gst/rtp/gstrtptheoradepay.c - mtk-gst-plugins-good-debian - Git at Google

 /* GStreamer
  * Copyright (C) <2006> Wim Taymans <wim.taymans@gmail.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 <gst/tag/tag.h>
 #include <gst/rtp/gstrtpbuffer.h>
 #include <gst/video/video.h>

 #include <string.h>
 #include "gstrtptheoradepay.h"
 #include "gstrtputils.h"

 GST_DEBUG_CATEGORY_STATIC (rtptheoradepay_debug);
 #define GST_CAT_DEFAULT (rtptheoradepay_debug)

 static GstStaticPadTemplate gst_rtp_theora_depay_sink_template =
 GST_STATIC_PAD_TEMPLATE ("sink",
     GST_PAD_SINK,
     GST_PAD_ALWAYS,
     GST_STATIC_CAPS ("application/x-rtp, "
         "media = (string) \"video\", "
         "clock-rate = (int) 90000, " "encoding-name = (string) \"THEORA\""
         /* All required parameters
          *
          * "sampling = (string) { "YCbCr-4:2:0", "YCbCr-4:2:2", "YCbCr-4:4:4" } "
          * "width = (string) [1, 1048561] (multiples of 16) "
          * "height = (string) [1, 1048561] (multiples of 16) "
          * "delivery-method = (string) { inline, in_band, out_band/<specific_name> } "
          * "configuration = (string) ANY"
          */
         /* All optional parameters
          *
          * "configuration-uri ="
          */
     )
     );

 static GstStaticPadTemplate gst_rtp_theora_depay_src_template =
 GST_STATIC_PAD_TEMPLATE ("src",
     GST_PAD_SRC,
     GST_PAD_ALWAYS,
     GST_STATIC_CAPS ("video/x-theora")
     );

 #define gst_rtp_theora_depay_parent_class parent_class
 G_DEFINE_TYPE (GstRtpTheoraDepay, gst_rtp_theora_depay,
     GST_TYPE_RTP_BASE_DEPAYLOAD);

 static gboolean gst_rtp_theora_depay_setcaps (GstRTPBaseDepayload * depayload,
     GstCaps * caps);
 static GstBuffer *gst_rtp_theora_depay_process (GstRTPBaseDepayload * depayload,
     GstRTPBuffer * rtp);
 static gboolean gst_rtp_theora_depay_packet_lost (GstRTPBaseDepayload *
     depayload, GstEvent * event);

 static void gst_rtp_theora_depay_finalize (GObject * object);

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

 static void
 gst_rtp_theora_depay_class_init (GstRtpTheoraDepayClass * klass)
 {
   GObjectClass *gobject_class;
   GstElementClass *gstelement_class;
   GstRTPBaseDepayloadClass *gstrtpbasedepayload_class;

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

   gobject_class->finalize = gst_rtp_theora_depay_finalize;

   gstelement_class->change_state = gst_rtp_theora_depay_change_state;

   gstrtpbasedepayload_class->process_rtp_packet = gst_rtp_theora_depay_process;
   gstrtpbasedepayload_class->set_caps = gst_rtp_theora_depay_setcaps;
   gstrtpbasedepayload_class->packet_lost = gst_rtp_theora_depay_packet_lost;

   gst_element_class_add_static_pad_template (gstelement_class,
       &gst_rtp_theora_depay_sink_template);
   gst_element_class_add_static_pad_template (gstelement_class,
       &gst_rtp_theora_depay_src_template);

   gst_element_class_set_static_metadata (gstelement_class,
       "RTP Theora depayloader", "Codec/Depayloader/Network/RTP",
       "Extracts Theora video from RTP packets (draft-01 of RFC XXXX)",
       "Wim Taymans <wim.taymans@gmail.com>");

   GST_DEBUG_CATEGORY_INIT (rtptheoradepay_debug, "rtptheoradepay", 0,
       "Theora RTP Depayloader");
 }

 static void
 gst_rtp_theora_depay_init (GstRtpTheoraDepay * rtptheoradepay)
 {
   rtptheoradepay->adapter = gst_adapter_new ();
 }

 static void
 free_config (GstRtpTheoraConfig * config)
 {
   g_list_free_full (config->headers, (GDestroyNotify) gst_buffer_unref);
   g_free (config);
 }

 static void
 free_indents (GstRtpTheoraDepay * rtptheoradepay)
 {
   g_list_free_full (rtptheoradepay->configs, (GDestroyNotify) free_config);
   rtptheoradepay->configs = NULL;
 }

 static void
 gst_rtp_theora_depay_finalize (GObject * object)
 {
   GstRtpTheoraDepay *rtptheoradepay = GST_RTP_THEORA_DEPAY (object);

   g_object_unref (rtptheoradepay->adapter);

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

 static gboolean
 gst_rtp_theora_depay_parse_configuration (GstRtpTheoraDepay * rtptheoradepay,
     GstBuffer * confbuf)
 {
   GstBuffer *buf;
   guint32 num_headers;
   GstMapInfo map;
   guint8 *data;
   gsize size;
   gint i, j;

   gst_buffer_map (confbuf, &map, GST_MAP_READ);
   data = map.data;
   size = map.size;

   GST_DEBUG_OBJECT (rtptheoradepay, "config size %" G_GSIZE_FORMAT, size);

   /* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * |                     Number of packed headers                  |
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * |                          Packed header                        |
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * |                          Packed header                        |
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * |                          ....                                 |
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    */
   if (size < 4)
     goto too_small;

   num_headers = GST_READ_UINT32_BE (data);
   size -= 4;
   data += 4;

