gstreamer/ext/gl/gstglimagesink.c

/*
 * GStreamer
 * Copyright (C) 2003 Julien Moutte <julien@moutte.net>
 * Copyright (C) 2005,2006,2007 David A. Schleef <ds@schleef.org>
 * Copyright (C) 2008 Julien Isorce <julien.isorce@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., 51 Franklin St, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

/**
 * SECTION:element-glimagesink
 *
 * glimagesink renders video frames to a drawable on a local or remote
 * display using OpenGL. This element can receive a Window ID from the
 * application through the VideoOverlay interface and will then render video
 * frames in this drawable.
 * If no Window ID was provided by the application, the element will
 * create its own internal window and render into it.
 *
 * See the #GstGLDisplay documentation for a list of environment variables that
 * can override window/platform detection.
 *
 * <refsect2>
 * <title>Scaling</title>
 * <para>
 * Depends on the driver, OpenGL handles hardware accelerated
 * scaling of video frames. This means that the element will just accept
 * incoming video frames no matter their geometry and will then put them to the
 * drawable scaling them on the fly. Using the #GstGLImageSink:force-aspect-ratio
 * property it is possible to enforce scaling with a constant aspect ratio,
 * which means drawing black borders around the video frame.
 * </para>
 * </refsect2>
 * <refsect2>
 * <title>Events</title>
 * <para>
 * Through the gl thread, glimagesink handle some events coming from the drawable
 * to manage its appearance even when the data is not flowing (GST_STATE_PAUSED).
 * That means that even when the element is paused, it will receive expose events
 * from the drawable and draw the latest frame with correct borders/aspect-ratio.
 * </para>
 * </refsect2>
 * <refsect2>
 * <title>Examples</title>
 * |[
 * gst-launch-1.0 -v videotestsrc ! video/x-raw ! glimagesink
 * ]| A pipeline to test hardware scaling.
 * No special opengl extension is used in this pipeline, that's why it should work
 * with OpenGL >= 1.1. That's the case if you are using the MESA3D driver v1.3.
 * |[
 * gst-launch-1.0 -v videotestsrc ! video/x-raw,format=I420 ! glimagesink
 * ]| A pipeline to test hardware scaling and hardware colorspace conversion.
 * When your driver supports GLSL (OpenGL Shading Language needs OpenGL >= 2.1),
 * the 4 following format YUY2, UYVY, I420, YV12 and AYUV are converted to RGB32
 * through some fragment shaders and using one framebuffer (FBO extension OpenGL >= 1.4).
 * If your driver does not support GLSL but supports MESA_YCbCr extension then
 * the you can use YUY2 and UYVY. In this case the colorspace conversion is automatically
 * made when loading the texture and therefore no framebuffer is used.
 * |[
 * gst-launch-1.0 -v gltestsrc ! glimagesink
 * ]| A pipeline 100% OpenGL.
 * No special opengl extension is used in this pipeline, that's why it should work
 * with OpenGL >= 1.1. That's the case if you are using the MESA3D driver v1.3.
 * |[
 * gst-plugins-bas/tests/examples/gl/generic/cube
 * ]| The graphic FPS scene can be greater than the input video FPS.
 * The graphic scene can be written from a client code through the
 * two glfilterapp properties.
 * </refsect2>
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <gst/video/videooverlay.h>
#include <gst/video/navigation.h>

#include "gstglimagesink.h"

#if GST_GL_HAVE_PLATFORM_EGL
#include <gst/gl/egl/gsteglimagememory.h>
#endif

GST_DEBUG_CATEGORY (gst_debug_glimage_sink);
#define GST_CAT_DEFAULT gst_debug_glimage_sink

#define GST_GLIMAGE_SINK_GET_LOCK(glsink) \
  (GST_GLIMAGE_SINK(glsink)->drawing_lock)
#define GST_GLIMAGE_SINK_LOCK(glsink) \
  (g_mutex_lock(&GST_GLIMAGE_SINK_GET_LOCK (glsink)))
#define GST_GLIMAGE_SINK_UNLOCK(glsink) \
  (g_mutex_unlock(&GST_GLIMAGE_SINK_GET_LOCK (glsink)))

#define USING_OPENGL(context) (gst_gl_context_check_gl_version (context, GST_GL_API_OPENGL, 1, 0))
#define USING_OPENGL3(context) (gst_gl_context_check_gl_version (context, GST_GL_API_OPENGL3, 3, 1))
#define USING_GLES(context) (gst_gl_context_check_gl_version (context, GST_GL_API_GLES, 1, 0))
#define USING_GLES2(context) (gst_gl_context_check_gl_version (context, GST_GL_API_GLES2, 2, 0))
#define USING_GLES3(context) (gst_gl_context_check_gl_version (context, GST_GL_API_GLES2, 3, 0))

#define SUPPORTED_GL_APIS GST_GL_API_OPENGL | GST_GL_API_GLES2 | GST_GL_API_OPENGL3

static void gst_glimage_sink_thread_init_redisplay (GstGLImageSink * gl_sink);
static void gst_glimage_sink_cleanup_glthread (GstGLImageSink * gl_sink);
static void gst_glimage_sink_on_close (GstGLImageSink * gl_sink);
static void gst_glimage_sink_on_resize (GstGLImageSink * gl_sink,
    gint width, gint height);
static void gst_glimage_sink_on_draw (GstGLImageSink * gl_sink);
static gboolean gst_glimage_sink_redisplay (GstGLImageSink * gl_sink);

static void gst_glimage_sink_finalize (GObject * object);
static void gst_glimage_sink_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * param_spec);
static void gst_glimage_sink_get_property (GObject * object, guint prop_id,
    GValue * value, GParamSpec * param_spec);

static gboolean gst_glimage_sink_stop (GstBaseSink * bsink);

static gboolean gst_glimage_sink_query (GstBaseSink * bsink, GstQuery * query);
static void gst_glimage_sink_set_context (GstElement * element,
    GstContext * context);

static GstStateChangeReturn
gst_glimage_sink_change_state (GstElement * element, GstStateChange transition);

static void gst_glimage_sink_get_times (GstBaseSink * bsink, GstBuffer * buf,
    GstClockTime * start, GstClockTime * end);
static gboolean gst_glimage_sink_set_caps (GstBaseSink * bsink, GstCaps * caps);
static GstCaps *gst_glimage_sink_get_caps (GstBaseSink * bsink,
    GstCaps * filter);
static GstFlowReturn gst_glimage_sink_prepare (GstBaseSink * bsink,
    GstBuffer * buf);
static GstFlowReturn gst_glimage_sink_show_frame (GstVideoSink * bsink,
    GstBuffer * buf);
static gboolean gst_glimage_sink_propose_allocation (GstBaseSink * bsink,
    GstQuery * query);

static void gst_glimage_sink_video_overlay_init (GstVideoOverlayInterface *
    iface);
static void gst_glimage_sink_set_window_handle (GstVideoOverlay * overlay,
    guintptr id);
static void gst_glimage_sink_expose (GstVideoOverlay * overlay);

static void
gst_glimage_sink_handle_events (GstVideoOverlay * overlay,
    gboolean handle_events);

