/* GStreamer plugin for forward error correction

 * Copyright (C) 2017 Pexip

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

 *

 * Author: Mikhail Fludkov <misha@pexip.com>

 */

/**

 * SECTION:element-rtpulpfecdec

 * @short_description: Generic RTP Forward Error Correction (FEC) decoder

 * @title: rtpulpfecdec

 *

 * Generic Forward Error Correction (FEC) decoder for Uneven Level

 * Protection (ULP) as described in RFC 5109.

 *

 * This element will work in combination with an upstream #GstRtpStorage

 * element and attempt to recover packets declared lost through custom

 * 'GstRTPPacketLost' events, usually emitted by #GstRtpJitterBuffer.

 *

 * As such, this element cannot be usefully used from the command line,

 * because a reference to the upstream storage object needs to be

 * provided to it through its #GstRtpUlpFecDec:storage property, example

 * programs are available at

 * <https://github.com/sdroege/gstreamer-rs/blob/master/examples/src/bin/rtpfecserver.rs>

 * and

 * <https://github.com/sdroege/gstreamer-rs/blob/master/examples/src/bin/rtpfecclient.rs>.

 *

 * Additionally, the payload types of the protection packets *must* be

 * provided to this element via its #GstRtpUlpFecDec:pt property.

 *

 * When using #GstRtpBin, this element should be inserted through the

 * #GstRtpBin::request-fec-decoder signal.

 *

 * See also: #GstRtpUlpFecEnc, #GstRtpBin, #GstRtpStorage

 * Since: 1.14

 */

#include <gst/rtp/gstrtpbuffer.h>

#include <gst/rtp/gstrtp-enumtypes.h>

#include "rtpulpfeccommon.h"

#include "gstrtpulpfecdec.h"

static GstStaticPadTemplate sinktemplate = GST_STATIC_PAD_TEMPLATE ("sink",

    GST_PAD_SINK,

    GST_PAD_ALWAYS,

    GST_STATIC_CAPS ("application/x-rtp")

    );

static GstStaticPadTemplate srctemplate = GST_STATIC_PAD_TEMPLATE ("src",

    GST_PAD_SRC,

    GST_PAD_ALWAYS,

    GST_STATIC_CAPS ("application/x-rtp")

    );

enum

{

  PROP_0,

  PROP_PT,

  PROP_STORAGE,

  PROP_RECOVERED,

  PROP_UNRECOVERED,

  N_PROPERTIES

};

#define DEFAULT_FEC_PT 0

static GParamSpec *klass_properties[N_PROPERTIES] = { NULL, };

GST_DEBUG_CATEGORY (gst_rtp_ulpfec_dec_debug);

#define GST_CAT_DEFAULT (gst_rtp_ulpfec_dec_debug)

G_DEFINE_TYPE (GstRtpUlpFecDec, gst_rtp_ulpfec_dec, GST_TYPE_ELEMENT);

#define RTP_FEC_MAP_INFO_NTH(dec, data) (&g_array_index (\

    ((GstRtpUlpFecDec *)dec)->info_arr, \

    RtpUlpFecMapInfo, \

    GPOINTER_TO_UINT(data)))

static gint

_compare_fec_map_info (gconstpointer a, gconstpointer b, gpointer userdata)

{

  guint16 aseq =

      gst_rtp_buffer_get_seq (&RTP_FEC_MAP_INFO_NTH (userdata, a)->rtp);

  guint16 bseq =

      gst_rtp_buffer_get_seq (&RTP_FEC_MAP_INFO_NTH (userdata, b)->rtp);

  return gst_rtp_buffer_compare_seqnum (bseq, aseq);

}

static void

gst_rtp_ulpfec_dec_start (GstRtpUlpFecDec * self, GstBufferList * buflist,

    guint8 fec_pt, guint16 lost_seq)

{

  guint fec_packets = 0;

  gsize i;

  g_assert (NULL == self->info_media);

  g_assert (0 == self->info_fec->len);

  g_assert (0 == self->info_arr->len);

  g_array_set_size (self->info_arr, gst_buffer_list_length (buflist));

  for (i = 0;

      i < gst_buffer_list_length (buflist) && !self->lost_packet_from_storage;

      ++i) {

    GstBuffer *buffer = gst_buffer_list_get (buflist, i);

    RtpUlpFecMapInfo *info = RTP_FEC_MAP_INFO_NTH (self, i);

    if (!rtp_ulpfec_map_info_map (gst_buffer_ref (buffer), info))

      g_assert_not_reached ();

    if (fec_pt == gst_rtp_buffer_get_payload_type (&info->rtp)) {

      GST_DEBUG_RTP_PACKET (self, "rtp header (fec)", &info->rtp);

