var video = document.getElementById("video");
if (navigator.mediaDevices && navigator.mediaDevices.getUserMedia) {
    navigator.mediaDevices.getUserMedia({
        video: true,
        audio: true
    }).then(function(stream) {
        console.log(stream);
        mediaStreamTrack = typeof stream.stop === 'function' ? stream : stream.getTracks()[1];
    video.src = (window.URL || window.webkitURL).createObjectURL(stream);
        video.play();
    }).catch(function(err) {
        console.log(err);
})
}

//媒体对象

	    window.navigator.getMedia = window.navigator.getUserMedia ||

	                         window.navigator.webkitGetUserMedia ||

	                         window.navigator.mozGetUserMedia ||

	                         window.navigator.msGetUserMedia;

	    window.navigator.getMedia({

	        video: true, //使用摄像头对象

	        audio: false  //不适用音频

	    }, function(strem){

	        console.log(strem);

	        video.src = vendorUrl.createObjectURL(strem);

	        video.play();

	    }, function(error) {

	        console.log(error);

	    });