handle missing live display preserve prview

openlp/core/ui/media/mediacontroller.py

@@ -125,8 +125,10 @@ class MediaController(RegistryBase, LogMixin, RegistryProperties):
         self.setup()
         self.vlc_player = VlcPlayer(self)
         State().add_service("mediacontroller", 0)
+        State().add_service("media_live", 0, requires="mediacontroller")
         if get_vlc() and pymediainfo_available:
             State().update_pre_conditions("mediacontroller", True)
+            State().update_pre_conditions('media_live', True)
         else:
             State().missing_text("mediacontroller", translate('OpenLP.SlideController',
                                  "VLC or pymediainfo are missing, so you are unable to play any media"))
@@ -141,7 +143,7 @@ class MediaController(RegistryBase, LogMixin, RegistryProperties):
         try:
             self.setup_display(self.live_controller.display, False)
         except AttributeError:
-            State().update_pre_conditions('media', False)
+            State().update_pre_conditions('media_live', False)
         self.setup_display(self.preview_controller.preview_display, True)
 
     def display_controllers(self, controller_type):

openlp/core/ui/media/mediatab.py

@@ -34,6 +34,19 @@ from openlp.core.ui.icons import UiIcons
 LINUX_STREAM = 'v4l2:///dev/video0'
 WIN_STREAM = 'dshow:// :dshow-vdev='
 
+#from PyQt5.QtMultimedia import QCameraInfo, QAudioDeviceInfo, QAudio
+
+#print('Video input:')
+#for cam in QCameraInfo.availableCameras():
+#    print('===============')
+ ###   print(cam.deviceName())
+  #  print(cam.description())#
+#print()
+#print('Audio input:')
+#for au in QAudioDeviceInfo.availableDevices(QAudio.AudioInput):
+#    print('===============')
+#    print(au.deviceName())
+
 
 class MediaTab(SettingsTab):
     """

openlp/plugins/media/lib/mediaitem.py

@@ -116,6 +116,8 @@ class MediaMediaItem(MediaManagerItem, RegistryProperties):
             self.can_preview = False
             self.can_make_live = False
             self.can_add_to_service = False
+        if State().check_preconditions('media_live'):
+            self.can_make_live = False
 
     def add_list_view_to_toolbar(self):
         """