Update app.py

app.py

@@ -17,7 +17,7 @@ def transcode_video(video_file, output_file, output_format, output_fps):
   """
 
   # Create a folder to save the transcoded video file to.
-  output_dir = os.path.dirname(output_dir)
+  output_dir = os.path.dirname(output_file)
   if not os.path.exists(output_dir):
     os.makedirs(output_dir)