diff --git a/ChangeLog b/ChangeLog
index 5e4553fd8d..ffe5a7c12b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2007-11-26  Stefan Kost  <ensonic@users.sf.net>
+
+	* gst/audiotestsrc/gstaudiotestsrc.c:
+	* gst/volume/gstvolume.c:
+	* gst/volume/gstvolume.h:
+	  Add GAP-flag support.
+
 2007-11-24  Julien MOUTTE  <julien@moutte.net>
 
 	* tests/examples/seek/seek.c: (main): Increase the range of the
diff --git a/gst/audiotestsrc/gstaudiotestsrc.c b/gst/audiotestsrc/gstaudiotestsrc.c
index 6d6cd3202d..a63bf45cb9 100644
--- a/gst/audiotestsrc/gstaudiotestsrc.c
+++ b/gst/audiotestsrc/gstaudiotestsrc.c
@@ -870,8 +870,15 @@ gst_audio_test_src_create (GstBaseSrc * basesrc, guint64 offset,
   src->running_time = next_time;
   src->n_samples = n_samples;
 
+  GST_LOG_OBJECT (src, "generating %u samples at ts %" GST_TIME_FORMAT,
+      length, GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (buf)));
+
   src->process (src, GST_BUFFER_DATA (buf));
 
+  if (src->wave == G_UNLIKELY (GST_AUDIO_TEST_SRC_WAVE_SILENCE)) {
+    GST_BUFFER_FLAG_SET (buf, GST_BUFFER_FLAG_GAP);
+  }
+
   *buffer = buf;
 
   return GST_FLOW_OK;
diff --git a/gst/volume/gstvolume.c b/gst/volume/gstvolume.c
index 942cda9537..222ea0b476 100644
--- a/gst/volume/gstvolume.c
+++ b/gst/volume/gstvolume.c
@@ -313,6 +313,8 @@ volume_update_real_volume (GstVolume * this)
     this->real_vol_i32 = this->volume_i32;
     passthrough = (this->volume_i16 == VOLUME_UNITY_INT16);
   }
+  if (this->real_vol_f != 0.0)
+    this->silent_buffer = FALSE;
   volume_choose_func (this);
   gst_base_transform_set_passthrough (GST_BASE_TRANSFORM (this), passthrough);
 }
@@ -747,11 +749,19 @@ volume_transform_ip (GstBaseTransform * base, GstBuffer * outbuf)
     gst_object_sync_values (G_OBJECT (this), timestamp);
 
   /* don't process data in passthrough-mode */
-  if (gst_base_transform_is_passthrough (base))
+  if (gst_base_transform_is_passthrough (base) ||
+      GST_BUFFER_FLAG_IS_SET (outbuf, GST_BUFFER_FLAG_GAP))
     return GST_FLOW_OK;
 
+  if (this->real_vol_f == 0.0)
+    this->silent_buffer = TRUE;
+
   this->process (this, GST_BUFFER_DATA (outbuf), GST_BUFFER_SIZE (outbuf));
 
+  if (this->silent_buffer)
+    GST_BUFFER_FLAG_SET (outbuf, GST_BUFFER_FLAG_GAP);
+  this->silent_buffer = FALSE;
+
   return GST_FLOW_OK;
 }
 
diff --git a/gst/volume/gstvolume.h b/gst/volume/gstvolume.h
index 5a180f571a..236d49db75 100644
--- a/gst/volume/gstvolume.h
+++ b/gst/volume/gstvolume.h
@@ -68,6 +68,7 @@ struct _GstVolume {
   GList *tracklist;
   GstVolumeFormat format;       /* caps variables */
   gint width;
+  gboolean silent_buffer;       /* flag for silent buffers */
 };
 
 struct _GstVolumeClass {