gst/faceoverlay/gstfaceoverlay.c - imx-gst-plugins-bad - Git at Google

 /* GStreamer faceoverlay plugin
  * Copyright (C) 2011 Laura Lucas Alday <lauralucas@gmail.com>
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  * DEALINGS IN THE SOFTWARE.
  *
  * Alternatively, the contents of this file may be used under the
  * GNU Lesser General Public License Version 2.1 (the "LGPL"), in
  * which case the following provisions apply instead of the ones
  * mentioned above:
  *
  * 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-faceoverlay
  *
  * Overlays a SVG image over a detected face in a video stream.
  * x, y, w, and h properties are optional, and change the image position and
  * size relative to the detected face position and size.
  *
  * <refsect2>
  * <title>Example launch line</title>
  * |[
  * gst-launch-1.0 autovideosrc ! videoconvert ! faceoverlay location=/path/to/gnome-video-effects/pixmaps/bow.svg x=0.5 y=0.5 w=0.7 h=0.7 ! videoconvert ! autovideosink
  * ]|
  * </refsect2>
  */

 #ifdef HAVE_CONFIG_H
 #  include <config.h>
 #endif

 #include <gst/gst.h>
 #include <gst/video/video.h>
 #include <string.h>

 #include "gstfaceoverlay.h"

 GST_DEBUG_CATEGORY_STATIC (gst_face_overlay_debug);
 #define GST_CAT_DEFAULT gst_face_overlay_debug

 enum
 {
   PROP_0,
   PROP_LOCATION,
   PROP_X,
   PROP_Y,
   PROP_W,
   PROP_H
 };

 static GstStaticPadTemplate sink_factory = GST_STATIC_PAD_TEMPLATE ("sink",
     GST_PAD_SINK,
     GST_PAD_ALWAYS,
     GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE ("{RGB}")));

 static GstStaticPadTemplate src_factory = GST_STATIC_PAD_TEMPLATE ("src",
     GST_PAD_SRC,
     GST_PAD_ALWAYS,
     GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE ("{BGRA}")));

 #define gst_face_overlay_parent_class parent_class
 G_DEFINE_TYPE (GstFaceOverlay, gst_face_overlay, GST_TYPE_BIN);

 static void gst_face_overlay_set_property (GObject * object, guint prop_id,
     const GValue * value, GParamSpec * pspec);
 static void gst_face_overlay_get_property (GObject * object, guint prop_id,
     GValue * value, GParamSpec * pspec);
 static void gst_face_overlay_message_handler (GstBin * bin,
     GstMessage * message);
 static GstStateChangeReturn gst_face_overlay_change_state (GstElement * element,
     GstStateChange transition);
 static gboolean gst_face_overlay_create_children (GstFaceOverlay * filter);

 static gboolean
 gst_face_overlay_create_children (GstFaceOverlay * filter)
 {
   GstElement *csp, *face_detect, *overlay;
   GstPad *pad;

   csp = gst_element_factory_make ("videoconvert", NULL);
   face_detect = gst_element_factory_make ("facedetect", NULL);
   overlay = gst_element_factory_make ("rsvgoverlay", NULL);

   /* FIXME: post missing-plugin messages on NULL->READY if needed */
   if (csp == NULL || face_detect == NULL || overlay == NULL)
     goto missing_element;

   g_object_set (face_detect, "display", FALSE, NULL);

   gst_bin_add_many (GST_BIN (filter), face_detect, csp, overlay, NULL);
   filter->svg_overlay = overlay;

   if (!gst_element_link_many (face_detect, csp, overlay, NULL))
     GST_ERROR_OBJECT (filter, "couldn't link elements");

   pad = gst_element_get_static_pad (face_detect, "sink");
   if (!gst_ghost_pad_set_target (GST_GHOST_PAD (filter->sinkpad), pad))
     GST_ERROR_OBJECT (filter->sinkpad, "couldn't set sinkpad target");
   gst_object_unref (pad);

   pad = gst_element_get_static_pad (overlay, "src");
   if (!gst_ghost_pad_set_target (GST_GHOST_PAD (filter->srcpad), pad))
     GST_ERROR_OBJECT (filter->srcpad, "couldn't set srcpad target");
   gst_object_unref (pad);

   return TRUE;

