gst/gdp/gstgdpdepay.c - imx-gst-plugins-bad - Git at Google

 /* GStreamer
  * Copyright (C) 2006 Thomas Vander Stichele <thomas at apestaart dot org>
  *
  * 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-gdpdepay
  * @see_also: gdppay
  *
  * This element depayloads GStreamer Data Protocol buffers back to deserialized
  * buffers and events.
  *
  * <refsect2>
  * |[
  * gst-launch -v -m filesrc location=test.gdp ! gdpdepay ! xvimagesink
  * ]| This pipeline plays back a serialized video stream as created in the
  * example for gdppay.
  * </refsect2>
  */

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

 #include <string.h>

 #include "dataprotocol.h"

 #include "gstgdpdepay.h"

 enum
 {
   PROP_0,
 };

 static GstStaticPadTemplate gdp_depay_sink_template =
 GST_STATIC_PAD_TEMPLATE ("sink",
     GST_PAD_SINK,
     GST_PAD_ALWAYS,
     GST_STATIC_CAPS ("application/x-gdp"));

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

 GST_DEBUG_CATEGORY_STATIC (gst_gdp_depay_debug);
 #define GST_CAT_DEFAULT gst_gdp_depay_debug

 #define _do_init \
     GST_DEBUG_CATEGORY_INIT (gst_gdp_depay_debug, "gdpdepay", 0, \
     "GDP depayloader");
 #define gst_gdp_depay_parent_class parent_class
 G_DEFINE_TYPE_WITH_CODE (GstGDPDepay, gst_gdp_depay,
     GST_TYPE_ELEMENT, _do_init);

 static gboolean gst_gdp_depay_sink_event (GstPad * pad, GstObject * parent,
     GstEvent * event);
 static gboolean gst_gdp_depay_src_event (GstPad * pad, GstObject * parent,
     GstEvent * event);

 static GstFlowReturn gst_gdp_depay_chain (GstPad * pad, GstObject * parent,
     GstBuffer * buffer);

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

 static void gst_gdp_depay_finalize (GObject * object);

 static void
 gst_gdp_depay_class_init (GstGDPDepayClass * klass)
 {
   GObjectClass *gobject_class;
   GstElementClass *gstelement_class;

   gobject_class = (GObjectClass *) klass;
   gstelement_class = (GstElementClass *) klass;

   gst_element_class_set_static_metadata (gstelement_class,
       "GDP Depayloader", "GDP/Depayloader",
       "Depayloads GStreamer Data Protocol buffers",
       "Thomas Vander Stichele <thomas at apestaart dot org>");

   gst_element_class_add_pad_template (gstelement_class,
       gst_static_pad_template_get (&gdp_depay_sink_template));
   gst_element_class_add_pad_template (gstelement_class,
       gst_static_pad_template_get (&gdp_depay_src_template));

   gstelement_class->change_state =
       GST_DEBUG_FUNCPTR (gst_gdp_depay_change_state);
   gobject_class->finalize = gst_gdp_depay_finalize;
 }

 static void
 gst_gdp_depay_init (GstGDPDepay * gdpdepay)
 {
   gdpdepay->sinkpad =
       gst_pad_new_from_static_template (&gdp_depay_sink_template, "sink");
   gst_pad_set_chain_function (gdpdepay->sinkpad,
       GST_DEBUG_FUNCPTR (gst_gdp_depay_chain));
   gst_pad_set_event_function (gdpdepay->sinkpad,
       GST_DEBUG_FUNCPTR (gst_gdp_depay_sink_event));
   gst_element_add_pad (GST_ELEMENT (gdpdepay), gdpdepay->sinkpad);

   gdpdepay->srcpad =
       gst_pad_new_from_static_template (&gdp_depay_src_template, "src");
   gst_pad_set_event_function (gdpdepay->srcpad,
       GST_DEBUG_FUNCPTR (gst_gdp_depay_src_event));
   /* our caps will always be decided by the incoming GDP caps buffers */
   gst_pad_use_fixed_caps (gdpdepay->srcpad);
   gst_element_add_pad (GST_ELEMENT (gdpdepay), gdpdepay->srcpad);

   gdpdepay->adapter = gst_adapter_new ();
 }

 static void
 gst_gdp_depay_finalize (GObject * gobject)
 {
   GstGDPDepay *this;

   this = GST_GDP_DEPAY (gobject);
   if (this->caps)
     gst_caps_unref (this->caps);
   g_free (this->header);
   gst_adapter_clear (this->adapter);
   g_object_unref (this->adapter);