static GstStaticPadTemplate gst_glimage_sink_template =
    GST_STATIC_PAD_TEMPLATE ("sink",
    GST_PAD_SINK,
    GST_PAD_ALWAYS,
    GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE_WITH_FEATURES
        (GST_CAPS_FEATURE_MEMORY_GL_MEMORY,
            "RGBA") "; "
#if GST_GL_HAVE_PLATFORM_EGL
        GST_VIDEO_CAPS_MAKE_WITH_FEATURES
        (GST_CAPS_FEATURE_MEMORY_EGL_IMAGE, "RGBA") "; "
#endif
        GST_VIDEO_CAPS_MAKE_WITH_FEATURES
        (GST_CAPS_FEATURE_META_GST_VIDEO_GL_TEXTURE_UPLOAD_META,
            "RGBA") "; " GST_VIDEO_CAPS_MAKE (GST_GL_COLOR_CONVERT_FORMATS))
    );

enum
{
  ARG_0,
  ARG_DISPLAY,
  PROP_FORCE_ASPECT_RATIO,
  PROP_PIXEL_ASPECT_RATIO,
  PROP_CONTEXT,
  PROP_HANDLE_EVENTS,
  PROP_IGNORE_ALPHA,
};

enum
{
  SIGNAL_0,
  CLIENT_DRAW_SIGNAL,
  CLIENT_RESHAPE_SIGNAL,
  LAST_SIGNAL
};

static guint gst_glimage_sink_signals[LAST_SIGNAL] = { 0 };

static void
gst_glimage_sink_navigation_send_event (GstNavigation * navigation, GstStructure
    * structure)
{
  GstGLImageSink *sink = GST_GLIMAGE_SINK (navigation);
  GstEvent *event = NULL;
  GstPad *pad = NULL;
  GstGLWindow *window;
  guint width, height;
  gdouble x, y, xscale, yscale;

  if (!sink->context)
    return;

  window = gst_gl_context_get_window (sink->context);
  g_return_if_fail (GST_GL_IS_WINDOW (window));

  width = GST_VIDEO_SINK_WIDTH (sink);
  height = GST_VIDEO_SINK_HEIGHT (sink);
  gst_gl_window_get_surface_dimensions (window, &width, &height);

  event = gst_event_new_navigation (structure);

  pad = gst_pad_get_peer (GST_VIDEO_SINK_PAD (sink));
  /* Converting pointer coordinates to the non scaled geometry */
  if (width != GST_VIDEO_SINK_WIDTH (sink) &&
      width != 0 && gst_structure_get_double (structure, "pointer_x", &x)) {
    xscale = (gdouble) GST_VIDEO_SINK_WIDTH (sink) / width;
    gst_structure_set (structure, "pointer_x", G_TYPE_DOUBLE,
        (gdouble) x * xscale, NULL);
  }
  if (height != GST_VIDEO_SINK_HEIGHT (sink) &&
      height != 0 && gst_structure_get_double (structure, "pointer_y", &y)) {
    yscale = (gdouble) GST_VIDEO_SINK_HEIGHT (sink) / height;
    gst_structure_set (structure, "pointer_y", G_TYPE_DOUBLE,
        (gdouble) y * yscale, NULL);
  }


  if (GST_IS_PAD (pad) && GST_IS_EVENT (event))
    gst_pad_send_event (pad, event);

  gst_object_unref (pad);
  gst_object_unref (window);
}

static void
gst_glimage_sink_navigation_interface_init (GstNavigationInterface * iface)
{
  iface->send_event = gst_glimage_sink_navigation_send_event;
}

#define gst_glimage_sink_parent_class parent_class
G_DEFINE_TYPE_WITH_CODE (GstGLImageSink, gst_glimage_sink,
    GST_TYPE_VIDEO_SINK, G_IMPLEMENT_INTERFACE (GST_TYPE_VIDEO_OVERLAY,
        gst_glimage_sink_video_overlay_init);
    G_IMPLEMENT_INTERFACE (GST_TYPE_NAVIGATION,
        gst_glimage_sink_navigation_interface_init);
    GST_DEBUG_CATEGORY_INIT (gst_debug_glimage_sink, "glimagesink", 0,
        "OpenGL Video Sink"));

static void
gst_glimage_sink_class_init (GstGLImageSinkClass * klass)
{
  GObjectClass *gobject_class;
  GstElementClass *gstelement_class;
  GstBaseSinkClass *gstbasesink_class;
  GstVideoSinkClass *gstvideosink_class;
  GstElementClass *element_class;

  gobject_class = (GObjectClass *) klass;
  gstelement_class = (GstElementClass *) klass;
  gstbasesink_class = (GstBaseSinkClass *) klass;
  gstvideosink_class = (GstVideoSinkClass *) klass;
  element_class = GST_ELEMENT_CLASS (klass);

  gobject_class->set_property = gst_glimage_sink_set_property;
  gobject_class->get_property = gst_glimage_sink_get_property;

  g_object_class_install_property (gobject_class, ARG_DISPLAY,
      g_param_spec_string ("display", "Display", "Display name",
          NULL, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (gobject_class, PROP_FORCE_ASPECT_RATIO,
      g_param_spec_boolean ("force-aspect-ratio",
          "Force aspect ratio",
          "When enabled, scaling will respect original aspect ratio", TRUE,
          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (gobject_class, PROP_PIXEL_ASPECT_RATIO,
      gst_param_spec_fraction ("pixel-aspect-ratio", "Pixel Aspect Ratio",
          "The pixel aspect ratio of the device", 0, 1, G_MAXINT, 1, 1, 1,
          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (gobject_class, PROP_CONTEXT,
      g_param_spec_object ("context",
          "OpenGL context",
          "Get OpenGL context",
          GST_GL_TYPE_CONTEXT, G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (gobject_class, PROP_HANDLE_EVENTS,
      g_param_spec_boolean ("handle-events", "Handle XEvents",
          "When enabled, XEvents will be selected and handled", TRUE,
          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (gobject_class, PROP_HANDLE_EVENTS,
      g_param_spec_boolean ("ignore-alpha", "Ignore Alpha",
          "When enabled, alpha will be ignored and converted to black", TRUE,
          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  gst_element_class_set_metadata (element_class, "OpenGL video sink",
      "Sink/Video", "A videosink based on OpenGL",
      "Julien Isorce <julien.isorce@gmail.com>");

  /**
   * GstGLImageSink::client-draw:
   * @object: the #GstGLImageSink
   * @texture: the #guint id of the texture.
   * @width: the #guint width of the texture.
   * @height: the #guint height of the texture.
   *
   * Will be emitted before actually drawing the texture.  The client should
   * redraw the surface/contents with the @texture, @width and @height and
   * and return %TRUE.
   *
   * Returns: whether the texture was redrawn by the signal.  If not, a
   *          default redraw will occur.
   */
  gst_glimage_sink_signals[CLIENT_DRAW_SIGNAL] =
      g_signal_new ("client-draw", G_TYPE_FROM_CLASS (klass),
      G_SIGNAL_RUN_LAST, 0, NULL, NULL, g_cclosure_marshal_generic,
      G_TYPE_BOOLEAN, 4, GST_GL_TYPE_CONTEXT,
      G_TYPE_UINT, G_TYPE_UINT, G_TYPE_UINT);