 /* ERRORS */
 missing_element:
   {
     /* clean up */
     if (csp == NULL)
       GST_ERROR_OBJECT (filter, "videoconvert element not found");
     else
       gst_object_unref (csp);

     if (face_detect == NULL)
       GST_ERROR_OBJECT (filter, "facedetect element not found (opencv plugin)");
     else
       gst_object_unref (face_detect);

     if (overlay == NULL)
       GST_ERROR_OBJECT (filter, "rsvgoverlay element not found (rsvg plugin)");
     else
       gst_object_unref (overlay);

     return FALSE;
   }
 }

 static GstStateChangeReturn
 gst_face_overlay_change_state (GstElement * element, GstStateChange transition)
 {
   GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
   GstFaceOverlay *filter = GST_FACEOVERLAY (element);

   switch (transition) {
     case GST_STATE_CHANGE_NULL_TO_READY:
       if (filter->svg_overlay == NULL) {
         GST_ELEMENT_ERROR (filter, CORE, MISSING_PLUGIN, (NULL),
             ("Some required plugins are missing, probably either the opencv "
                 "facedetect element or rsvgoverlay"));
         return GST_STATE_CHANGE_FAILURE;
       }
       filter->update_svg = TRUE;
       break;
     default:
       break;
   }

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

   switch (transition) {
     default:
       break;
   }

   return ret;
 }

 static void
 gst_face_overlay_handle_faces (GstFaceOverlay * filter, const GstStructure * s)
 {
   guint x, y, width, height;
   gint svg_x, svg_y, svg_width, svg_height;
   const GstStructure *face;
   const GValue *faces_list, *face_val;
   gchar *new_location = NULL;
   gint face_count;

 #if 0
   /* optionally draw the image once every two messages for better performance */
   filter->process_message = !filter->process_message;
   if (!filter->process_message)
     return;
 #endif

   faces_list = gst_structure_get_value (s, "faces");
   face_count = gst_value_list_get_size (faces_list);
   GST_LOG_OBJECT (filter, "face count: %d", face_count);

   if (face_count == 0) {
     GST_DEBUG_OBJECT (filter, "no face, clearing overlay");
     g_object_set (filter->svg_overlay, "location", NULL, NULL);
     GST_OBJECT_LOCK (filter);
     filter->update_svg = TRUE;
     GST_OBJECT_UNLOCK (filter);
     return;
   }

   /* The last face in the list seems to be the right one, objects mistakenly
    * detected as faces for a couple of frames seem to be in the list
    * beginning. TODO: needs confirmation. */
   face_val = gst_value_list_get_value (faces_list, face_count - 1);
   face = gst_value_get_structure (face_val);
   gst_structure_get_uint (face, "x", &x);
   gst_structure_get_uint (face, "y", &y);
   gst_structure_get_uint (face, "width", &width);
   gst_structure_get_uint (face, "height", &height);

   /* Apply x and y offsets relative to face position and size.
    * Set image width and height as a fraction of face width and height.
    * Cast to int since face position and size will never be bigger than
    * G_MAX_INT and we may have negative values as svg_x or svg_y */

   GST_OBJECT_LOCK (filter);

   svg_x = (gint) x + (gint) (filter->x * width);
   svg_y = (gint) y + (gint) (filter->y * height);

   svg_width = (gint) (filter->w * width);
   svg_height = (gint) (filter->h * height);

   if (filter->update_svg) {
     new_location = g_strdup (filter->location);
     filter->update_svg = FALSE;
   }
   GST_OBJECT_UNLOCK (filter);

   if (new_location != NULL) {
     GST_DEBUG_OBJECT (filter, "set rsvgoverlay location=%s", new_location);
     g_object_set (filter->svg_overlay, "location", new_location, NULL);
     g_free (new_location);
   }

   GST_LOG_OBJECT (filter, "overlay dimensions: %d x %d @ %d,%d",
       svg_width, svg_height, svg_x, svg_y);

   g_object_set (filter->svg_overlay,
       "x", svg_x, "y", svg_y, "width", svg_width, "height", svg_height, NULL);
 }

 static void
 gst_face_overlay_message_handler (GstBin * bin, GstMessage * message)
 {
   if (GST_MESSAGE_TYPE (message) == GST_MESSAGE_ELEMENT) {
     const GstStructure *s = gst_message_get_structure (message);

     if (gst_structure_has_name (s, "facedetect")) {
       gst_face_overlay_handle_faces (GST_FACEOVERLAY (bin), s);
     }
   }