   GST_DEBUG_OBJECT (rtptheoradepay, "have %u headers", num_headers);

   /*  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
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * |                   Ident                       | length       ..
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * ..              | n. of headers |    length1    |    length2   ..
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * ..              |             Identification Header            ..
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * .................................................................
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * ..              |         Comment Header                       ..
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * .................................................................
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * ..                        Comment Header                        |
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * |                          Setup Header                        ..
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * .................................................................
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * ..                         Setup Header                         |
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    */
   for (i = 0; i < num_headers; i++) {
     guint32 ident;
     guint16 length;
     guint8 n_headers, b;
     GstRtpTheoraConfig *conf;
     guint *h_sizes;
     guint extra = 1;

     if (size < 6)
       goto too_small;

     ident = (data[0] << 16) | (data[1] << 8) | data[2];
     length = (data[3] << 8) | data[4];
     n_headers = data[5];
     size -= 6;
     data += 6;

     GST_DEBUG_OBJECT (rtptheoradepay,
         "header %d, ident 0x%08x, length %u, left %" G_GSIZE_FORMAT, i, ident,
         length, size);

     /* FIXME check if we already got this ident */

     /* length might also include count of following size fields */
     if (size < length && size + 1 != length)
       goto too_small;

     /* read header sizes we read 2 sizes, the third size (for which we allocate
      * space) must be derived from the total packed header length. */
     h_sizes = g_newa (guint, n_headers + 1);
     for (j = 0; j < n_headers; j++) {
       guint h_size;

       h_size = 0;
       do {
         if (size < 1)
           goto too_small;
         b = *data++;
         size--;
         extra++;
         h_size = (h_size << 7) | (b & 0x7f);
       } while (b & 0x80);
       GST_DEBUG_OBJECT (rtptheoradepay, "headers %d: size: %u", j, h_size);
       h_sizes[j] = h_size;
       length -= h_size;
     }
     /* last header length is the remaining space */
     GST_DEBUG_OBJECT (rtptheoradepay, "last header size: %u", length);
     h_sizes[j] = length;

     GST_DEBUG_OBJECT (rtptheoradepay, "preparing headers");
     conf = g_new0 (GstRtpTheoraConfig, 1);
     conf->ident = ident;

     for (j = 0; j <= n_headers; j++) {
       guint h_size;

       h_size = h_sizes[j];
       if (size < h_size) {
         if (j != n_headers || size + extra != h_size) {
           free_config (conf);
           goto too_small;
         } else {
           /* otherwise means that overall length field contained total length,
            * including extra fields */
           h_size -= extra;
         }
       }

       GST_DEBUG_OBJECT (rtptheoradepay, "reading header %d, size %u", j,
           h_size);

       buf =
           gst_buffer_copy_region (confbuf, GST_BUFFER_COPY_ALL, data - map.data,
           h_size);
       conf->headers = g_list_append (conf->headers, buf);
       data += h_size;
       size -= h_size;
     }
     rtptheoradepay->configs = g_list_append (rtptheoradepay->configs, conf);
   }

   gst_buffer_unmap (confbuf, &map);
   gst_buffer_unref (confbuf);

   return TRUE;

   /* ERRORS */
 too_small:
   {
     GST_DEBUG_OBJECT (rtptheoradepay, "configuration too small");
     gst_buffer_unmap (confbuf, &map);
     gst_buffer_unref (confbuf);
     return FALSE;
   }
 }

 static gboolean
 gst_rtp_theora_depay_parse_inband_configuration (GstRtpTheoraDepay *
     rtptheoradepay, guint ident, guint8 * configuration, guint size,
     guint length)
 {
   GstBuffer *confbuf;
   GstMapInfo map;

   if (G_UNLIKELY (size < 4))
     return FALSE;

   /* transform inline to out-of-band and parse that one */
   confbuf = gst_buffer_new_and_alloc (size + 9);
   gst_buffer_map (confbuf, &map, GST_MAP_WRITE);
   /* 1 header */
   GST_WRITE_UINT32_BE (map.data, 1);
   /* write Ident */
   GST_WRITE_UINT24_BE (map.data + 4, ident);
   /* write sort-of-length */
   GST_WRITE_UINT16_BE (map.data + 7, length);
   /* copy remainder */
   memcpy (map.data + 9, configuration, size);
   gst_buffer_unmap (confbuf, &map);

   return gst_rtp_theora_depay_parse_configuration (rtptheoradepay, confbuf);
 }

 static gboolean
 gst_rtp_theora_depay_setcaps (GstRTPBaseDepayload * depayload, GstCaps * caps)
 {
   GstStructure *structure;
   GstRtpTheoraDepay *rtptheoradepay;
   GstCaps *srccaps;
   const gchar *configuration;
   gboolean res;

   rtptheoradepay = GST_RTP_THEORA_DEPAY (depayload);

   rtptheoradepay->needs_keyframe = FALSE;

   structure = gst_caps_get_structure (caps, 0);

   /* read and parse configuration string */
   configuration = gst_structure_get_string (structure, "configuration");
   if (configuration) {
     GstBuffer *confbuf;
     guint8 *data;
     gsize size;

     /* deserialize base64 to buffer */
     data = g_base64_decode (configuration, &size);

     confbuf = gst_buffer_new ();
     gst_buffer_append_memory (confbuf,
         gst_memory_new_wrapped (0, data, size, 0, size, data, g_free));

     if (!gst_rtp_theora_depay_parse_configuration (rtptheoradepay, confbuf))
       goto invalid_configuration;
   }

