diff -r c1c762ad1697 -r b4c6e64acb2d src/widgets/AnnotationsList.js
--- a/src/widgets/AnnotationsList.js	Wed Sep 26 18:55:36 2012 +0200
+++ b/src/widgets/AnnotationsList.js	Tue Oct 02 12:05:15 2012 +0200
@@ -17,7 +17,7 @@
     ajax_url : false,
     /* number of milliseconds before/after the current timecode when calling the segment API
      */
-    ajax_granularity : 300000, 
+    ajax_granularity : 600000, 
     default_thumbnail : "",
     /* URL when the annotation is not in the current project,
      * e.g. http://ldt.iri.centrepompidou.fr/ldtplatform/ldt/front/player/{{media}}/{{project}}/{{annotationType}}#id={{annotation}}
@@ -220,7 +220,7 @@
                 url : _url,
                 tags : _annotation.getTagTexts(),
                 specific_style : (typeof _bgcolor !== "undefined" ? "background-color: " + _bgcolor : ""),
-                audio : (_this.show_audio && _annotation.audio ? _annotation.audio.href : undefined),
+                audio : (_this.show_audio && _annotation.audio && _annotation.audio.href && _annotation.audio.href != "null" ? _annotation.audio.href : undefined),
                 l10n: _this.l10n
             };
             var _html = Mustache.to_html(_this.annotationTemplate, _data);