gst/rtp/gstrtph263depay.c - imx-gst-plugins-good - Git at Google

 /* GStreamer
  *
  * Copyright 2007 Nokia Corporation
  * Copyright 2007 Collabora Ltd,
  *  @author: Philippe Kalaf <philippe.kalaf@collabora.co.uk>
  *
  * Copyright (C) <2005> Wim Taymans <wim.taymans@gmail.com>
  *               <2007> Edward Hervey <bilboed@bilboed.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.
  */

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

 #include <string.h>

 #include <gst/rtp/gstrtpbuffer.h>
 #include <gst/video/video.h>
 #include "gstrtph263depay.h"
 #include "gstrtputils.h"

 GST_DEBUG_CATEGORY_STATIC (rtph263depay_debug);
 #define GST_CAT_DEFAULT (rtph263depay_debug)

 #define GST_RFC2190A_HEADER_LEN 4
 #define GST_RFC2190B_HEADER_LEN 8
 #define GST_RFC2190C_HEADER_LEN 12

 static GstStaticPadTemplate gst_rtp_h263_depay_src_template =
 GST_STATIC_PAD_TEMPLATE ("src",
     GST_PAD_SRC,
     GST_PAD_ALWAYS,
     GST_STATIC_CAPS ("video/x-h263, "
         "variant = (string) \"itu\", " "h263version = (string) \"h263\"")
     );

 static GstStaticPadTemplate gst_rtp_h263_depay_sink_template =
     GST_STATIC_PAD_TEMPLATE ("sink",
     GST_PAD_SINK,
     GST_PAD_ALWAYS,
     GST_STATIC_CAPS ("application/x-rtp, "
         "media = (string) \"video\", "
         "payload = (int) " GST_RTP_PAYLOAD_H263_STRING ", "
         "clock-rate = (int) 90000; "
         /* optional SDP attribute:
          * "a-framesize = (string) \"1234-1234\", "
          */
         "application/x-rtp, "
         "media = (string) \"video\", "
         "clock-rate = (int) 90000, " "encoding-name = (string) \"H263\""
         /* optional SDP attribute:
          * "a-framesize = (string) \"1234-1234\", "
          */
     )
     );

 #define gst_rtp_h263_depay_parent_class parent_class
 G_DEFINE_TYPE (GstRtpH263Depay, gst_rtp_h263_depay,
     GST_TYPE_RTP_BASE_DEPAYLOAD);

 static void gst_rtp_h263_depay_finalize (GObject * object);

 static GstStateChangeReturn gst_rtp_h263_depay_change_state (GstElement *
     element, GstStateChange transition);

 static GstBuffer *gst_rtp_h263_depay_process (GstRTPBaseDepayload * depayload,
     GstRTPBuffer * rtp);
 gboolean gst_rtp_h263_depay_setcaps (GstRTPBaseDepayload * filter,
     GstCaps * caps);

 static void
 gst_rtp_h263_depay_class_init (GstRtpH263DepayClass * klass)
 {
   GObjectClass *gobject_class;
   GstElementClass *gstelement_class;
   GstRTPBaseDepayloadClass *gstrtpbasedepayload_class;

   GST_DEBUG_CATEGORY_INIT (rtph263depay_debug, "rtph263depay", 0,
       "H263 Video RTP Depayloader");

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

   gobject_class->finalize = gst_rtp_h263_depay_finalize;

   gstelement_class->change_state = gst_rtp_h263_depay_change_state;

   gst_element_class_add_static_pad_template (gstelement_class,
       &gst_rtp_h263_depay_src_template);
   gst_element_class_add_static_pad_template (gstelement_class,
       &gst_rtp_h263_depay_sink_template);

   gst_element_class_set_static_metadata (gstelement_class,
       "RTP H263 depayloader", "Codec/Depayloader/Network/RTP",
       "Extracts H263 video from RTP packets (RFC 2190)",
       "Philippe Kalaf <philippe.kalaf@collabora.co.uk>, "
       "Edward Hervey <bilboed@bilboed.com>");

   gstrtpbasedepayload_class->process_rtp_packet = gst_rtp_h263_depay_process;
   gstrtpbasedepayload_class->set_caps = gst_rtp_h263_depay_setcaps;
 }

 static void
 gst_rtp_h263_depay_init (GstRtpH263Depay * rtph263depay)
 {
   rtph263depay->adapter = gst_adapter_new ();

   rtph263depay->offset = 0;
   rtph263depay->leftover = 0;
 }

 static void
 gst_rtp_h263_depay_finalize (GObject * object)
 {
   GstRtpH263Depay *rtph263depay;

   rtph263depay = GST_RTP_H263_DEPAY (object);

   g_object_unref (rtph263depay->adapter);
   rtph263depay->adapter = NULL;

