gst/spectrum/: port to use message to get results, cleanly exit when closing the window

Original commit message from CVS:
* gst/spectrum/demo-audiotest.c: (on_window_destroy),
(draw_spectrum), (message_handler), (main):
* gst/spectrum/demo-osssrc.c: (on_window_destroy), (draw_spectrum),
(message_handler), (main):
port to use message to get results, cleanly exit when closing the window
* gst/spectrum/gstspectrum.c: (gst_spectrum_class_init),
(gst_spectrum_init), (gst_spectrum_dispose),
(gst_spectrum_set_property), (gst_spectrum_get_property),
(gst_spectrum_set_caps), (gst_spectrum_start),
(gst_spectrum_message_new), (gst_spectrum_transform_ip):
* gst/spectrum/gstspectrum.h:
port to derive from basetransform and send results via messages
(like level element)

4 files changed, 402 insertions, 107 deletions

diff --git a/gst/spectrum/demo-audiotest.c b/gst/spectrum/demo-audiotest.c
index 11ebf9df..e69aef34 100644
--- a/gst/spectrum/demo-audiotest.c
+++ b/gst/spectrum/demo-audiotest.c
@@ -1,15 +1,45 @@
+/* GStreamer
+ * Copyright (C) 2006 Stefan Kost <ensonic@users.sf.net>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
+
+#include <string.h>
+#include <math.h>
 #include <gst/gst.h>
 #include <gtk/gtk.h>
 
+#define DEFAULT_AUDIOSINK "alsasink"
 #define SPECT_BANDS 256
 
 static GtkWidget *drawingarea = NULL;
-static gint ct = 0;
 
 static void
+on_window_destroy (GtkObject * object, gpointer user_data)
+{
+  drawingarea = NULL;
+  gtk_main_quit ();
+}
+
+/* control audiotestsrc frequency */
+static void
 on_frequency_changed (GtkRange * range, gpointer user_data)
 {
   GstElement *machine = GST_ELEMENT (user_data);
@@ -18,26 +48,51 @@ on_frequency_changed (GtkRange * range, gpointer user_data)
   g_object_set (machine, "freq", value, NULL);
 }
 
+/* draw frequency spectrum as a bunch of bars */
 static void
-spectrum_chain (GstElement * sink, GstBuffer * buf, GstPad * pad,
-    gpointer unused)
+draw_spectrum (guchar * data)
 {
-  ct = (ct + 1) & 0x15;
-  if (!ct) {
-    gint i;
-    guchar *data = buf->data;
-    gint width = GST_BUFFER_SIZE (buf);
-    GdkRectangle rect = { 0, 0, width, 50 };
-
-    gdk_window_begin_paint_rect (drawingarea->window, &rect);
-    gdk_draw_rectangle (drawingarea->window, drawingarea->style->black_gc,
-        TRUE, 0, 0, width, 50);
-    for (i = 0; i < width; i++) {
-      gdk_draw_rectangle (drawingarea->window, drawingarea->style->white_gc,
-          TRUE, i, 64 - data[i], 1, data[i]);
+  gint i;
+  GdkRectangle rect = { 0, 0, SPECT_BANDS, 50 };
+
+  if (!drawingarea)
+    return;
+
+  gdk_window_begin_paint_rect (drawingarea->window, &rect);
+  gdk_draw_rectangle (drawingarea->window, drawingarea->style->black_gc,
+      TRUE, 0, 0, SPECT_BANDS, 50);
+  for (i = 0; i < SPECT_BANDS; i++) {
+    gdk_draw_rectangle (drawingarea->window, drawingarea->style->white_gc,
+        TRUE, i, 64 - data[i], 1, data[i]);
+  }
+  gdk_window_end_paint (drawingarea->window);
+}
+
+/* receive spectral data from element message */
+gboolean
+message_handler (GstBus * bus, GstMessage * message, gpointer data)
+{
+  if (message->type == GST_MESSAGE_ELEMENT) {
+    const GstStructure *s = gst_message_get_structure (message);
+    const gchar *name = gst_structure_get_name (s);
+
+    if (strcmp (name, "spectrum") == 0) {
+      guchar spect[SPECT_BANDS];
+      const GValue *list;
+      const GValue *value;
+      guint i;
+
+      list = gst_structure_get_value (s, "spectrum");
+      for (i = 0; i < SPECT_BANDS; ++i) {
+        value = gst_value_list_get_value (list, i);
+        spect[i] = g_value_get_uchar (value);
+      }
+      draw_spectrum (spect);
     }
-    gdk_window_end_paint (drawingarea->window);
   }
+  /* we handled the message we want, and ignored the ones we didn't want.
+   * so the core can unref the message for us */
+  return TRUE;
 }
 