  /**
   * GstGLImageSink::client-reshape:
   * @object: the #GstGLImageSink
   * @width: the #guint width of the texture.
   * @height: the #guint height of the texture.
   *
   * The client should resize the surface/window/viewport with the @width and
   * @height and return %TRUE.
   *
   * Returns: whether the content area was resized by the signal.  If not, a
   *          default viewport resize will occur.
   */
  gst_glimage_sink_signals[CLIENT_RESHAPE_SIGNAL] =
      g_signal_new ("client-reshape", G_TYPE_FROM_CLASS (klass),
      G_SIGNAL_RUN_LAST, 0, NULL, NULL, g_cclosure_marshal_generic,
      G_TYPE_BOOLEAN, 3, GST_GL_TYPE_CONTEXT, G_TYPE_UINT, G_TYPE_UINT);

  gst_element_class_add_pad_template (element_class,
      gst_static_pad_template_get (&gst_glimage_sink_template));

  gobject_class->finalize = gst_glimage_sink_finalize;

  gstelement_class->change_state = gst_glimage_sink_change_state;
  gstelement_class->set_context = gst_glimage_sink_set_context;
  gstbasesink_class->query = GST_DEBUG_FUNCPTR (gst_glimage_sink_query);
  gstbasesink_class->set_caps = gst_glimage_sink_set_caps;
  gstbasesink_class->get_caps = gst_glimage_sink_get_caps;
  gstbasesink_class->get_times = gst_glimage_sink_get_times;
  gstbasesink_class->prepare = gst_glimage_sink_prepare;
  gstbasesink_class->propose_allocation = gst_glimage_sink_propose_allocation;
  gstbasesink_class->stop = gst_glimage_sink_stop;

  gstvideosink_class->show_frame =
      GST_DEBUG_FUNCPTR (gst_glimage_sink_show_frame);
}

static void
gst_glimage_sink_init (GstGLImageSink * glimage_sink)
{
  glimage_sink->display_name = NULL;
  glimage_sink->window_id = 0;
  glimage_sink->new_window_id = 0;
  glimage_sink->display = NULL;
  glimage_sink->keep_aspect_ratio = TRUE;
  glimage_sink->par_n = 0;
  glimage_sink->par_d = 1;
  glimage_sink->pool = NULL;
  glimage_sink->stored_buffer = NULL;
  glimage_sink->redisplay_texture = 0;
  glimage_sink->handle_events = TRUE;
  glimage_sink->ignore_alpha = TRUE;

  g_mutex_init (&glimage_sink->drawing_lock);
}

static void
gst_glimage_sink_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec)
{
  GstGLImageSink *glimage_sink;

  g_return_if_fail (GST_IS_GLIMAGE_SINK (object));

  glimage_sink = GST_GLIMAGE_SINK (object);

  switch (prop_id) {
    case ARG_DISPLAY:
    {
      g_free (glimage_sink->display_name);
      glimage_sink->display_name = g_strdup (g_value_get_string (value));
      break;
    }
    case PROP_FORCE_ASPECT_RATIO:
    {
      glimage_sink->keep_aspect_ratio = g_value_get_boolean (value);
      break;
    }
    case PROP_PIXEL_ASPECT_RATIO:
    {
      glimage_sink->par_n = gst_value_get_fraction_numerator (value);
      glimage_sink->par_d = gst_value_get_fraction_denominator (value);
      break;
    }
    case PROP_HANDLE_EVENTS:
      gst_glimage_sink_handle_events (GST_VIDEO_OVERLAY (glimage_sink),
          g_value_get_boolean (value));
      break;
    case PROP_IGNORE_ALPHA:
      glimage_sink->ignore_alpha = g_value_get_boolean (value);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_glimage_sink_finalize (GObject * object)
{
  GstGLImageSink *glimage_sink;

  g_return_if_fail (GST_IS_GLIMAGE_SINK (object));

  glimage_sink = GST_GLIMAGE_SINK (object);

  g_mutex_clear (&glimage_sink->drawing_lock);

  if (glimage_sink->other_context) {
    gst_object_unref (glimage_sink->other_context);
    glimage_sink->other_context = NULL;
  }

  g_free (glimage_sink->display_name);

  GST_DEBUG ("finalized");
  G_OBJECT_CLASS (parent_class)->finalize (object);
}

static void
gst_glimage_sink_get_property (GObject * object, guint prop_id,
    GValue * value, GParamSpec * pspec)
{
  GstGLImageSink *glimage_sink;

  g_return_if_fail (GST_IS_GLIMAGE_SINK (object));

  glimage_sink = GST_GLIMAGE_SINK (object);

  switch (prop_id) {
    case ARG_DISPLAY:
      g_value_set_string (value, glimage_sink->display_name);
      break;
    case PROP_FORCE_ASPECT_RATIO:
      g_value_set_boolean (value, glimage_sink->keep_aspect_ratio);
      break;
    case PROP_PIXEL_ASPECT_RATIO:
      gst_value_set_fraction (value, glimage_sink->par_n, glimage_sink->par_d);
      break;
    case PROP_CONTEXT:
      g_value_set_object (value, glimage_sink->context);
      break;
    case PROP_HANDLE_EVENTS:
      g_value_set_boolean (value, glimage_sink->handle_events);
      break;
    case PROP_IGNORE_ALPHA:
      g_value_set_boolean (value, glimage_sink->ignore_alpha);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_glimage_sink_key_event_cb (GstGLWindow * window, char *event_name, char
    *key_string, GstGLImageSink * gl_sink)
{
  GST_DEBUG_OBJECT (gl_sink, "glimagesink event %s key %s pressed", event_name,
      key_string);
  gst_navigation_send_key_event (GST_NAVIGATION (gl_sink),
      event_name, key_string);
}

static void
gst_glimage_sink_mouse_event_cb (GstGLWindow * window, char *event_name,
    int button, double posx, double posy, GstGLImageSink * gl_sink)
{
  GST_DEBUG_OBJECT (gl_sink, "glimagesink event %s at %g, %g", event_name, posx,
      posy);
  gst_navigation_send_mouse_event (GST_NAVIGATION (gl_sink),
      event_name, button, posx, posy);
}

static gboolean
_ensure_gl_setup (GstGLImageSink * gl_sink)
{
  GError *error = NULL;

  if (!gst_gl_ensure_element_data (gl_sink, &gl_sink->display,
          &gl_sink->other_context))
    return FALSE;

  gst_gl_display_filter_gl_api (gl_sink->display, SUPPORTED_GL_APIS);

  if (!gl_sink->context) {
    GstGLWindow *window;

    gl_sink->context = gst_gl_context_new (gl_sink->display);
    if (!gl_sink->context)
      goto context_creation_error;

    window = gst_gl_context_get_window (gl_sink->context);

    if (!gl_sink->window_id && !gl_sink->new_window_id)
      gst_video_overlay_prepare_window_handle (GST_VIDEO_OVERLAY (gl_sink));

    if (gl_sink->window_id != gl_sink->new_window_id) {
      gl_sink->window_id = gl_sink->new_window_id;
      gst_gl_window_set_window_handle (window, gl_sink->window_id);
    }

    if (!gst_gl_context_create (gl_sink->context, gl_sink->other_context,
            &error)) {
      gst_object_unref (window);
      goto context_error;
    }

    gst_gl_window_handle_events (window, gl_sink->handle_events);