   GST_BIN_CLASS (parent_class)->handle_message (bin, message);
 }

 static void
 gst_face_overlay_class_init (GstFaceOverlayClass * klass)
 {
   GObjectClass *gobject_class;
   GstBinClass *gstbin_class;
   GstElementClass *gstelement_class;

   gobject_class = G_OBJECT_CLASS (klass);
   gstbin_class = GST_BIN_CLASS (klass);
   gstelement_class = GST_ELEMENT_CLASS (klass);

   gobject_class->set_property = gst_face_overlay_set_property;
   gobject_class->get_property = gst_face_overlay_get_property;

   g_object_class_install_property (gobject_class, PROP_LOCATION,
       g_param_spec_string ("location", "Location",
           "Location of SVG file to use for face overlay",
           "", G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
   g_object_class_install_property (G_OBJECT_CLASS (klass), PROP_X,
       g_param_spec_float ("x", "face x offset",
           "Specify image x relative to detected face x.", -G_MAXFLOAT,
           G_MAXFLOAT, 0, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
   g_object_class_install_property (G_OBJECT_CLASS (klass), PROP_Y,
       g_param_spec_float ("y", "face y offset",
           "Specify image y relative to detected face y.", -G_MAXFLOAT,
           G_MAXFLOAT, 0, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
   g_object_class_install_property (G_OBJECT_CLASS (klass), PROP_W,
       g_param_spec_float ("w", "face width percent",
           "Specify image width relative to face width.", 0, G_MAXFLOAT, 1,
           G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
   g_object_class_install_property (G_OBJECT_CLASS (klass), PROP_H,
       g_param_spec_float ("h", "face height percent",
           "Specify image height relative to face height.", 0, G_MAXFLOAT, 1,
           G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

   gst_element_class_set_static_metadata (gstelement_class,
       "faceoverlay",
       "Filter/Editor/Video",
       "Overlays SVG graphics over a detected face in a video stream",
       "Laura Lucas Alday <lauralucas@gmail.com>");

   gst_element_class_add_pad_template (gstelement_class,
       gst_static_pad_template_get (&src_factory));
   gst_element_class_add_pad_template (gstelement_class,
       gst_static_pad_template_get (&sink_factory));

   gstbin_class->handle_message =
       GST_DEBUG_FUNCPTR (gst_face_overlay_message_handler);
   gstelement_class->change_state =
       GST_DEBUG_FUNCPTR (gst_face_overlay_change_state);
 }

 static void
 gst_face_overlay_init (GstFaceOverlay * filter)
 {
   GstPadTemplate *tmpl;

   filter->x = 0;
   filter->y = 0;
   filter->w = 1;
   filter->h = 1;
   filter->svg_overlay = NULL;
   filter->location = NULL;
   filter->process_message = TRUE;

   tmpl = gst_static_pad_template_get (&sink_factory);
   filter->sinkpad = gst_ghost_pad_new_no_target_from_template ("sink", tmpl);
   gst_object_unref (tmpl);
   gst_element_add_pad (GST_ELEMENT (filter), filter->sinkpad);

   tmpl = gst_static_pad_template_get (&src_factory);
   filter->srcpad = gst_ghost_pad_new_no_target_from_template ("src", tmpl);
   gst_object_unref (tmpl);
   gst_element_add_pad (GST_ELEMENT (filter), filter->srcpad);

   gst_face_overlay_create_children (filter);
 }

 static void
 gst_face_overlay_set_property (GObject * object, guint prop_id,
     const GValue * value, GParamSpec * pspec)
 {
   GstFaceOverlay *filter = GST_FACEOVERLAY (object);

   switch (prop_id) {
     case PROP_LOCATION:
       GST_OBJECT_LOCK (filter);
       g_free (filter->location);
       filter->location = g_value_dup_string (value);
       filter->update_svg = TRUE;
       GST_OBJECT_UNLOCK (filter);
       break;
     case PROP_X:
       GST_OBJECT_LOCK (filter);
       filter->x = g_value_get_float (value);
       GST_OBJECT_UNLOCK (filter);
       break;
     case PROP_Y:
       GST_OBJECT_LOCK (filter);
       filter->y = g_value_get_float (value);
       GST_OBJECT_UNLOCK (filter);
       break;
     case PROP_W:
       GST_OBJECT_LOCK (filter);
       filter->w = g_value_get_float (value);
       GST_OBJECT_UNLOCK (filter);
       break;
     case PROP_H:
       GST_OBJECT_LOCK (filter);
       filter->h = g_value_get_float (value);
       GST_OBJECT_UNLOCK (filter);
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
   }
 }