   /* set caps on pad and on header */
   srccaps = gst_caps_new_empty_simple ("video/x-theora");
   res = gst_pad_set_caps (depayload->srcpad, srccaps);
   gst_caps_unref (srccaps);

   /* Clock rate is always 90000 according to draft-barbato-avt-rtp-theora-01 */
   depayload->clock_rate = 90000;

   return res;

   /* ERRORS */
 invalid_configuration:
   {
     GST_ERROR_OBJECT (rtptheoradepay, "invalid configuration specified");
     return FALSE;
   }
 }

 static gboolean
 gst_rtp_theora_depay_switch_codebook (GstRtpTheoraDepay * rtptheoradepay,
     guint32 ident)
 {
   GList *walk;
   gboolean res = FALSE;

   for (walk = rtptheoradepay->configs; walk; walk = g_list_next (walk)) {
     GstRtpTheoraConfig *conf = (GstRtpTheoraConfig *) walk->data;

     if (conf->ident == ident) {
       GList *headers;

       /* FIXME, remove pads, create new pad.. */

       /* push out all the headers */
       for (headers = conf->headers; headers; headers = g_list_next (headers)) {
         GstBuffer *header = GST_BUFFER_CAST (headers->data);

         gst_buffer_ref (header);
         gst_rtp_base_depayload_push (GST_RTP_BASE_DEPAYLOAD (rtptheoradepay),
             header);
       }
       /* remember the current config */
       rtptheoradepay->config = conf;
       res = TRUE;
     }
   }
   if (!res) {
     /* we don't know about the headers, figure out an alternative method for
      * getting the codebooks. FIXME, fail for now. */
   }
   return res;
 }

 static GstBuffer *
 gst_rtp_theora_depay_process (GstRTPBaseDepayload * depayload,
     GstRTPBuffer * rtp)
 {
   GstRtpTheoraDepay *rtptheoradepay;
   GstBuffer *outbuf;
   GstFlowReturn ret;
   gint payload_len;
   GstMapInfo map;
   GstBuffer *payload_buffer = NULL;
   guint8 *payload;
   guint32 header, ident;
   guint8 F, TDT, packets;
   guint length;

   rtptheoradepay = GST_RTP_THEORA_DEPAY (depayload);

   payload_len = gst_rtp_buffer_get_payload_len (rtp);

   GST_DEBUG_OBJECT (depayload, "got RTP packet of size %d", payload_len);

   /* we need at least 4 bytes for the packet header */
   if (G_UNLIKELY (payload_len < 4))
     goto packet_short;

   payload = gst_rtp_buffer_get_payload (rtp);

   header = GST_READ_UINT32_BE (payload);
   /*
    *  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
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * |                     Ident                     | F |TDT|# pkts.|
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    *
    * F: Fragment type (0=none, 1=start, 2=cont, 3=end)
    * TDT: Theora data type (0=theora, 1=config, 2=comment, 3=reserved)
    * pkts: number of packets.
    */
   TDT = (header & 0x30) >> 4;
   if (G_UNLIKELY (TDT == 3))
     goto ignore_reserved;

   ident = (header >> 8) & 0xffffff;
   F = (header & 0xc0) >> 6;
   packets = (header & 0xf);

   GST_DEBUG_OBJECT (depayload, "ident: 0x%08x, F: %d, TDT: %d, packets: %d",
       ident, F, TDT, packets);

   if (TDT == 0) {
     gboolean do_switch = FALSE;

     /* we have a raw payload, find the codebook for the ident */
     if (!rtptheoradepay->config) {
       /* we don't have an active codebook, find the codebook and
        * activate it */
       do_switch = TRUE;
     } else if (rtptheoradepay->config->ident != ident) {
       /* codebook changed */
       do_switch = TRUE;
     }
     if (do_switch) {
       if (!gst_rtp_theora_depay_switch_codebook (rtptheoradepay, ident))
         goto switch_failed;
     }
   }

   /* fragmented packets, assemble */
   if (F != 0) {
     GstBuffer *vdata;

     if (F == 1) {
       /* if we start a packet, clear adapter and start assembling. */
       gst_adapter_clear (rtptheoradepay->adapter);
       GST_DEBUG_OBJECT (depayload, "start assemble");
       rtptheoradepay->assembling = TRUE;
     }

     if (!rtptheoradepay->assembling)
       goto no_output;

     /* skip header and length. */
     vdata = gst_rtp_buffer_get_payload_subbuffer (rtp, 6, -1);

     GST_DEBUG_OBJECT (depayload, "assemble theora packet");
     gst_adapter_push (rtptheoradepay->adapter, vdata);

     /* packet is not complete, we are done */
     if (F != 3)
       goto no_output;

     /* construct assembled buffer */
     length = gst_adapter_available (rtptheoradepay->adapter);
     payload_buffer = gst_adapter_take_buffer (rtptheoradepay->adapter, length);
   } else {
     length = 0;
     payload_buffer = gst_rtp_buffer_get_payload_subbuffer (rtp, 4, -1);
   }

   GST_DEBUG_OBJECT (depayload, "assemble done, payload_len %d", payload_len);

   gst_buffer_map (payload_buffer, &map, GST_MAP_READ);
   payload = map.data;
   payload_len = map.size;

   /* we not assembling anymore now */
   rtptheoradepay->assembling = FALSE;
   gst_adapter_clear (rtptheoradepay->adapter);

