gst/camerabin2/gstdigitalzoom.c - imx-gst-plugins-bad - Git at Google

 /*
  * GStreamer
  * Copyright (C) 2015 Thiago Santos <thiagoss@osg.samsung.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-digitalzoom
  * @title: digitalzoom
  *
  * Does digital zooming by cropping and scaling an image.
  *
  * It is a bin that contains the internal pipeline:
  * videocrop ! videoscale ! capsfilter
  *
  * It keeps monitoring the input caps and when it is set/updated
  * the capsfilter gets set the same caps to guarantee that the same
  * input resolution is provided as output.
  *
  * Exposes the 'zoom' property as a float to allow setting the amount
  * of zoom desired. Zooming is done in the center.
  */

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

 #include <gst/gst-i18n-plugin.h>
 #include "gstdigitalzoom.h"

 enum
 {
   PROP_0,
   PROP_ZOOM
 };

 GST_DEBUG_CATEGORY (digital_zoom_debug);
 #define GST_CAT_DEFAULT digital_zoom_debug

 #define gst_digital_zoom_parent_class parent_class
 G_DEFINE_TYPE (GstDigitalZoom, gst_digital_zoom, GST_TYPE_BIN);

 static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("src",
     GST_PAD_SRC,
     GST_PAD_ALWAYS,
     GST_STATIC_CAPS_ANY);

 static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
     GST_PAD_SINK,
     GST_PAD_ALWAYS,
     GST_STATIC_CAPS_ANY);

 static void
 gst_digital_zoom_update_crop (GstDigitalZoom * self, GstCaps * caps)
 {
   gint w2_crop = 0, h2_crop = 0;
   gint left = 0;
   gint right = 0;
   gint top = 0;
   gint bottom = 0;
   gint width, height;
   gfloat zoom;
   GstStructure *structure;

   if (caps == NULL || gst_caps_is_any (caps)) {
     g_object_set (self->capsfilter, "caps", NULL, NULL);
     return;
   }

   structure = gst_caps_get_structure (caps, 0);
   gst_structure_get (structure, "width", G_TYPE_INT, &width, "height",
       G_TYPE_INT, &height, NULL);

   zoom = self->zoom;

   if (self->videocrop) {
     /* Update capsfilters to apply the zoom */
     GST_INFO_OBJECT (self, "zoom: %f, orig size: %dx%d", zoom, width, height);

     if (zoom != 1.0) {
       w2_crop = (width - (gint) (width * 1.0 / zoom)) / 2;
       h2_crop = (height - (gint) (height * 1.0 / zoom)) / 2;

       left += w2_crop;
       right += w2_crop;
       top += h2_crop;
       bottom += h2_crop;

       /* force number of pixels cropped from left to be even, to avoid slow code
        * path on videoscale */
       left &= 0xFFFE;
     }

     GST_INFO_OBJECT (self,
         "sw cropping: left:%d, right:%d, top:%d, bottom:%d", left, right, top,
         bottom);

     g_object_set (self->videocrop, "left", left, "right", right, "top",
         top, "bottom", bottom, NULL);
   }
 }

 static void
 gst_digital_zoom_update_zoom (GstDigitalZoom * self)
 {
   GstCaps *caps = NULL;

   if (!self->elements_created)
     return;

   g_object_get (self->capsfilter, "caps", &caps, NULL);
   if (caps) {
     gst_digital_zoom_update_crop (self, caps);
     gst_caps_unref (caps);
   }
 }

 static void
 gst_digital_zoom_set_property (GObject * object,
     guint prop_id, const GValue * value, GParamSpec * pspec)
 {
   GstDigitalZoom *self = GST_DIGITAL_ZOOM_CAST (object);

   switch (prop_id) {
     case PROP_ZOOM:
       self->zoom = g_value_get_float (value);
       GST_DEBUG_OBJECT (self, "Setting zoom: %f", self->zoom);
       gst_digital_zoom_update_zoom (self);
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (self, prop_id, pspec);
       break;
   }
 }