 static void
 gst_face_overlay_get_property (GObject * object, guint prop_id,
     GValue * value, GParamSpec * pspec)
 {
   GstFaceOverlay *filter = GST_FACEOVERLAY (object);

   switch (prop_id) {
     case PROP_LOCATION:
       GST_OBJECT_LOCK (filter);
       g_value_set_string (value, filter->location);
       GST_OBJECT_UNLOCK (filter);
       break;
     case PROP_X:
       GST_OBJECT_LOCK (filter);
       g_value_set_float (value, filter->x);
       GST_OBJECT_UNLOCK (filter);
       break;
     case PROP_Y:
       GST_OBJECT_LOCK (filter);
       g_value_set_float (value, filter->y);
       GST_OBJECT_UNLOCK (filter);
       break;
     case PROP_W:
       GST_OBJECT_LOCK (filter);
       g_value_set_float (value, filter->w);
       GST_OBJECT_UNLOCK (filter);
       break;
     case PROP_H:
       GST_OBJECT_LOCK (filter);
       g_value_set_float (value, filter->h);
       GST_OBJECT_UNLOCK (filter);
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
   }
 }

 static gboolean
 faceoverlay_init (GstPlugin * faceoverlay)
 {
   GST_DEBUG_CATEGORY_INIT (gst_face_overlay_debug, "faceoverlay",
       0, "SVG Face Overlay");

   return gst_element_register (faceoverlay, "faceoverlay", GST_RANK_NONE,
       GST_TYPE_FACEOVERLAY);
 }

 GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
     GST_VERSION_MINOR,
     faceoverlay,
     "SVG Face Overlay",
     faceoverlay_init, VERSION, "LGPL", GST_PACKAGE_NAME, GST_PACKAGE_ORIGIN)
	/* GStreamer faceoverlay plugin
	* Copyright (C) 2011 Laura Lucas Alday <lauralucas@gmail.com>
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the "Software"),
	* to deal in the Software without restriction, including without limitation
	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	* and/or sell copies of the Software, and to permit persons to whom the
	* Software is furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
	* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
	* DEALINGS IN THE SOFTWARE.
	*
	* Alternatively, the contents of this file may be used under the
	* GNU Lesser General Public License Version 2.1 (the "LGPL"), in
	* which case the following provisions apply instead of the ones
	* mentioned above:
	*
	* 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-faceoverlay
	*
	* Overlays a SVG image over a detected face in a video stream.
	* x, y, w, and h properties are optional, and change the image position and
	* size relative to the detected face position and size.
	*
	* <refsect2>
	* <title>Example launch line</title>
	* \|[
	* gst-launch-1.0 autovideosrc ! videoconvert ! faceoverlay location=/path/to/gnome-video-effects/pixmaps/bow.svg x=0.5 y=0.5 w=0.7 h=0.7 ! videoconvert ! autovideosink
	* ]\|
	* </refsect2>
	*/

	#ifdef HAVE_CONFIG_H
	# include <config.h>
	#endif

	#include <gst/gst.h>
	#include <gst/video/video.h>
	#include <string.h>

	#include "gstfaceoverlay.h"

	GST_DEBUG_CATEGORY_STATIC (gst_face_overlay_debug);
	#define GST_CAT_DEFAULT gst_face_overlay_debug

	enum
	{
	PROP_0,
	PROP_LOCATION,
	PROP_X,
	PROP_Y,
	PROP_W,
	PROP_H
	};

	static GstStaticPadTemplate sink_factory = GST_STATIC_PAD_TEMPLATE ("sink",
	GST_PAD_SINK,
	GST_PAD_ALWAYS,
	GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE ("{RGB}")));

	static GstStaticPadTemplate src_factory = GST_STATIC_PAD_TEMPLATE ("src",
	GST_PAD_SRC,
	GST_PAD_ALWAYS,
	GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE ("{BGRA}")));