    /* setup callbacks */
    gst_gl_window_set_resize_callback (window,
        GST_GL_WINDOW_RESIZE_CB (gst_glimage_sink_on_resize),
        gst_object_ref (gl_sink), (GDestroyNotify) gst_object_unref);
    gst_gl_window_set_draw_callback (window,
        GST_GL_WINDOW_CB (gst_glimage_sink_on_draw),
        gst_object_ref (gl_sink), (GDestroyNotify) gst_object_unref);
    gst_gl_window_set_close_callback (window,
        GST_GL_WINDOW_CB (gst_glimage_sink_on_close),
        gst_object_ref (gl_sink), (GDestroyNotify) gst_object_unref);
    gl_sink->key_sig_id = g_signal_connect (window, "key-event", G_CALLBACK
        (gst_glimage_sink_key_event_cb), gl_sink);
    gl_sink->mouse_sig_id = g_signal_connect (window, "mouse-event", G_CALLBACK
        (gst_glimage_sink_mouse_event_cb), gl_sink);

    gst_object_unref (window);
  }

  return TRUE;

context_creation_error:
  {
    GST_ELEMENT_ERROR (gl_sink, RESOURCE, NOT_FOUND,
        ("Failed to create GL context"), (NULL));
    return FALSE;
  }

context_error:
  {
    GST_ELEMENT_ERROR (gl_sink, RESOURCE, NOT_FOUND, ("%s", error->message),
        (NULL));
    gst_object_unref (gl_sink->context);
    gl_sink->context = NULL;
    return FALSE;
  }
}

static gboolean
gst_glimage_sink_query (GstBaseSink * bsink, GstQuery * query)
{
  GstGLImageSink *glimage_sink = GST_GLIMAGE_SINK (bsink);
  gboolean res = FALSE;

  switch (GST_QUERY_TYPE (query)) {
    case GST_QUERY_CONTEXT:
    {
      gboolean ret =
          gst_gl_handle_context_query ((GstElement *) glimage_sink, query,
          &glimage_sink->display, &glimage_sink->other_context);
      if (glimage_sink->display)
        gst_gl_display_filter_gl_api (glimage_sink->display, SUPPORTED_GL_APIS);
      return ret;
    }
    case GST_QUERY_DRAIN:
    {
      GstBuffer *buf = NULL;

      GST_GLIMAGE_SINK_LOCK (glimage_sink);
      glimage_sink->redisplay_texture = 0;
      buf = glimage_sink->stored_buffer;
      glimage_sink->stored_buffer = NULL;
      GST_GLIMAGE_SINK_UNLOCK (glimage_sink);

      if (buf)
        gst_buffer_unref (buf);

      gst_buffer_replace (&glimage_sink->next_buffer, NULL);
      gst_gl_upload_release_buffer (glimage_sink->upload);

      res = GST_BASE_SINK_CLASS (parent_class)->query (bsink, query);
      break;
    }
    default:
      res = GST_BASE_SINK_CLASS (parent_class)->query (bsink, query);
      break;
  }

  return res;
}

static gboolean
gst_glimage_sink_stop (GstBaseSink * bsink)
{
  GstGLImageSink *glimage_sink = GST_GLIMAGE_SINK (bsink);

  if (glimage_sink->pool) {
    gst_object_unref (glimage_sink->pool);
    glimage_sink->pool = NULL;
  }

  if (glimage_sink->gl_caps) {
    gst_caps_unref (glimage_sink->gl_caps);
    glimage_sink->gl_caps = NULL;
  }

  return TRUE;
}

static void
gst_glimage_sink_set_context (GstElement * element, GstContext * context)
{
  GstGLImageSink *gl_sink = GST_GLIMAGE_SINK (element);

  gst_gl_handle_set_context (element, context, &gl_sink->display,
      &gl_sink->other_context);

  if (gl_sink->display)
    gst_gl_display_filter_gl_api (gl_sink->display, SUPPORTED_GL_APIS);
}

static GstStateChangeReturn
gst_glimage_sink_change_state (GstElement * element, GstStateChange transition)
{
  GstGLImageSink *glimage_sink;
  GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;

  GST_DEBUG ("changing state: %s => %s",
      gst_element_state_get_name (GST_STATE_TRANSITION_CURRENT (transition)),
      gst_element_state_get_name (GST_STATE_TRANSITION_NEXT (transition)));

  glimage_sink = GST_GLIMAGE_SINK (element);

  switch (transition) {
    case GST_STATE_CHANGE_NULL_TO_READY:
      break;
    case GST_STATE_CHANGE_READY_TO_PAUSED:
      g_atomic_int_set (&glimage_sink->to_quit, 0);
      break;
    case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
      break;
    default:
      break;
  }

  ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
  if (ret == GST_STATE_CHANGE_FAILURE)
    return ret;

  switch (transition) {
    case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
      break;
    case GST_STATE_CHANGE_PAUSED_TO_READY:
    {
      /* mark the redisplay_texture as unavailable (=0)
       * to avoid drawing
       */
      GST_GLIMAGE_SINK_LOCK (glimage_sink);
      glimage_sink->redisplay_texture = 0;
      if (glimage_sink->stored_buffer) {
        gst_buffer_unref (glimage_sink->stored_buffer);
        glimage_sink->stored_buffer = NULL;
      }
      GST_GLIMAGE_SINK_UNLOCK (glimage_sink);
      gst_buffer_replace (&glimage_sink->next_buffer, NULL);

      if (glimage_sink->upload) {
        gst_object_unref (glimage_sink->upload);
        glimage_sink->upload = NULL;
      }

      if (glimage_sink->convert) {
        gst_object_unref (glimage_sink->convert);
        glimage_sink->convert = NULL;
      }

      glimage_sink->window_id = 0;
      //but do not reset glimage_sink->new_window_id

      if (glimage_sink->pool) {
        gst_buffer_pool_set_active (glimage_sink->pool, FALSE);
        gst_object_unref (glimage_sink->pool);
        glimage_sink->pool = NULL;
      }

