faceoverlay: Add element that displays an SVG image over a detected face

Fixes bug #642759.

configure.ac

@@ -310,6 +310,7 @@ AG_GST_CHECK_PLUGIN(debugutils)
 AG_GST_CHECK_PLUGIN(dtmf)
 AG_GST_CHECK_PLUGIN(dvbsuboverlay)
 AG_GST_CHECK_PLUGIN(dvdspu)
+AG_GST_CHECK_PLUGIN(faceoverlay)
 AG_GST_CHECK_PLUGIN(festival)
 AG_GST_CHECK_PLUGIN(fieldanalysis)
 AG_GST_CHECK_PLUGIN(freeze)
@@ -1822,6 +1823,7 @@ gst/debugutils/Makefile
 gst/dtmf/Makefile
 gst/dvbsuboverlay/Makefile
 gst/dvdspu/Makefile
+gst/faceoverlay/Makefile
 gst/festival/Makefile
 gst/fieldanalysis/Makefile
 gst/freeze/Makefile

gst/faceoverlay/Makefile.am

@@ -0,0 +1,13 @@
+plugin_LTLIBRARIES = libgstfaceoverlay.la
+
+# sources used to compile this plug-in
+libgstfaceoverlay_la_SOURCES = gstfaceoverlay.c
+
+# compiler and linker flags used to compile this plugin, set in configure.ac
+libgstfaceoverlay_la_CFLAGS = $(GST_CFLAGS)
+libgstfaceoverlay_la_LIBADD = $(GST_LIBS)
+libgstfaceoverlay_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS)
+libgstfaceoverlay_la_LIBTOOLFLAGS = --tag=disable-static
+
+# headers we need but don't want installed
+noinst_HEADERS = gstfaceoverlay.h