	#define gst_face_overlay_parent_class parent_class
	G_DEFINE_TYPE (GstFaceOverlay, gst_face_overlay, GST_TYPE_BIN);

	static void gst_face_overlay_set_property (GObject * object, guint prop_id,
	const GValue * value, GParamSpec * pspec);
	static void gst_face_overlay_get_property (GObject * object, guint prop_id,
	GValue * value, GParamSpec * pspec);
	static void gst_face_overlay_message_handler (GstBin * bin,
	GstMessage * message);
	static GstStateChangeReturn gst_face_overlay_change_state (GstElement * element,
	GstStateChange transition);
	static gboolean gst_face_overlay_create_children (GstFaceOverlay * filter);

	static gboolean
	gst_face_overlay_create_children (GstFaceOverlay * filter)
	{
	GstElement csp, face_detect, *overlay;
	GstPad *pad;

	csp = gst_element_factory_make ("videoconvert", NULL);
	face_detect = gst_element_factory_make ("facedetect", NULL);
	overlay = gst_element_factory_make ("rsvgoverlay", NULL);

	/* FIXME: post missing-plugin messages on NULL->READY if needed */
	if (csp == NULL \|\| face_detect == NULL \|\| overlay == NULL)
	goto missing_element;

	g_object_set (face_detect, "display", FALSE, NULL);

	gst_bin_add_many (GST_BIN (filter), face_detect, csp, overlay, NULL);
	filter->svg_overlay = overlay;

	if (!gst_element_link_many (face_detect, csp, overlay, NULL))
	GST_ERROR_OBJECT (filter, "couldn't link elements");

	pad = gst_element_get_static_pad (face_detect, "sink");
	if (!gst_ghost_pad_set_target (GST_GHOST_PAD (filter->sinkpad), pad))
	GST_ERROR_OBJECT (filter->sinkpad, "couldn't set sinkpad target");
	gst_object_unref (pad);

	pad = gst_element_get_static_pad (overlay, "src");
	if (!gst_ghost_pad_set_target (GST_GHOST_PAD (filter->srcpad), pad))
	GST_ERROR_OBJECT (filter->srcpad, "couldn't set srcpad target");
	gst_object_unref (pad);

	return TRUE;

	/* ERRORS */
	missing_element:
	{
	/* clean up */
	if (csp == NULL)
	GST_ERROR_OBJECT (filter, "videoconvert element not found");
	else
	gst_object_unref (csp);

	if (face_detect == NULL)
	GST_ERROR_OBJECT (filter, "facedetect element not found (opencv plugin)");
	else
	gst_object_unref (face_detect);

	if (overlay == NULL)
	GST_ERROR_OBJECT (filter, "rsvgoverlay element not found (rsvg plugin)");
	else
	gst_object_unref (overlay);

	return FALSE;
	}
	}

	static GstStateChangeReturn
	gst_face_overlay_change_state (GstElement * element, GstStateChange transition)
	{
	GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
	GstFaceOverlay *filter = GST_FACEOVERLAY (element);

	switch (transition) {
	case GST_STATE_CHANGE_NULL_TO_READY:
	if (filter->svg_overlay == NULL) {
	GST_ELEMENT_ERROR (filter, CORE, MISSING_PLUGIN, (NULL),
	("Some required plugins are missing, probably either the opencv "
	"facedetect element or rsvgoverlay"));
	return GST_STATE_CHANGE_FAILURE;
	}
	filter->update_svg = TRUE;
	break;
	default:
	break;
	}

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

	switch (transition) {
	default:
	break;
	}

	return ret;
	}

	static void
	gst_face_overlay_handle_faces (GstFaceOverlay * filter, const GstStructure * s)
	{
	guint x, y, width, height;
	gint svg_x, svg_y, svg_width, svg_height;
	const GstStructure *face;
	const GValue faces_list, face_val;
	gchar *new_location = NULL;
	gint face_count;

	#if 0
	/* optionally draw the image once every two messages for better performance */
	filter->process_message = !filter->process_message;
	if (!filter->process_message)
	return;
	#endif

	faces_list = gst_structure_get_value (s, "faces");
	face_count = gst_value_list_get_size (faces_list);
	GST_LOG_OBJECT (filter, "face count: %d", face_count);

	if (face_count == 0) {
	GST_DEBUG_OBJECT (filter, "no face, clearing overlay");
	g_object_set (filter->svg_overlay, "location", NULL, NULL);
	GST_OBJECT_LOCK (filter);
	filter->update_svg = TRUE;
	GST_OBJECT_UNLOCK (filter);
	return;
	}