 int
@@ -45,7 +100,7 @@ main (int argc, char *argv[])
 {
   GstElement *bin;
   GstElement *src, *spectrum, *sink;
-
+  GstBus *bus;
   GtkWidget *appwindow, *vbox, *widget;
 
   gst_init (&argc, &argv);
@@ -54,16 +109,15 @@ main (int argc, char *argv[])
   bin = gst_pipeline_new ("bin");
 
   src = gst_element_factory_make ("audiotestsrc", "src");
-  g_object_set (G_OBJECT (src), "blocksize", (gulong) 1024 * 2, NULL);
+  /*
+     g_object_set (G_OBJECT (src), "wave", 0, NULL);
+   */
 
   spectrum = gst_element_factory_make ("spectrum", "spectrum");
-  g_object_set (G_OBJECT (spectrum), "width", SPECT_BANDS, "threshold", -80,
-      NULL);
-
-  sink = gst_element_factory_make ("fakesink", "sink");
-  g_object_set (G_OBJECT (sink), "signal-handoffs", TRUE, NULL);
+  g_object_set (G_OBJECT (spectrum), "bands", SPECT_BANDS, "threshold", -80,
+      "message", TRUE, NULL);
 
-  g_signal_connect (sink, "handoff", G_CALLBACK (spectrum_chain), NULL);
+  sink = gst_element_factory_make (DEFAULT_AUDIOSINK, "sink");
 
   gst_bin_add_many (GST_BIN (bin), src, spectrum, sink, NULL);
   if (!gst_element_link_many (src, spectrum, sink, NULL)) {
@@ -71,7 +125,13 @@ main (int argc, char *argv[])
     exit (1);
   }
 
+  bus = gst_element_get_bus (bin);
+  gst_bus_add_watch (bus, message_handler, NULL);
+  gst_object_unref (bus);
+
   appwindow = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  g_signal_connect (G_OBJECT (appwindow), "destroy",
+      G_CALLBACK (on_window_destroy), NULL);
   vbox = gtk_vbox_new (FALSE, 6);
 
   widget = gtk_hscale_new_with_range (50.0, 20000.0, 10);
diff --git a/gst/spectrum/demo-osssrc.c b/gst/spectrum/demo-osssrc.c
index 5dc04ab2..522a3e7a 100644
--- a/gst/spectrum/demo-osssrc.c
+++ b/gst/spectrum/demo-osssrc.c
@@ -1,6 +1,27 @@
+/* GStreamer
+ * Copyright (C) 2006 Stefan Kost <ensonic@users.sf.net>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
+#include <string.h>
+#include <math.h>
 #include <gst/gst.h>
 #include <gtk/gtk.h>
 
@@ -10,30 +31,65 @@
 static GtkWidget *drawingarea = NULL;
 
 static void
-spectrum_chain (GstElement * sink, GstBuffer * buf, GstPad * pad,
-    gpointer unused)
+on_window_destroy (GtkObject * object, gpointer user_data)
+{
+  drawingarea = NULL;
+  gtk_main_quit ();
+}
+
+/* draw frequency spectrum as a bunch of bars */
+static void
+draw_spectrum (guchar * data)
 {
   gint i;
-  guchar *data = buf->data;
-  gint width = GST_BUFFER_SIZE (buf);
-  GdkRectangle rect = { 0, 0, width, 50 };
+  GdkRectangle rect = { 0, 0, SPECT_BANDS, 50 };
+
+  if (!drawingarea)
+    return;
 
   gdk_window_begin_paint_rect (drawingarea->window, &rect);
   gdk_draw_rectangle (drawingarea->window, drawingarea->style->black_gc,
-      TRUE, 0, 0, width, 50);
-  for (i = 0; i < width; i++) {
+      TRUE, 0, 0, SPECT_BANDS, 50);
+  for (i = 0; i < SPECT_BANDS; i++) {
     gdk_draw_rectangle (drawingarea->window, drawingarea->style->white_gc,
         TRUE, i, 64 - data[i], 1, data[i]);
   }
   gdk_window_end_paint (drawingarea->window);
 }
 