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

 static gboolean
 gst_rtp_h263_parse_framesize (GstRTPBaseDepayload * filter,
     const gchar * media_attr, GstCaps * srccaps)
 {
   gchar *dimension, *endptr;
   gint width, height;
   GstStructure *d;

   width = g_ascii_strtoull (media_attr, &endptr, 10);
   if (width <= 0) {
     GST_ERROR_OBJECT (filter,
         "Framesize media attribute width out of valid range");
     return FALSE;
   } else if (*endptr != '-') {
     GST_ERROR_OBJECT (filter,
         "Framesize media attribute has invalid dimension separator");
     return FALSE;
   }

   dimension = endptr + 1;
   height = g_ascii_strtoull (dimension, &endptr, 10);
   if (height <= 0) {
     GST_ERROR_OBJECT (filter,
         "Framesize media attribute height out of valid range");
     return FALSE;
   } else if (*endptr != '\0') {
     GST_ERROR_OBJECT (filter,
         "Framesize media attribute unexpectedly has trailing characters");
     return FALSE;
   }

   d = gst_caps_get_structure (srccaps, 0);
   gst_structure_set (d, "width", G_TYPE_INT, width, "height", G_TYPE_INT,
       height, NULL);

   return TRUE;
 }

 gboolean
 gst_rtp_h263_depay_setcaps (GstRTPBaseDepayload * filter, GstCaps * caps)
 {
   GstCaps *srccaps;
   GstStructure *structure = gst_caps_get_structure (caps, 0);
   gint clock_rate;
   const gchar *framesize;

   srccaps = gst_caps_new_simple ("video/x-h263",
       "variant", G_TYPE_STRING, "itu",
       "h263version", G_TYPE_STRING, "h263", NULL);

   if (!gst_structure_get_int (structure, "clock-rate", &clock_rate))
     clock_rate = 90000;         /* default */
   filter->clock_rate = clock_rate;

   framesize = gst_structure_get_string (structure, "a-framesize");
   if (framesize != NULL) {
     if (!gst_rtp_h263_parse_framesize (filter, framesize, srccaps)) {
       return FALSE;
     }
   }

   gst_pad_set_caps (GST_RTP_BASE_DEPAYLOAD_SRCPAD (filter), srccaps);
   gst_caps_unref (srccaps);

   return TRUE;
 }

 static GstBuffer *
 gst_rtp_h263_depay_process (GstRTPBaseDepayload * depayload, GstRTPBuffer * rtp)
 {
   GstRtpH263Depay *rtph263depay;
   GstBuffer *outbuf;
   gint payload_len;
   guint8 *payload;
   guint header_len;
   guint SBIT, EBIT;
   gboolean F, P, M;
   gboolean I;

   rtph263depay = GST_RTP_H263_DEPAY (depayload);

   /* flush remaining data on discont */
   if (GST_BUFFER_IS_DISCONT (rtp->buffer)) {
     GST_LOG_OBJECT (depayload, "Discont buffer, flushing adapter");
     gst_adapter_clear (rtph263depay->adapter);
     rtph263depay->offset = 0;
     rtph263depay->leftover = 0;
     rtph263depay->start = FALSE;
   }

   payload_len = gst_rtp_buffer_get_payload_len (rtp);
   payload = gst_rtp_buffer_get_payload (rtp);

   M = gst_rtp_buffer_get_marker (rtp);

   if (payload_len < 1)
     goto too_small;

   /* Let's see what mode we are using */
   F = (payload[0] & 0x80) == 0x80;
   P = (payload[0] & 0x40) == 0x40;

   /* Bit shifting */
   SBIT = (payload[0] & 0x38) >> 3;
   EBIT = (payload[0] & 0x07);

   /* Figure out header length and I-flag */
   if (F == 0) {
     /* F == 0 and P == 0 or 1
      * mode A */
     header_len = GST_RFC2190A_HEADER_LEN;
     GST_LOG ("Mode A");