      ++fec_packets;

      if (rtp_ulpfec_buffer_is_valid (&info->rtp)) {

        GST_DEBUG_FEC_PACKET (self, &info->rtp);

        g_ptr_array_add (self->info_fec, GUINT_TO_POINTER (i));

      }

    } else {

      GST_LOG_RTP_PACKET (self, "rtp header (incoming)", &info->rtp);

      if (lost_seq == gst_rtp_buffer_get_seq (&info->rtp)) {

        GST_DEBUG_OBJECT (self, "Received lost packet from from the storage");

        g_list_free (self->info_media);

        self->info_media = NULL;

        self->lost_packet_from_storage = TRUE;

      }

      self->info_media =

          g_list_insert_sorted_with_data (self->info_media,

          GUINT_TO_POINTER (i), _compare_fec_map_info, self);

    }

  }

  if (!self->lost_packet_from_storage) {

    self->fec_packets_received += fec_packets;

    self->fec_packets_rejected += fec_packets - self->info_fec->len;

  }

}

static void

gst_rtp_ulpfec_dec_stop (GstRtpUlpFecDec * self)

{

  g_array_set_size (self->info_arr, 0);

  g_ptr_array_set_size (self->info_fec, 0);

  g_list_free (self->info_media);

  self->info_media = NULL;

  self->lost_packet_from_storage = FALSE;

  self->lost_packet_returned = FALSE;

}

static guint64

gst_rtp_ulpfec_dec_get_media_buffers_mask (GstRtpUlpFecDec * self,

    guint16 fec_seq_base)

{

  guint64 mask = 0;

  GList *it;

  for (it = self->info_media; it; it = it->next) {

    RtpUlpFecMapInfo *info = RTP_FEC_MAP_INFO_NTH (self, it->data);

    mask |=

        rtp_ulpfec_packet_mask_from_seqnum (gst_rtp_buffer_get_seq (&info->rtp),

        fec_seq_base, TRUE);

  }

  return mask;

}

static gboolean

gst_rtp_ulpfec_dec_is_recovered_pt_valid (GstRtpUlpFecDec * self, gint media_pt,

    guint8 recovered_pt)

{

  GList *it;

  if (media_pt == recovered_pt)

    return TRUE;

  for (it = self->info_media; it; it = it->next) {

    RtpUlpFecMapInfo *info = RTP_FEC_MAP_INFO_NTH (self, it->data);

    if (gst_rtp_buffer_get_payload_type (&info->rtp) == recovered_pt)

      return TRUE;

  }

  return FALSE;

}

static GstBuffer *

gst_rtp_ulpfec_dec_recover_from_fec (GstRtpUlpFecDec * self,

    RtpUlpFecMapInfo * info_fec, guint32 ssrc, gint media_pt, guint16 seq,

    guint8 * dst_pt)

{

  guint64 fec_mask = rtp_ulpfec_buffer_get_mask (&info_fec->rtp);

  gboolean fec_mask_long = rtp_ulpfec_buffer_get_fechdr (&info_fec->rtp)->L;

  guint16 fec_seq_base = rtp_ulpfec_buffer_get_seq_base (&info_fec->rtp);

  GstBuffer *ret;

  GList *it;

  g_array_set_size (self->scratch_buf, 0);

  rtp_buffer_to_ulpfec_bitstring (&info_fec->rtp, self->scratch_buf, TRUE,

      fec_mask_long);

  for (it = self->info_media; it; it = it->next) {

    RtpUlpFecMapInfo *info = RTP_FEC_MAP_INFO_NTH (self, it->data);

    guint64 packet_mask =

        rtp_ulpfec_packet_mask_from_seqnum (gst_rtp_buffer_get_seq (&info->rtp),

        fec_seq_base, TRUE);

    if (fec_mask & packet_mask) {

      fec_mask ^= packet_mask;

      rtp_buffer_to_ulpfec_bitstring (&info->rtp, self->scratch_buf, FALSE,

          fec_mask_long);

    }

  }

  ret =

      rtp_ulpfec_bitstring_to_media_rtp_buffer (self->scratch_buf,

      fec_mask_long, ssrc, seq);

  if (ret) {

    /* We are about to put recovered packet back in self->info_media to be able

     * to reuse it later for recovery of other packets

     **/

    gint i = self->info_arr->len;

    RtpUlpFecMapInfo *info;

    guint8 recovered_pt;

    g_array_set_size (self->info_arr, self->info_arr->len + 1);

    info = RTP_FEC_MAP_INFO_NTH (self, i);

    if (!rtp_ulpfec_map_info_map (gst_buffer_ref (ret), info)) {

      GST_WARNING_OBJECT (self, "Invalid recovered packet");

      goto recovered_packet_invalid;

