diff --git a/management/commands/update_subtitles.py b/management/commands/update_subtitles.py
index e103375..1b39dfa 100644
--- a/management/commands/update_subtitles.py
+++ b/management/commands/update_subtitles.py
@@ -13,7 +13,7 @@ class Command(BaseCommand):
 
     def add_arguments(self, parser):
         parser.add_argument('--prefix', action='store', dest='prefix', default=default_prefix, help='prefix to build clips in')
-        parser.add_argument('--offset', action='store', dest='offset', default="1024", help='inital offset in pi')
+        parser.add_argument('--offset', action='store', dest='offset', default=None, help='inital offset in pi')
 
     def handle(self, **options):
         update_subtitles(options)
diff --git a/render.py b/render.py
index 4ac80ac..a21d608 100644
--- a/render.py
+++ b/render.py
@@ -825,9 +825,16 @@ def load_defaults(options):
 
 def update_subtitles(options):
     import item.models
-
     options = load_defaults(options)
     prefix = Path(options['prefix'])
+
+    if options['offset'] is None:
+        offsets = [int(folder) for folder in os.listdir(prefix / 'render') if folder.isdigit()]
+        for offset in offsets:
+            options['offset'] = offset
+            update_subtitles(options)
+        return
+
     base = int(options['offset'])
     lang, tlang = parse_lang(options["lang"])