 static void
 gst_digital_zoom_get_property (GObject * object,
     guint prop_id, GValue * value, GParamSpec * pspec)
 {
   GstDigitalZoom *self = GST_DIGITAL_ZOOM_CAST (object);

   switch (prop_id) {
     case PROP_ZOOM:
       g_value_set_float (value, self->zoom);
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (self, prop_id, pspec);
       break;
   }
 }

 static gboolean
 gst_digital_zoom_sink_query (GstPad * sink, GstObject * parent,
     GstQuery * query)
 {
   GstDigitalZoom *self = GST_DIGITAL_ZOOM_CAST (parent);
   switch (GST_QUERY_TYPE (query)) {
       /* for caps related queries we want to skip videocrop ! videoscale
        * as the digital zoom preserves input dimensions */
     case GST_QUERY_CAPS:
     case GST_QUERY_ACCEPT_CAPS:
       if (self->elements_created)
         return gst_pad_peer_query (self->srcpad, query);
       /* fall through */
     default:
       return gst_pad_query_default (sink, parent, query);
   }
 }

 static gboolean
 gst_digital_zoom_src_query (GstPad * sink, GstObject * parent, GstQuery * query)
 {
   GstDigitalZoom *self = GST_DIGITAL_ZOOM_CAST (parent);
   switch (GST_QUERY_TYPE (query)) {
       /* for caps related queries we want to skip videocrop ! videoscale
        * as the digital zoom preserves input dimensions */
     case GST_QUERY_CAPS:
     case GST_QUERY_ACCEPT_CAPS:
       if (self->elements_created)
         return gst_pad_peer_query (self->sinkpad, query);
       /* fall through */
     default:
       return gst_pad_query_default (sink, parent, query);
   }
 }

 static gboolean
 gst_digital_zoom_sink_event (GstPad * sink, GstObject * parent,
     GstEvent * event)
 {
   gboolean ret;
   gboolean is_caps;
   GstDigitalZoom *self = GST_DIGITAL_ZOOM_CAST (parent);
   GstCaps *old_caps = NULL;
   GstCaps *caps = NULL;

   is_caps = GST_EVENT_TYPE (event) == GST_EVENT_CAPS;

   if (is_caps) {
     gst_event_parse_caps (event, &caps);
     g_object_get (self->capsfilter, "caps", &old_caps, NULL);
     g_object_set (self->capsfilter, "caps", caps, NULL);
     gst_digital_zoom_update_crop (self, caps);
   }

   ret = gst_pad_event_default (sink, parent, event);

   if (is_caps) {
     if (!ret) {
       gst_digital_zoom_update_crop (self, old_caps);
       g_object_set (self->capsfilter, "caps", old_caps, NULL);
     }

     if (old_caps)
       gst_caps_unref (old_caps);
   }

   return ret;
 }

 static void
 gst_digital_zoom_dispose (GObject * object)
 {
   GstDigitalZoom *self = GST_DIGITAL_ZOOM_CAST (object);

   if (self->capsfilter_sinkpad) {
     gst_object_unref (self->capsfilter_sinkpad);
     self->capsfilter_sinkpad = NULL;
   }

   G_OBJECT_CLASS (parent_class)->dispose (object);
 }

 static void
 gst_digital_zoom_init (GstDigitalZoom * self)
 {
   GstPadTemplate *tmpl;

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

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

   gst_pad_set_event_function (self->sinkpad,
       GST_DEBUG_FUNCPTR (gst_digital_zoom_sink_event));
   gst_pad_set_query_function (self->sinkpad,
       GST_DEBUG_FUNCPTR (gst_digital_zoom_sink_query));

   gst_pad_set_query_function (self->srcpad,
       GST_DEBUG_FUNCPTR (gst_digital_zoom_src_query));