   /* payload now points to a length with that many theora data bytes.
    * Iterate over the packets and send them out.
    *
    *  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
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * |             length            |          theora data         ..
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * ..                        theora data                           |
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * |            length             |   next theora packet data    ..
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * ..                        theora data                           |
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+*
    */
   while (payload_len >= 2) {
     /* If length is not 0, we have a reassembled packet for which we
      * calculated the length already and don't have to skip over the
      * length field anymore
      */
     if (length == 0) {
       length = GST_READ_UINT16_BE (payload);
       payload += 2;
       payload_len -= 2;
     }

     GST_DEBUG_OBJECT (depayload, "read length %u, avail: %d", length,
         payload_len);

     /* skip packet if something odd happens */
     if (G_UNLIKELY (length > payload_len))
       goto length_short;

     /* handle in-band configuration */
     if (G_UNLIKELY (TDT == 1)) {
       GST_DEBUG_OBJECT (rtptheoradepay, "in-band configuration");
       if (!gst_rtp_theora_depay_parse_inband_configuration (rtptheoradepay,
               ident, payload, payload_len, length))
         goto invalid_configuration;
       goto no_output;
     }

     /* create buffer for packet */
     outbuf =
         gst_buffer_copy_region (payload_buffer, GST_BUFFER_COPY_ALL,
         payload - map.data, length);

     if (payload_len > 0 && (payload[0] & 0xC0) == 0x0) {
       rtptheoradepay->needs_keyframe = FALSE;
     } else {
       GST_BUFFER_FLAG_SET (outbuf, GST_BUFFER_FLAG_DELTA_UNIT);
     }

     payload += length;
     payload_len -= length;
     /* make sure to read next length */
     length = 0;

     ret = gst_rtp_base_depayload_push (depayload, outbuf);
     if (ret != GST_FLOW_OK)
       break;
   }

   if (rtptheoradepay->needs_keyframe)
     goto request_keyframe;

 out:
 no_output:

   if (payload_buffer) {
     gst_buffer_unmap (payload_buffer, &map);
     gst_buffer_unref (payload_buffer);
   }

   return NULL;

   /* ERORRS */
 switch_failed:
   {
     GST_ELEMENT_WARNING (rtptheoradepay, STREAM, DECODE,
         (NULL), ("Could not switch codebooks"));
     goto request_config;
   }
 packet_short:
   {
     GST_ELEMENT_WARNING (rtptheoradepay, STREAM, DECODE,
         (NULL), ("Packet was too short (%d < 4)", payload_len));
     goto request_keyframe;
   }
 ignore_reserved:
   {
     GST_WARNING_OBJECT (rtptheoradepay, "reserved TDT ignored");
     goto out;
   }
 length_short:
   {
     GST_ELEMENT_WARNING (rtptheoradepay, STREAM, DECODE,
         (NULL), ("Packet contains invalid data"));
     goto request_keyframe;
   }
 invalid_configuration:
   {
     /* fatal, as we otherwise risk carrying on without output */
     GST_ELEMENT_ERROR (rtptheoradepay, STREAM, DECODE,
         (NULL), ("Packet contains invalid configuration"));
     goto request_config;
   }
 request_config:
   {
     gst_pad_push_event (GST_RTP_BASE_DEPAYLOAD_SINKPAD (depayload),
         gst_event_new_custom (GST_EVENT_CUSTOM_UPSTREAM,
             gst_structure_new ("GstForceKeyUnit",
                 "all-headers", G_TYPE_BOOLEAN, TRUE, NULL)));
     goto out;
   }
 request_keyframe:
   {
     rtptheoradepay->needs_keyframe = TRUE;
     gst_pad_push_event (GST_RTP_BASE_DEPAYLOAD_SINKPAD (depayload),
         gst_event_new_custom (GST_EVENT_CUSTOM_UPSTREAM,
             gst_structure_new_empty ("GstForceKeyUnit")));
     goto out;
   }
 }

 static GstStateChangeReturn
 gst_rtp_theora_depay_change_state (GstElement * element,
     GstStateChange transition)
 {
   GstRtpTheoraDepay *rtptheoradepay;
   GstStateChangeReturn ret;

   rtptheoradepay = GST_RTP_THEORA_DEPAY (element);

   switch (transition) {
     case GST_STATE_CHANGE_NULL_TO_READY:
       break;
     case GST_STATE_CHANGE_READY_TO_PAUSED:
       break;
     default:
       break;
   }

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

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

 gboolean
 gst_rtp_theora_depay_plugin_init (GstPlugin * plugin)
 {
   return gst_element_register (plugin, "rtptheoradepay",
       GST_RANK_SECONDARY, GST_TYPE_RTP_THEORA_DEPAY);
 }

 static gboolean
 gst_rtp_theora_depay_packet_lost (GstRTPBaseDepayload * depayload,
     GstEvent * event)
 {
   GstRtpTheoraDepay *rtptheoradepay = GST_RTP_THEORA_DEPAY (depayload);
   guint seqnum = 0;

   gst_structure_get_uint (gst_event_get_structure (event), "seqnum", &seqnum);
   GST_LOG_OBJECT (depayload, "Requested keyframe because frame with seqnum %u"
       " is missing", seqnum);
   rtptheoradepay->needs_keyframe = TRUE;

   gst_pad_push_event (GST_RTP_BASE_DEPAYLOAD_SINKPAD (depayload),
       gst_event_new_custom (GST_EVENT_CUSTOM_UPSTREAM,
           gst_structure_new_empty ("GstForceKeyUnit")));

   return TRUE;
 }
	/* GStreamer
	* Copyright (C) <2006> Wim Taymans <wim.taymans@gmail.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 <gst/tag/tag.h>
	#include <gst/rtp/gstrtpbuffer.h>
	#include <gst/video/video.h>

