Add stream source for amcrest component (#21983)

homeassistant/components/amcrest/camera.py

@@ -97,3 +97,8 @@ class AmcrestCam(Camera):
     def name(self):
         """Return the name of this camera."""
         return self._name
+
+    @property
+    def stream_source(self):
+        """Return the source of the stream."""
+        return self._camera.rtsp_url(typeno=self._resolution)