   GST_CALL_PARENT (G_OBJECT_CLASS, finalize, (gobject));
 }

 static gboolean
 gst_gdp_depay_sink_event (GstPad * pad, GstObject * parent, GstEvent * event)
 {
   GstGDPDepay *this;
   gboolean res = TRUE;

   this = GST_GDP_DEPAY (parent);

   switch (GST_EVENT_TYPE (event)) {
     case GST_EVENT_FLUSH_START:
       /* forward flush start */
       res = gst_pad_push_event (this->srcpad, event);
       break;
     case GST_EVENT_FLUSH_STOP:
       /* clear adapter on flush */
       gst_adapter_clear (this->adapter);
       /* forward flush stop */
       res = gst_pad_push_event (this->srcpad, event);
       break;
     case GST_EVENT_EOS:
       /* after EOS, we don't expect to output anything anymore */
       res = gst_pad_push_event (this->srcpad, event);
       break;
     case GST_EVENT_SEGMENT:
     case GST_EVENT_TAG:
     case GST_EVENT_BUFFERSIZE:
     default:
       /* we unref most events as we take them from the datastream */
       gst_event_unref (event);
       break;
   }

   return res;
 }

 static gboolean
 gst_gdp_depay_src_event (GstPad * pad, GstObject * parent, GstEvent * event)
 {
   GstGDPDepay *this;
   gboolean res = TRUE;

   this = GST_GDP_DEPAY (parent);

   switch (GST_EVENT_TYPE (event)) {
     case GST_EVENT_SEEK:
       /* we refuse seek for now. */
       gst_event_unref (event);
       res = FALSE;
       break;
     case GST_EVENT_QOS:
     case GST_EVENT_NAVIGATION:
     default:
       /* everything else is passed */
       res = gst_pad_push_event (this->sinkpad, event);
       break;
   }

   return res;
 }

 static GstFlowReturn
 gst_gdp_depay_chain (GstPad * pad, GstObject * parent, GstBuffer * buffer)
 {
   GstGDPDepay *this;
   GstFlowReturn ret = GST_FLOW_OK;
   GstCaps *caps;
   GstBuffer *buf;
   GstEvent *event;
   guint available;

   this = GST_GDP_DEPAY (parent);

   /* On DISCONT, get rid of accumulated data. We assume a buffer after the
    * DISCONT contains (part of) a new valid header, if not we error because we
    * lost sync */
   if (GST_BUFFER_IS_DISCONT (buffer)) {
     gst_adapter_clear (this->adapter);
     this->state = GST_GDP_DEPAY_STATE_HEADER;
   }
   gst_adapter_push (this->adapter, buffer);

   while (TRUE) {
     switch (this->state) {
       case GST_GDP_DEPAY_STATE_HEADER:
       {
         guint8 *header;

         /* collect a complete header, validate and store the header. Figure out
          * the payload length and switch to the PAYLOAD state */
         available = gst_adapter_available (this->adapter);
         if (available < GST_DP_HEADER_LENGTH)
           goto done;

         GST_LOG_OBJECT (this, "reading GDP header from adapter");
         header = gst_adapter_take (this->adapter, GST_DP_HEADER_LENGTH);
         if (!gst_dp_validate_header (GST_DP_HEADER_LENGTH, header)) {
           g_free (header);
           goto header_validate_error;
         }