	#include <string.h>
	#include "gstrtptheoradepay.h"
	#include "gstrtputils.h"

	GST_DEBUG_CATEGORY_STATIC (rtptheoradepay_debug);
	#define GST_CAT_DEFAULT (rtptheoradepay_debug)

	static GstStaticPadTemplate gst_rtp_theora_depay_sink_template =
	GST_STATIC_PAD_TEMPLATE ("sink",
	GST_PAD_SINK,
	GST_PAD_ALWAYS,
	GST_STATIC_CAPS ("application/x-rtp, "
	"media = (string) \"video\", "
	"clock-rate = (int) 90000, " "encoding-name = (string) \"THEORA\""
	/* All required parameters
	*
	* "sampling = (string) { "YCbCr-4:2:0", "YCbCr-4:2:2", "YCbCr-4:4:4" } "
	* "width = (string) [1, 1048561] (multiples of 16) "
	* "height = (string) [1, 1048561] (multiples of 16) "
	* "delivery-method = (string) { inline, in_band, out_band/<specific_name> } "
	* "configuration = (string) ANY"
	*/
	/* All optional parameters
	*
	* "configuration-uri ="
	*/
	)
	);

	static GstStaticPadTemplate gst_rtp_theora_depay_src_template =
	GST_STATIC_PAD_TEMPLATE ("src",
	GST_PAD_SRC,
	GST_PAD_ALWAYS,
	GST_STATIC_CAPS ("video/x-theora")
	);

	#define gst_rtp_theora_depay_parent_class parent_class
	G_DEFINE_TYPE (GstRtpTheoraDepay, gst_rtp_theora_depay,
	GST_TYPE_RTP_BASE_DEPAYLOAD);

	static gboolean gst_rtp_theora_depay_setcaps (GstRTPBaseDepayload * depayload,
	GstCaps * caps);
	static GstBuffer gst_rtp_theora_depay_process (GstRTPBaseDepayload depayload,
	GstRTPBuffer * rtp);
	static gboolean gst_rtp_theora_depay_packet_lost (GstRTPBaseDepayload *
	depayload, GstEvent * event);

	static void gst_rtp_theora_depay_finalize (GObject * object);

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

	static void
	gst_rtp_theora_depay_class_init (GstRtpTheoraDepayClass * klass)
	{
	GObjectClass *gobject_class;
	GstElementClass *gstelement_class;
	GstRTPBaseDepayloadClass *gstrtpbasedepayload_class;

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

	gobject_class->finalize = gst_rtp_theora_depay_finalize;

	gstelement_class->change_state = gst_rtp_theora_depay_change_state;

	gstrtpbasedepayload_class->process_rtp_packet = gst_rtp_theora_depay_process;
	gstrtpbasedepayload_class->set_caps = gst_rtp_theora_depay_setcaps;
	gstrtpbasedepayload_class->packet_lost = gst_rtp_theora_depay_packet_lost;

	gst_element_class_add_static_pad_template (gstelement_class,
	&gst_rtp_theora_depay_sink_template);
	gst_element_class_add_static_pad_template (gstelement_class,
	&gst_rtp_theora_depay_src_template);

	gst_element_class_set_static_metadata (gstelement_class,
	"RTP Theora depayloader", "Codec/Depayloader/Network/RTP",
	"Extracts Theora video from RTP packets (draft-01 of RFC XXXX)",
	"Wim Taymans <wim.taymans@gmail.com>");

	GST_DEBUG_CATEGORY_INIT (rtptheoradepay_debug, "rtptheoradepay", 0,
	"Theora RTP Depayloader");
	}

	static void
	gst_rtp_theora_depay_init (GstRtpTheoraDepay * rtptheoradepay)
	{
	rtptheoradepay->adapter = gst_adapter_new ();
	}

	static void
	free_config (GstRtpTheoraConfig * config)
	{
	g_list_free_full (config->headers, (GDestroyNotify) gst_buffer_unref);
	g_free (config);
	}

	static void
	free_indents (GstRtpTheoraDepay * rtptheoradepay)
	{
	g_list_free_full (rtptheoradepay->configs, (GDestroyNotify) free_config);
	rtptheoradepay->configs = NULL;
	}

	static void
	gst_rtp_theora_depay_finalize (GObject * object)
	{
	GstRtpTheoraDepay *rtptheoradepay = GST_RTP_THEORA_DEPAY (object);

	g_object_unref (rtptheoradepay->adapter);

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

	static gboolean
	gst_rtp_theora_depay_parse_configuration (GstRtpTheoraDepay * rtptheoradepay,
	GstBuffer * confbuf)
	{
	GstBuffer *buf;
	guint32 num_headers;
	GstMapInfo map;
	guint8 *data;
	gsize size;
	gint i, j;

	gst_buffer_map (confbuf, &map, GST_MAP_READ);
	data = map.data;
	size = map.size;

	GST_DEBUG_OBJECT (rtptheoradepay, "config size %" G_GSIZE_FORMAT, size);

	/* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* \| Number of packed headers \|
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* \| Packed header \|
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* \| Packed header \|
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* \| .... \|
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	*/
	if (size < 4)
	goto too_small;

	num_headers = GST_READ_UINT32_BE (data);
	size -= 4;
	data += 4;