      GST_VIDEO_SINK_WIDTH (glimage_sink) = 1;
      GST_VIDEO_SINK_HEIGHT (glimage_sink) = 1;
      if (glimage_sink->context) {
        GstGLWindow *window = gst_gl_context_get_window (glimage_sink->context);

        gst_gl_window_send_message (window,
            GST_GL_WINDOW_CB (gst_glimage_sink_cleanup_glthread), glimage_sink);

        gst_gl_window_set_resize_callback (window, NULL, NULL, NULL);
        gst_gl_window_set_draw_callback (window, NULL, NULL, NULL);
        gst_gl_window_set_close_callback (window, NULL, NULL, NULL);

        gst_object_unref (window);
        gst_object_unref (glimage_sink->context);
        glimage_sink->context = NULL;
      }

      if (glimage_sink->display) {
        gst_object_unref (glimage_sink->display);
        glimage_sink->display = NULL;
      }
      break;
    }
    case GST_STATE_CHANGE_READY_TO_NULL:
      break;
    default:
      break;
  }

  return ret;
}

static void
gst_glimage_sink_get_times (GstBaseSink * bsink, GstBuffer * buf,
    GstClockTime * start, GstClockTime * end)
{
  GstGLImageSink *glimagesink;

  glimagesink = GST_GLIMAGE_SINK (bsink);

  if (GST_BUFFER_TIMESTAMP_IS_VALID (buf)) {
    *start = GST_BUFFER_TIMESTAMP (buf);
    if (GST_BUFFER_DURATION_IS_VALID (buf))
      *end = *start + GST_BUFFER_DURATION (buf);
    else {
      if (GST_VIDEO_INFO_FPS_N (&glimagesink->info) > 0) {
        *end = *start +
            gst_util_uint64_scale_int (GST_SECOND,
            GST_VIDEO_INFO_FPS_D (&glimagesink->info),
            GST_VIDEO_INFO_FPS_N (&glimagesink->info));
      }
    }
  }
}

/* copies the given caps */
static GstCaps *
gst_glimage_sink_caps_remove_format_info (GstCaps * caps)
{
  GstStructure *st;
  GstCapsFeatures *f;
  gint i, n;
  GstCaps *res;

  res = gst_caps_new_empty ();

  n = gst_caps_get_size (caps);
  for (i = 0; i < n; i++) {
    st = gst_caps_get_structure (caps, i);
    f = gst_caps_get_features (caps, i);

    /* If this is already expressed by the existing caps
     * skip this structure */
    if (i > 0 && gst_caps_is_subset_structure_full (res, st, f))
      continue;

    st = gst_structure_copy (st);
    /* Only remove format info for the cases when we can actually convert */
    if (!gst_caps_features_is_any (f)
        && gst_caps_features_is_equal (f,
            GST_CAPS_FEATURES_MEMORY_SYSTEM_MEMORY))
      gst_structure_remove_fields (st, "format", "colorimetry", "chroma-site",
          NULL);
    gst_structure_remove_fields (st, "width", "height", NULL);

    gst_caps_append_structure_full (res, st, gst_caps_features_copy (f));
  }

  return res;
}

static GstCaps *
gst_glimage_sink_get_caps (GstBaseSink * bsink, GstCaps * filter)
{
  GstGLImageSink *gl_sink = GST_GLIMAGE_SINK (bsink);
  GstCaps *tmp = NULL;
  GstCaps *result = NULL;

  tmp = gst_caps_from_string ("video/x-raw(memory:GLMemory),format=RGBA");

  result = gst_glimage_sink_caps_remove_format_info (tmp);
  gst_caps_unref (tmp);
  tmp = result;
  GST_DEBUG_OBJECT (bsink, "remove format returned caps %" GST_PTR_FORMAT, tmp);

  result =
      gst_gl_color_convert_transform_caps (gl_sink->context, GST_PAD_SRC, tmp,
      NULL);
  gst_caps_unref (tmp);
  tmp = result;

  result =
      gst_gl_upload_transform_caps (gl_sink->context, GST_PAD_SRC, tmp, NULL);
  gst_caps_unref (tmp);
  tmp = result;
  GST_DEBUG_OBJECT (bsink, "transfer returned caps %" GST_PTR_FORMAT, tmp);

  if (filter) {
    result = gst_caps_intersect_full (filter, tmp, GST_CAPS_INTERSECT_FIRST);
    gst_caps_unref (tmp);
  } else {
    result = tmp;
  }

  GST_DEBUG_OBJECT (bsink, "returning caps: %" GST_PTR_FORMAT, result);

  return result;
}

static gboolean
gst_glimage_sink_set_caps (GstBaseSink * bsink, GstCaps * caps)
{
  GstGLImageSink *glimage_sink;
  gint width;
  gint height;
  gboolean ok;
  gint par_n, par_d;
  gint display_par_n, display_par_d;
  guint display_ratio_num, display_ratio_den;
  GstVideoInfo vinfo;
  GstStructure *structure;
  GstBufferPool *newpool, *oldpool;
  GstCapsFeatures *gl_features;
  GstCaps *uploaded_caps;

  GST_DEBUG ("set caps with %" GST_PTR_FORMAT, caps);

  glimage_sink = GST_GLIMAGE_SINK (bsink);

  ok = gst_video_info_from_caps (&vinfo, caps);
  if (!ok)
    return FALSE;

  width = GST_VIDEO_INFO_WIDTH (&vinfo);
  height = GST_VIDEO_INFO_HEIGHT (&vinfo);

  par_n = GST_VIDEO_INFO_PAR_N (&vinfo);
  par_d = GST_VIDEO_INFO_PAR_D (&vinfo);

  if (!par_n)
    par_n = 1;

  /* get display's PAR */
  if (glimage_sink->par_n != 0 && glimage_sink->par_d != 0) {
    display_par_n = glimage_sink->par_n;
    display_par_d = glimage_sink->par_d;
  } else {
    display_par_n = 1;
    display_par_d = 1;
  }

  ok = gst_video_calculate_display_ratio (&display_ratio_num,
      &display_ratio_den, width, height, par_n, par_d, display_par_n,
      display_par_d);

  if (!ok)
    return FALSE;

  GST_TRACE ("PAR: %u/%u DAR:%u/%u", par_n, par_d, display_par_n,
      display_par_d);

  if (height % display_ratio_den == 0) {
    GST_DEBUG ("keeping video height");
    GST_VIDEO_SINK_WIDTH (glimage_sink) = (guint)
        gst_util_uint64_scale_int (height, display_ratio_num,
        display_ratio_den);
    GST_VIDEO_SINK_HEIGHT (glimage_sink) = height;
  } else if (width % display_ratio_num == 0) {
    GST_DEBUG ("keeping video width");
    GST_VIDEO_SINK_WIDTH (glimage_sink) = width;
    GST_VIDEO_SINK_HEIGHT (glimage_sink) = (guint)
        gst_util_uint64_scale_int (width, display_ratio_den, display_ratio_num);
  } else {
    GST_DEBUG ("approximating while keeping video height");
    GST_VIDEO_SINK_WIDTH (glimage_sink) = (guint)
        gst_util_uint64_scale_int (height, display_ratio_num,
        display_ratio_den);
    GST_VIDEO_SINK_HEIGHT (glimage_sink) = height;
  }
  GST_DEBUG ("scaling to %dx%d", GST_VIDEO_SINK_WIDTH (glimage_sink),
      GST_VIDEO_SINK_HEIGHT (glimage_sink));

  glimage_sink->info = vinfo;
  if (!_ensure_gl_setup (glimage_sink))
    return FALSE;

  newpool = gst_gl_buffer_pool_new (glimage_sink->context);
  structure = gst_buffer_pool_get_config (newpool);
  gst_buffer_pool_config_set_params (structure, caps, vinfo.size, 2, 0);
  gst_buffer_pool_set_config (newpool, structure);

  oldpool = glimage_sink->pool;
  /* we don't activate the pool yet, this will be done by downstream after it
   * has configured the pool. If downstream does not want our pool we will
   * activate it when we render into it */
  glimage_sink->pool = newpool;