         /* store types and payload length. Also store the header, which we need
          * to make the payload. */
         this->payload_length = gst_dp_header_payload_length (header);
         this->payload_type = gst_dp_header_payload_type (header);
         /* free previous header and store new one. */
         g_free (this->header);
         this->header = header;

         GST_LOG_OBJECT (this,
             "read GDP header, payload size %d, payload type %d, switching to state PAYLOAD",
             this->payload_length, this->payload_type);
         this->state = GST_GDP_DEPAY_STATE_PAYLOAD;
         break;
       }
       case GST_GDP_DEPAY_STATE_PAYLOAD:
       {
         /* in this state we wait for all the payload data to be available in the
          * adapter. Then we switch to the state where we actually process the
          * payload. */
         available = gst_adapter_available (this->adapter);
         if (available < this->payload_length)
           goto done;

         /* change state based on type */
         if (this->payload_type == GST_DP_PAYLOAD_BUFFER) {
           GST_LOG_OBJECT (this, "switching to state BUFFER");
           this->state = GST_GDP_DEPAY_STATE_BUFFER;
         } else if (this->payload_type == GST_DP_PAYLOAD_CAPS) {
           GST_LOG_OBJECT (this, "switching to state CAPS");
           this->state = GST_GDP_DEPAY_STATE_CAPS;
         } else if (this->payload_type >= GST_DP_PAYLOAD_EVENT_NONE) {
           GST_LOG_OBJECT (this, "switching to state EVENT");
           this->state = GST_GDP_DEPAY_STATE_EVENT;
         } else {
           goto wrong_type;
         }

         if (this->payload_length) {
           const guint8 *data;
           gboolean res;

           data = gst_adapter_map (this->adapter, this->payload_length);
           res = gst_dp_validate_payload (GST_DP_HEADER_LENGTH, this->header,
               data);
           gst_adapter_unmap (this->adapter);

           if (!res)
             goto payload_validate_error;
         }

         break;
       }
       case GST_GDP_DEPAY_STATE_BUFFER:
       {
         /* if we receive a buffer without caps first, we error out */
         if (!this->caps)
           goto no_caps;

         GST_LOG_OBJECT (this, "reading GDP buffer from adapter");
         buf = gst_dp_buffer_from_header (GST_DP_HEADER_LENGTH, this->header);
         if (!buf)
           goto buffer_failed;

         /* now take the payload if there is any */
         if (this->payload_length > 0) {
           GstMapInfo map;

           gst_buffer_map (buf, &map, GST_MAP_WRITE);
           gst_adapter_copy (this->adapter, map.data, 0, this->payload_length);
           gst_buffer_unmap (buf, &map);

           gst_adapter_flush (this->adapter, this->payload_length);
         }

         /* set caps and push */
         GST_LOG_OBJECT (this, "deserialized buffer %p, pushing, timestamp %"
             GST_TIME_FORMAT ", duration %" GST_TIME_FORMAT
             ", offset %" G_GINT64_FORMAT ", offset_end %" G_GINT64_FORMAT
             ", size %" G_GSIZE_FORMAT ", flags 0x%x",
             buf,
             GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (buf)),
             GST_TIME_ARGS (GST_BUFFER_DURATION (buf)),
             GST_BUFFER_OFFSET (buf), GST_BUFFER_OFFSET_END (buf),
             gst_buffer_get_size (buf), GST_BUFFER_FLAGS (buf));
         ret = gst_pad_push (this->srcpad, buf);
         if (ret != GST_FLOW_OK)
           goto push_error;

         GST_LOG_OBJECT (this, "switching to state HEADER");
         this->state = GST_GDP_DEPAY_STATE_HEADER;
         break;
       }
       case GST_GDP_DEPAY_STATE_CAPS:
       {
         guint8 *payload;

         /* take the payload of the caps */
         GST_LOG_OBJECT (this, "reading GDP caps from adapter");
         payload = gst_adapter_take (this->adapter, this->payload_length);
         caps = gst_dp_caps_from_packet (GST_DP_HEADER_LENGTH, this->header,
             payload);
         g_free (payload);
         if (!caps)
           goto caps_failed;