     /* 0                   1                   2                   3
      * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      * |F|P|SBIT |EBIT | SRC |I|U|S|A|R      |DBQ| TRB |    TR         |
      * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      */
     if (payload_len <= header_len)
       goto too_small;
     I = (payload[1] & 0x10) == 0x10;
   } else {
     if (P == 0) {
       /* F == 1 and P == 0
        * mode B */
       header_len = GST_RFC2190B_HEADER_LEN;
       GST_LOG ("Mode B");

       /* 0                   1                   2                   3
        * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
        * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        * |F|P|SBIT |EBIT | SRC | QUANT   |  GOBN   |   MBA           |R  |
        * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        * |I|U|S|A| HMV1        | VMV1        | HMV2        | VMV2        |
        * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        */
       if (payload_len <= header_len)
         goto too_small;
       I = (payload[4] & 0x80) == 0x80;
     } else {
       /* F == 1 and P == 1
        * mode C */
       header_len = GST_RFC2190C_HEADER_LEN;
       GST_LOG ("Mode C");

       /* 0                   1                   2                   3
        * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
        * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        * |F|P|SBIT |EBIT | SRC | QUANT   |  GOBN   |   MBA           |R  |
        * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        * |I|U|S|A| HMV1        | VMV1        | HMV2        | VMV2        |
        * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        * | RR                                  |DBQ| TRB |    TR         |
        * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        */
       if (payload_len <= header_len)
         goto too_small;
       I = (payload[4] & 0x80) == 0x80;
     }
   }

   GST_LOG ("F/P/M/I : %d/%d/%d/%d", F, P, M, I);
   GST_LOG ("SBIT : %d , EBIT : %d", SBIT, EBIT);
   GST_LOG ("payload_len : %d, header_len : %d , leftover : 0x%x",
       payload_len, header_len, rtph263depay->leftover);

   /* skip header */
   payload += header_len;
   payload_len -= header_len;

   if (!rtph263depay->start) {
     /* only mode A should be used when there is a picture start code, but
      * buggy payloaders may send mode B/C in start of frame */
     if (payload_len > 4 && (GST_READ_UINT32_BE (payload) >> 10 == 0x20)) {
       GST_DEBUG ("Mode %c with PSC => frame start", "ABC"[F + P]);
       rtph263depay->start = TRUE;
       if ((! !(payload[4] & 0x02)) != I) {
         GST_DEBUG ("Wrong Picture Coding Type Flag in rtp header");
         I = !I;
       }
       rtph263depay->psc_I = I;
     } else {
       GST_DEBUG ("no frame start yet, skipping payload");
       goto skip;
     }
   }

   /* only trust I info from Mode A starting packet
    * from buggy payloaders or hw */
   I = rtph263depay->psc_I;

   if (SBIT) {
     /* take the leftover and merge it at the beginning, FIXME make the buffer
      * data writable. */
     GST_LOG ("payload[0] : 0x%x", payload[0]);
     payload[0] &= 0xFF >> SBIT;
     GST_LOG ("payload[0] : 0x%x", payload[0]);
     payload[0] |= rtph263depay->leftover;
     GST_LOG ("payload[0] : 0x%x", payload[0]);
     rtph263depay->leftover = 0;
     rtph263depay->offset = 0;
   }

   if (!EBIT) {
     GstBuffer *tmp;

     /* Take the entire buffer */
     tmp = gst_rtp_buffer_get_payload_subbuffer (rtp, header_len, payload_len);
     gst_adapter_push (rtph263depay->adapter, tmp);
   } else {
     GstBuffer *tmp;

     /* Take the entire buffer except for the last byte */
     tmp = gst_rtp_buffer_get_payload_subbuffer (rtp, header_len,
         payload_len - 1);
     gst_adapter_push (rtph263depay->adapter, tmp);

     /* Put the last byte into the leftover */
     GST_DEBUG ("payload[payload_len - 1] : 0x%x", payload[payload_len - 1]);
     GST_DEBUG ("mask : 0x%x", 0xFF << EBIT);
     rtph263depay->leftover = (payload[payload_len - 1] >> EBIT) << EBIT;
     rtph263depay->offset = 1;
     GST_DEBUG ("leftover : 0x%x", rtph263depay->leftover);
   }

 skip:
   if (M) {
     if (rtph263depay->start) {
       /* frame is completed */
       guint avail;

       if (rtph263depay->offset) {
         /* push in the leftover */
         GstBuffer *buf = gst_buffer_new_and_alloc (1);

