--- a/src/js/widgets/arrowWidget.js	Tue Feb 21 17:26:51 2012 +0100
+++ b/src/js/widgets/arrowWidget.js	Wed Feb 29 18:13:14 2012 +0100
@@ -43,7 +43,7 @@
     var begin = (+ currentAnnotation.begin) / 1000;
     var end = (+ currentAnnotation.end) / 1000;
 
-    var duration = +this._serializer.currentMedia().meta["dc:duration"] / 1000;
+    var duration = this._serializer.getDuration() / 1000;
     var middle_time = (begin + end) / 2;
     var percents = middle_time / duration;