         GST_DEBUG_OBJECT (this, "deserialized caps %" GST_PTR_FORMAT, caps);
         gst_caps_replace (&(this->caps), caps);
         gst_pad_set_caps (this->srcpad, caps);
         /* drop the creation ref we still have */
         gst_caps_unref (caps);

         GST_LOG_OBJECT (this, "switching to state HEADER");
         this->state = GST_GDP_DEPAY_STATE_HEADER;
         break;
       }
       case GST_GDP_DEPAY_STATE_EVENT:
       {
         guint8 *payload;

         GST_LOG_OBJECT (this, "reading GDP event from adapter");

         /* adapter doesn't like 0 length payload */
         if (this->payload_length > 0)
           payload = gst_adapter_take (this->adapter, this->payload_length);
         else
           payload = NULL;
         event = gst_dp_event_from_packet (GST_DP_HEADER_LENGTH, this->header,
             payload);
         g_free (payload);
         if (!event)
           goto event_failed;

         GST_DEBUG_OBJECT (this, "deserialized event %p of type %s, pushing",
             event, gst_event_type_get_name (event->type));
         gst_pad_push_event (this->srcpad, event);

         GST_LOG_OBJECT (this, "switching to state HEADER");
         this->state = GST_GDP_DEPAY_STATE_HEADER;
         break;
       }
     }
   }

 done:
   return ret;

   /* ERRORS */
 header_validate_error:
   {
     GST_ELEMENT_ERROR (this, STREAM, DECODE, (NULL),
         ("GDP packet header does not validate"));
     ret = GST_FLOW_ERROR;
     goto done;
   }
 payload_validate_error:
   {
     GST_ELEMENT_ERROR (this, STREAM, DECODE, (NULL),
         ("GDP packet payload does not validate"));
     ret = GST_FLOW_ERROR;
     goto done;
   }
 wrong_type:
   {
     GST_ELEMENT_ERROR (this, STREAM, DECODE, (NULL),
         ("GDP packet header is of wrong type"));
     ret = GST_FLOW_ERROR;
     goto done;
   }
 no_caps:
   {
     GST_ELEMENT_ERROR (this, STREAM, DECODE, (NULL),
         ("Received a buffer without first receiving caps"));
     ret = GST_FLOW_NOT_NEGOTIATED;
     goto done;
   }
 buffer_failed:
   {
     GST_ELEMENT_ERROR (this, STREAM, DECODE, (NULL),
         ("could not create buffer from GDP packet"));
     ret = GST_FLOW_ERROR;
     goto done;
   }
 push_error:
   {
     GST_WARNING_OBJECT (this, "pushing depayloaded buffer returned %d", ret);
     goto done;
   }
 caps_failed:
   {
     GST_ELEMENT_ERROR (this, STREAM, DECODE, (NULL),
         ("could not create caps from GDP packet"));
     ret = GST_FLOW_ERROR;
     goto done;
   }
 event_failed:
   {
     GST_ELEMENT_ERROR (this, STREAM, DECODE, (NULL),
         ("could not create event from GDP packet"));
     ret = GST_FLOW_ERROR;
     goto done;
   }
 }

 static GstStateChangeReturn
 gst_gdp_depay_change_state (GstElement * element, GstStateChange transition)
 {
   GstStateChangeReturn ret;
   GstGDPDepay *this = GST_GDP_DEPAY (element);