         GST_DEBUG ("Pushing leftover in adapter");
         gst_buffer_fill (buf, 0, &rtph263depay->leftover, 1);
         gst_adapter_push (rtph263depay->adapter, buf);
       }

       avail = gst_adapter_available (rtph263depay->adapter);
       outbuf = gst_adapter_take_buffer (rtph263depay->adapter, avail);

       if (I)
         GST_BUFFER_FLAG_SET (outbuf, GST_BUFFER_FLAG_DELTA_UNIT);

       GST_DEBUG ("Pushing out a buffer of %d bytes", avail);

       gst_rtp_drop_non_video_meta (rtph263depay, outbuf);

       gst_rtp_base_depayload_push (depayload, outbuf);
       rtph263depay->offset = 0;
       rtph263depay->leftover = 0;
       rtph263depay->start = FALSE;
     } else {
       rtph263depay->start = TRUE;
     }
   }

   return NULL;

 too_small:
   {
     GST_ELEMENT_WARNING (rtph263depay, STREAM, DECODE,
         ("Packet payload was too small"), (NULL));
     return NULL;
   }
 }

 static GstStateChangeReturn
 gst_rtp_h263_depay_change_state (GstElement * element,
     GstStateChange transition)
 {
   GstRtpH263Depay *rtph263depay;
   GstStateChangeReturn ret;

   rtph263depay = GST_RTP_H263_DEPAY (element);

   switch (transition) {
     case GST_STATE_CHANGE_NULL_TO_READY:
       break;
     case GST_STATE_CHANGE_READY_TO_PAUSED:
       gst_adapter_clear (rtph263depay->adapter);
       rtph263depay->start = TRUE;
       break;
     default:
       break;
   }

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

   switch (transition) {
     case GST_STATE_CHANGE_READY_TO_NULL:
       break;
     default:
       break;
   }
   return ret;
 }

 gboolean
 gst_rtp_h263_depay_plugin_init (GstPlugin * plugin)
 {
   return gst_element_register (plugin, "rtph263depay",
       GST_RANK_SECONDARY, GST_TYPE_RTP_H263_DEPAY);
 }
	/* GStreamer
	*
	* Copyright 2007 Nokia Corporation
	* Copyright 2007 Collabora Ltd,
	* @author: Philippe Kalaf <philippe.kalaf@collabora.co.uk>
	*
	* Copyright (C) <2005> Wim Taymans <wim.taymans@gmail.com>
	* <2007> Edward Hervey <bilboed@bilboed.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.
	*/

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

	#include <string.h>

	#include <gst/rtp/gstrtpbuffer.h>
	#include <gst/video/video.h>
	#include "gstrtph263depay.h"
	#include "gstrtputils.h"

	GST_DEBUG_CATEGORY_STATIC (rtph263depay_debug);
	#define GST_CAT_DEFAULT (rtph263depay_debug)

	#define GST_RFC2190A_HEADER_LEN 4
	#define GST_RFC2190B_HEADER_LEN 8
	#define GST_RFC2190C_HEADER_LEN 12

	static GstStaticPadTemplate gst_rtp_h263_depay_src_template =
	GST_STATIC_PAD_TEMPLATE ("src",
	GST_PAD_SRC,
	GST_PAD_ALWAYS,
	GST_STATIC_CAPS ("video/x-h263, "
	"variant = (string) \"itu\", " "h263version = (string) \"h263\"")
	);

	static GstStaticPadTemplate gst_rtp_h263_depay_sink_template =
	GST_STATIC_PAD_TEMPLATE ("sink",
	GST_PAD_SINK,
	GST_PAD_ALWAYS,
	GST_STATIC_CAPS ("application/x-rtp, "
	"media = (string) \"video\", "
	"payload = (int) " GST_RTP_PAYLOAD_H263_STRING ", "
	"clock-rate = (int) 90000; "
	/* optional SDP attribute:
	* "a-framesize = (string) \"1234-1234\", "
	*/
	"application/x-rtp, "
	"media = (string) \"video\", "
	"clock-rate = (int) 90000, " "encoding-name = (string) \"H263\""
	/* optional SDP attribute:
	* "a-framesize = (string) \"1234-1234\", "
	*/
	)
	);

