examples: add stepping example.

Add an example of using playbin2 and frame stepping to simulate variable rate
playback based on a sine wave.

tests/examples/seek/Makefile.am

@@ -2,7 +2,7 @@ if HAVE_GTK_X11
 GTK_EXAMPLES=seek scrubby
 endif
 
-examples = $(GTK_EXAMPLES)
+examples = $(GTK_EXAMPLES) stepping
 
 noinst_PROGRAMS = $(examples)
 

tests/examples/seek/stepping.c

@@ -0,0 +1,124 @@
+/* GStreamer
+ *
+ * stepping.c: stepping sample application
+ *
+ * Copyright (C) 2009 Wim Taymans <wim.taymans@gmail.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 <stdlib.h>
+#include <math.h>
+
+#include <gst/gst.h>
+
+static GMainLoop *loop;
+
+static gdouble period = 0.0;
+
+static gboolean
+do_step (GstElement * bin)
+{
+  gdouble length;
+
+  length = sin (period);
+
+  period += M_PI / 40;
+
+  length += 1.1;
+  length *= 100 * GST_MSECOND;
+
+  gst_element_send_event (bin,
+      gst_event_new_step (GST_FORMAT_TIME, length, 1.0, TRUE, FALSE));
+
+  return FALSE;
+}
+
+static gboolean
+handle_message (GstBus * bus, GstMessage * message, gpointer data)
+{
+  GstElement *bin = GST_ELEMENT_CAST (data);
+
+  switch (message->type) {
+    case GST_MESSAGE_EOS:
+      g_message ("got EOS");
+      g_main_loop_quit (loop);
+      break;
+    case GST_MESSAGE_WARNING:
+    case GST_MESSAGE_ERROR:
+    {
+      GError *gerror;
+      gchar *debug;
+
+      if (message->type == GST_MESSAGE_ERROR)
+        gst_message_parse_error (message, &gerror, &debug);
+      else
+        gst_message_parse_warning (message, &gerror, &debug);
+
+      gst_object_default_error (GST_MESSAGE_SRC (message), gerror, debug);
+      g_error_free (gerror);
+      g_free (debug);
+      g_main_loop_quit (loop);
+      break;
+    }
+    case GST_MESSAGE_ASYNC_DONE:
+      g_timeout_add (40, (GSourceFunc) do_step, bin);
+      break;
+    default:
+      break;
+  }
+  return TRUE;
+}
+
+int
+main (int argc, char *argv[])
+{
+  GstElement *bin;
+  GstBus *bus;
+
+  gst_init (&argc, &argv);
+
+  if (argc < 2) {
+    g_print ("usage: %s <uri>\n", argv[0]);
+    return -1;
+  }
+
+  /* create a new bin to hold the elements */
+  bin = gst_element_factory_make ("playbin2", "bin");
+  g_assert (bin);
+  g_object_set (bin, "uri", argv[1], NULL);
+
+  bus = gst_pipeline_get_bus (GST_PIPELINE (bin));
+  gst_bus_add_watch (bus, handle_message, bin);
+
+  /* go to the PAUSED state and wait for preroll */
+  g_message ("prerolling first frame");
+  gst_element_set_state (bin, GST_STATE_PAUSED);
+  gst_element_get_state (bin, NULL, NULL, -1);
+
+  loop = g_main_loop_new (NULL, TRUE);
+  g_main_loop_run (loop);
+
+  g_message ("finished");
+
+  /* stop the bin */
+  gst_element_set_state (bin, GST_STATE_NULL);
+
+  g_main_loop_unref (loop);
+  gst_object_unref (bus);
+
+  exit (0);
+}