我想了解用户的设备是否具有连接的摄像头和麦克风,如果有,是否已授予使用Javascript获取音频和视频流的权限。我想至少在Chrome和Firefox上进行此项检查。什么是一致的API?
现场演示:
如果用户不允许使用网络摄像头和/或麦克风,则媒体设备的“标签”属性将具有“ NULL”值。上面的页面将显示以下消息:“请调用一次getUserMedia。”
PS。您可以在Chrome控制台开发人员工具中输入“ DetectRTC.MediaDevices”。
注意:仅适用于Chrome。 Firefox还不支持类似的API。(已更新: Firefox也支持)
注意:以下代码段可在Chrome和Firefox中使用。
if (navigator.mediaDevices && navigator.mediaDevices.enumerateDevices) {
// Firefox 38+ seems having support of enumerateDevicesx
navigator.enumerateDevices = function(callback) {
navigator.mediaDevices.enumerateDevices().then(callback);
};
}
var MediaDevices = [];
var isHTTPs = location.protocol === 'https:';
var canEnumerate = false;
if (typeof MediaStreamTrack !== 'undefined' && 'getSources' in MediaStreamTrack) {
canEnumerate = true;
} else if (navigator.mediaDevices && !!navigator.mediaDevices.enumerateDevices) {
canEnumerate = true;
}
var hasMicrophone = false;
var hasSpeakers = false;
var hasWebcam = false;
var isMicrophoneAlreadyCaptured = false;
var isWebcamAlreadyCaptured = false;
function checkDeviceSupport(callback) {
if (!canEnumerate) {
return;
}
if (!navigator.enumerateDevices && window.MediaStreamTrack && window.MediaStreamTrack.getSources) {
navigator.enumerateDevices = window.MediaStreamTrack.getSources.bind(window.MediaStreamTrack);
}
if (!navigator.enumerateDevices && navigator.enumerateDevices) {
navigator.enumerateDevices = navigator.enumerateDevices.bind(navigator);
}
if (!navigator.enumerateDevices) {
if (callback) {
callback();
}
return;
}
MediaDevices = [];
navigator.enumerateDevices(function(devices) {
devices.forEach(function(_device) {
var device = {};
for (var d in _device) {
device[d] = _device[d];
}
if (device.kind === 'audio') {
device.kind = 'audioinput';
}
if (device.kind === 'video') {
device.kind = 'videoinput';
}
var skip;
MediaDevices.forEach(function(d) {
if (d.id === device.id && d.kind === device.kind) {
skip = true;
}
});
if (skip) {
return;
}
if (!device.deviceId) {
device.deviceId = device.id;
}
if (!device.id) {
device.id = device.deviceId;
}
if (!device.label) {
device.label = 'Please invoke getUserMedia once.';
if (!isHTTPs) {
device.label = 'HTTPs is required to get label of this ' + device.kind + ' device.';
}
} else {
if (device.kind === 'videoinput' && !isWebcamAlreadyCaptured) {
isWebcamAlreadyCaptured = true;
}
if (device.kind === 'audioinput' && !isMicrophoneAlreadyCaptured) {
isMicrophoneAlreadyCaptured = true;
}
}
if (device.kind === 'audioinput') {
hasMicrophone = true;
}
if (device.kind === 'audiooutput') {
hasSpeakers = true;
}
if (device.kind === 'videoinput') {
hasWebcam = true;
}
// there is no 'videoouput' in the spec.
MediaDevices.push(device);
});
if (callback) {
callback();
}
});
}
// check for microphone/camera support!
checkDeviceSupport(function() {
document.write('hasWebCam: ', hasWebcam, '<br>');
document.write('hasMicrophone: ', hasMicrophone, '<br>');
document.write('isMicrophoneAlreadyCaptured: ', isMicrophoneAlreadyCaptured, '<br>');
document.write('isWebcamAlreadyCaptured: ', isWebcamAlreadyCaptured, '<br>');
});
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