+/* receive spectral data from element message */
+gboolean
+message_handler (GstBus * bus, GstMessage * message, gpointer data)
+{
+  if (message->type == GST_MESSAGE_ELEMENT) {
+    const GstStructure *s = gst_message_get_structure (message);
+    const gchar *name = gst_structure_get_name (s);
+
+    if (strcmp (name, "spectrum") == 0) {
+      guchar spect[SPECT_BANDS];
+      const GValue *list;
+      const GValue *value;
+      guint i;
+
+      list = gst_structure_get_value (s, "spectrum");
+      for (i = 0; i < SPECT_BANDS; ++i) {
+        value = gst_value_list_get_value (list, i);
+        spect[i] = g_value_get_uchar (value);
+      }
+      draw_spectrum (spect);
+    }
+  }
+  /* we handled the message we want, and ignored the ones we didn't want.
+   * so the core can unref the message for us */
+  return TRUE;
+}
+
 int
 main (int argc, char *argv[])
 {
   GstElement *bin;
   GstElement *src, *spectrum, *sink;
-
+  GstBus *bus;
   GtkWidget *appwindow;
 
   gst_init (&argc, &argv);
@@ -42,16 +98,12 @@ main (int argc, char *argv[])
   bin = gst_pipeline_new ("bin");
 
   src = gst_element_factory_make (DEFAULT_AUDIOSRC, "src");
-  g_object_set (G_OBJECT (src), "blocksize", (gulong) 1024 * 2, NULL);
 
   spectrum = gst_element_factory_make ("spectrum", "spectrum");
-  g_object_set (G_OBJECT (spectrum), "width", SPECT_BANDS, "threshold", -80,
-      NULL);
+  g_object_set (G_OBJECT (spectrum), "bands", SPECT_BANDS, "threshold", -80,
+      "message", TRUE, NULL);
 
   sink = gst_element_factory_make ("fakesink", "sink");
-  g_object_set (G_OBJECT (sink), "signal-handoffs", TRUE, NULL);
-
-  g_signal_connect (sink, "handoff", G_CALLBACK (spectrum_chain), NULL);
 
   gst_bin_add_many (GST_BIN (bin), src, spectrum, sink, NULL);
   if (!gst_element_link_many (src, spectrum, sink, NULL)) {
@@ -59,7 +111,14 @@ main (int argc, char *argv[])
     exit (1);
   }
 
+  bus = gst_element_get_bus (bin);
+  gst_bus_add_watch (bus, message_handler, NULL);
+  gst_object_unref (bus);
+
   appwindow = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  g_signal_connect (G_OBJECT (appwindow), "destroy",
+      G_CALLBACK (on_window_destroy), NULL);
+
   drawingarea = gtk_drawing_area_new ();
   gtk_drawing_area_size (GTK_DRAWING_AREA (drawingarea), SPECT_BANDS, 64);
   gtk_container_add (GTK_CONTAINER (appwindow), drawingarea);
diff --git a/gst/spectrum/gstspectrum.c b/gst/spectrum/gstspectrum.c
index c373cccd..b81da633 100644
--- a/gst/spectrum/gstspectrum.c
+++ b/gst/spectrum/gstspectrum.c
@@ -22,21 +22,41 @@
  *
  * <refsect2>
  * The Spectrum element analyzes the frequency spectrum of an audio signal.
- * Analysis results are send as outgoing buffers.
- * The buffer contains a guint8 value per frequency band.
- * A value of 0 maps to the threshold property.
+ * If <link linkend="GstSpectrum--message">message property</link> is #TRUE it
+ * sends analysis results as application message named
+ * <classname>&quot;spectrum&quot;</classname> after each interval of time given
+ * by the <link linkend="GstSpectrum--interval">interval property</link>.
+ * The message's structure contains two fields:
+ * <itemizedlist>
+ * <listitem>
+ *   <para>
+ *   #GstClockTime
+ *   <classname>&quot;endtime&quot;</classname>:
+ *   the end time of the buffer that triggered the message
+ *   </para>
+ * </listitem>
+ * <listitem>
+ *   <para>
+ *   #GstValueList of #guchar
+ *   <classname>&quot;spectrum&quot;</classname>:
+ *   the level for each frequency band. A value of 0 maps to the
+ *   db value given by the
+ *   <link linkend="GstSpectrum--threshold">threshold property.</link>.
+ *   </para>
+ * </listitem>
  *
- * It cannot be used with the gst-launch command in a sensible way. Instead the
- * included demo shows how to use it.
+ * This element cannot be used with the gst-launch command in a sensible way.
+ * The included demo shows how to use it in an application.
  *
  * Last reviewed on 2006-05-21 (0.10.3)
+ * </refsect2>
  */
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
 #include <string.h>
-
+#include <gst/audio/audio.h>
 #include "gstspectrum.h"
 
 GST_DEBUG_CATEGORY_STATIC (gst_spectrum_debug);
@@ -65,33 +85,53 @@ static GstStaticPadTemplate src_template_factory =
 GST_STATIC_PAD_TEMPLATE ("src",
     GST_PAD_SRC,
     GST_PAD_ALWAYS,
-    GST_STATIC_CAPS_ANY);
+    GST_STATIC_CAPS ("audio/x-raw-int, "
+        "rate = (int) [ 1, MAX ], "
+        "channels = (int) [1, MAX], "
+        "endianness = (int) BYTE_ORDER, "
+        "width = (int) 16, " "depth = (int) 16, " "signed = (boolean) true")
+    );
 
-/* Spectrum signals and args */
-enum
-{
-  /* FILL ME */
-  LAST_SIGNAL
-};
+/*
+static GstStaticPadTemplate src_template_factory =
+GST_STATIC_PAD_TEMPLATE ("src",
+    GST_PAD_SRC,
+    GST_PAD_ALWAYS,
+    GST_STATIC_CAPS_ANY);
+*/
 
+/* Spectrum properties */
 enum
 {
-  ARG_0,
-  ARG_WIDTH,
-  ARG_THRESHOLD
+  PROP_0,
+  PROP_SIGNAL_SPECTRUM,
+  PROP_SIGNAL_INTERVAL,
+  PROP_BANDS,
+  PROP_THRESHOLD
 };
 
-GST_BOILERPLATE (GstSpectrum, gst_spectrum, GstElement, GST_TYPE_ELEMENT);
+GST_BOILERPLATE (GstSpectrum, gst_spectrum, GstBaseTransform,
+    GST_TYPE_BASE_TRANSFORM);
 
 static void gst_spectrum_dispose (GObject * object);
 static void gst_spectrum_set_property (GObject * object, guint prop_id,
     const GValue * value, GParamSpec * pspec);
+static void gst_spectrum_get_property (GObject * object, guint prop_id,
+    GValue * value, GParamSpec * pspec);
 
+/*
 static gboolean gst_spectrum_set_sink_caps (GstPad * pad, GstCaps * caps);
 static GstCaps *gst_spectrum_get_sink_caps (GstPad * pad);
 static GstFlowReturn gst_spectrum_chain (GstPad * pad, GstBuffer * buffer);
 static GstStateChangeReturn gst_spectrum_change_state (GstElement * element,
     GstStateChange transition);
+*/
+static gboolean gst_spectrum_set_caps (GstBaseTransform * trans, GstCaps * in,
+    GstCaps * out);
+static gboolean gst_spectrum_start (GstBaseTransform * trans);
+static GstFlowReturn gst_spectrum_transform_ip (GstBaseTransform * trans,
+    GstBuffer * in);
+
 
 #define fixed short
 extern int gst_spectrum_fix_fft (fixed fr[], fixed fi[], int m, int inverse);
@@ -99,8 +139,6 @@ extern void gst_spectrum_fix_loud (fixed loud[], fixed fr[], fixed fi[], int n,
     int scale_shift);
 extern void gst_spectrum_window (fixed fr[], int n);
 
-/*static guint gst_spectrum_signals[LAST_SIGNAL] = { 0 }; */
-
 static void
 gst_spectrum_base_init (gpointer g_class)
 {
@@ -117,21 +155,36 @@ static void
 gst_spectrum_class_init (GstSpectrumClass * klass)
 {
   GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
-  GstElementClass *element = GST_ELEMENT_CLASS (klass);
+  GstBaseTransformClass *trans_class = GST_BASE_TRANSFORM_CLASS (klass);
 
   gobject_class->set_property = gst_spectrum_set_property;
+  gobject_class->get_property = gst_spectrum_get_property;
   gobject_class->dispose = gst_spectrum_dispose;
 
-  element->change_state = gst_spectrum_change_state;
+  /*element->change_state = gst_spectrum_change_state; */
+  trans_class->set_caps = GST_DEBUG_FUNCPTR (gst_spectrum_set_caps);
+  trans_class->start = GST_DEBUG_FUNCPTR (gst_spectrum_start);
+  trans_class->transform_ip = GST_DEBUG_FUNCPTR (gst_spectrum_transform_ip);
+  trans_class->passthrough_on_same_caps = TRUE;
+
+  g_object_class_install_property (gobject_class, PROP_SIGNAL_SPECTRUM,
+      g_param_spec_boolean ("message", "mesage",
+          "Post a level message for each passed interval",
+          TRUE, G_PARAM_READWRITE));
+
+  g_object_class_install_property (gobject_class, PROP_SIGNAL_INTERVAL,
+      g_param_spec_uint64 ("interval", "Interval",
+          "Interval of time between message posts (in nanoseconds)",
+          1, G_MAXUINT64, GST_SECOND / 10, G_PARAM_READWRITE));
 
-  g_object_class_install_property (gobject_class, ARG_WIDTH,
-      g_param_spec_uint ("width", "Width", "number of frequency bands",
-          0, G_MAXUINT, 0, G_PARAM_WRITABLE));
+  g_object_class_install_property (gobject_class, PROP_BANDS,
+      g_param_spec_uint ("bands", "Bands", "number of frequency bands",
+          0, G_MAXUINT, 0, G_PARAM_READWRITE));
 
-  g_object_class_install_property (gobject_class, ARG_THRESHOLD,
+  g_object_class_install_property (gobject_class, PROP_THRESHOLD,
       g_param_spec_int ("threshold", "Threshold",
           "db threshold for result, maps to 0", G_MININT, 0, -60,
-          G_PARAM_WRITABLE));
+          G_PARAM_READWRITE));
 
   GST_DEBUG_CATEGORY_INIT (gst_spectrum_debug, "spectrum", 0,
       "audio spectrum analyser element");
@@ -140,20 +193,22 @@ gst_spectrum_class_init (GstSpectrumClass * klass)
 static void
 gst_spectrum_init (GstSpectrum * spectrum, GstSpectrumClass * g_class)
 {
-  spectrum->sinkpad =
-      gst_pad_new_from_static_template (&sink_template_factory, "sink");
-  gst_pad_set_chain_function (spectrum->sinkpad, gst_spectrum_chain);
-  gst_pad_set_setcaps_function (spectrum->sinkpad, gst_spectrum_set_sink_caps);
-  gst_pad_set_getcaps_function (spectrum->sinkpad, gst_spectrum_get_sink_caps);
-  gst_element_add_pad (GST_ELEMENT (spectrum), spectrum->sinkpad);
-
-  spectrum->srcpad =
-      gst_pad_new_from_static_template (&src_template_factory, "src");
-  gst_element_add_pad (GST_ELEMENT (spectrum), spectrum->srcpad);
+  /*
+     spectrum->sinkpad =
+     gst_pad_new_from_static_template (&sink_template_factory, "sink");
+     gst_pad_set_chain_function (spectrum->sinkpad, gst_spectrum_chain);
+     gst_pad_set_setcaps_function (spectrum->sinkpad, gst_spectrum_set_sink_caps);
+     gst_pad_set_getcaps_function (spectrum->sinkpad, gst_spectrum_get_sink_caps);
+     gst_element_add_pad (GST_ELEMENT (spectrum), spectrum->sinkpad);
+
+     spectrum->srcpad =
+     gst_pad_new_from_static_template (&src_template_factory, "src");
+     gst_element_add_pad (GST_ELEMENT (spectrum), spectrum->srcpad);
+   */
 
   spectrum->adapter = gst_adapter_new ();
 
-  spectrum->width = 128;
+  spectrum->bands = 128;
   spectrum->base = 9;
   spectrum->len = 1024;         /* 2 ^ (base+1) */
 
@@ -162,6 +217,7 @@ gst_spectrum_init (GstSpectrum * spectrum, GstSpectrumClass * g_class)
   memset (spectrum->im, 0, spectrum->len * sizeof (gint16));
   spectrum->re = g_malloc (spectrum->len * sizeof (gint16));
   memset (spectrum->re, 0, spectrum->len * sizeof (gint16));
+  spectrum->spect = g_malloc (spectrum->bands * sizeof (guchar));
 }
 
 static void
@@ -177,6 +233,7 @@ gst_spectrum_dispose (GObject * object)
   g_free (spectrum->re);
   g_free (spectrum->im);
   g_free (spectrum->loud);
+  g_free (spectrum->spect);
 
   G_OBJECT_CLASS (parent_class)->dispose (object);
 }
@@ -185,14 +242,24 @@ static void
 gst_spectrum_set_property (GObject * object, guint prop_id,
     const GValue * value, GParamSpec * pspec)
 {
-  GstSpectrum *spectrum = GST_SPECTRUM (object);
+  GstSpectrum *filter = GST_SPECTRUM (object);
 
   switch (prop_id) {
-    case ARG_WIDTH:
-      spectrum->width = g_value_get_uint (value);
+    case PROP_SIGNAL_SPECTRUM:
+      filter->message = g_value_get_boolean (value);
+      break;
+    case PROP_SIGNAL_INTERVAL:
+      filter->interval = gst_guint64_to_gdouble (g_value_get_uint64 (value));
+      break;
+    case PROP_BANDS:
+      filter->bands = g_value_get_uint (value);
+      g_free (filter->spect);
+      filter->spect = g_malloc (filter->bands * sizeof (guchar));
+      GST_DEBUG_OBJECT (filter, "reallocation, spect = %p, bands =%d ",
+          filter->spect, filter->bands);
       break;
-    case ARG_THRESHOLD:
-      spectrum->threshold = g_value_get_int (value);
+    case PROP_THRESHOLD:
+      filter->threshold = g_value_get_int (value);
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
@@ -200,6 +267,32 @@ gst_spectrum_set_property (GObject * object, guint prop_id,
   }
 }
 
+static void
+gst_spectrum_get_property (GObject * object, guint prop_id,
+    GValue * value, GParamSpec * pspec)
+{
+  GstSpectrum *filter = GST_SPECTRUM (object);
+
+  switch (prop_id) {
+    case PROP_SIGNAL_SPECTRUM:
+      g_value_set_boolean (value, filter->message);
+      break;
+    case PROP_SIGNAL_INTERVAL:
+      g_value_set_uint64 (value, filter->interval);
+      break;
+    case PROP_BANDS:
+      g_value_set_uint (value, filter->bands);
+      break;
+    case PROP_THRESHOLD:
+      g_value_set_int (value, filter->threshold);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+/*
 static gboolean
 gst_spectrum_set_sink_caps (GstPad * pad, GstCaps * caps)
 {
@@ -232,29 +325,89 @@ gst_spectrum_get_sink_caps (GstPad * pad)
   gst_object_unref (spectrum);
   return res;
 }
+*/
+
+static gboolean
+gst_spectrum_set_caps (GstBaseTransform * trans, GstCaps * in, GstCaps * out)
+{
+  GstSpectrum *filter = GST_SPECTRUM (trans);
+  GstStructure *structure;
+
+  structure = gst_caps_get_structure (in, 0);
+  gst_structure_get_int (structure, "rate", &filter->rate);
+  gst_structure_get_int (structure, "width", &filter->width);
+  gst_structure_get_int (structure, "channels", &filter->channels);
+
+  return TRUE;
+}
+
+static gboolean
+gst_spectrum_start (GstBaseTransform * trans)
+{
+  GstSpectrum *filter = GST_SPECTRUM (trans);
+
+  gst_adapter_clear (filter->adapter);
+  filter->num_frames = 0;
+
+  return TRUE;
+}
+
+static GstMessage *
+gst_spectrum_message_new (GstSpectrum * spectrum, GstClockTime endtime)
+{
+  GstStructure *s;
+  GValue v = { 0, };
+  GValue *l;
+  guint i;
+  guchar *spect = spectrum->spect;
+
+  GST_DEBUG_OBJECT (spectrum, "preparing message, spect = %p, bands =%d ",
+      spect, spectrum->bands);
+
+  s = gst_structure_new ("spectrum", "endtime", GST_TYPE_CLOCK_TIME,
+      endtime, NULL);
+
+  g_value_init (&v, GST_TYPE_LIST);
+  /* will copy-by-value */
+  gst_structure_set_value (s, "spectrum", &v);
+  g_value_unset (&v);
+
+  g_value_init (&v, G_TYPE_UCHAR);
+  l = (GValue *) gst_structure_get_value (s, "spectrum");
+  for (i = 0; i < spectrum->bands; i++) {
+    g_value_set_uchar (&v, spect[i]);
+    gst_value_list_append_value (l, &v);        /* copies by value */
+  }
+  g_value_unset (&v);
+
+  return gst_message_new_element (GST_OBJECT (spectrum), s);
+}
 
 static GstFlowReturn
-gst_spectrum_chain (GstPad * pad, GstBuffer * buffer)
+gst_spectrum_transform_ip (GstBaseTransform * trans, GstBuffer * in)
 {
-  GstSpectrum *spectrum = GST_SPECTRUM (gst_pad_get_parent (pad));
+  GstSpectrum *spectrum = GST_SPECTRUM (trans);
   gint16 *samples;
   gint wanted;
   gint i, j, k;
   gint32 acc;
   gfloat pos, step;
-  guchar *spect;
-  GstBuffer *outbuf;
-  GstFlowReturn ret = GST_FLOW_OK;
+  guchar *spect = spectrum->spect;
+  GstClockTime endtime = GST_BUFFER_TIMESTAMP (in);
+  GstClockTime blktime =
+      GST_FRAMES_TO_CLOCK_TIME (spectrum->len, spectrum->rate);
+
+  GST_DEBUG ("transform : %ld bytes", GST_BUFFER_SIZE (in));
 
-  gst_adapter_push (spectrum->adapter, buffer);
+  gst_adapter_push (spectrum->adapter, gst_buffer_ref (in));
   /* required number of bytes */
   wanted = spectrum->channels * spectrum->len * 2;
   /* FIXME: 4.0 was 2.0 before, but that include the mirrored spectrum */
-  step = (gfloat) spectrum->len / (spectrum->width * 4.0);
+  step = (gfloat) spectrum->len / (spectrum->bands * 4.0);
 
-  while (gst_adapter_available (spectrum->adapter) > wanted &&
-      (ret == GST_FLOW_OK)) {
+  while (gst_adapter_available (spectrum->adapter) > wanted) {
 
+    GST_DEBUG ("  adapter loop");
     samples = (gint16 *) gst_adapter_take (spectrum->adapter, wanted);
 
     for (i = 0, j = 0; i < spectrum->len; i++) {
@@ -263,19 +416,17 @@ gst_spectrum_chain (GstPad * pad, GstBuffer * buffer)
       spectrum->re[i] = (gint16) (acc / spectrum->channels);
     }
 