   self->zoom = 1;
 }

 static GstElement *
 zoom_create_element (GstDigitalZoom * self, const gchar * element_name,
     const gchar * name)
 {
   GstElement *element;
   element = gst_element_factory_make (element_name, name);
   if (element == NULL) {
     GST_ELEMENT_ERROR (self, CORE, MISSING_PLUGIN,
         (_("Missing element '%s' - check your GStreamer installation."),
             element_name), (NULL));
   }
   return element;
 }

 static gboolean
 gst_digital_zoom_create_elements (GstDigitalZoom * self)
 {
   GstPad *pad;

   if (self->elements_created)
     return TRUE;

   self->videocrop = zoom_create_element (self, "videocrop", "zoom-videocrop");
   if (self->videocrop == NULL)
     return FALSE;
   if (!gst_bin_add (GST_BIN_CAST (self), self->videocrop))
     return FALSE;

   self->videoscale =
       zoom_create_element (self, "videoscale", "zoom-videoscale");
   if (self->videoscale == NULL)
     return FALSE;
   if (!gst_bin_add (GST_BIN_CAST (self), self->videoscale))
     return FALSE;

   self->capsfilter =
       zoom_create_element (self, "capsfilter", "zoom-capsfilter");
   if (self->capsfilter == NULL)
     return FALSE;
   if (!gst_bin_add (GST_BIN_CAST (self), self->capsfilter))
     return FALSE;

   if (!gst_element_link_pads_full (self->videocrop, "src", self->videoscale,
           "sink", GST_PAD_LINK_CHECK_CAPS))
     return FALSE;
   if (!gst_element_link_pads_full (self->videoscale, "src", self->capsfilter,
           "sink", GST_PAD_LINK_CHECK_CAPS))
     return FALSE;

   pad = gst_element_get_static_pad (self->videocrop, "sink");
   gst_ghost_pad_set_target (GST_GHOST_PAD (self->sinkpad), pad);
   gst_object_unref (pad);

   pad = gst_element_get_static_pad (self->capsfilter, "src");
   gst_ghost_pad_set_target (GST_GHOST_PAD (self->srcpad), pad);
   gst_object_unref (pad);

   self->capsfilter_sinkpad =
       gst_element_get_static_pad (self->capsfilter, "sink");

   self->elements_created = TRUE;
   return TRUE;
 }

 static GstStateChangeReturn
 gst_digital_zoom_change_state (GstElement * element, GstStateChange trans)
 {
   GstDigitalZoom *self = GST_DIGITAL_ZOOM_CAST (element);

   switch (trans) {
     case GST_STATE_CHANGE_NULL_TO_READY:
       if (!gst_digital_zoom_create_elements (self)) {
         return GST_STATE_CHANGE_FAILURE;
       }
       break;
     default:
       break;
   }

   return GST_ELEMENT_CLASS (parent_class)->change_state (element, trans);
 }

 static void
 gst_digital_zoom_class_init (GstDigitalZoomClass * klass)
 {
   GObjectClass *gobject_class;
   GstElementClass *gstelement_class;

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

   gobject_class->dispose = gst_digital_zoom_dispose;
   gobject_class->set_property = gst_digital_zoom_set_property;
   gobject_class->get_property = gst_digital_zoom_get_property;

   /* g_object_class_install_property .... */
   g_object_class_install_property (gobject_class, PROP_ZOOM,
       g_param_spec_float ("zoom", "Zoom",
           "Digital zoom level to be used", 1.0, G_MAXFLOAT, 1.0,
           G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
   gstelement_class->change_state = gst_digital_zoom_change_state;

   GST_DEBUG_CATEGORY_INIT (digital_zoom_debug, "digitalzoom",
       0, "digital zoom");

   gst_element_class_add_static_pad_template (gstelement_class, &sink_template);
   gst_element_class_add_static_pad_template (gstelement_class, &src_template);

   gst_element_class_set_static_metadata (gstelement_class,
       "Digital zoom bin", "Generic/Video",
       "Digital zoom bin", "Thiago Santos <thiagoss@osg.samsung.com>");
 }
	/*
	* GStreamer
	* Copyright (C) 2015 Thiago Santos <thiagoss@osg.samsung.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-digitalzoom
	* @title: digitalzoom
	*
	* Does digital zooming by cropping and scaling an image.
	*
	* It is a bin that contains the internal pipeline:
	* videocrop ! videoscale ! capsfilter
	*
	* It keeps monitoring the input caps and when it is set/updated
	* the capsfilter gets set the same caps to guarantee that the same
	* input resolution is provided as output.
	*
	* Exposes the 'zoom' property as a float to allow setting the amount
	* of zoom desired. Zooming is done in the center.
	*/

