/* on OS X compile with:
 * gcc -o bgst `pkg-config --cflags --libs gstreamer-0.10` -m32 bgst.c
 *
 * On Linux/Ubuntu use:
 * gcc `pkg-config gstreamer-0.10 --cflags` bgst.c -o bgst `pkg-config gstreamer-0.10 --libs`
 */

#include <gst/gst.h>
#include <glib.h>
 
// callback to call when volume changes
void vol_cb (void* ar) {
	printf ("Volume got changed!\n");
}

int main(int argc, char *argv[]) {
  GstElement *pipeline;

  GstBus *bus;
  GstMessage *msg;
   
  /* Initialize GStreamer */
  gst_init (&argc, &argv);
	
  /* Build the pipeline */
  pipeline = gst_parse_launch ("playbin2 uri=http://docs.gstreamer.com/media/sintel_trailer-480p.webm", NULL);

  /* register the callback */
  g_signal_connect (pipeline, "notify::volume", G_CALLBACK (vol_cb), NULL);

  /* Start playing */
  gst_element_set_state (pipeline, GST_STATE_PLAYING);
   
  /* Wait until error or EOS */
  bus = gst_element_get_bus (pipeline);
  msg = gst_bus_timed_pop_filtered (bus, GST_CLOCK_TIME_NONE, GST_MESSAGE_ERROR | GST_MESSAGE_EOS);
   
  /* Free resources */
  if (msg != NULL)
    gst_message_unref (msg);
  gst_object_unref (bus);
  gst_element_set_state (pipeline, GST_STATE_NULL);
  gst_object_unref (pipeline);
  return 0;
}
