1 files changed, 89 insertions, 0 deletions
diff --git a/gst/level/level-example.c b/gst/level/level-example.c
new file mode 100644
index 00000000..dcfdec0c
--- /dev/null
+++ b/gst/level/level-example.c
@@ -0,0 +1,89 @@
+#include <string.h>
+#include <math.h>
+
+#include <gst/gst.h>
+
+gboolean
+message_handler (GstBus * bus, GstMessage * message, gpointer data)
+{
+
+  if (message->type == GST_MESSAGE_APPLICATION) {
+    const GstStructure *s = gst_message_get_structure (message);
+    const gchar *name = gst_structure_get_name (s);
+
+    if (strcmp (name, "level") == 0) {
+      gint channels;
+      gdouble endtime, rms_dB, peak_dB, decay_dB;
+      gdouble rms;
+      const GValue *list;
+      const GValue *value;
+
+      if (!gst_structure_get_double (s, "endtime", &endtime))
+        g_warning ("Could not parse endtime");
+      list = gst_structure_get_value (s, "rms");
+      /* we can get the number of channels as the length of any of the value
+       * lists */
+      channels = gst_value_list_get_size (list);
+
+      /* we will only get values for the first channel, since we know sinesrc
+       * is mono */
+      value = gst_value_list_get_value (list, 0);
+      rms_dB = g_value_get_double (value);
+      list = gst_structure_get_value (s, "peak");
+      value = gst_value_list_get_value (list, 0);
+      peak_dB = g_value_get_double (value);
+      list = gst_structure_get_value (s, "decay");
+      value = gst_value_list_get_value (list, 0);
+      decay_dB = g_value_get_double (value);
+      g_print ("endtime: %f, channels: %d\n", endtime, channels);
+      g_print ("RMS: %f dB, peak: %f dB, decay: %f dB\n",
+          rms_dB, peak_dB, decay_dB);
+
+      /* converting from dB to normal gives us a value between 0.0 and 1.0 */
+      rms = pow (10, rms_dB / 20);
+      g_print ("normalized rms value: %f\n", rms);
+    }
+  }
+  /* 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 *sinesrc, *level, *fakesink;
+  GstElement *pipeline;
+  GstBus *bus;
+  gint watch_id;
+  GMainLoop *loop;
+
+  gst_init (&argc, &argv);
+
+  pipeline = gst_pipeline_new (NULL);
+  g_assert (pipeline);
+  sinesrc = gst_element_factory_make ("sinesrc", NULL);
+  g_assert (sinesrc);
+  level = gst_element_factory_make ("level", NULL);
+  g_assert (level);
+  fakesink = gst_element_factory_make ("fakesink", NULL);
+  g_assert (fakesink);
+
+  gst_bin_add_many (GST_BIN (pipeline), sinesrc, level, fakesink, NULL);
+  gst_element_link (sinesrc, level);
+  gst_element_link (level, fakesink);
+
+  /* make sure we'll get messages */
+  g_object_set (G_OBJECT (level), "message", TRUE, NULL);
+
+  bus = gst_element_get_bus (pipeline);
+  watch_id = gst_bus_add_watch (bus, message_handler, NULL);
+
+  gst_element_set_state (pipeline, 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);
+
+  return 0;
+}