qtmux: Do not check timecode data for mp4 container

Timecode trak is only supported for mov right now, not for mp4. That
code would otherwise create an invalid trak if the muxed video contained
timecode metadata.

https://bugzilla.gnome.org/show_bug.cgi?id=782684

gst/isomp4/gstqtmux.c

@@ -2599,6 +2599,10 @@ gst_qt_mux_update_timecode (GstQTMux * qtmux, GstQTPad * qtpad)
   GstBuffer *buf;
   GstMapInfo map;
   guint64 offset = qtpad->tc_pos;
+  GstQTMuxClass *qtmux_klass = (GstQTMuxClass *) (G_OBJECT_GET_CLASS (qtmux));
+
+  if (qtmux_klass->format != GST_QT_MUX_FORMAT_QT)
+    return GST_FLOW_OK;
 
   g_assert (qtpad->tc_pos != -1);
 
@@ -3112,6 +3116,10 @@ gst_qt_mux_check_and_update_timecode (GstQTMux * qtmux, GstQTPad * pad,
   GstBuffer *tc_buf;
   gsize szret;
   guint32 frames_since_daily_jam;
+  GstQTMuxClass *qtmux_klass = (GstQTMuxClass *) (G_OBJECT_GET_CLASS (qtmux));
+
+  if (qtmux_klass->format != GST_QT_MUX_FORMAT_QT)
+    return ret;
 
   if (buf == NULL || (pad->tc_trak != NULL && pad->tc_pos == -1))
     return ret;