	#define gst_rtp_h263_depay_parent_class parent_class
	G_DEFINE_TYPE (GstRtpH263Depay, gst_rtp_h263_depay,
	GST_TYPE_RTP_BASE_DEPAYLOAD);

	static void gst_rtp_h263_depay_finalize (GObject * object);

	static GstStateChangeReturn gst_rtp_h263_depay_change_state (GstElement *
	element, GstStateChange transition);

	static GstBuffer gst_rtp_h263_depay_process (GstRTPBaseDepayload depayload,
	GstRTPBuffer * rtp);
	gboolean gst_rtp_h263_depay_setcaps (GstRTPBaseDepayload * filter,
	GstCaps * caps);

	static void
	gst_rtp_h263_depay_class_init (GstRtpH263DepayClass * klass)
	{
	GObjectClass *gobject_class;
	GstElementClass *gstelement_class;
	GstRTPBaseDepayloadClass *gstrtpbasedepayload_class;

	GST_DEBUG_CATEGORY_INIT (rtph263depay_debug, "rtph263depay", 0,
	"H263 Video RTP Depayloader");

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

	gobject_class->finalize = gst_rtp_h263_depay_finalize;

	gstelement_class->change_state = gst_rtp_h263_depay_change_state;

	gst_element_class_add_static_pad_template (gstelement_class,
	&gst_rtp_h263_depay_src_template);
	gst_element_class_add_static_pad_template (gstelement_class,
	&gst_rtp_h263_depay_sink_template);

	gst_element_class_set_static_metadata (gstelement_class,
	"RTP H263 depayloader", "Codec/Depayloader/Network/RTP",
	"Extracts H263 video from RTP packets (RFC 2190)",
	"Philippe Kalaf <philippe.kalaf@collabora.co.uk>, "
	"Edward Hervey <bilboed@bilboed.com>");

	gstrtpbasedepayload_class->process_rtp_packet = gst_rtp_h263_depay_process;
	gstrtpbasedepayload_class->set_caps = gst_rtp_h263_depay_setcaps;
	}

	static void
	gst_rtp_h263_depay_init (GstRtpH263Depay * rtph263depay)
	{
	rtph263depay->adapter = gst_adapter_new ();

	rtph263depay->offset = 0;
	rtph263depay->leftover = 0;
	}

	static void
	gst_rtp_h263_depay_finalize (GObject * object)
	{
	GstRtpH263Depay *rtph263depay;

	rtph263depay = GST_RTP_H263_DEPAY (object);

	g_object_unref (rtph263depay->adapter);
	rtph263depay->adapter = NULL;

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

	static gboolean
	gst_rtp_h263_parse_framesize (GstRTPBaseDepayload * filter,
	const gchar * media_attr, GstCaps * srccaps)
	{
	gchar dimension, endptr;
	gint width, height;
	GstStructure *d;

	width = g_ascii_strtoull (media_attr, &endptr, 10);
	if (width <= 0) {
	GST_ERROR_OBJECT (filter,
	"Framesize media attribute width out of valid range");
	return FALSE;
	} else if (*endptr != '-') {
	GST_ERROR_OBJECT (filter,
	"Framesize media attribute has invalid dimension separator");
	return FALSE;
	}

	dimension = endptr + 1;
	height = g_ascii_strtoull (dimension, &endptr, 10);
	if (height <= 0) {
	GST_ERROR_OBJECT (filter,
	"Framesize media attribute height out of valid range");
	return FALSE;
	} else if (*endptr != '\0') {
	GST_ERROR_OBJECT (filter,
	"Framesize media attribute unexpectedly has trailing characters");
	return FALSE;
	}

	d = gst_caps_get_structure (srccaps, 0);
	gst_structure_set (d, "width", G_TYPE_INT, width, "height", G_TYPE_INT,
	height, NULL);

	return TRUE;
	}

	gboolean
	gst_rtp_h263_depay_setcaps (GstRTPBaseDepayload * filter, GstCaps * caps)
	{
	GstCaps *srccaps;
	GstStructure *structure = gst_caps_get_structure (caps, 0);
	gint clock_rate;
	const gchar *framesize;

	srccaps = gst_caps_new_simple ("video/x-h263",
	"variant", G_TYPE_STRING, "itu",
	"h263version", G_TYPE_STRING, "h263", NULL);

	if (!gst_structure_get_int (structure, "clock-rate", &clock_rate))
	clock_rate = 90000; /* default */
	filter->clock_rate = clock_rate;