  /* unref the old sink */
  if (oldpool) {
    /* we don't deactivate, some elements might still be using it, it will
     * be deactivated when the last ref is gone */
    gst_object_unref (oldpool);
  }

  if (glimage_sink->upload)
    gst_object_unref (glimage_sink->upload);
  glimage_sink->upload = gst_gl_upload_new (glimage_sink->context);

  gl_features =
      gst_caps_features_from_string (GST_CAPS_FEATURE_MEMORY_GL_MEMORY);

  uploaded_caps = gst_caps_copy (caps);
  gst_caps_set_features (uploaded_caps, 0,
      gst_caps_features_copy (gl_features));
  gst_gl_upload_set_caps (glimage_sink->upload, caps, uploaded_caps);

  if (glimage_sink->gl_caps)
    gst_caps_unref (glimage_sink->gl_caps);
  glimage_sink->gl_caps = gst_caps_copy (caps);
  gst_caps_set_simple (glimage_sink->gl_caps, "format", G_TYPE_STRING, "RGBA",
      NULL);
  gst_caps_set_features (glimage_sink->gl_caps, 0,
      gst_caps_features_copy (gl_features));

  if (glimage_sink->convert)
    gst_object_unref (glimage_sink->convert);
  glimage_sink->convert = gst_gl_color_convert_new (glimage_sink->context);
  if (!gst_gl_color_convert_set_caps (glimage_sink->convert, uploaded_caps,
          glimage_sink->gl_caps)) {
    gst_caps_unref (uploaded_caps);
    gst_caps_features_free (gl_features);
    return FALSE;
  }
  gst_caps_unref (uploaded_caps);
  gst_caps_features_free (gl_features);

  glimage_sink->caps_change = TRUE;

  return TRUE;
}

static GstFlowReturn
gst_glimage_sink_prepare (GstBaseSink * bsink, GstBuffer * buf)
{
  GstGLImageSink *glimage_sink;
  GstBuffer *uploaded_buffer, *next_buffer = NULL;
  GstVideoFrame gl_frame;
  GstVideoInfo gl_info;

  glimage_sink = GST_GLIMAGE_SINK (bsink);

  GST_TRACE ("preparing buffer:%p", buf);

  if (GST_VIDEO_SINK_WIDTH (glimage_sink) < 1 ||
      GST_VIDEO_SINK_HEIGHT (glimage_sink) < 1) {
    return GST_FLOW_NOT_NEGOTIATED;
  }

  if (!_ensure_gl_setup (glimage_sink))
    return GST_FLOW_NOT_NEGOTIATED;

  if (gst_gl_upload_perform_with_buffer (glimage_sink->upload, buf,
          &uploaded_buffer) != GST_GL_UPLOAD_DONE)
    goto upload_failed;

  if (!(next_buffer =
          gst_gl_color_convert_perform (glimage_sink->convert,
              uploaded_buffer))) {
    gst_buffer_unref (uploaded_buffer);
    goto upload_failed;
  }

  gst_video_info_from_caps (&gl_info, glimage_sink->gl_caps);

  if (!gst_video_frame_map (&gl_frame, &gl_info, next_buffer,
          GST_MAP_READ | GST_MAP_GL)) {
    gst_buffer_unref (uploaded_buffer);
    gst_buffer_unref (next_buffer);
    goto upload_failed;
  }
  gst_buffer_unref (uploaded_buffer);

  glimage_sink->next_tex = *(guint *) gl_frame.data[0];

  gst_buffer_replace (&glimage_sink->next_buffer, next_buffer);
  gst_buffer_unref (next_buffer);

  gst_video_frame_unmap (&gl_frame);

  if (glimage_sink->window_id != glimage_sink->new_window_id) {
    GstGLWindow *window = gst_gl_context_get_window (glimage_sink->context);

    glimage_sink->window_id = glimage_sink->new_window_id;
    gst_gl_window_set_window_handle (window, glimage_sink->window_id);

    gst_object_unref (window);
  }

  return GST_FLOW_OK;

upload_failed:
  {
    GST_ELEMENT_ERROR (glimage_sink, RESOURCE, NOT_FOUND,
        ("%s", "Failed to upload buffer"), (NULL));
    return GST_FLOW_ERROR;
  }
}

static GstFlowReturn
gst_glimage_sink_show_frame (GstVideoSink * vsink, GstBuffer * buf)
{
  GstGLImageSink *glimage_sink;
  GstBuffer *stored_buffer;

  GST_TRACE ("rendering buffer:%p", buf);

  glimage_sink = GST_GLIMAGE_SINK (vsink);

  GST_TRACE ("redisplay texture:%u of size:%ux%u, window size:%ux%u",
      glimage_sink->next_tex, GST_VIDEO_INFO_WIDTH (&glimage_sink->info),
      GST_VIDEO_INFO_HEIGHT (&glimage_sink->info),
      GST_VIDEO_SINK_WIDTH (glimage_sink),
      GST_VIDEO_SINK_HEIGHT (glimage_sink));

  /* Avoid to release the texture while drawing */
  GST_GLIMAGE_SINK_LOCK (glimage_sink);
  glimage_sink->redisplay_texture = glimage_sink->next_tex;
  stored_buffer = glimage_sink->stored_buffer;
  glimage_sink->stored_buffer = gst_buffer_ref (glimage_sink->next_buffer);
  GST_GLIMAGE_SINK_UNLOCK (glimage_sink);

  /* Ask the underlying window to redraw its content */
  if (!gst_glimage_sink_redisplay (glimage_sink))
    goto redisplay_failed;

  GST_TRACE ("post redisplay");

  if (stored_buffer)
    gst_buffer_unref (stored_buffer);

  if (g_atomic_int_get (&glimage_sink->to_quit) != 0) {
    GST_ELEMENT_ERROR (glimage_sink, RESOURCE, NOT_FOUND,
        ("%s", gst_gl_context_get_error ()), (NULL));
    gst_gl_upload_release_buffer (glimage_sink->upload);
    return GST_FLOW_ERROR;
  }

  return GST_FLOW_OK;

/* ERRORS */
redisplay_failed:
  {
    gst_gl_upload_release_buffer (glimage_sink->upload);
    GST_ELEMENT_ERROR (glimage_sink, RESOURCE, NOT_FOUND,
        ("%s", gst_gl_context_get_error ()), (NULL));
    return GST_FLOW_ERROR;
  }
}


static void
gst_glimage_sink_video_overlay_init (GstVideoOverlayInterface * iface)
{
  iface->set_window_handle = gst_glimage_sink_set_window_handle;
  iface->handle_events = gst_glimage_sink_handle_events;
  iface->expose = gst_glimage_sink_expose;
}


static void
gst_glimage_sink_set_window_handle (GstVideoOverlay * overlay, guintptr id)
{
  GstGLImageSink *glimage_sink = GST_GLIMAGE_SINK (overlay);
  guintptr window_id = (guintptr) id;

  g_return_if_fail (GST_IS_GLIMAGE_SINK (overlay));

  GST_DEBUG ("set_xwindow_id %" G_GUINT64_FORMAT, (guint64) window_id);

  glimage_sink->new_window_id = window_id;
}


static void
gst_glimage_sink_expose (GstVideoOverlay * overlay)
{
  GstGLImageSink *glimage_sink = GST_GLIMAGE_SINK (overlay);