    }

    recovered_pt = gst_rtp_buffer_get_payload_type (&info->rtp);

    if (!gst_rtp_ulpfec_dec_is_recovered_pt_valid (self, media_pt,

            recovered_pt)) {

      GST_WARNING_OBJECT (self,

          "Recovered packet has unexpected payload type (%u)", recovered_pt);

      goto recovered_packet_invalid;

    }

    GST_DEBUG_RTP_PACKET (self, "rtp header (recovered)", &info->rtp);

    self->info_media =

        g_list_insert_sorted_with_data (self->info_media, GUINT_TO_POINTER (i),

        _compare_fec_map_info, self);

    *dst_pt = recovered_pt;

  }

  return ret;

recovered_packet_invalid:

  g_array_set_size (self->info_arr, self->info_arr->len - 1);

  gst_buffer_unref (ret);

  return NULL;

}

static GstBuffer *

gst_rtp_ulpfec_dec_recover_from_storage (GstRtpUlpFecDec * self,

    guint8 * dst_pt, guint16 * dst_seq)

{

  RtpUlpFecMapInfo *info;

  if (self->lost_packet_returned)

    return NULL;

  g_assert (g_list_length (self->info_media) == 1);

  info = RTP_FEC_MAP_INFO_NTH (self, self->info_media->data);

  *dst_seq = gst_rtp_buffer_get_seq (&info->rtp);

  *dst_pt = gst_rtp_buffer_get_payload_type (&info->rtp);

  self->lost_packet_returned = TRUE;

  GST_DEBUG_RTP_PACKET (self, "rtp header (recovered)", &info->rtp);

  return gst_buffer_ref (info->rtp.buffer);

}

/* __has_builtin only works with clang, so test compiler version for gcc */

/* Intel compiler and MSVC probably have their own things as well */

/* TODO: make sure we use builtin for clang as well */

#if defined(__GNUC__) && __GNUC__ >= 4

#define rtp_ulpfec_ctz64 __builtin_ctzll

#else

static inline gint

rtp_ulpfec_ctz64_inline (guint64 mask)

{

  gint nth_bit = 0;

  do {

    if ((mask & 1))

      return nth_bit;

    mask = mask >> 1;

  } while (++nth_bit < 64);

  return -1;                    /* should not be reached, since mask must not be 0 */

}

#define rtp_ulpfec_ctz64 rtp_ulpfec_ctz64_inline

#endif

static GstBuffer *

gst_rtp_ulpfec_dec_recover (GstRtpUlpFecDec * self, guint32 ssrc, gint media_pt,

    guint8 * dst_pt, guint16 * dst_seq)

{

  guint64 media_mask = 0;

  gint media_mask_seq_base = -1;

  gsize i;

  if (self->lost_packet_from_storage)

    return gst_rtp_ulpfec_dec_recover_from_storage (self, dst_pt, dst_seq);

  /* Looking for a FEC packet which can be used for recovery */

  for (i = 0; i < self->info_fec->len; ++i) {

    RtpUlpFecMapInfo *info = RTP_FEC_MAP_INFO_NTH (self,

        g_ptr_array_index (self->info_fec, i));

    guint16 seq_base = rtp_ulpfec_buffer_get_seq_base (&info->rtp);

    guint64 fec_mask = rtp_ulpfec_buffer_get_mask (&info->rtp);

    guint64 missing_packets_mask;

    if (media_mask_seq_base != (gint) seq_base) {

      media_mask_seq_base = seq_base;

      media_mask = gst_rtp_ulpfec_dec_get_media_buffers_mask (self, seq_base);

    }

    /* media_mask has 1s if packet exist.

     * fec_mask is the mask of protected packets

     * The statement below excludes existing packets from the protected. So

     * we are left with 1s only for missing packets which can be recovered

     * by this FEC packet. */

    missing_packets_mask = fec_mask & (~media_mask);

    /* Do we have any 1s? Checking if current FEC packet can be used for recovery */

    if (0 != missing_packets_mask) {

      guint trailing_zeros = rtp_ulpfec_ctz64 (missing_packets_mask);

      /* Is it the only 1 in the mask? Checking if we lacking single packet in

       * that case FEC packet can be used for recovery */

      if (missing_packets_mask == (G_GUINT64_CONSTANT (1) << trailing_zeros)) {

        GstBuffer *ret;

        *dst_seq =

            seq_base + (RTP_ULPFEC_SEQ_BASE_OFFSET_MAX (TRUE) - trailing_zeros);

        ret =

            gst_rtp_ulpfec_dec_recover_from_fec (self, info, ssrc, media_pt,

            *dst_seq, dst_pt);

        if (ret)

          return ret;

      }

    }

  }

  return NULL;

}

static GstFlowReturn

gst_rtp_ulpfec_dec_chain (GstPad * pad, GstObject * parent, GstBuffer * buf)