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

   switch (transition) {
     case GST_STATE_CHANGE_PAUSED_TO_READY:
       if (this->caps) {
         gst_caps_unref (this->caps);
         this->caps = NULL;
       }
       gst_adapter_clear (this->adapter);
       break;
     default:
       break;
   }
   return ret;
 }

 gboolean
 gst_gdp_depay_plugin_init (GstPlugin * plugin)
 {
   if (!gst_element_register (plugin, "gdpdepay", GST_RANK_NONE,
           GST_TYPE_GDP_DEPAY))
     return FALSE;

   return TRUE;
 }
	/* GStreamer
	* Copyright (C) 2006 Thomas Vander Stichele <thomas at apestaart dot org>
	*
	* 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-gdpdepay
	* @see_also: gdppay
	*
	* This element depayloads GStreamer Data Protocol buffers back to deserialized
	* buffers and events.
	*
	* <refsect2>
	* \|[
	* gst-launch -v -m filesrc location=test.gdp ! gdpdepay ! xvimagesink
	* ]\| This pipeline plays back a serialized video stream as created in the
	* example for gdppay.
	* </refsect2>
	*/

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

	#include <string.h>

	#include "dataprotocol.h"

	#include "gstgdpdepay.h"

	enum
	{
	PROP_0,
	};

	static GstStaticPadTemplate gdp_depay_sink_template =
	GST_STATIC_PAD_TEMPLATE ("sink",
	GST_PAD_SINK,
	GST_PAD_ALWAYS,
	GST_STATIC_CAPS ("application/x-gdp"));

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

	GST_DEBUG_CATEGORY_STATIC (gst_gdp_depay_debug);
	#define GST_CAT_DEFAULT gst_gdp_depay_debug

	#define _do_init \
	GST_DEBUG_CATEGORY_INIT (gst_gdp_depay_debug, "gdpdepay", 0, \
	"GDP depayloader");
	#define gst_gdp_depay_parent_class parent_class
	G_DEFINE_TYPE_WITH_CODE (GstGDPDepay, gst_gdp_depay,
	GST_TYPE_ELEMENT, _do_init);

	static gboolean gst_gdp_depay_sink_event (GstPad * pad, GstObject * parent,
	GstEvent * event);
	static gboolean gst_gdp_depay_src_event (GstPad * pad, GstObject * parent,
	GstEvent * event);

	static GstFlowReturn gst_gdp_depay_chain (GstPad * pad, GstObject * parent,
	GstBuffer * buffer);

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

	static void gst_gdp_depay_finalize (GObject * object);

	static void
	gst_gdp_depay_class_init (GstGDPDepayClass * klass)
	{
	GObjectClass *gobject_class;
	GstElementClass *gstelement_class;

	gobject_class = (GObjectClass *) klass;
	gstelement_class = (GstElementClass *) klass;

	gst_element_class_set_static_metadata (gstelement_class,
	"GDP Depayloader", "GDP/Depayloader",
	"Depayloads GStreamer Data Protocol buffers",
	"Thomas Vander Stichele <thomas at apestaart dot org>");

	gst_element_class_add_pad_template (gstelement_class,
	gst_static_pad_template_get (&gdp_depay_sink_template));
	gst_element_class_add_pad_template (gstelement_class,
	gst_static_pad_template_get (&gdp_depay_src_template));

	gstelement_class->change_state =
	GST_DEBUG_FUNCPTR (gst_gdp_depay_change_state);
	gobject_class->finalize = gst_gdp_depay_finalize;
	}

	static void
	gst_gdp_depay_init (GstGDPDepay * gdpdepay)
	{
	gdpdepay->sinkpad =
	gst_pad_new_from_static_template (&gdp_depay_sink_template, "sink");
	gst_pad_set_chain_function (gdpdepay->sinkpad,
	GST_DEBUG_FUNCPTR (gst_gdp_depay_chain));
	gst_pad_set_event_function (gdpdepay->sinkpad,
	GST_DEBUG_FUNCPTR (gst_gdp_depay_sink_event));
	gst_element_add_pad (GST_ELEMENT (gdpdepay), gdpdepay->sinkpad);

	gdpdepay->srcpad =
	gst_pad_new_from_static_template (&gdp_depay_src_template, "src");
	gst_pad_set_event_function (gdpdepay->srcpad,
	GST_DEBUG_FUNCPTR (gst_gdp_depay_src_event));
	/* our caps will always be decided by the incoming GDP caps buffers */
	gst_pad_use_fixed_caps (gdpdepay->srcpad);
	gst_element_add_pad (GST_ELEMENT (gdpdepay), gdpdepay->srcpad);

	gdpdepay->adapter = gst_adapter_new ();
	}

	static void
	gst_gdp_depay_finalize (GObject * gobject)
	{
	GstGDPDepay *this;

	this = GST_GDP_DEPAY (gobject);
	if (this->caps)
	gst_caps_unref (this->caps);
	g_free (this->header);
	gst_adapter_clear (this->adapter);
	g_object_unref (this->adapter);

