如何在Flex应用程序中检测相机是否已由另一个应用程序使用？ [英] How to detect in a Flex app if a camera is already in use by another application?

问题描述

我正在播放来自用户本地系统（Windows和Mac）的视频流的应用程序。我使用Camera.getCamera（）方法，依次Camera.names获取系统附带的摄像机列表。

I am making an application that plays the video stream from the user's local system (both Windows and Mac). I use the Camera.getCamera() method and in turn Camera.names to get a list of camera attached with the system.

不幸的是，如果相机已被另一个应用程序使用，比如在用户系统上的桌面应用程序，浏览器崩溃。是否有任何方法，我可以检测，如果可用的相机列表中的特定相机已被任何其他应用程序使用？

Unfortunately, if the camera is already in use by another application, say a desktop application on user's system, the browser is crashed. Is there any way that I can detect if a specific camera from the list of available camera is already in use by any other application?

推荐答案

这是真的，对于一些网络摄像头驱动程序，Camera对象不会为null，即使网络摄像头正在被另一个应用程序使用。唯一的区别是，如果相机已经在使用，则相机连接到Video对象后，ActivityEvent永远不会触发。

It's true that with some webcam drivers, the Camera object will not be null even if the webcam is in use by another application. The only difference is that the ActivityEvent will never be fired after the camera is attached to the Video object if the camera is already in use.

我通过设置一个超时5秒，并且如果活动事件尚未触发则引发事件：

I solved the issue by setting a timeout of 5 seconds and raising an event if the activity event had not yet fired:

public function WebCam(w:Number, h:Number, eventClient:Object) {
  _camera = Camera.getCamera();
  _micLive = Microphone.getMicrophone();
  _cameraWidth = w; // DEFAULT_CAMERA_WIDTH;
  _cameraHeight = h; // DEFAULT_CAMERA_HEIGHT;
  if (_camera != null) {
    video = new Video(_camera.width, _camera.height);   //displays video feed
    video.attachCamera(_camera);
    addChild(video); 
    _camera.addEventListener(StatusEvent.STATUS, cameraStatus);
    _camera.addEventListener(ActivityEvent.ACTIVITY, activityHandler);
    _camera.setMode(_cameraWidth, _cameraHeight, DEFAULT_CAMERA_FPS)

   //set timer to ensure that the camera activates.  If not, it might be in use by another application
    _waitingActivation = true;
    _timer = new Timer(TIMER_INTERVAL);
    _timer.addEventListener(TimerEvent.TIMER, activationTimeout);
    _timer.start();
  }
  else {
    //Security.showSettings(SecurityPanel.CAMERA)
  }
}
private function cameraStatus(event:StatusEvent):void{
    trace(_camera.muted);
}
private function activityHandler(e:ActivityEvent):void {
    trace('camera Activity');

    trace(_camera.activityLevel);
    if (e.activating){
        this._waitingActivation = false;
    }
}
protected function activationTimeout(e:TimerEvent):void{
    if (this._waitingActivation)
        this.dispatchEvent(new Event(WebCam.ACTIVATION_TIMEOUT, true));

    _timer.stop();
}

希望这有助于某人。

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