如何html5在浏览器里访问手机后置摄像头

如题所述

html5需要使用接口chrome30+ for android 已经实现了利用webcam,调用手机后置摄像头,代码如下:

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>HTML5 GetUserMedia Demo</title>
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0" />
</head>
<body>
<input type="button" title="开启摄像头" value="开启摄像头" onclick="getMedia();" /><br />
<video height="120px" autoplay="autoplay"></video><hr />
<input type="button" title="拍照" value="拍照" onclick="getPhoto();" /><br />
<canvas id="canvas1" height="120px" ></canvas><hr />
<input type="button" title="视频" value="视频" onclick="getVedio();" /><br />
<canvas id="canvas2" height="120px"></canvas>

<script type="text/javascript">
var video = document.querySelector('video');
var audio, audioType;

var canvas1 = document.getElementById('canvas1');
var context1 = canvas1.getContext('2d');

var canvas2 = document.getElementById('canvas2');
var context2 = canvas2.getContext('2d');

navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia;
window.URL = window.URL || window.webkitURL || window.mozURL || window.msURL;

var exArray = []; //存储设备源ID
MediaStreamTrack.getSources(function (sourceInfos) {
for (var i = 0; i != sourceInfos.length; ++i) {
var sourceInfo = sourceInfos[i];
//这里会遍历audio,video,所以要加以区分
if (sourceInfo.kind === 'video') {
exArray.push(sourceInfo.id);
}
}
});

function getMedia() {
if (navigator.getUserMedia) {
navigator.getUserMedia({
'video': {
'optional': [{
'sourceId': exArray[1] //0为前置摄像头,1为后置
}]
},
'audio':true
}, successFunc, errorFunc); //success是获取成功的回调函数
}
else {
alert('Native device media streaming (getUserMedia) not supported in this browser.');
}
}

function successFunc(stream) {
//alert('Succeed to get media!');
if (video.mozSrcObject !== undefined) {
//Firefox中,video.mozSrcObject最初为null,而不是未定义的,我们可以靠这个来检测Firefox的支持
video.mozSrcObject = stream;
}
else {
video.src = window.URL && window.URL.createObjectURL(stream) || stream;
}

//video.play();

// 音频
audio = new Audio();
audioType = getAudioType(audio);
if (audioType) {
audio.src = 'polaroid.' + audioType;
audio.play();
}
}
function errorFunc(e) {
alert('Error!'+e);
}

// 将视频帧绘制到Canvas对象上,Canvas每60ms切换帧,形成肉眼视频效果
function drawVideoAtCanvas(video,context) {
window.setInterval(function () {
context.drawImage(video, 0, 0,90,120);
}, 60);
}

//获取音频格式
function getAudioType(element) {
if (element.canPlayType) {
if (element.canPlayType('audio/mp4; codecs="mp4a.40.5"') !== '') {
return ('aac');
} else if (element.canPlayType('audio/ogg; codecs="vorbis"') !== '') {
return ("ogg");
}
}
return false;
}

// vedio播放时触发,绘制vedio帧图像到canvas
// video.addEventListener('play', function () {
// drawVideoAtCanvas(video, context2);
// }, false);

//拍照
function getPhoto() {
context1.drawImage(video, 0, 0,90,120); //将video对象内指定的区域捕捉绘制到画布上指定的区域,实现拍照。
}

//视频
function getVedio() {
drawVideoAtCanvas(video, context2);
}

</script>
</body>
</html>

HTML5 The Media Capture API提供了对摄像头的可编程访问,用户可以直接用getUserMedia获得摄像头提供的视频流。但实际上用html5调用手机摄像头存在很多问题:1)谷歌的发布的Chrome到了21版本后,才新增了一个用于高质量视频音频通讯的getUserMedia API,该API允许Web应用程序访问摄像头和麦克风,其他手机浏览器只有opera支持html5调用本地拍照功能2)两个浏览器均不支持访问多个摄像头:chrome不支持访问后置摄像头,pera支持访问后置摄像头的
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