	GST_CALL_PARENT (G_OBJECT_CLASS, finalize, (gobject));
	}

	static gboolean
	gst_gdp_depay_sink_event (GstPad * pad, GstObject * parent, GstEvent * event)
	{
	GstGDPDepay *this;
	gboolean res = TRUE;

	this = GST_GDP_DEPAY (parent);

	switch (GST_EVENT_TYPE (event)) {
	case GST_EVENT_FLUSH_START:
	/* forward flush start */
	res = gst_pad_push_event (this->srcpad, event);
	break;
	case GST_EVENT_FLUSH_STOP:
	/* clear adapter on flush */
	gst_adapter_clear (this->adapter);
	/* forward flush stop */
	res = gst_pad_push_event (this->srcpad, event);
	break;
	case GST_EVENT_EOS:
	/* after EOS, we don't expect to output anything anymore */
	res = gst_pad_push_event (this->srcpad, event);
	break;
	case GST_EVENT_SEGMENT:
	case GST_EVENT_TAG:
	case GST_EVENT_BUFFERSIZE:
	default:
	/* we unref most events as we take them from the datastream */
	gst_event_unref (event);
	break;
	}

	return res;
	}

	static gboolean
	gst_gdp_depay_src_event (GstPad * pad, GstObject * parent, GstEvent * event)
	{
	GstGDPDepay *this;
	gboolean res = TRUE;

	this = GST_GDP_DEPAY (parent);

	switch (GST_EVENT_TYPE (event)) {
	case GST_EVENT_SEEK:
	/* we refuse seek for now. */
	gst_event_unref (event);
	res = FALSE;
	break;
	case GST_EVENT_QOS:
	case GST_EVENT_NAVIGATION:
	default:
	/* everything else is passed */
	res = gst_pad_push_event (this->sinkpad, event);
	break;
	}

	return res;
	}

	static GstFlowReturn
	gst_gdp_depay_chain (GstPad * pad, GstObject * parent, GstBuffer * buffer)
	{
	GstGDPDepay *this;
	GstFlowReturn ret = GST_FLOW_OK;
	GstCaps *caps;
	GstBuffer *buf;
	GstEvent *event;
	guint available;

	this = GST_GDP_DEPAY (parent);

	/* On DISCONT, get rid of accumulated data. We assume a buffer after the
	* DISCONT contains (part of) a new valid header, if not we error because we
	* lost sync */
	if (GST_BUFFER_IS_DISCONT (buffer)) {
	gst_adapter_clear (this->adapter);
	this->state = GST_GDP_DEPAY_STATE_HEADER;
	}
	gst_adapter_push (this->adapter, buffer);

	while (TRUE) {
	switch (this->state) {
	case GST_GDP_DEPAY_STATE_HEADER:
	{
	guint8 *header;

	/* collect a complete header, validate and store the header. Figure out
	* the payload length and switch to the PAYLOAD state */
	available = gst_adapter_available (this->adapter);
	if (available < GST_DP_HEADER_LENGTH)
	goto done;

	GST_LOG_OBJECT (this, "reading GDP header from adapter");
	header = gst_adapter_take (this->adapter, GST_DP_HEADER_LENGTH);
	if (!gst_dp_validate_header (GST_DP_HEADER_LENGTH, header)) {
	g_free (header);
	goto header_validate_error;
	}