  /* redisplay opengl scene */
  if (glimage_sink->display && glimage_sink->window_id) {

    if (glimage_sink->window_id != glimage_sink->new_window_id) {
      GstGLWindow *window = gst_gl_context_get_window (glimage_sink->context);

      glimage_sink->window_id = glimage_sink->new_window_id;
      gst_gl_window_set_window_handle (window, glimage_sink->window_id);

      gst_object_unref (window);
    }

    gst_glimage_sink_redisplay (glimage_sink);
  }
}

static void
gst_glimage_sink_handle_events (GstVideoOverlay * overlay,
    gboolean handle_events)
{
  GstGLImageSink *glimage_sink = GST_GLIMAGE_SINK (overlay);

  glimage_sink->handle_events = handle_events;
  if (G_LIKELY (glimage_sink->context)) {
    GstGLWindow *window;
    window = gst_gl_context_get_window (glimage_sink->context);
    gst_gl_window_handle_events (window, handle_events);
    gst_object_unref (window);
  }
}

static gboolean
gst_glimage_sink_propose_allocation (GstBaseSink * bsink, GstQuery * query)
{
  GstGLImageSink *glimage_sink = GST_GLIMAGE_SINK (bsink);
  GstBufferPool *pool;
  GstStructure *config;
  GstCaps *caps;
  guint size;
  gboolean need_pool;

  if (!_ensure_gl_setup (glimage_sink))
    return FALSE;

  gst_query_parse_allocation (query, &caps, &need_pool);

  if (caps == NULL)
    goto no_caps;

  if ((pool = glimage_sink->pool))
    gst_object_ref (pool);

  if (pool != NULL) {
    GstCaps *pcaps;

    /* we had a pool, check caps */
    GST_DEBUG_OBJECT (glimage_sink, "check existing pool caps");
    config = gst_buffer_pool_get_config (pool);
    gst_buffer_pool_config_get_params (config, &pcaps, &size, NULL, NULL);

    if (!gst_caps_is_equal (caps, pcaps)) {
      GST_DEBUG_OBJECT (glimage_sink, "pool has different caps");
      /* different caps, we can't use this pool */
      gst_object_unref (pool);
      pool = NULL;
    }
    gst_structure_free (config);
  }

  if (pool == NULL && need_pool) {
    GstVideoInfo info;

    if (!gst_video_info_from_caps (&info, caps))
      goto invalid_caps;

    GST_DEBUG_OBJECT (glimage_sink, "create new pool");
    pool = gst_gl_buffer_pool_new (glimage_sink->context);

    /* the normal size of a frame */
    size = info.size;

    config = gst_buffer_pool_get_config (pool);
    gst_buffer_pool_config_set_params (config, caps, size, 0, 0);
    if (!gst_buffer_pool_set_config (pool, config))
      goto config_failed;
  }
  /* we need at least 2 buffer because we hold on to the last one */
  if (pool) {
    gst_query_add_allocation_pool (query, pool, size, 2, 0);
    gst_object_unref (pool);
  }

  gst_gl_upload_propose_allocation (glimage_sink->upload, NULL, query);

  if (glimage_sink->context->gl_vtable->FenceSync)
    gst_query_add_allocation_meta (query, GST_GL_SYNC_META_API_TYPE, 0);

  return TRUE;

  /* ERRORS */
no_caps:
  {
    GST_DEBUG_OBJECT (bsink, "no caps specified");
    return FALSE;
  }
invalid_caps:
  {
    GST_DEBUG_OBJECT (bsink, "invalid caps specified");
    return FALSE;
  }
config_failed:
  {
    GST_DEBUG_OBJECT (bsink, "failed setting config");
    return FALSE;
  }
}

/* *INDENT-OFF* */
static const GLfloat vertices[] = {
     1.0f,  1.0f, 0.0f, 1.0f, 0.0f,
    -1.0f,  1.0f, 0.0f, 0.0f, 0.0f,
    -1.0f, -1.0f, 0.0f, 0.0f, 1.0f,
     1.0f, -1.0f, 0.0f, 1.0f, 1.0f
};
/* *INDENT-ON* */

static void
_bind_buffer (GstGLImageSink * gl_sink)
{
  const GstGLFuncs *gl = gl_sink->context->gl_vtable;

  gl->BindBuffer (GL_ARRAY_BUFFER, gl_sink->vertex_buffer);
  gl->BufferData (GL_ARRAY_BUFFER, 4 * 5 * sizeof (GLfloat), vertices,
      GL_STATIC_DRAW);

  /* Load the vertex position */
  gl->VertexAttribPointer (gl_sink->attr_position, 3, GL_FLOAT, GL_FALSE,
      5 * sizeof (GLfloat), (void *) 0);

  /* Load the texture coordinate */
  gl->VertexAttribPointer (gl_sink->attr_texture, 2, GL_FLOAT, GL_FALSE,
      5 * sizeof (GLfloat), (void *) (3 * sizeof (GLfloat)));

  gl->EnableVertexAttribArray (gl_sink->attr_position);
  gl->EnableVertexAttribArray (gl_sink->attr_texture);
}

static void
_unbind_buffer (GstGLImageSink * gl_sink)
{
  const GstGLFuncs *gl = gl_sink->context->gl_vtable;

  gl->BindBuffer (GL_ARRAY_BUFFER, 0);

  gl->DisableVertexAttribArray (gl_sink->attr_position);
  gl->DisableVertexAttribArray (gl_sink->attr_texture);
}

/* Called in the gl thread */
static void
gst_glimage_sink_thread_init_redisplay (GstGLImageSink * gl_sink)
{
  const GstGLFuncs *gl = gl_sink->context->gl_vtable;

  gl_sink->redisplay_shader = gst_gl_shader_new (gl_sink->context);

  if (!gst_gl_shader_compile_with_default_vf_and_check
      (gl_sink->redisplay_shader, &gl_sink->attr_position,
          &gl_sink->attr_texture))
    gst_glimage_sink_cleanup_glthread (gl_sink);

  if (gl->GenVertexArrays) {
    gl->GenVertexArrays (1, &gl_sink->vao);
    gl->BindVertexArray (gl_sink->vao);
  }

  gl->GenBuffers (1, &gl_sink->vertex_buffer);
  _bind_buffer (gl_sink);

  if (gl->GenVertexArrays) {
    gl->BindVertexArray (0);
    gl->BindBuffer (GL_ARRAY_BUFFER, 0);
  } else {
    _unbind_buffer (gl_sink);
  }
}

static void
gst_glimage_sink_cleanup_glthread (GstGLImageSink * gl_sink)
{
  const GstGLFuncs *gl = gl_sink->context->gl_vtable;

  if (gl_sink->redisplay_shader) {
    gst_object_unref (gl_sink->redisplay_shader);
    gl_sink->redisplay_shader = NULL;
  }

  if (gl_sink->vao) {
    gl->DeleteVertexArrays (1, &gl_sink->vao);
    gl_sink->vao = 0;
  }
}

static void
gst_glimage_sink_on_resize (GstGLImageSink * gl_sink, gint width, gint height)
{
  /* Here gl_sink members (ex:gl_sink->info) have a life time of set_caps.
   * It means that they cannot not change between two set_caps
   */
  const GstGLFuncs *gl = gl_sink->context->gl_vtable;
  gboolean do_reshape;

