java.lang.RuntimeException: startPreview failed
	at android.hardware.Camera.startPreview(Native Method)
	at com.google.android.gms.vision.a.d(Unknown Source:20)
	at com.entitcs.office_attendance.camera.CameraSourcePreview.f(Unknown Source:29)
	at com.entitcs.office_attendance.camera.CameraSourcePreview.d(Unknown Source:12)
	at com.entitcs.office_attendance.camera.CameraSourcePreview.e(Unknown Source:2)
	at com.entitcs.office_attendance.camera.FaceTrackerActivity.R(Unknown Source:37)
	at com.entitcs.office_attendance.camera.FaceTrackerActivity.B(Unknown Source:85)
	at com.entitcs.office_attendance.camera.FaceTrackerActivity$h.onClick(Unknown Source:19)
	at android.view.View.performClick(View.java:8160)
	at com.entitcs.office_attendance.java_classes.MovableFloatingActionButton.onTouch(Unknown Source:171)
	at android.view.View.dispatchTouchEvent(View.java:15195)
	at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3942)
	at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:3594)
	at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3920)
	at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:3594)
	at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3920)
	at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:3594)
	at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3920)
	at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:3594)
	at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3920)
	at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:3594)
	at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3920)
	at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:3594)
	at com.android.internal.policy.DecorView.superDispatchTouchEvent(DecorView.java:915)
	at com.android.internal.policy.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1957)
	at android.app.Activity.dispatchTouchEvent(Activity.java:4182)
	at c.a.n.i.dispatchTouchEvent(Unknown Source:2)
	at com.android.internal.policy.DecorView.dispatchTouchEvent(DecorView.java:873)
	at android.view.View.dispatchPointerEvent(View.java:15458)
	at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:7457)
	at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:7233)
	at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:6595)
	at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:6652)
	at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:6618)
	at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:6786)
	at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:6626)
	at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:6843)
	at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:6599)
	at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:6652)
	at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:6618)
	at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:6626)
	at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:6599)
	at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:9880)
	at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:9718)
	at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:9671)
	at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:10014)
	at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:220)
	at android.os.MessageQueue.nativePollOnce(Native Method)
	at android.os.MessageQueue.next(MessageQueue.java:335)
	at android.os.Looper.loop(Looper.java:206)
	at android.app.ActivityThread.main(ActivityThread.java:8653)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:602)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1130)