音
    // 分别放入缓存。
    recorder.onaudioprocess = function(e){
        console.log(&#39;recording&#39;);        
        var left = e.inputBuffer.getChannelData(0);        
        var right = e.inputBuffer.getChannelData(1);        
        // we clone the samples
        leftchannel.push(new Float32Array(left));
        rightchannel.push(new Float32Array(right));
        recordingLength += bufferSize;
    }    // 将音量节点连上缓存节点,换言之,音量节点是输入
    // 和输出的中间环节。    
    volume.connect(recorder);    
    // 将缓存节点连上输出的目的地,可以是扩音器,也可以
    // 是音频文件。    
    recorder.connect(context.destination); 

}

3. Real-time data exchange

The other two APIs of WebRTC, RTCPeerConnection is used for point-to-point connections between browsers, and RTCDataChannel is used for point-to-point data communication.

RTCPeerConnection has a browser prefix, which is webkitRTCPeerConnection in Chrome browser and mozRTCPeerConnection in Firefox browser. Google maintains a function library adapter.js to abstract away the differences between browsers.

var dataChannelOptions = {
  ordered: false, // do not guarantee order
  maxRetransmitTime: 3000, // in milliseconds};
  var peerConnection = new RTCPeerConnection();
  // Establish your peer connection using your signaling channel herevar dataChannel =
  peerConnection.createDataChannel("myLabel", dataChannelOptions);

dataChannel.onerror = function (error) {
  console.log("Data Channel Error:", error);
};

dataChannel.onmessage = function (event) {
  console.log("Got Data Channel Message:", event.data);
};

dataChannel.onopen = function () {
  dataChannel.send("Hello World!");
};

dataChannel.onclose = function () {
  console.log("The Data Channel is Closed");
};

4. Reference link

[1] Andi Smith, Get Started with WebRTC

[2] Thibault Imbert, From microphone to .WAV with: getUserMedia and Web Audio

[3] Ian Devlin, Using the getUserMedia API with the

HTML5 video and canvas elements

[4] Eric Bidelman, Capturing Audio & Video in HTML5

[5] Sam Dutton, Getting Started with WebRTC

[6] Dan Ristic, WebRTC data channels

[7] Ruanyf, WebRTC

The above is the detailed content of Detailed explanation of WebRTC new features of HTML5. For more information, please follow other related articles on the PHP Chinese website!

Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
html5的div一行可以放两个吗html5的div一行可以放两个吗Apr 25, 2022 pm 05:32 PM

html5的div元素默认一行不可以放两个。div是一个块级元素,一个元素会独占一行,两个div默认无法在同一行显示;但可以通过给div元素添加“display:inline;”样式,将其转为行内元素,就可以实现多个div在同一行显示了。

html5中列表和表格的区别是什么html5中列表和表格的区别是什么Apr 28, 2022 pm 01:58 PM

html5中列表和表格的区别:1、表格主要是用于显示数据的,而列表主要是用于给数据进行布局;2、表格是使用table标签配合tr、td、th等标签进行定义的,列表是利用li标签配合ol、ul等标签进行定义的。

html5怎么让头和尾固定不动html5怎么让头和尾固定不动Apr 25, 2022 pm 02:30 PM

固定方法:1、使用header标签定义文档头部内容,并添加“position:fixed;top:0;”样式让其固定不动;2、使用footer标签定义尾部内容,并添加“position: fixed;bottom: 0;”样式让其固定不动。

HTML5中画布标签是什么HTML5中画布标签是什么May 18, 2022 pm 04:55 PM

HTML5中画布标签是“<canvas>”。canvas标签用于图形的绘制,它只是一个矩形的图形容器,绘制图形必须通过脚本(通常是JavaScript)来完成;开发者可利用多种js方法来在canvas中绘制路径、盒、圆、字符以及添加图像等。

html5中不支持的标签有哪些html5中不支持的标签有哪些Mar 17, 2022 pm 05:43 PM

html5中不支持的标签有:1、acronym,用于定义首字母缩写,可用abbr替代;2、basefont,可利用css样式替代;3、applet,可用object替代;4、dir,定义目录列表,可用ul替代;5、big,定义大号文本等等。

html5废弃了哪个列表标签html5废弃了哪个列表标签Jun 01, 2022 pm 06:32 PM

html5废弃了dir列表标签。dir标签被用来定义目录列表,一般和li标签配合使用,在dir标签对中通过li标签来设置列表项,语法“<dir><li>列表项值</li>...</dir>”。HTML5已经不支持dir,可使用ul标签取代。

html5是什么意思html5是什么意思Apr 26, 2021 pm 03:02 PM

html5是指超文本标记语言(HTML)的第五次重大修改,即第5代HTML。HTML5是Web中核心语言HTML的规范,用户使用任何手段进行网页浏览时看到的内容原本都是HTML格式的,在浏览器中通过一些技术处理将其转换成为了可识别的信息。HTML5由不同的技术构成,其在互联网中得到了非常广泛的应用,提供更多增强网络应用的标准机。

Html5怎么取消td边框Html5怎么取消td边框May 18, 2022 pm 06:57 PM

3种取消方法:1、给td元素添加“border:none”无边框样式即可,语法“td{border:none}”。2、给td元素添加“border:0”样式,语法“td{border:0;}”,将td边框的宽度设置为0即可。3、给td元素添加“border:transparent”样式,语法“td{border:transparent;}”,将td边框的颜色设置为透明即可。

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Article

R.E.P.O. Energy Crystals Explained and What They Do (Yellow Crystal)
2 weeks agoBy尊渡假赌尊渡假赌尊渡假赌
Repo: How To Revive Teammates
4 weeks agoBy尊渡假赌尊渡假赌尊渡假赌
Hello Kitty Island Adventure: How To Get Giant Seeds
3 weeks agoBy尊渡假赌尊渡假赌尊渡假赌

Hot Tools

WebStorm Mac version

WebStorm Mac version

Useful JavaScript development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Safe Exam Browser

Safe Exam Browser

Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

Dreamweaver Mac version

Dreamweaver Mac version

Visual web development tools