	framesize = gst_structure_get_string (structure, "a-framesize");
	if (framesize != NULL) {
	if (!gst_rtp_h263_parse_framesize (filter, framesize, srccaps)) {
	return FALSE;
	}
	}

	gst_pad_set_caps (GST_RTP_BASE_DEPAYLOAD_SRCPAD (filter), srccaps);
	gst_caps_unref (srccaps);

	return TRUE;
	}

	static GstBuffer *
	gst_rtp_h263_depay_process (GstRTPBaseDepayload * depayload, GstRTPBuffer * rtp)
	{
	GstRtpH263Depay *rtph263depay;
	GstBuffer *outbuf;
	gint payload_len;
	guint8 *payload;
	guint header_len;
	guint SBIT, EBIT;
	gboolean F, P, M;
	gboolean I;

	rtph263depay = GST_RTP_H263_DEPAY (depayload);

	/* flush remaining data on discont */
	if (GST_BUFFER_IS_DISCONT (rtp->buffer)) {
	GST_LOG_OBJECT (depayload, "Discont buffer, flushing adapter");
	gst_adapter_clear (rtph263depay->adapter);
	rtph263depay->offset = 0;
	rtph263depay->leftover = 0;
	rtph263depay->start = FALSE;
	}

	payload_len = gst_rtp_buffer_get_payload_len (rtp);
	payload = gst_rtp_buffer_get_payload (rtp);

	M = gst_rtp_buffer_get_marker (rtp);

	if (payload_len < 1)
	goto too_small;

	/* Let's see what mode we are using */
	F = (payload[0] & 0x80) == 0x80;
	P = (payload[0] & 0x40) == 0x40;

	/* Bit shifting */
	SBIT = (payload[0] & 0x38) >> 3;
	EBIT = (payload[0] & 0x07);

	/* Figure out header length and I-flag */
	if (F == 0) {
	/* F == 0 and P == 0 or 1
	* mode A */
	header_len = GST_RFC2190A_HEADER_LEN;
	GST_LOG ("Mode A");

	/* 0 1 2 3
	* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* \|F\|P\|SBIT \|EBIT \| SRC \|I\|U\|S\|A\|R \|DBQ\| TRB \| TR \|
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	*/
	if (payload_len <= header_len)
	goto too_small;
	I = (payload[1] & 0x10) == 0x10;
	} else {
	if (P == 0) {
	/* F == 1 and P == 0
	* mode B */
	header_len = GST_RFC2190B_HEADER_LEN;
	GST_LOG ("Mode B");

	/* 0 1 2 3
	* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* \|F\|P\|SBIT \|EBIT \| SRC \| QUANT \| GOBN \| MBA \|R \|
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* \|I\|U\|S\|A\| HMV1 \| VMV1 \| HMV2 \| VMV2 \|
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	*/
	if (payload_len <= header_len)
	goto too_small;
	I = (payload[4] & 0x80) == 0x80;
	} else {
	/* F == 1 and P == 1
	* mode C */
	header_len = GST_RFC2190C_HEADER_LEN;
	GST_LOG ("Mode C");

	/* 0 1 2 3
	* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* \|F\|P\|SBIT \|EBIT \| SRC \| QUANT \| GOBN \| MBA \|R \|
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* \|I\|U\|S\|A\| HMV1 \| VMV1 \| HMV2 \| VMV2 \|
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* \| RR \|DBQ\| TRB \| TR \|
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	*/
	if (payload_len <= header_len)
	goto too_small;
	I = (payload[4] & 0x80) == 0x80;
	}
	}

	GST_LOG ("F/P/M/I : %d/%d/%d/%d", F, P, M, I);
	GST_LOG ("SBIT : %d , EBIT : %d", SBIT, EBIT);
	GST_LOG ("payload_len : %d, header_len : %d , leftover : 0x%x",
	payload_len, header_len, rtph263depay->leftover);

	/* skip header */
	payload += header_len;
	payload_len -= header_len;

	if (!rtph263depay->start) {
	/* only mode A should be used when there is a picture start code, but
	* buggy payloaders may send mode B/C in start of frame */
	if (payload_len > 4 && (GST_READ_UINT32_BE (payload) >> 10 == 0x20)) {
	GST_DEBUG ("Mode %c with PSC => frame start", "ABC"[F + P]);
	rtph263depay->start = TRUE;
	if ((! !(payload[4] & 0x02)) != I) {
	GST_DEBUG ("Wrong Picture Coding Type Flag in rtp header");
	I = !I;
	}
	rtph263depay->psc_I = I;
	} else {
	GST_DEBUG ("no frame start yet, skipping payload");
	goto skip;
	}
	}

