diff -r 54505b8bad88 -r 179f9381965b src/pyams_media/zmi/media.py
--- a/src/pyams_media/zmi/media.py	Fri Dec 04 16:33:41 2015 +0100
+++ b/src/pyams_media/zmi/media.py	Fri Dec 04 16:34:30 2015 +0100
@@ -99,6 +99,12 @@
                                                  extension=converter.format)
         return name in conversions
 
+    def get_conversion(self, converter, frame_size):
+        conversions = IMediaConversions(self.context)
+        name = 'video{width}.{extension}'.format(width='-{0}'.format(frame_size) if frame_size else '',
+                                                 extension=converter.format)
+        return conversions.get(name)
+
 
 #
 # Audio conversions