gstreamer/subprojects/gst-docs/examples/tutorials/basic-tutorial-15.c

#include <clutter-gst/clutter-gst.h>

/* Setup the video texture once its size is known */
void
size_change (ClutterActor * texture, gint width, gint height,
    gpointer user_data)
{
  ClutterActor *stage;
  gfloat new_x, new_y, new_width, new_height;
  gfloat stage_width, stage_height;
  ClutterAnimation *animation = NULL;

  stage = clutter_actor_get_stage (texture);
  if (stage == NULL)
    return;

  clutter_actor_get_size (stage, &stage_width, &stage_height);

  /* Center video on window and calculate new size preserving aspect ratio */
  new_height = (height * stage_width) / width;
  if (new_height <= stage_height) {
    new_width = stage_width;

    new_x = 0;
    new_y = (stage_height - new_height) / 2;
  } else {
    new_width = (width * stage_height) / height;
    new_height = stage_height;

    new_x = (stage_width - new_width) / 2;
    new_y = 0;
  }
  clutter_actor_set_position (texture, new_x, new_y);
  clutter_actor_set_size (texture, new_width, new_height);
  clutter_actor_set_rotation (texture, CLUTTER_Y_AXIS, 0.0, stage_width / 2, 0,
      0);
  /* Animate it */
  animation =
      clutter_actor_animate (texture, CLUTTER_LINEAR, 10000, "rotation-angle-y",
      360.0, NULL);
  clutter_animation_set_loop (animation, TRUE);
}

int
main (int argc, char *argv[])
{
  GstElement *pipeline, *sink;
  ClutterTimeline *timeline;
  ClutterActor *stage, *texture;

  /* clutter-gst takes care of initializing Clutter and GStreamer */
  if (clutter_gst_init (&argc, &argv) != CLUTTER_INIT_SUCCESS) {
    g_error ("Failed to initialize clutter\n");
    return -1;
  }

  stage = clutter_stage_get_default ();

  /* Make a timeline */
  timeline = clutter_timeline_new (1000);
  g_object_set (timeline, "loop", TRUE, NULL);

  /* Create new texture and disable slicing so the video is properly mapped onto it */
  texture =
      CLUTTER_ACTOR (g_object_new (CLUTTER_TYPE_TEXTURE, "disable-slicing",
          TRUE, NULL));
  g_signal_connect (texture, "size-change", G_CALLBACK (size_change), NULL);

  /* Build the GStreamer pipeline */
  pipeline =
      gst_parse_launch
      ("playbin uri=https://www.freedesktop.org/software/gstreamer-sdk/data/media/sintel_trailer-480p.webm",
      NULL);

  /* Instantiate the Clutter sink */
  sink = gst_element_factory_make ("autocluttersink", NULL);
  if (sink == NULL) {
    /* Revert to the older cluttersink, in case autocluttersink was not found */
    sink = gst_element_factory_make ("cluttersink", NULL);
  }
  if (sink == NULL) {
    g_printerr ("Unable to find a Clutter sink.\n");
    return -1;
  }

  /* Link GStreamer with Clutter by passing the Clutter texture to the Clutter sink */
  g_object_set (sink, "texture", texture, NULL);

  /* Add the Clutter sink to the pipeline */
  g_object_set (pipeline, "video-sink", sink, NULL);

  /* Start playing */
  gst_element_set_state (pipeline, GST_STATE_PLAYING);

  /* start the timeline */
  clutter_timeline_start (timeline);

  /* Add texture to the stage, and show it */
  clutter_group_add (CLUTTER_GROUP (stage), texture);
  clutter_actor_show_all (stage);

  clutter_main ();

  /* Free resources */
  gst_element_set_state (pipeline, GST_STATE_NULL);
  gst_object_unref (pipeline);
  return 0;
}