gst/faceoverlay/gstfaceoverlay.c

@@ -0,0 +1,500 @@
+/*
+ * 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., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, 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 autovideosrc ! ffmpegcolorspace ! faceoverlay location=/path/to/gnome-video-effects/pixmaps/bow.svg x=-5 y=-15 w=0.3 h=0.1 ! ffmpegcolorspace ! 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
+
+#if G_BYTE_ORDER == G_LITTLE_ENDIAN
+#define GST_STR_VIDEO_CAPS GST_VIDEO_CAPS_BGRA
+#else
+#define GST_STR_VIDEO_CAPS GST_VIDEO_CAPS_ARGB
+#endif
+
+/* Filter signals and args */
+enum
+{
+  /* FILL ME */
+  LAST_SIGNAL
+};
+
+enum
+{
+  PROP_0,
+  PROP_LOCATION,
+  PROP_X,
+  PROP_Y,
+  PROP_W,
+  PROP_H
+};
+
+/* the capabilities of the inputs and outputs. */
+static GstStaticPadTemplate sink_factory = GST_STATIC_PAD_TEMPLATE ("sink",
+    GST_PAD_SINK,
+    GST_PAD_ALWAYS,
+    GST_STATIC_CAPS (GST_STR_VIDEO_CAPS)
+    );
+
+static GstStaticPadTemplate src_factory = GST_STATIC_PAD_TEMPLATE ("src",
+    GST_PAD_SRC,
+    GST_PAD_ALWAYS,
+    GST_STATIC_CAPS (GST_STR_VIDEO_CAPS)
+    );
+
+GST_BOILERPLATE (GstFaceOverlay, gst_face_overlay, GstBin, 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_reset (GstFaceOverlay * filter);
+static gboolean gst_face_overlay_create_pad (GstFaceOverlay * filter,
+    GstPad * filter_pad, const char *pad_name, GstElement * child_element);
+static gboolean toggle_pads_link_state (GstPad * pad1, GstPad * pad2);
+
+
+static gboolean
+toggle_pads_link_state (GstPad * pad1, GstPad * pad2)
+{
+  gboolean ok = TRUE;
+
+  if (gst_pad_is_linked (pad1)) {
+    if (gst_pad_get_direction (pad1) == GST_PAD_SINK)
+      gst_pad_unlink (pad2, pad1);
+    else
+      gst_pad_unlink (pad1, pad2);
+  } else {
+    if (gst_pad_get_direction (pad1) == GST_PAD_SINK)
+      ok &= (gst_pad_link (pad2, pad1) == 0);
+    else
+      ok &= (gst_pad_link (pad1, pad2) == 0);
+  }
+
+  return ok;
+}
+
+/* Unlinks and removes the pad that was created in gst_face_overlay_init ()
+ * and adds the internal element ghost pad instead  */
+static gboolean
+gst_face_overlay_create_pad (GstFaceOverlay * filter, GstPad * filter_pad,
+    const char *pad_name, GstElement * child_element)
+{
+  GstPad *peer = NULL;
+  GstPad *pad = NULL;
+  gboolean ok = TRUE;
+
+  /* get the outside world pad connected to faceoverlay src/sink pad */
+  peer = gst_pad_get_peer (filter_pad);
+
+  /* unlink and remove the faceoverlay src/sink pad */
+  toggle_pads_link_state (peer, filter_pad);
+
+  gst_element_remove_pad (GST_ELEMENT (filter), filter_pad);
+
+  /* add a ghost pad pointing to the child element pad (facedetect sink or
+   * svg_overlay src depending on filter_pad direction) and add it to
+   * faceoverlay bin */
+  pad = gst_element_get_static_pad (child_element, pad_name);
+  filter_pad = gst_ghost_pad_new (pad_name, pad);
+  gst_object_unref (GST_OBJECT (pad));
+
+  gst_element_add_pad (GST_ELEMENT (filter), filter_pad);
+
+  /* link the child element pad to the outside world thru the ghost pad */
+  toggle_pads_link_state (peer, filter_pad);
+
+  g_object_unref (peer);
+
+  return ok;
+}
+
+static gboolean
+gst_face_overlay_reset (GstFaceOverlay * filter)
+{
+  gst_element_set_state (filter->face_detect, GST_STATE_NULL);
+  gst_bin_remove (GST_BIN (filter), filter->face_detect);
+  filter->face_detect = NULL;
+
+  gst_element_set_state (filter->svg_overlay, GST_STATE_NULL);
+  gst_bin_remove (GST_BIN (filter), filter->svg_overlay);
+  filter->svg_overlay = NULL;
+
+  gst_element_set_state (filter->colorspace, GST_STATE_NULL);
+  gst_bin_remove (GST_BIN (filter), filter->colorspace);
+  filter->colorspace = NULL;
+
+  return TRUE;
+}
+
+static gboolean
+gst_face_overlay_create_children (GstFaceOverlay * filter)
+{
+  gboolean ret = TRUE;
+
+  if ((filter->colorspace = gst_element_factory_make ("ffmpegcolorspace",
+              NULL)) == NULL) {
+    return FALSE;
+  }
+
+  if ((filter->face_detect = gst_element_factory_make ("facedetect",
+              NULL)) == NULL) {
+    return FALSE;
+  }
+  g_object_set (filter->face_detect, "display", 0, NULL);
+
+  if ((filter->svg_overlay = gst_element_factory_make ("rsvgoverlay",
+              NULL)) == NULL) {
+    return FALSE;
+  }
+
+  gst_bin_add_many (GST_BIN (filter),
+      filter->face_detect, filter->colorspace, filter->svg_overlay, NULL);
+
+  ret &= gst_element_link_pads (filter->face_detect, "src",
+      filter->colorspace, "sink");
+  ret &= gst_element_link_pads (filter->colorspace, "src",
+      filter->svg_overlay, "sink");
+
+  ret &= gst_face_overlay_create_pad (filter, filter->sinkpad, "sink",
+      filter->face_detect);
+  ret &= gst_face_overlay_create_pad (filter, filter->srcpad, "src",
+      filter->svg_overlay);
+
+  return ret;
+
+}
+
+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 (!gst_face_overlay_create_children (filter))
+        return GST_STATE_CHANGE_FAILURE;
+      break;
+    default:
+      break;
+  }
+
+  ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
+
+  switch (transition) {
+    case GST_STATE_CHANGE_READY_TO_NULL:
+      gst_face_overlay_reset (filter);
+      break;
+    default:
+      break;
+  }
+
+  return ret;
+}
+
+static void
+gst_face_overlay_message_handler (GstBin * bin, GstMessage * message)
+{
+  if (GST_MESSAGE_TYPE (message) == GST_MESSAGE_ELEMENT &&
+      strcmp (gst_structure_get_name (message->structure), "facedetect") == 0) {
+    GstFaceOverlay *filter = GST_FACEOVERLAY (bin);
+
+    /* optionally draw the image once every two messages for better performance
+     * filter->process_message = !filter->process_message;
+     *  if(!filter->process_message)
+     *    return;
+     */
+
+    guint x, y, width, height;
+    int delta_x, delta_y, svg_x, svg_y, svg_width, svg_height;
+    const GstStructure *face;
+    int face_count;
+
+    face_count =
+        gst_value_list_get_size (gst_structure_get_value (message->structure,
+            "faces"));
+
+    /* 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 =
+        gst_value_get_structure (gst_value_list_get_value
+        (gst_structure_get_value (message->structure, "faces"),
+            face_count - 1));
+    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 */
+
+    delta_x = (int) (filter->x * (int) width);
+    svg_x = (int) x + delta_x;
+
+    delta_y = (int) (filter->y * (int) height);
+    svg_y = (int) y + delta_y;
+
+    svg_width = (int) width *filter->w;
+    svg_height = (int) height *filter->h;
+
+    g_object_set (filter->svg_overlay,
+        "location", filter->location,
+        "x", svg_x, "y", svg_y, "width", svg_width, "height", svg_height, NULL);
+
+  }
+
+  GST_BIN_CLASS (parent_class)->handle_message (bin, message);
+}
+
+/* GObject vmethod implementations */
+/* the _base_init() function is meant to initialize class and child class
+ * properties during each new child class creation */
+static void
+gst_face_overlay_base_init (gpointer gclass)
+{
+  GstElementClass *element_class = GST_ELEMENT_CLASS (gclass);
+
+  gst_element_class_set_details_simple (element_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 (element_class,
+      gst_static_pad_template_get (&src_factory));
+  gst_element_class_add_pad_template (element_class,
+      gst_static_pad_template_get (&sink_factory));
+}
+
+/* initialize the faceoverlay's class */
+/* the _class_init() function is used to initialise the class only once
+ * (specifying what signals, arguments and virtual functions the class has and
+ * setting up global state) */
+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));
+
+  gstbin_class->handle_message =
+      GST_DEBUG_FUNCPTR (gst_face_overlay_message_handler);
+  gstelement_class->change_state =
+      GST_DEBUG_FUNCPTR (gst_face_overlay_change_state);
+
+}
+
+/* initialize the new element
+ * instantiate pads and add them to element
+ * set pad calback functions
+ * initialize instance structure
+ * the _init() function is used to initialise a specific instance of this type.
+ */
+static void
+gst_face_overlay_init (GstFaceOverlay * filter, GstFaceOverlayClass * gclass)
+{
+  filter->x = 0;
+  filter->y = 0;
+  filter->w = 1;
+  filter->h = 1;
+  filter->colorspace = NULL;
+  filter->svg_overlay = NULL;
+  filter->face_detect = NULL;
+  filter->location = NULL;
+  filter->process_message = TRUE;
+
+  filter->sinkpad = gst_pad_new_from_static_template (&sink_factory, "sink");
+  gst_element_add_pad (GST_ELEMENT (filter), filter->sinkpad);
+
+  filter->srcpad = gst_pad_new_from_static_template (&src_factory, "src");
+  gst_element_add_pad (GST_ELEMENT (filter), filter->srcpad);
+
+}
+
+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:
+      filter->location = g_value_dup_string (value);
+      break;
+    case PROP_X:
+      filter->x = g_value_get_float (value);
+      break;
+    case PROP_Y:
+      filter->y = g_value_get_float (value);
+      break;
+    case PROP_W:
+      filter->w = g_value_get_float (value);
+      break;
+    case PROP_H:
+      filter->h = g_value_get_float (value);
+      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:
+      g_value_set_string (value, filter->location);
+      break;
+    case PROP_X:
+      g_value_set_float (value, filter->x);
+      break;
+    case PROP_Y:
+      g_value_set_float (value, filter->y);
+      break;
+    case PROP_W:
+      g_value_set_float (value, filter->w);
+      break;
+    case PROP_H:
+      g_value_set_float (value, filter->h);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+/* entry point to initialize the plug-in
+ * initialize the plug-in itself
+ * register the element factories and other features
+ */
+static gboolean
+faceoverlay_init (GstPlugin * faceoverlay)
+{
+  /* debug category for fltering log messages */
+  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);
+}
+
+/* PACKAGE: this is usually set by autotools depending on some _INIT macro
+ * in configure.ac and then written into and defined in config.h, but we can
+ * just set it ourselves here in case someone doesn't use autotools to
+ * compile this code. GST_PLUGIN_DEFINE needs PACKAGE to be defined.
+ */
+#ifndef PACKAGE
+#define PACKAGE "faceoverlay"
+#endif
+
+/* gstreamer looks for this structure to register plugins */
+GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
+    GST_VERSION_MINOR,
+    "faceoverlay",
+    "SVG Face Overlay",
+    faceoverlay_init, VERSION, "LGPL", "GStreamer", "http://gstreamer.net/")