  GST_TRACE ("GL Window resized to %ux%u", width, height);

  /* check if a client reshape callback is registered */
  g_signal_emit (gl_sink, gst_glimage_sink_signals[CLIENT_RESHAPE_SIGNAL], 0,
      gl_sink->context, width, height, &do_reshape);

  width = MAX (1, width);
  height = MAX (1, height);

  gl_sink->window_width = width;
  gl_sink->window_height = height;

  /* default reshape */
  if (!do_reshape) {
    if (gl_sink->keep_aspect_ratio) {
      GstVideoRectangle src, dst, result;

      src.x = 0;
      src.y = 0;
      src.w = GST_VIDEO_SINK_WIDTH (gl_sink);
      src.h = GST_VIDEO_SINK_HEIGHT (gl_sink);

      dst.x = 0;
      dst.y = 0;
      dst.w = width;
      dst.h = height;

      gst_video_sink_center_rect (src, dst, &result, TRUE);
      gl->Viewport (result.x, result.y, result.w, result.h);
    } else {
      gl->Viewport (0, 0, width, height);
    }
  }
}

static void
gst_glimage_sink_on_draw (GstGLImageSink * gl_sink)
{
  /* Here gl_sink members (ex:gl_sink->info) have a life time of set_caps.
   * It means that they cannot not change between two set_caps as well as
   * for the redisplay_texture size.
   * Whereas redisplay_texture id changes every sink_render
   */

  const GstGLFuncs *gl = NULL;
  GstGLWindow *window = NULL;
  gboolean do_redisplay;
  GstGLSyncMeta *sync_meta;

  g_return_if_fail (GST_IS_GLIMAGE_SINK (gl_sink));

  gl = gl_sink->context->gl_vtable;

  GST_GLIMAGE_SINK_LOCK (gl_sink);

  /* check if texture is ready for being drawn */
  if (!gl_sink->redisplay_texture) {
    GST_GLIMAGE_SINK_UNLOCK (gl_sink);
    return;
  }

  window = gst_gl_context_get_window (gl_sink->context);
  window->is_drawing = TRUE;

  /* opengl scene */
  GST_TRACE ("redrawing texture:%u", gl_sink->redisplay_texture);

  if (gl_sink->caps_change && gl_sink->window_width > 0
      && gl_sink->window_height > 0) {
    GST_GLIMAGE_SINK_UNLOCK (gl_sink);
    gst_glimage_sink_on_resize (gl_sink, gl_sink->window_width,
        gl_sink->window_height);
    GST_GLIMAGE_SINK_LOCK (gl_sink);
    gl_sink->caps_change = FALSE;
  }

  sync_meta = gst_buffer_get_gl_sync_meta (gl_sink->stored_buffer);
  if (sync_meta)
    gst_gl_sync_meta_wait (sync_meta);

  /* make sure that the environnement is clean */
  gst_gl_context_clear_shader (gl_sink->context);

#if GST_GL_HAVE_OPENGL
  if (USING_OPENGL (gl_sink->context))
    gl->Disable (GL_TEXTURE_2D);
#endif

  gl->BindTexture (GL_TEXTURE_2D, 0);

  g_signal_emit (gl_sink, gst_glimage_sink_signals[CLIENT_DRAW_SIGNAL], 0,
      gl_sink->context,
      gl_sink->redisplay_texture, GST_VIDEO_INFO_WIDTH (&gl_sink->info),
      GST_VIDEO_INFO_HEIGHT (&gl_sink->info), &do_redisplay);

  if (!do_redisplay) {
    gfloat alpha = gl_sink->ignore_alpha ? 1.0f : 0.0f;
    GLushort indices[] = { 0, 1, 2, 0, 2, 3 };

    gl->ClearColor (0.0, 0.0, 0.0, alpha);
    gl->Clear (GL_COLOR_BUFFER_BIT);

    if (gl_sink->ignore_alpha) {
      GLenum dst_func =
          gl_sink->ignore_alpha ? GL_CONSTANT_COLOR : GL_ONE_MINUS_SRC_ALPHA;

      gl->BlendColor (0.0, 0.0, 0.0, alpha);
      gl->BlendFunc (GL_SRC_ALPHA, dst_func);
      gl->BlendEquation (GL_FUNC_ADD);
      gl->Enable (GL_BLEND);
    }

    gst_gl_shader_use (gl_sink->redisplay_shader);

    if (gl->GenVertexArrays)
      gl->BindVertexArray (gl_sink->vao);
    else
      _bind_buffer (gl_sink);

    gl->ActiveTexture (GL_TEXTURE0);
    gl->BindTexture (GL_TEXTURE_2D, gl_sink->redisplay_texture);
    gst_gl_shader_set_uniform_1i (gl_sink->redisplay_shader, "tex", 0);

    gl->DrawElements (GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices);

    if (gl->GenVertexArrays)
      gl->BindVertexArray (0);
    else
      _unbind_buffer (gl_sink);

    if (gl_sink->ignore_alpha)
      gl->Disable (GL_BLEND);
  }
  /* end default opengl scene */
  window->is_drawing = FALSE;
  gst_object_unref (window);

  GST_GLIMAGE_SINK_UNLOCK (gl_sink);
}

static void
gst_glimage_sink_on_close (GstGLImageSink * gl_sink)
{
  GstGLWindow *window;

  gst_gl_context_set_error (gl_sink->context, "Output window was closed");

  window = gst_gl_context_get_window (gl_sink->context);

  g_signal_handler_disconnect (window, gl_sink->key_sig_id);
  g_signal_handler_disconnect (window, gl_sink->mouse_sig_id);

  g_atomic_int_set (&gl_sink->to_quit, 1);

  gst_object_unref (window);
}

static gboolean
gst_glimage_sink_redisplay (GstGLImageSink * gl_sink)
{
  GstGLWindow *window;
  gboolean alive;

  window = gst_gl_context_get_window (gl_sink->context);
  if (!window)
    return FALSE;

  if (gst_gl_window_is_running (window)) {
    if (G_UNLIKELY (!gl_sink->redisplay_shader)) {
      gst_gl_window_send_message (window,
          GST_GL_WINDOW_CB (gst_glimage_sink_thread_init_redisplay), gl_sink);

      /* if the shader is still null it means it failed to be useable */
      if (G_UNLIKELY (!gl_sink->redisplay_shader)) {
        gst_object_unref (window);
        return FALSE;
      }

      gst_gl_window_set_preferred_size (window, GST_VIDEO_SINK_WIDTH (gl_sink),
          GST_VIDEO_SINK_HEIGHT (gl_sink));
      gst_gl_window_show (window);
    }

    /* Drawing is asynchronous: gst_gl_window_draw is not blocking
     * It means that it does not wait for stuff to be executed in other threads
     */
    gst_gl_window_draw (window);
  }
  alive = gst_gl_window_is_running (window);
  gst_object_unref (window);

  return alive;
}