gistfile1.c

#include <gst/gst.h>

static GMainLoop *loop;

static gboolean my_bus_callback (GstBus *bus, GstMessage *message, gpointer data)
{
  g_print ("Got %s message\n", GST_MESSAGE_TYPE_NAME (message));
  switch (GST_MESSAGE_TYPE (message)) {
    case GST_MESSAGE_ERROR: {
      GError *err;
      gchar *debug;
      gst_message_parse_error (message, &err, &debug);
      g_print ("Error: %s\n", err->message);
      g_error_free (err);
      g_free (debug);
      g_main_loop_quit (loop);
      break;
    }
    case GST_MESSAGE_EOS:
      /* end-of-stream */
      g_main_loop_quit (loop);
      break;
    default:
      /* unhandled message */
      break;
  }
  /* we want to be notified again the next time there is a message
  * on the bus, so returning TRUE (FALSE means we want to stop watching
  * for messages on the bus and our callback should not be called again)
  */
  return TRUE;
}

gint main (gint argc, gchar *argv[])
{
  GstElement *pipeline;
  GstBus *bus;
  
  /* init */
  gst_init (&argc, &argv);

  /* create pipeline, add handler */
  pipeline = gst_pipeline_new ("my_pipeline");

  /* adds a watch for new message on our pipeline’s message bus to
  * the default GLib main context, which is the main context that our
  * GLib main loop is attached to below
  */
  bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
  gst_bus_add_watch (bus, my_bus_callback, NULL);
  gst_object_unref (bus);
  [..]

  /* create a mainloop that runs/iterates the default GLib main context
  * (context NULL), in other words: makes the context check if anything
  * it watches for has happened. When a message has been posted on the
  * bus, the default main context will automatically call our
  * my_bus_callback() function to notify us of that message.
  * The main loop will be run until someone calls g_main_loop_quit()
  */
  loop = g_main_loop_new (NULL, FALSE);
  g_main_loop_run (loop);

  /* clean up */
  gst_element_set_state (pipeline, GST_STATE_NULL);
  gst_object_unref (pipeline);
  g_main_loop_unref (loop);
  return 0;
}