	/* only trust I info from Mode A starting packet
	* from buggy payloaders or hw */
	I = rtph263depay->psc_I;

	if (SBIT) {
	/* take the leftover and merge it at the beginning, FIXME make the buffer
	* data writable. */
	GST_LOG ("payload[0] : 0x%x", payload[0]);
	payload[0] &= 0xFF >> SBIT;
	GST_LOG ("payload[0] : 0x%x", payload[0]);
	payload[0] \|= rtph263depay->leftover;
	GST_LOG ("payload[0] : 0x%x", payload[0]);
	rtph263depay->leftover = 0;
	rtph263depay->offset = 0;
	}

	if (!EBIT) {
	GstBuffer *tmp;

	/* Take the entire buffer */
	tmp = gst_rtp_buffer_get_payload_subbuffer (rtp, header_len, payload_len);
	gst_adapter_push (rtph263depay->adapter, tmp);
	} else {
	GstBuffer *tmp;

	/* Take the entire buffer except for the last byte */
	tmp = gst_rtp_buffer_get_payload_subbuffer (rtp, header_len,
	payload_len - 1);
	gst_adapter_push (rtph263depay->adapter, tmp);

	/* Put the last byte into the leftover */
	GST_DEBUG ("payload[payload_len - 1] : 0x%x", payload[payload_len - 1]);
	GST_DEBUG ("mask : 0x%x", 0xFF << EBIT);
	rtph263depay->leftover = (payload[payload_len - 1] >> EBIT) << EBIT;
	rtph263depay->offset = 1;
	GST_DEBUG ("leftover : 0x%x", rtph263depay->leftover);
	}

	skip:
	if (M) {
	if (rtph263depay->start) {
	/* frame is completed */
	guint avail;

	if (rtph263depay->offset) {
	/* push in the leftover */
	GstBuffer *buf = gst_buffer_new_and_alloc (1);

	GST_DEBUG ("Pushing leftover in adapter");
	gst_buffer_fill (buf, 0, &rtph263depay->leftover, 1);
	gst_adapter_push (rtph263depay->adapter, buf);
	}

	avail = gst_adapter_available (rtph263depay->adapter);
	outbuf = gst_adapter_take_buffer (rtph263depay->adapter, avail);

	if (I)
	GST_BUFFER_FLAG_SET (outbuf, GST_BUFFER_FLAG_DELTA_UNIT);

	GST_DEBUG ("Pushing out a buffer of %d bytes", avail);

	gst_rtp_drop_non_video_meta (rtph263depay, outbuf);

	gst_rtp_base_depayload_push (depayload, outbuf);
	rtph263depay->offset = 0;
	rtph263depay->leftover = 0;
	rtph263depay->start = FALSE;
	} else {
	rtph263depay->start = TRUE;
	}
	}

	return NULL;

	too_small:
	{
	GST_ELEMENT_WARNING (rtph263depay, STREAM, DECODE,
	("Packet payload was too small"), (NULL));
	return NULL;
	}
	}

	static GstStateChangeReturn
	gst_rtp_h263_depay_change_state (GstElement * element,
	GstStateChange transition)
	{
	GstRtpH263Depay *rtph263depay;
	GstStateChangeReturn ret;

	rtph263depay = GST_RTP_H263_DEPAY (element);

	switch (transition) {
	case GST_STATE_CHANGE_NULL_TO_READY:
	break;
	case GST_STATE_CHANGE_READY_TO_PAUSED:
	gst_adapter_clear (rtph263depay->adapter);
	rtph263depay->start = TRUE;
	break;
	default:
	break;
	}

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

	switch (transition) {
	case GST_STATE_CHANGE_READY_TO_NULL:
	break;
	default:
	break;
	}
	return ret;
	}

	gboolean
	gst_rtp_h263_depay_plugin_init (GstPlugin * plugin)
	{
	return gst_element_register (plugin, "rtph263depay",
	GST_RANK_SECONDARY, GST_TYPE_RTP_H263_DEPAY);
	}