	GST_DEBUG_OBJECT (rtptheoradepay, "have %u headers", num_headers);

	/* 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
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* \| Ident \| length ..
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* .. \| n. of headers \| length1 \| length2 ..
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* .. \| Identification Header ..
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* .................................................................
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* .. \| Comment Header ..
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* .................................................................
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* .. Comment Header \|
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* \| Setup Header ..
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* .................................................................
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* .. Setup Header \|
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	*/
	for (i = 0; i < num_headers; i++) {
	guint32 ident;
	guint16 length;
	guint8 n_headers, b;
	GstRtpTheoraConfig *conf;
	guint *h_sizes;
	guint extra = 1;

	if (size < 6)
	goto too_small;

	ident = (data[0] << 16) \| (data[1] << 8) \| data[2];
	length = (data[3] << 8) \| data[4];
	n_headers = data[5];
	size -= 6;
	data += 6;

	GST_DEBUG_OBJECT (rtptheoradepay,
	"header %d, ident 0x%08x, length %u, left %" G_GSIZE_FORMAT, i, ident,
	length, size);

	/* FIXME check if we already got this ident */

	/* length might also include count of following size fields */
	if (size < length && size + 1 != length)
	goto too_small;

	/* read header sizes we read 2 sizes, the third size (for which we allocate
	* space) must be derived from the total packed header length. */
	h_sizes = g_newa (guint, n_headers + 1);
	for (j = 0; j < n_headers; j++) {
	guint h_size;

	h_size = 0;
	do {
	if (size < 1)
	goto too_small;
	b = *data++;
	size--;
	extra++;
	h_size = (h_size << 7) \| (b & 0x7f);
	} while (b & 0x80);
	GST_DEBUG_OBJECT (rtptheoradepay, "headers %d: size: %u", j, h_size);
	h_sizes[j] = h_size;
	length -= h_size;
	}
	/* last header length is the remaining space */
	GST_DEBUG_OBJECT (rtptheoradepay, "last header size: %u", length);
	h_sizes[j] = length;

	GST_DEBUG_OBJECT (rtptheoradepay, "preparing headers");
	conf = g_new0 (GstRtpTheoraConfig, 1);
	conf->ident = ident;

	for (j = 0; j <= n_headers; j++) {
	guint h_size;

	h_size = h_sizes[j];
	if (size < h_size) {
	if (j != n_headers \|\| size + extra != h_size) {
	free_config (conf);
	goto too_small;
	} else {
	/* otherwise means that overall length field contained total length,
	* including extra fields */
	h_size -= extra;
	}
	}

	GST_DEBUG_OBJECT (rtptheoradepay, "reading header %d, size %u", j,
	h_size);

	buf =
	gst_buffer_copy_region (confbuf, GST_BUFFER_COPY_ALL, data - map.data,
	h_size);
	conf->headers = g_list_append (conf->headers, buf);
	data += h_size;
	size -= h_size;
	}
	rtptheoradepay->configs = g_list_append (rtptheoradepay->configs, conf);
	}

	gst_buffer_unmap (confbuf, &map);
	gst_buffer_unref (confbuf);

	return TRUE;

	/* ERRORS */
	too_small:
	{
	GST_DEBUG_OBJECT (rtptheoradepay, "configuration too small");
	gst_buffer_unmap (confbuf, &map);
	gst_buffer_unref (confbuf);
	return FALSE;
	}
	}

	static gboolean
	gst_rtp_theora_depay_parse_inband_configuration (GstRtpTheoraDepay *
	rtptheoradepay, guint ident, guint8 * configuration, guint size,
	guint length)
	{
	GstBuffer *confbuf;
	GstMapInfo map;

	if (G_UNLIKELY (size < 4))
	return FALSE;

	/* transform inline to out-of-band and parse that one */
	confbuf = gst_buffer_new_and_alloc (size + 9);
	gst_buffer_map (confbuf, &map, GST_MAP_WRITE);
	/* 1 header */
	GST_WRITE_UINT32_BE (map.data, 1);
	/* write Ident */
	GST_WRITE_UINT24_BE (map.data + 4, ident);
	/* write sort-of-length */
	GST_WRITE_UINT16_BE (map.data + 7, length);
	/* copy remainder */
	memcpy (map.data + 9, configuration, size);
	gst_buffer_unmap (confbuf, &map);

	return gst_rtp_theora_depay_parse_configuration (rtptheoradepay, confbuf);
	}

	static gboolean
	gst_rtp_theora_depay_setcaps (GstRTPBaseDepayload * depayload, GstCaps * caps)
	{
	GstStructure *structure;
	GstRtpTheoraDepay *rtptheoradepay;
	GstCaps *srccaps;
	const gchar *configuration;
	gboolean res;

	rtptheoradepay = GST_RTP_THEORA_DEPAY (depayload);

	rtptheoradepay->needs_keyframe = FALSE;

	structure = gst_caps_get_structure (caps, 0);

	/* read and parse configuration string */
	configuration = gst_structure_get_string (structure, "configuration");
	if (configuration) {
	GstBuffer *confbuf;
	guint8 *data;
	gsize size;

	/* deserialize base64 to buffer */
	data = g_base64_decode (configuration, &size);

	confbuf = gst_buffer_new ();
	gst_buffer_append_memory (confbuf,
	gst_memory_new_wrapped (0, data, size, 0, size, data, g_free));

	if (!gst_rtp_theora_depay_parse_configuration (rtptheoradepay, confbuf))
	goto invalid_configuration;
	}