	/* The last face in the list seems to be the right one, objects mistakenly
	* detected as faces for a couple of frames seem to be in the list
	* beginning. TODO: needs confirmation. */
	face_val = gst_value_list_get_value (faces_list, face_count - 1);
	face = gst_value_get_structure (face_val);
	gst_structure_get_uint (face, "x", &x);
	gst_structure_get_uint (face, "y", &y);
	gst_structure_get_uint (face, "width", &width);
	gst_structure_get_uint (face, "height", &height);

	/* Apply x and y offsets relative to face position and size.
	* Set image width and height as a fraction of face width and height.
	* Cast to int since face position and size will never be bigger than
	* G_MAX_INT and we may have negative values as svg_x or svg_y */

	GST_OBJECT_LOCK (filter);

	svg_x = (gint) x + (gint) (filter->x * width);
	svg_y = (gint) y + (gint) (filter->y * height);

	svg_width = (gint) (filter->w * width);
	svg_height = (gint) (filter->h * height);

	if (filter->update_svg) {
	new_location = g_strdup (filter->location);
	filter->update_svg = FALSE;
	}
	GST_OBJECT_UNLOCK (filter);

	if (new_location != NULL) {
	GST_DEBUG_OBJECT (filter, "set rsvgoverlay location=%s", new_location);
	g_object_set (filter->svg_overlay, "location", new_location, NULL);
	g_free (new_location);
	}

	GST_LOG_OBJECT (filter, "overlay dimensions: %d x %d @ %d,%d",
	svg_width, svg_height, svg_x, svg_y);

	g_object_set (filter->svg_overlay,
	"x", svg_x, "y", svg_y, "width", svg_width, "height", svg_height, NULL);
	}

	static void
	gst_face_overlay_message_handler (GstBin * bin, GstMessage * message)
	{
	if (GST_MESSAGE_TYPE (message) == GST_MESSAGE_ELEMENT) {
	const GstStructure *s = gst_message_get_structure (message);

	if (gst_structure_has_name (s, "facedetect")) {
	gst_face_overlay_handle_faces (GST_FACEOVERLAY (bin), s);
	}
	}

	GST_BIN_CLASS (parent_class)->handle_message (bin, message);
	}

	static void
	gst_face_overlay_class_init (GstFaceOverlayClass * klass)
	{
	GObjectClass *gobject_class;
	GstBinClass *gstbin_class;
	GstElementClass *gstelement_class;

	gobject_class = G_OBJECT_CLASS (klass);
	gstbin_class = GST_BIN_CLASS (klass);
	gstelement_class = GST_ELEMENT_CLASS (klass);

	gobject_class->set_property = gst_face_overlay_set_property;
	gobject_class->get_property = gst_face_overlay_get_property;

	g_object_class_install_property (gobject_class, PROP_LOCATION,
	g_param_spec_string ("location", "Location",
	"Location of SVG file to use for face overlay",
	"", G_PARAM_READWRITE \| G_PARAM_STATIC_STRINGS));
	g_object_class_install_property (G_OBJECT_CLASS (klass), PROP_X,
	g_param_spec_float ("x", "face x offset",
	"Specify image x relative to detected face x.", -G_MAXFLOAT,
	G_MAXFLOAT, 0, G_PARAM_READWRITE \| G_PARAM_STATIC_STRINGS));
	g_object_class_install_property (G_OBJECT_CLASS (klass), PROP_Y,
	g_param_spec_float ("y", "face y offset",
	"Specify image y relative to detected face y.", -G_MAXFLOAT,
	G_MAXFLOAT, 0, G_PARAM_READWRITE \| G_PARAM_STATIC_STRINGS));
	g_object_class_install_property (G_OBJECT_CLASS (klass), PROP_W,
	g_param_spec_float ("w", "face width percent",
	"Specify image width relative to face width.", 0, G_MAXFLOAT, 1,
	G_PARAM_READWRITE \| G_PARAM_STATIC_STRINGS));
	g_object_class_install_property (G_OBJECT_CLASS (klass), PROP_H,
	g_param_spec_float ("h", "face height percent",
	"Specify image height relative to face height.", 0, G_MAXFLOAT, 1,
	G_PARAM_READWRITE \| G_PARAM_STATIC_STRINGS));

	gst_element_class_set_static_metadata (gstelement_class,
	"faceoverlay",
	"Filter/Editor/Video",
	"Overlays SVG graphics over a detected face in a video stream",
	"Laura Lucas Alday <lauralucas@gmail.com>");

	gst_element_class_add_pad_template (gstelement_class,
	gst_static_pad_template_get (&src_factory));
	gst_element_class_add_pad_template (gstelement_class,
	gst_static_pad_template_get (&sink_factory));

	gstbin_class->handle_message =
	GST_DEBUG_FUNCPTR (gst_face_overlay_message_handler);
	gstelement_class->change_state =
	GST_DEBUG_FUNCPTR (gst_face_overlay_change_state);
	}

	static void
	gst_face_overlay_init (GstFaceOverlay * filter)
	{
	GstPadTemplate *tmpl;

	filter->x = 0;
	filter->y = 0;
	filter->w = 1;
	filter->h = 1;
	filter->svg_overlay = NULL;
	filter->location = NULL;
	filter->process_message = TRUE;

	tmpl = gst_static_pad_template_get (&sink_factory);
	filter->sinkpad = gst_ghost_pad_new_no_target_from_template ("sink", tmpl);
	gst_object_unref (tmpl);
	gst_element_add_pad (GST_ELEMENT (filter), filter->sinkpad);

	tmpl = gst_static_pad_template_get (&src_factory);
	filter->srcpad = gst_ghost_pad_new_no_target_from_template ("src", tmpl);
	gst_object_unref (tmpl);
	gst_element_add_pad (GST_ELEMENT (filter), filter->srcpad);

	gst_face_overlay_create_children (filter);
	}

	static void
	gst_face_overlay_set_property (GObject * object, guint prop_id,
	const GValue * value, GParamSpec * pspec)
	{
	GstFaceOverlay *filter = GST_FACEOVERLAY (object);

	switch (prop_id) {
	case PROP_LOCATION:
	GST_OBJECT_LOCK (filter);
	g_free (filter->location);
	filter->location = g_value_dup_string (value);
	filter->update_svg = TRUE;
	GST_OBJECT_UNLOCK (filter);
	break;
	case PROP_X:
	GST_OBJECT_LOCK (filter);
	filter->x = g_value_get_float (value);
	GST_OBJECT_UNLOCK (filter);
	break;
	case PROP_Y:
	GST_OBJECT_LOCK (filter);
	filter->y = g_value_get_float (value);
	GST_OBJECT_UNLOCK (filter);
	break;
	case PROP_W:
	GST_OBJECT_LOCK (filter);
	filter->w = g_value_get_float (value);
	GST_OBJECT_UNLOCK (filter);
	break;
	case PROP_H:
	GST_OBJECT_LOCK (filter);
	filter->h = g_value_get_float (value);
	GST_OBJECT_UNLOCK (filter);
	break;
	default:
	G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
	break;
	}
	}

	static void
	gst_face_overlay_get_property (GObject * object, guint prop_id,
	GValue * value, GParamSpec * pspec)
	{
	GstFaceOverlay *filter = GST_FACEOVERLAY (object);

	switch (prop_id) {
	case PROP_LOCATION:
	GST_OBJECT_LOCK (filter);
	g_value_set_string (value, filter->location);
	GST_OBJECT_UNLOCK (filter);
	break;
	case PROP_X:
	GST_OBJECT_LOCK (filter);
	g_value_set_float (value, filter->x);
	GST_OBJECT_UNLOCK (filter);
	break;
	case PROP_Y:
	GST_OBJECT_LOCK (filter);
	g_value_set_float (value, filter->y);
	GST_OBJECT_UNLOCK (filter);
	break;
	case PROP_W:
	GST_OBJECT_LOCK (filter);
	g_value_set_float (value, filter->w);
	GST_OBJECT_UNLOCK (filter);
	break;
	case PROP_H:
	GST_OBJECT_LOCK (filter);
	g_value_set_float (value, filter->h);
	GST_OBJECT_UNLOCK (filter);
	break;
	default:
	G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
	break;
	}
	}

	static gboolean
	faceoverlay_init (GstPlugin * faceoverlay)
	{
	GST_DEBUG_CATEGORY_INIT (gst_face_overlay_debug, "faceoverlay",
	0, "SVG Face Overlay");

	return gst_element_register (faceoverlay, "faceoverlay", GST_RANK_NONE,
	GST_TYPE_FACEOVERLAY);
	}

	GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
	GST_VERSION_MINOR,
	faceoverlay,
	"SVG Face Overlay",
	faceoverlay_init, VERSION, "LGPL", GST_PACKAGE_NAME, GST_PACKAGE_ORIGIN)