1 files changed, 137 insertions, 0 deletions
diff --git a/tests/examples/audiofx/iirfilter-example.c b/tests/examples/audiofx/iirfilter-example.c
new file mode 100644
index 00000000..8ccffb74
--- /dev/null
+++ b/tests/examples/audiofx/iirfilter-example.c
@@ -0,0 +1,137 @@
+/* GStreamer
+ * Copyright (C) 2009 Sebastian Droege <sebastian.droege@collabora.co.uk>
+ *
+ * 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.
+ */
+
+/* This small sample application creates a lowpass IIR filter
+ * and applies it to white noise.
+ * See http://www.dspguide.com/ch19/2.htm for a description
+ * of the IIR filter that is used.
+ */
+
+#include <string.h>
+#include <math.h>
+
+#include <gst/gst.h>
+
+/* Cutoff of 4000 Hz */
+#define CUTOFF (4000.0)
+
+static gboolean
+on_message (GstBus * bus, GstMessage * message, gpointer user_data)
+{
+  GMainLoop *loop = (GMainLoop *) user_data;
+
+  switch (GST_MESSAGE_TYPE (message)) {
+    case GST_MESSAGE_ERROR:
+      g_error ("Got ERROR");
+      g_main_loop_quit (loop);
+      break;
+    case GST_MESSAGE_WARNING:
+      g_warning ("Got WARNING");
+      g_main_loop_quit (loop);
+      break;
+    case GST_MESSAGE_EOS:
+      g_main_loop_quit (loop);
+      break;
+    default:
+      break;
+  }
+
+  return TRUE;
+}
+
+static void
+on_rate_changed (GstElement * element, gint rate, gpointer user_data)
+{
+  GValueArray *va;
+  GValue v = { 0, };
+  gdouble x;
+
+  if (rate / 2.0 > CUTOFF)
+    x = exp (-2.0 * M_PI * (CUTOFF / rate));
+  else
+    x = 0.0;
+
+  va = g_value_array_new (1);
+
+  g_value_init (&v, G_TYPE_DOUBLE);
+  g_value_set_double (&v, 1.0 - x);
+  g_value_array_append (va, &v);
+  g_value_reset (&v);
+  g_object_set (G_OBJECT (element), "a", va, NULL);
+  g_value_array_free (va);
+
+  va = g_value_array_new (1);
+  g_value_set_double (&v, x);
+  g_value_array_append (va, &v);
+  g_value_reset (&v);
+  g_object_set (G_OBJECT (element), "b", va, NULL);
+  g_value_array_free (va);
+}
+
+gint
+main (gint argc, gchar * argv[])
+{
+  GstElement *pipeline, *src, *filter, *conv, *sink;
+  GstBus *bus;
+  GMainLoop *loop;
+
+  gst_init (NULL, NULL);
+
+  pipeline = gst_element_factory_make ("pipeline", NULL);
+
+  src = gst_element_factory_make ("audiotestsrc", NULL);
+  g_object_set (G_OBJECT (src), "wave", 5, NULL);
+
+  filter = gst_element_factory_make ("audioiirfilter", NULL);
+  g_signal_connect (G_OBJECT (filter), "rate-changed",
+      G_CALLBACK (on_rate_changed), NULL);
+
+  conv = gst_element_factory_make ("audioconvert", NULL);
+
+  sink = gst_element_factory_make ("autoaudiosink", NULL);
+  g_return_val_if_fail (sink != NULL, -1);
+
+  gst_bin_add_many (GST_BIN (pipeline), src, filter, conv, sink, NULL);
+  if (!gst_element_link_many (src, filter, conv, sink, NULL)) {
+    g_error ("Failed to link elements");
+    return -2;
+  }
+
+  loop = g_main_loop_new (NULL, FALSE);
+
+  bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
+  gst_bus_add_signal_watch (bus);
+  g_signal_connect (G_OBJECT (bus), "message", G_CALLBACK (on_message), loop);
+  gst_object_unref (GST_OBJECT (bus));
+
+  if (gst_element_set_state (pipeline,
+          GST_STATE_PLAYING) == GST_STATE_CHANGE_FAILURE) {
+    g_error ("Failed to go into PLAYING state");
+    return -3;
+  }
+
+  g_main_loop_run (loop);
+
+  gst_element_set_state (pipeline, GST_STATE_NULL);
+
+  g_main_loop_unref (loop);
+  gst_object_unref (pipeline);
+
+  return 0;
+}