	/* set caps on pad and on header */
	srccaps = gst_caps_new_empty_simple ("video/x-theora");
	res = gst_pad_set_caps (depayload->srcpad, srccaps);
	gst_caps_unref (srccaps);

	/* Clock rate is always 90000 according to draft-barbato-avt-rtp-theora-01 */
	depayload->clock_rate = 90000;

	return res;

	/* ERRORS */
	invalid_configuration:
	{
	GST_ERROR_OBJECT (rtptheoradepay, "invalid configuration specified");
	return FALSE;
	}
	}

	static gboolean
	gst_rtp_theora_depay_switch_codebook (GstRtpTheoraDepay * rtptheoradepay,
	guint32 ident)
	{
	GList *walk;
	gboolean res = FALSE;

	for (walk = rtptheoradepay->configs; walk; walk = g_list_next (walk)) {
	GstRtpTheoraConfig conf = (GstRtpTheoraConfig ) walk->data;

	if (conf->ident == ident) {
	GList *headers;

	/* FIXME, remove pads, create new pad.. */

	/* push out all the headers */
	for (headers = conf->headers; headers; headers = g_list_next (headers)) {
	GstBuffer *header = GST_BUFFER_CAST (headers->data);

	gst_buffer_ref (header);
	gst_rtp_base_depayload_push (GST_RTP_BASE_DEPAYLOAD (rtptheoradepay),
	header);
	}
	/* remember the current config */
	rtptheoradepay->config = conf;
	res = TRUE;
	}
	}
	if (!res) {
	/* we don't know about the headers, figure out an alternative method for
	* getting the codebooks. FIXME, fail for now. */
	}
	return res;
	}

	static GstBuffer *
	gst_rtp_theora_depay_process (GstRTPBaseDepayload * depayload,
	GstRTPBuffer * rtp)
	{
	GstRtpTheoraDepay *rtptheoradepay;
	GstBuffer *outbuf;
	GstFlowReturn ret;
	gint payload_len;
	GstMapInfo map;
	GstBuffer *payload_buffer = NULL;
	guint8 *payload;
	guint32 header, ident;
	guint8 F, TDT, packets;
	guint length;

	rtptheoradepay = GST_RTP_THEORA_DEPAY (depayload);

	payload_len = gst_rtp_buffer_get_payload_len (rtp);

	GST_DEBUG_OBJECT (depayload, "got RTP packet of size %d", payload_len);

	/* we need at least 4 bytes for the packet header */
	if (G_UNLIKELY (payload_len < 4))
	goto packet_short;

	payload = gst_rtp_buffer_get_payload (rtp);

	header = GST_READ_UINT32_BE (payload);
	/*
	* 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
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* \| Ident \| F \|TDT\|# pkts.\|
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	*
	* F: Fragment type (0=none, 1=start, 2=cont, 3=end)
	* TDT: Theora data type (0=theora, 1=config, 2=comment, 3=reserved)
	* pkts: number of packets.
	*/
	TDT = (header & 0x30) >> 4;
	if (G_UNLIKELY (TDT == 3))
	goto ignore_reserved;

	ident = (header >> 8) & 0xffffff;
	F = (header & 0xc0) >> 6;
	packets = (header & 0xf);

	GST_DEBUG_OBJECT (depayload, "ident: 0x%08x, F: %d, TDT: %d, packets: %d",
	ident, F, TDT, packets);

	if (TDT == 0) {
	gboolean do_switch = FALSE;

	/* we have a raw payload, find the codebook for the ident */
	if (!rtptheoradepay->config) {
	/* we don't have an active codebook, find the codebook and
	* activate it */
	do_switch = TRUE;
	} else if (rtptheoradepay->config->ident != ident) {
	/* codebook changed */
	do_switch = TRUE;
	}
	if (do_switch) {
	if (!gst_rtp_theora_depay_switch_codebook (rtptheoradepay, ident))
	goto switch_failed;
	}
	}

	/* fragmented packets, assemble */
	if (F != 0) {
	GstBuffer *vdata;

	if (F == 1) {
	/* if we start a packet, clear adapter and start assembling. */
	gst_adapter_clear (rtptheoradepay->adapter);
	GST_DEBUG_OBJECT (depayload, "start assemble");
	rtptheoradepay->assembling = TRUE;
	}

	if (!rtptheoradepay->assembling)
	goto no_output;

	/* skip header and length. */
	vdata = gst_rtp_buffer_get_payload_subbuffer (rtp, 6, -1);

	GST_DEBUG_OBJECT (depayload, "assemble theora packet");
	gst_adapter_push (rtptheoradepay->adapter, vdata);

	/* packet is not complete, we are done */
	if (F != 3)
	goto no_output;

	/* construct assembled buffer */
	length = gst_adapter_available (rtptheoradepay->adapter);
	payload_buffer = gst_adapter_take_buffer (rtptheoradepay->adapter, length);
	} else {
	length = 0;
	payload_buffer = gst_rtp_buffer_get_payload_subbuffer (rtp, 4, -1);
	}

	GST_DEBUG_OBJECT (depayload, "assemble done, payload_len %d", payload_len);

	gst_buffer_map (payload_buffer, &map, GST_MAP_READ);
	payload = map.data;
	payload_len = map.size;

	/* we not assembling anymore now */
	rtptheoradepay->assembling = FALSE;
	gst_adapter_clear (rtptheoradepay->adapter);