	/* store types and payload length. Also store the header, which we need
	* to make the payload. */
	this->payload_length = gst_dp_header_payload_length (header);
	this->payload_type = gst_dp_header_payload_type (header);
	/* free previous header and store new one. */
	g_free (this->header);
	this->header = header;

	GST_LOG_OBJECT (this,
	"read GDP header, payload size %d, payload type %d, switching to state PAYLOAD",
	this->payload_length, this->payload_type);
	this->state = GST_GDP_DEPAY_STATE_PAYLOAD;
	break;
	}
	case GST_GDP_DEPAY_STATE_PAYLOAD:
	{
	/* in this state we wait for all the payload data to be available in the
	* adapter. Then we switch to the state where we actually process the
	* payload. */
	available = gst_adapter_available (this->adapter);
	if (available < this->payload_length)
	goto done;

	/* change state based on type */
	if (this->payload_type == GST_DP_PAYLOAD_BUFFER) {
	GST_LOG_OBJECT (this, "switching to state BUFFER");
	this->state = GST_GDP_DEPAY_STATE_BUFFER;
	} else if (this->payload_type == GST_DP_PAYLOAD_CAPS) {
	GST_LOG_OBJECT (this, "switching to state CAPS");
	this->state = GST_GDP_DEPAY_STATE_CAPS;
	} else if (this->payload_type >= GST_DP_PAYLOAD_EVENT_NONE) {
	GST_LOG_OBJECT (this, "switching to state EVENT");
	this->state = GST_GDP_DEPAY_STATE_EVENT;
	} else {
	goto wrong_type;
	}

	if (this->payload_length) {
	const guint8 *data;
	gboolean res;

	data = gst_adapter_map (this->adapter, this->payload_length);
	res = gst_dp_validate_payload (GST_DP_HEADER_LENGTH, this->header,
	data);
	gst_adapter_unmap (this->adapter);

	if (!res)
	goto payload_validate_error;
	}

	break;
	}
	case GST_GDP_DEPAY_STATE_BUFFER:
	{
	/* if we receive a buffer without caps first, we error out */
	if (!this->caps)
	goto no_caps;

	GST_LOG_OBJECT (this, "reading GDP buffer from adapter");
	buf = gst_dp_buffer_from_header (GST_DP_HEADER_LENGTH, this->header);
	if (!buf)
	goto buffer_failed;

	/* now take the payload if there is any */
	if (this->payload_length > 0) {
	GstMapInfo map;

	gst_buffer_map (buf, &map, GST_MAP_WRITE);
	gst_adapter_copy (this->adapter, map.data, 0, this->payload_length);
	gst_buffer_unmap (buf, &map);

	gst_adapter_flush (this->adapter, this->payload_length);
	}

	/* set caps and push */
	GST_LOG_OBJECT (this, "deserialized buffer %p, pushing, timestamp %"
	GST_TIME_FORMAT ", duration %" GST_TIME_FORMAT
	", offset %" G_GINT64_FORMAT ", offset_end %" G_GINT64_FORMAT
	", size %" G_GSIZE_FORMAT ", flags 0x%x",
	buf,
	GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (buf)),
	GST_TIME_ARGS (GST_BUFFER_DURATION (buf)),
	GST_BUFFER_OFFSET (buf), GST_BUFFER_OFFSET_END (buf),
	gst_buffer_get_size (buf), GST_BUFFER_FLAGS (buf));
	ret = gst_pad_push (this->srcpad, buf);
	if (ret != GST_FLOW_OK)
	goto push_error;

	GST_LOG_OBJECT (this, "switching to state HEADER");
	this->state = GST_GDP_DEPAY_STATE_HEADER;
	break;
	}
	case GST_GDP_DEPAY_STATE_CAPS:
	{
	guint8 *payload;

	/* take the payload of the caps */
	GST_LOG_OBJECT (this, "reading GDP caps from adapter");
	payload = gst_adapter_take (this->adapter, this->payload_length);
	caps = gst_dp_caps_from_packet (GST_DP_HEADER_LENGTH, this->header,
	payload);
	g_free (payload);
	if (!caps)
	goto caps_failed;