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

	#include <gst/gst-i18n-plugin.h>
	#include "gstdigitalzoom.h"

	enum
	{
	PROP_0,
	PROP_ZOOM
	};

	GST_DEBUG_CATEGORY (digital_zoom_debug);
	#define GST_CAT_DEFAULT digital_zoom_debug

	#define gst_digital_zoom_parent_class parent_class
	G_DEFINE_TYPE (GstDigitalZoom, gst_digital_zoom, GST_TYPE_BIN);

	static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("src",
	GST_PAD_SRC,
	GST_PAD_ALWAYS,
	GST_STATIC_CAPS_ANY);

	static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
	GST_PAD_SINK,
	GST_PAD_ALWAYS,
	GST_STATIC_CAPS_ANY);

	static void
	gst_digital_zoom_update_crop (GstDigitalZoom * self, GstCaps * caps)
	{
	gint w2_crop = 0, h2_crop = 0;
	gint left = 0;
	gint right = 0;
	gint top = 0;
	gint bottom = 0;
	gint width, height;
	gfloat zoom;
	GstStructure *structure;

	if (caps == NULL \|\| gst_caps_is_any (caps)) {
	g_object_set (self->capsfilter, "caps", NULL, NULL);
	return;
	}

	structure = gst_caps_get_structure (caps, 0);
	gst_structure_get (structure, "width", G_TYPE_INT, &width, "height",
	G_TYPE_INT, &height, NULL);

	zoom = self->zoom;

	if (self->videocrop) {
	/* Update capsfilters to apply the zoom */
	GST_INFO_OBJECT (self, "zoom: %f, orig size: %dx%d", zoom, width, height);

	if (zoom != 1.0) {
	w2_crop = (width - (gint) (width * 1.0 / zoom)) / 2;
	h2_crop = (height - (gint) (height * 1.0 / zoom)) / 2;

	left += w2_crop;
	right += w2_crop;
	top += h2_crop;
	bottom += h2_crop;

	/* force number of pixels cropped from left to be even, to avoid slow code
	* path on videoscale */
	left &= 0xFFFE;
	}

	GST_INFO_OBJECT (self,
	"sw cropping: left:%d, right:%d, top:%d, bottom:%d", left, right, top,
	bottom);

	g_object_set (self->videocrop, "left", left, "right", right, "top",
	top, "bottom", bottom, NULL);
	}
	}

	static void
	gst_digital_zoom_update_zoom (GstDigitalZoom * self)
	{
	GstCaps *caps = NULL;

	if (!self->elements_created)
	return;

	g_object_get (self->capsfilter, "caps", &caps, NULL);
	if (caps) {
	gst_digital_zoom_update_crop (self, caps);
	gst_caps_unref (caps);
	}
	}

	static void
	gst_digital_zoom_set_property (GObject * object,
	guint prop_id, const GValue * value, GParamSpec * pspec)
	{
	GstDigitalZoom *self = GST_DIGITAL_ZOOM_CAST (object);

	switch (prop_id) {
	case PROP_ZOOM:
	self->zoom = g_value_get_float (value);
	GST_DEBUG_OBJECT (self, "Setting zoom: %f", self->zoom);
	gst_digital_zoom_update_zoom (self);
	break;
	default:
	G_OBJECT_WARN_INVALID_PROPERTY_ID (self, prop_id, pspec);
	break;
	}
	}