gst/faceoverlay/gstfaceoverlay.h

@@ -0,0 +1,91 @@
+/*
+ * 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., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifndef __GST_FACEOVERLAY_H__
+#define __GST_FACEOVERLAY_H__
+
+#include <gst/gst.h>
+
+G_BEGIN_DECLS
+/* #defines don't like whitespacey bits */
+#define GST_TYPE_FACEOVERLAY \
+  (gst_face_overlay_get_type())
+#define GST_FACEOVERLAY(obj) \
+  (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_FACEOVERLAY,GstFaceOverlay))
+#define GST_FACEOVERLAY_CLASS(klass) \
+  (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_FACEOVERLAY,GstFaceOverlayClass))
+#define GST_IS_FACEOVERLAY(obj) \
+  (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_FACEOVERLAY))
+#define GST_IS_FACEOVERLAY_CLASS(klass) \
+  (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_FACEOVERLAY))
+typedef struct _GstFaceOverlay GstFaceOverlay;
+typedef struct _GstFaceOverlayClass GstFaceOverlayClass;
+
+struct _GstFaceOverlay
+{
+  GstBin parent;
+
+  GstPad *sinkpad, *srcpad;
+
+  GstElement *face_detect;
+  GstElement *colorspace;
+  GstElement *svg_overlay;
+
+  gboolean process_message;
+
+  gchar *location;
+  gfloat x;
+  gfloat y;
+  gfloat w;
+  gfloat h;
+};
+
+struct _GstFaceOverlayClass
+{
+  GstBinClass parent_class;
+};
+
+GType gst_face_overlay_get_type (void);
+
+G_END_DECLS
+#endif /* __GST_FACEOVERLAY_H__ */