webhooks: use closest aspect ratio to transcode

* When running the transcode task it can happen that the aspect ratio is
  not in the list and therefore needs to be change by the closest one.
  We call use the display_aspect_ratio to call several API function so
  it might be better to fix it from the beginning.
  NOTE: this is a hack until CERNDocumentServer/cds-sorenson#37 is
  fixed.

cds/modules/webhooks/tasks.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 #
 # This file is part of CERN Document Server.
-# Copyright (C) 2016, 2017 CERN.
+# Copyright (C) 2016, 2017, 2018 CERN.
 #
 # CERN Document Server is free software; you can redistribute it
 # and/or modify it under the terms of the GNU General Public License as
@@ -36,8 +36,8 @@
 
 import jsonpatch
 import requests
-from cds_sorenson.api import (get_encoding_status, get_preset_info,
-                              start_encoding, stop_encoding)
+from cds_sorenson.api import (get_closest_aspect_ratio, get_encoding_status,
+                              get_preset_info, start_encoding, stop_encoding)
 from cds_sorenson.error import InvalidResolutionError, TooHighResolutionError
 from celery import current_app as celery_app
 from celery import Task, shared_task
@@ -580,11 +580,14 @@ def run(self, preset_quality, sleep_time=5, *args, **kwargs):
         master_key = self.object.key
 
         tags = self.object.get_tags()
-        # Get master file's aspect ratio
-        aspect_ratio = tags['display_aspect_ratio']
         # Get master file's width x height
         width = int(tags['width']) if 'width' in tags else None
         height = int(tags['height']) if 'height' in tags else None
+        # Get master file's aspect ratio
+        aspect_ratio = tags['display_aspect_ratio']
+        # HACK: correct aspect ratio in case not in the list
+        if width is not None and height is not None:
+            aspect_ratio = get_closest_aspect_ratio(width, height)
 
         with db.session.begin_nested():
             # Create FileInstance