Blender image sequences now generate a preview mp4 on completion

lib/render_workers/base_worker.py

@@ -187,6 +187,10 @@ class BaseRenderWorker(object):
             if not self.errors:
                 self.errors = [self.last_output]
         self.is_finished = True
+        self.post_processing()
+
+    def post_processing(self):
+        pass
 
     def is_running(self):
         if self.__thread: