* <refsect2>
* <para>
* The Spectrum element analyzes the frequency spectrum of an audio signal.
- * If #GstSpectrum:message property is #TRUE it sends analysis results as
- * application message named
+ * If the #GstSpectrum:message property is #TRUE, it sends analysis results as
+ * application messages named
* <classname>"spectrum"</classname> after each interval of time given
* by the #GstSpectrum:interval property.
* </para>
* <para>
- * The message's structure contains three fields:
+ * The message's structure contains some combination of these fields:
* <itemizedlist>
* <listitem>
* <para>
* #GstClockTime
* <classname>"endtime"</classname>:
- * the end time of the buffer that triggered the message
+ * the end time of the buffer that triggered the message. Always present.
* </para>
* </listitem>
* <listitem>
* #GstValueList of #gfloat
* <classname>"magnitude"</classname>:
* the level for each frequency band in dB. All values below the value of the
- * #GstSpectrum:threshold property will be set to the threshold.
+ * #GstSpectrum:threshold property will be set to the threshold. Only present
+ * if the message-magnitude property is true.
* </para>
* </listitem>
* <listitem>
* <para>
* #GstValueList of #gfloat
* <classname>"phase"</classname>:
- * the phase for each frequency band. The value is between -pi and pi.
+ * The phase for each frequency band. The value is between -pi and pi. Only
+ * present if the message-phase property is true.
* </para>
* </listitem>
* </itemizedlist>
* </para>
* <para>
* 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.
+ * This sample code demonstrates how to use it in an application.
* </para>
+ * <title>Example application</title>
* <para>
- * Last reviewed on 2008-02-07 (0.10.6)
+ * <include xmlns="http://www.w3.org/2003/XInclude" href="element-spectrum-example.xml" />
+ * </para>
+ * <para>
+ * Last reviewed on 2008-02-09 (0.10.6)
* </para>
* </refsect2>
*/
--- /dev/null
+/* GStreamer
+ * Copyright (C) 2006 Stefan Kost <ensonic@users.sf.net>
+ * Copyright (C) 2008 Jan Schmidt <jan.schmidt@sun.com>
+ *
+ * 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.
+ */
+
+#include <string.h>
+#include <gst/gst.h>
+
+static guint spect_bands = 20;
+
+#define AUDIOFREQ 32000
+
+/* 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);
+ GstClockTime endtime;
+
+ if (strcmp (name, "spectrum") == 0) {
+ const GValue *magnitudes;
+ const GValue *phases;
+ const GValue *mag, *phase;
+ gdouble freq;
+ guint i;
+
+ if (!gst_structure_get_clock_time (s, "endtime", &endtime))
+ endtime = GST_CLOCK_TIME_NONE;
+
+ g_print ("New spectrum message, endtime %" GST_TIME_FORMAT "\n",
+ GST_TIME_ARGS (endtime));
+
+ magnitudes = gst_structure_get_value (s, "magnitude");
+ phases = gst_structure_get_value (s, "phase");
+
+ for (i = 0; i < spect_bands; ++i) {
+ freq = (gdouble) ((AUDIOFREQ / 2) * i + AUDIOFREQ / 4) / spect_bands;
+ mag = gst_value_list_get_value (magnitudes, i);
+ phase = gst_value_list_get_value (phases, i);
+
+ if (mag != NULL && phase != NULL) {
+ g_print ("band %d (freq %g): magnitude %f dB phase %f\n", i, freq,
+ g_value_get_float (mag), g_value_get_float (phase));
+ }
+ }
+ g_print ("\n");
+ }
+ }
+ return TRUE;
+}
+
+int
+main (int argc, char *argv[])
+{
+ GstElement *bin;
+ GstElement *src, *audioconvert, *spectrum, *sink;
+ GstBus *bus;
+ GstCaps *caps;
+ GMainLoop *loop;
+
+ gst_init (&argc, &argv);
+
+ bin = gst_pipeline_new ("bin");
+
+ src = gst_element_factory_make ("audiotestsrc", "src");
+ g_object_set (G_OBJECT (src), "wave", 0, "freq", 6000.0, NULL);
+ audioconvert = gst_element_factory_make ("audioconvert", NULL);
+ g_assert (audioconvert);
+
+ spectrum = gst_element_factory_make ("spectrum", "spectrum");
+ g_object_set (G_OBJECT (spectrum), "bands", spect_bands, "threshold", -80,
+ "message", TRUE, "message-phase", TRUE, NULL);
+
+ sink = gst_element_factory_make ("fakesink", "sink");
+ g_object_set (G_OBJECT (sink), "sync", TRUE, NULL);
+
+ gst_bin_add_many (GST_BIN (bin), src, audioconvert, spectrum, sink, NULL);
+
+ caps = gst_caps_new_simple ("audio/x-raw-int",
+ "rate", G_TYPE_INT, AUDIOFREQ, NULL);
+
+ if (!gst_element_link (src, audioconvert) ||
+ !gst_element_link_filtered (audioconvert, spectrum, caps) ||
+ !gst_element_link (spectrum, sink)) {
+ fprintf (stderr, "can't link elements\n");
+ exit (1);
+ }
+ gst_caps_unref (caps);
+
+ bus = gst_element_get_bus (bin);
+ gst_bus_add_watch (bus, message_handler, NULL);
+ gst_object_unref (bus);
+
+ gst_element_set_state (bin, GST_STATE_PLAYING);
+
+ /* we need to run a GLib main loop to get the messages */
+ loop = g_main_loop_new (NULL, FALSE);
+ g_main_loop_run (loop);
+
+ gst_element_set_state (bin, GST_STATE_NULL);
+
+ gst_object_unref (bin);
+
+ return 0;
+}
projects / platform / upstream / gstreamer.git / commitdiff