+    GST_DEBUG ("  fft");
+
     gst_spectrum_window (spectrum->re, spectrum->len);
     gst_spectrum_fix_fft (spectrum->re, spectrum->im, spectrum->base, FALSE);
     gst_spectrum_fix_loud (spectrum->loud, spectrum->re, spectrum->im,
         spectrum->len, 0);
 
-    ret = gst_pad_alloc_buffer_and_set_caps (spectrum->srcpad,
-        GST_BUFFER_OFFSET_NONE, spectrum->width,
-        GST_PAD_CAPS (spectrum->srcpad), &outbuf);
+    GST_DEBUG ("  resampling");
 
-    /* resample to requested width */
-    spect = GST_BUFFER_DATA (outbuf);
-    for (i = 0, pos = 0.0; i < spectrum->width; i++, pos += step) {
-      /* > -60 db? FIXME: make this a gobject property */
+    /* resample to requested number of bands */
+    for (i = 0, pos = 0.0; i < spectrum->bands; i++, pos += step) {
       if (spectrum->loud[(gint) pos] > spectrum->threshold) {
         spect[i] = spectrum->loud[(gint) pos] - spectrum->threshold;
         /*
@@ -287,13 +438,27 @@ gst_spectrum_chain (GstPad * pad, GstBuffer * buffer)
         spect[i] = 0;
     }
 
-    ret = gst_pad_push (spectrum->srcpad, outbuf);
+    GST_DEBUG ("  send message?");
+    //ret = gst_pad_push (spectrum->srcpad, outbuf);
+    spectrum->num_frames += spectrum->len;
+    endtime += blktime;
+    /* do we need to message ? */
+    if (spectrum->num_frames >=
+        GST_CLOCK_TIME_TO_FRAMES (spectrum->interval, spectrum->rate)) {
+      if (spectrum->message) {
+        GstMessage *m = gst_spectrum_message_new (spectrum, endtime);
+
+        GST_DEBUG ("  sending message");
+        gst_element_post_message (GST_ELEMENT (spectrum), m);
+      }
+      spectrum->num_frames = 0;
+    }
   }
 
-  gst_object_unref (spectrum);
-  return ret;
+  return GST_FLOW_OK;
 }
 
+/*
 static GstStateChangeReturn
 gst_spectrum_change_state (GstElement * element, GstStateChange transition)
 {
@@ -327,7 +492,7 @@ gst_spectrum_change_state (GstElement * element, GstStateChange transition)
 
   return ret;
 }
-
+*/
 
 static gboolean
 plugin_init (GstPlugin * plugin)
diff --git a/gst/spectrum/gstspectrum.h b/gst/spectrum/gstspectrum.h
index a6c918c0..51e2000c 100644
--- a/gst/spectrum/gstspectrum.h
+++ b/gst/spectrum/gstspectrum.h
@@ -24,6 +24,7 @@
 
 #include <gst/gst.h>
 #include <gst/base/gstadapter.h>
+#include <gst/base/gstbasetransform.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -40,25 +41,35 @@ typedef struct _GstSpectrum GstSpectrum;
 typedef struct _GstSpectrumClass GstSpectrumClass;
 
 struct _GstSpectrum {
-  GstElement element;
+  GstBaseTransform element;
 
   GstPad *sinkpad,*srcpad;
   GstAdapter *adapter;
 
   /* properties */
-  guint width;
-  gint threshold;
-
+  gboolean message;             /* whether or not to post messages */
+  gdouble interval;             /* how many seconds between emits */
+  guint bands;                  /* number of spectrum bands */
+  gint threshold;               /* energy level treshold */
+
+  gint num_frames;              /* frame count (1 sample per channel)
+                                 * since last emit */
+                                 
+  gint rate;                    /* caps variables */
+  gint width;
   gint channels;
+
+  /* <private> */
   gint base, len;
   gint16 *re, *im, *loud;
+  guchar *spect;
 };
 
 struct _GstSpectrumClass {
-  GstElementClass parent_class;
+  GstBaseTransformClass parent_class;
 };
 
-GType gst_spectrum_get_type(void);
+GType gst_spectrum_get_type (void);
 
 
 #ifdef __cplusplus