diff --git a/gst/isomp4/gstqtmux.c b/gst/isomp4/gstqtmux.c
index 0f18d5ab1c..f9759cea1f 100644
--- a/gst/isomp4/gstqtmux.c
+++ b/gst/isomp4/gstqtmux.c
@@ -3156,6 +3156,9 @@ gst_qt_mux_video_sink_set_caps (GstPad * pad, GstCaps * caps)
   } else if (strcmp (mimetype, "video/x-vp8") == 0) {
     entry.fourcc = FOURCC_VP80;
     sync = FALSE;
+  } else if (strcmp (mimetype, "video/x-dirac") == 0) {
+    entry.fourcc = FOURCC_drac;
+    qtpad->have_dts = TRUE;
   } else if (strcmp (mimetype, "video/x-qt-part") == 0) {
     guint32 fourcc;
 
diff --git a/gst/isomp4/gstqtmuxmap.c b/gst/isomp4/gstqtmuxmap.c
index e62c5eec44..a595c2234b 100644
--- a/gst/isomp4/gstqtmuxmap.c
+++ b/gst/isomp4/gstqtmuxmap.c
@@ -166,6 +166,8 @@ GstQTMuxFormatProp gst_qt_mux_format_list[] = {
             "image/jpeg, "
             COMMON_VIDEO_CAPS_NO_FRAMERATE "; "
             "video/x-vp8, "
+            COMMON_VIDEO_CAPS "; "
+            "video/x-dirac, "
             COMMON_VIDEO_CAPS "; " "video/x-qt-part, " COMMON_VIDEO_CAPS),
         GST_STATIC_CAPS (PCM_CAPS_FULL "; "
             MP3_CAPS " ; "
diff --git a/gst/matroska/matroska-demux.c b/gst/matroska/matroska-demux.c
index c82400dbe1..0eac2b769c 100644
--- a/gst/matroska/matroska-demux.c
+++ b/gst/matroska/matroska-demux.c
@@ -2961,7 +2961,7 @@ gst_matroska_demux_parse_blockgroup_or_simpleblock (GstMatroskaDemux * demux,
   GstFlowReturn ret = GST_FLOW_OK;
   gboolean readblock = FALSE;
   guint32 id;
-  guint64 block_duration = 0;
+  guint64 block_duration = -1;
   GstBuffer *buf = NULL;
   gint stream_num = -1, n, laces = 0;
   guint size = 0;
@@ -3249,7 +3249,7 @@ gst_matroska_demux_parse_blockgroup_or_simpleblock (GstMatroskaDemux * demux,
       demux->need_newsegment = FALSE;
     }
 
-    if (block_duration) {
+    if (block_duration != -1) {
       if (stream->timecodescale == 1.0)
         duration = gst_util_uint64_scale (block_duration,
             demux->common.time_scale, 1);