	/* payload now points to a length with that many theora data bytes.
	* Iterate over the packets and send them out.
	*
	* 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
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* \| length \| theora data ..
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* .. theora data \|
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* \| length \| next theora packet data ..
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	* .. theora data \|
	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+*
	*/
	while (payload_len >= 2) {
	/* If length is not 0, we have a reassembled packet for which we
	* calculated the length already and don't have to skip over the
	* length field anymore
	*/
	if (length == 0) {
	length = GST_READ_UINT16_BE (payload);
	payload += 2;
	payload_len -= 2;
	}

	GST_DEBUG_OBJECT (depayload, "read length %u, avail: %d", length,
	payload_len);

	/* skip packet if something odd happens */
	if (G_UNLIKELY (length > payload_len))
	goto length_short;

	/* handle in-band configuration */
	if (G_UNLIKELY (TDT == 1)) {
	GST_DEBUG_OBJECT (rtptheoradepay, "in-band configuration");
	if (!gst_rtp_theora_depay_parse_inband_configuration (rtptheoradepay,
	ident, payload, payload_len, length))
	goto invalid_configuration;
	goto no_output;
	}

	/* create buffer for packet */
	outbuf =
	gst_buffer_copy_region (payload_buffer, GST_BUFFER_COPY_ALL,
	payload - map.data, length);

	if (payload_len > 0 && (payload[0] & 0xC0) == 0x0) {
	rtptheoradepay->needs_keyframe = FALSE;
	} else {
	GST_BUFFER_FLAG_SET (outbuf, GST_BUFFER_FLAG_DELTA_UNIT);
	}

	payload += length;
	payload_len -= length;
	/* make sure to read next length */
	length = 0;

	ret = gst_rtp_base_depayload_push (depayload, outbuf);
	if (ret != GST_FLOW_OK)
	break;
	}

	if (rtptheoradepay->needs_keyframe)
	goto request_keyframe;

	out:
	no_output:

	if (payload_buffer) {
	gst_buffer_unmap (payload_buffer, &map);
	gst_buffer_unref (payload_buffer);
	}

	return NULL;

	/* ERORRS */
	switch_failed:
	{
	GST_ELEMENT_WARNING (rtptheoradepay, STREAM, DECODE,
	(NULL), ("Could not switch codebooks"));
	goto request_config;
	}
	packet_short:
	{
	GST_ELEMENT_WARNING (rtptheoradepay, STREAM, DECODE,
	(NULL), ("Packet was too short (%d < 4)", payload_len));
	goto request_keyframe;
	}
	ignore_reserved:
	{
	GST_WARNING_OBJECT (rtptheoradepay, "reserved TDT ignored");
	goto out;
	}
	length_short:
	{
	GST_ELEMENT_WARNING (rtptheoradepay, STREAM, DECODE,
	(NULL), ("Packet contains invalid data"));
	goto request_keyframe;
	}
	invalid_configuration:
	{
	/* fatal, as we otherwise risk carrying on without output */
	GST_ELEMENT_ERROR (rtptheoradepay, STREAM, DECODE,
	(NULL), ("Packet contains invalid configuration"));
	goto request_config;
	}
	request_config:
	{
	gst_pad_push_event (GST_RTP_BASE_DEPAYLOAD_SINKPAD (depayload),
	gst_event_new_custom (GST_EVENT_CUSTOM_UPSTREAM,
	gst_structure_new ("GstForceKeyUnit",
	"all-headers", G_TYPE_BOOLEAN, TRUE, NULL)));
	goto out;
	}
	request_keyframe:
	{
	rtptheoradepay->needs_keyframe = TRUE;
	gst_pad_push_event (GST_RTP_BASE_DEPAYLOAD_SINKPAD (depayload),
	gst_event_new_custom (GST_EVENT_CUSTOM_UPSTREAM,
	gst_structure_new_empty ("GstForceKeyUnit")));
	goto out;
	}
	}

	static GstStateChangeReturn
	gst_rtp_theora_depay_change_state (GstElement * element,
	GstStateChange transition)
	{
	GstRtpTheoraDepay *rtptheoradepay;
	GstStateChangeReturn ret;

	rtptheoradepay = GST_RTP_THEORA_DEPAY (element);

	switch (transition) {
	case GST_STATE_CHANGE_NULL_TO_READY:
	break;
	case GST_STATE_CHANGE_READY_TO_PAUSED:
	break;
	default:
	break;
	}

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

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

	gboolean
	gst_rtp_theora_depay_plugin_init (GstPlugin * plugin)
	{
	return gst_element_register (plugin, "rtptheoradepay",
	GST_RANK_SECONDARY, GST_TYPE_RTP_THEORA_DEPAY);
	}

	static gboolean
	gst_rtp_theora_depay_packet_lost (GstRTPBaseDepayload * depayload,
	GstEvent * event)
	{
	GstRtpTheoraDepay *rtptheoradepay = GST_RTP_THEORA_DEPAY (depayload);
	guint seqnum = 0;

	gst_structure_get_uint (gst_event_get_structure (event), "seqnum", &seqnum);
	GST_LOG_OBJECT (depayload, "Requested keyframe because frame with seqnum %u"
	" is missing", seqnum);
	rtptheoradepay->needs_keyframe = TRUE;

	gst_pad_push_event (GST_RTP_BASE_DEPAYLOAD_SINKPAD (depayload),
	gst_event_new_custom (GST_EVENT_CUSTOM_UPSTREAM,
	gst_structure_new_empty ("GstForceKeyUnit")));

	return TRUE;
	}