	GST_DEBUG_OBJECT (this, "deserialized caps %" GST_PTR_FORMAT, caps);
	gst_caps_replace (&(this->caps), caps);
	gst_pad_set_caps (this->srcpad, caps);
	/* drop the creation ref we still have */
	gst_caps_unref (caps);

	GST_LOG_OBJECT (this, "switching to state HEADER");
	this->state = GST_GDP_DEPAY_STATE_HEADER;
	break;
	}
	case GST_GDP_DEPAY_STATE_EVENT:
	{
	guint8 *payload;

	GST_LOG_OBJECT (this, "reading GDP event from adapter");

	/* adapter doesn't like 0 length payload */
	if (this->payload_length > 0)
	payload = gst_adapter_take (this->adapter, this->payload_length);
	else
	payload = NULL;
	event = gst_dp_event_from_packet (GST_DP_HEADER_LENGTH, this->header,
	payload);
	g_free (payload);
	if (!event)
	goto event_failed;

	GST_DEBUG_OBJECT (this, "deserialized event %p of type %s, pushing",
	event, gst_event_type_get_name (event->type));
	gst_pad_push_event (this->srcpad, event);

	GST_LOG_OBJECT (this, "switching to state HEADER");
	this->state = GST_GDP_DEPAY_STATE_HEADER;
	break;
	}
	}
	}

	done:
	return ret;

	/* ERRORS */
	header_validate_error:
	{
	GST_ELEMENT_ERROR (this, STREAM, DECODE, (NULL),
	("GDP packet header does not validate"));
	ret = GST_FLOW_ERROR;
	goto done;
	}
	payload_validate_error:
	{
	GST_ELEMENT_ERROR (this, STREAM, DECODE, (NULL),
	("GDP packet payload does not validate"));
	ret = GST_FLOW_ERROR;
	goto done;
	}
	wrong_type:
	{
	GST_ELEMENT_ERROR (this, STREAM, DECODE, (NULL),
	("GDP packet header is of wrong type"));
	ret = GST_FLOW_ERROR;
	goto done;
	}
	no_caps:
	{
	GST_ELEMENT_ERROR (this, STREAM, DECODE, (NULL),
	("Received a buffer without first receiving caps"));
	ret = GST_FLOW_NOT_NEGOTIATED;
	goto done;
	}
	buffer_failed:
	{
	GST_ELEMENT_ERROR (this, STREAM, DECODE, (NULL),
	("could not create buffer from GDP packet"));
	ret = GST_FLOW_ERROR;
	goto done;
	}
	push_error:
	{
	GST_WARNING_OBJECT (this, "pushing depayloaded buffer returned %d", ret);
	goto done;
	}
	caps_failed:
	{
	GST_ELEMENT_ERROR (this, STREAM, DECODE, (NULL),
	("could not create caps from GDP packet"));
	ret = GST_FLOW_ERROR;
	goto done;
	}
	event_failed:
	{
	GST_ELEMENT_ERROR (this, STREAM, DECODE, (NULL),
	("could not create event from GDP packet"));
	ret = GST_FLOW_ERROR;
	goto done;
	}
	}

	static GstStateChangeReturn
	gst_gdp_depay_change_state (GstElement * element, GstStateChange transition)
	{
	GstStateChangeReturn ret;
	GstGDPDepay *this = GST_GDP_DEPAY (element);

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

	switch (transition) {
	case GST_STATE_CHANGE_PAUSED_TO_READY:
	if (this->caps) {
	gst_caps_unref (this->caps);
	this->caps = NULL;
	}
	gst_adapter_clear (this->adapter);
	break;
	default:
	break;
	}
	return ret;
	}

	gboolean
	gst_gdp_depay_plugin_init (GstPlugin * plugin)
	{
	if (!gst_element_register (plugin, "gdpdepay", GST_RANK_NONE,
	GST_TYPE_GDP_DEPAY))
	return FALSE;

	return TRUE;
	}