Move ffmpeg to dispatcher from hass.data entity store. (#6211)

* Move ffmpeg to dispatcher from hass.data entity store.

* fix lint

* address paulus comments

* add more unittest for better coverage

homeassistant/components/binary_sensor/ffmpeg_noise.py

@@ -54,9 +54,6 @@ def async_setup_platform(hass, config, async_add_devices, discovery_info=None):
 
     # generate sensor object
     entity = FFmpegNoise(hass, manager, config)
-
-    # add to system
-    manager.async_register_device(entity)
     yield from async_add_devices([entity])
 
 
@@ -67,15 +64,19 @@ class FFmpegNoise(FFmpegBinarySensor):
         """Initialize ffmpeg noise binary sensor."""
         from haffmpeg import SensorNoise
 
-        super().__init__(hass, config)
+        super().__init__(config)
         self.ffmpeg = SensorNoise(
             manager.binary, hass.loop, self._async_callback)
 
-    def async_start_ffmpeg(self):
+    @asyncio.coroutine
+    def _async_start_ffmpeg(self, entity_ids):
         """Start a FFmpeg instance.
 
-        This method must be run in the event loop and returns a coroutine.
+        This method is a coroutine.
         """
+        if entity_ids is not None and self.entity_id not in entity_ids:
+            return
+
         # init config
         self.ffmpeg.set_options(
             time_duration=self._config.get(CONF_DURATION),
@@ -84,7 +85,7 @@ class FFmpegNoise(FFmpegBinarySensor):
         )
 
         # run
-        return self.ffmpeg.open_sensor(
+        yield from self.ffmpeg.open_sensor(
             input_source=self._config.get(CONF_INPUT),
             output_dest=self._config.get(CONF_OUTPUT),
             extra_cmd=self._config.get(CONF_EXTRA_ARGUMENTS),