	static void
	gst_digital_zoom_get_property (GObject * object,
	guint prop_id, GValue * value, GParamSpec * pspec)
	{
	GstDigitalZoom *self = GST_DIGITAL_ZOOM_CAST (object);

	switch (prop_id) {
	case PROP_ZOOM:
	g_value_set_float (value, self->zoom);
	break;
	default:
	G_OBJECT_WARN_INVALID_PROPERTY_ID (self, prop_id, pspec);
	break;
	}
	}

	static gboolean
	gst_digital_zoom_sink_query (GstPad * sink, GstObject * parent,
	GstQuery * query)
	{
	GstDigitalZoom *self = GST_DIGITAL_ZOOM_CAST (parent);
	switch (GST_QUERY_TYPE (query)) {
	/* for caps related queries we want to skip videocrop ! videoscale
	* as the digital zoom preserves input dimensions */
	case GST_QUERY_CAPS:
	case GST_QUERY_ACCEPT_CAPS:
	if (self->elements_created)
	return gst_pad_peer_query (self->srcpad, query);
	/* fall through */
	default:
	return gst_pad_query_default (sink, parent, query);
	}
	}

	static gboolean
	gst_digital_zoom_src_query (GstPad * sink, GstObject * parent, GstQuery * query)
	{
	GstDigitalZoom *self = GST_DIGITAL_ZOOM_CAST (parent);
	switch (GST_QUERY_TYPE (query)) {
	/* for caps related queries we want to skip videocrop ! videoscale
	* as the digital zoom preserves input dimensions */
	case GST_QUERY_CAPS:
	case GST_QUERY_ACCEPT_CAPS:
	if (self->elements_created)
	return gst_pad_peer_query (self->sinkpad, query);
	/* fall through */
	default:
	return gst_pad_query_default (sink, parent, query);
	}
	}

	static gboolean
	gst_digital_zoom_sink_event (GstPad * sink, GstObject * parent,
	GstEvent * event)
	{
	gboolean ret;
	gboolean is_caps;
	GstDigitalZoom *self = GST_DIGITAL_ZOOM_CAST (parent);
	GstCaps *old_caps = NULL;
	GstCaps *caps = NULL;

	is_caps = GST_EVENT_TYPE (event) == GST_EVENT_CAPS;

	if (is_caps) {
	gst_event_parse_caps (event, &caps);
	g_object_get (self->capsfilter, "caps", &old_caps, NULL);
	g_object_set (self->capsfilter, "caps", caps, NULL);
	gst_digital_zoom_update_crop (self, caps);
	}

	ret = gst_pad_event_default (sink, parent, event);

	if (is_caps) {
	if (!ret) {
	gst_digital_zoom_update_crop (self, old_caps);
	g_object_set (self->capsfilter, "caps", old_caps, NULL);
	}

	if (old_caps)
	gst_caps_unref (old_caps);
	}

	return ret;
	}

	static void
	gst_digital_zoom_dispose (GObject * object)
	{
	GstDigitalZoom *self = GST_DIGITAL_ZOOM_CAST (object);

	if (self->capsfilter_sinkpad) {
	gst_object_unref (self->capsfilter_sinkpad);
	self->capsfilter_sinkpad = NULL;
	}

	G_OBJECT_CLASS (parent_class)->dispose (object);
	}

	static void
	gst_digital_zoom_init (GstDigitalZoom * self)
	{
	GstPadTemplate *tmpl;

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

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

	gst_pad_set_event_function (self->sinkpad,
	GST_DEBUG_FUNCPTR (gst_digital_zoom_sink_event));
	gst_pad_set_query_function (self->sinkpad,
	GST_DEBUG_FUNCPTR (gst_digital_zoom_sink_query));

	gst_pad_set_query_function (self->srcpad,
	GST_DEBUG_FUNCPTR (gst_digital_zoom_src_query));

	self->zoom = 1;
	}

	static GstElement *
	zoom_create_element (GstDigitalZoom * self, const gchar * element_name,
	const gchar * name)
	{
	GstElement *element;
	element = gst_element_factory_make (element_name, name);
	if (element == NULL) {
	GST_ELEMENT_ERROR (self, CORE, MISSING_PLUGIN,
	(_("Missing element '%s' - check your GStreamer installation."),
	element_name), (NULL));
	}
	return element;
	}

	static gboolean
	gst_digital_zoom_create_elements (GstDigitalZoom * self)
	{
	GstPad *pad;

	if (self->elements_created)
	return TRUE;

	self->videocrop = zoom_create_element (self, "videocrop", "zoom-videocrop");
	if (self->videocrop == NULL)
	return FALSE;
	if (!gst_bin_add (GST_BIN_CAST (self), self->videocrop))
	return FALSE;

	self->videoscale =
	zoom_create_element (self, "videoscale", "zoom-videoscale");
	if (self->videoscale == NULL)
	return FALSE;
	if (!gst_bin_add (GST_BIN_CAST (self), self->videoscale))
	return FALSE;

	self->capsfilter =
	zoom_create_element (self, "capsfilter", "zoom-capsfilter");
	if (self->capsfilter == NULL)
	return FALSE;
	if (!gst_bin_add (GST_BIN_CAST (self), self->capsfilter))
	return FALSE;

	if (!gst_element_link_pads_full (self->videocrop, "src", self->videoscale,
	"sink", GST_PAD_LINK_CHECK_CAPS))
	return FALSE;
	if (!gst_element_link_pads_full (self->videoscale, "src", self->capsfilter,
	"sink", GST_PAD_LINK_CHECK_CAPS))
	return FALSE;

	pad = gst_element_get_static_pad (self->videocrop, "sink");
	gst_ghost_pad_set_target (GST_GHOST_PAD (self->sinkpad), pad);
	gst_object_unref (pad);

	pad = gst_element_get_static_pad (self->capsfilter, "src");
	gst_ghost_pad_set_target (GST_GHOST_PAD (self->srcpad), pad);
	gst_object_unref (pad);

	self->capsfilter_sinkpad =
	gst_element_get_static_pad (self->capsfilter, "sink");

	self->elements_created = TRUE;
	return TRUE;
	}

	static GstStateChangeReturn
	gst_digital_zoom_change_state (GstElement * element, GstStateChange trans)
	{
	GstDigitalZoom *self = GST_DIGITAL_ZOOM_CAST (element);

	switch (trans) {
	case GST_STATE_CHANGE_NULL_TO_READY:
	if (!gst_digital_zoom_create_elements (self)) {
	return GST_STATE_CHANGE_FAILURE;
	}
	break;
	default:
	break;
	}

	return GST_ELEMENT_CLASS (parent_class)->change_state (element, trans);
	}

	static void
	gst_digital_zoom_class_init (GstDigitalZoomClass * klass)
	{
	GObjectClass *gobject_class;
	GstElementClass *gstelement_class;

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

	gobject_class->dispose = gst_digital_zoom_dispose;
	gobject_class->set_property = gst_digital_zoom_set_property;
	gobject_class->get_property = gst_digital_zoom_get_property;

	/* g_object_class_install_property .... */
	g_object_class_install_property (gobject_class, PROP_ZOOM,
	g_param_spec_float ("zoom", "Zoom",
	"Digital zoom level to be used", 1.0, G_MAXFLOAT, 1.0,
	G_PARAM_READWRITE \| G_PARAM_STATIC_STRINGS));
	gstelement_class->change_state = gst_digital_zoom_change_state;

	GST_DEBUG_CATEGORY_INIT (digital_zoom_debug, "digitalzoom",
	0, "digital zoom");

	gst_element_class_add_static_pad_template (gstelement_class, &sink_template);
	gst_element_class_add_static_pad_template (gstelement_class, &src_template);

	gst_element_class_set_static_metadata (gstelement_class,
	"Digital zoom bin", "Generic/Video",
	"Digital zoom bin", "Thiago Santos <thiagoss@osg.samsung.com>");
	}