{

  GstRtpUlpFecDec *self = GST_RTP_ULPFEC_DEC (parent);

  if (G_LIKELY (GST_FLOW_OK == self->chain_return_val)) {

    if (G_UNLIKELY (self->unset_discont_flag)) {

      self->unset_discont_flag = FALSE;

      buf = gst_buffer_make_writable (buf);

      GST_BUFFER_FLAG_UNSET (buf, GST_BUFFER_FLAG_DISCONT);

    }

    return gst_pad_push (self->srcpad, buf);

  }

  gst_buffer_unref (buf);

  return self->chain_return_val;

}

static gboolean

gst_rtp_ulpfec_dec_handle_packet_loss (GstRtpUlpFecDec * self, guint16 seqnum,

    GstClockTime timestamp, GstClockTime duration)

{

  gint caps_pt = self->have_caps_pt ? self->caps_pt : -1;

  gboolean ret = TRUE;

  GstBufferList *buflist =

      rtp_storage_get_packets_for_recovery (self->storage, self->fec_pt,

      self->caps_ssrc, seqnum);

  if (buflist) {

    GstBuffer *recovered_buffer = NULL;

    guint16 recovered_seq = 0;

    guint8 recovered_pt = 0;

    gst_rtp_ulpfec_dec_start (self, buflist, self->fec_pt, seqnum);

    while (NULL != (recovered_buffer =

            gst_rtp_ulpfec_dec_recover (self, self->caps_ssrc, caps_pt,

                &recovered_pt, &recovered_seq))) {

      if (seqnum == recovered_seq) {

        recovered_buffer = gst_buffer_make_writable (recovered_buffer);

        GST_BUFFER_PTS (recovered_buffer) = timestamp;

        /* GST_BUFFER_DURATION (recovered_buffer) = duration;

         * JB does not set the duration, so we will not too */

        if (!self->lost_packet_from_storage)

          rtp_storage_put_recovered_packet (self->storage,

              gst_buffer_ref (recovered_buffer), recovered_pt, self->caps_ssrc,

              recovered_seq);

        GST_DEBUG_OBJECT (self,

            "Pushing recovered packet ssrc=0x%08x seq=%u %" GST_PTR_FORMAT,

            self->caps_ssrc, seqnum, recovered_buffer);

        ret = FALSE;

        self->unset_discont_flag = TRUE;

        self->chain_return_val = gst_pad_push (self->srcpad, recovered_buffer);

        break;

      }

      rtp_storage_put_recovered_packet (self->storage,

          recovered_buffer, recovered_pt, self->caps_ssrc, recovered_seq);

    }

    gst_rtp_ulpfec_dec_stop (self);

    gst_buffer_list_unref (buflist);

  }

  GST_DEBUG_OBJECT (self, "Packet lost ssrc=0x%08x seq=%u", self->caps_ssrc,

      seqnum);

  return ret;

}

static gboolean

gst_rtp_ulpfec_dec_handle_sink_event (GstPad * pad, GstObject * parent,

    GstEvent * event)

{

  GstRtpUlpFecDec *self = GST_RTP_ULPFEC_DEC (parent);

  gboolean forward = TRUE;

  GST_LOG_OBJECT (self, "Received event %" GST_PTR_FORMAT, event);

  if (GST_FLOW_OK == self->chain_return_val &&

      GST_EVENT_CUSTOM_DOWNSTREAM == GST_EVENT_TYPE (event) &&

      gst_event_has_name (event, "GstRTPPacketLost")) {

    guint seqnum;

    GstClockTime timestamp, duration;

    g_assert (self->have_caps_ssrc);

    g_assert (self->storage);

    if (!gst_structure_get (gst_event_get_structure (event),

            "seqnum", G_TYPE_UINT, &seqnum,

            "timestamp", G_TYPE_UINT64, &timestamp,

            "duration", G_TYPE_UINT64, &duration, NULL))

      g_assert_not_reached ();

    forward =

        gst_rtp_ulpfec_dec_handle_packet_loss (self, seqnum, timestamp,

        duration);

    if (forward)

      ++self->packets_unrecovered;

    else

      ++self->packets_recovered;

    GST_DEBUG_OBJECT (self, "Unrecovered / Recovered: %lu / %lu",

        (gulong) self->packets_unrecovered, (gulong) self->packets_recovered);

  } else if (GST_EVENT_CAPS == GST_EVENT_TYPE (event)) {

    GstCaps *caps;

    gboolean have_caps_pt = FALSE;

    gboolean have_caps_ssrc = FALSE;

    guint caps_ssrc = 0;

    gint caps_pt = 0;

    gst_event_parse_caps (event, &caps);

    have_caps_ssrc =

        gst_structure_get_uint (gst_caps_get_structure (caps, 0), "ssrc",

        &caps_ssrc);

    have_caps_pt =

        gst_structure_get_int (gst_caps_get_structure (caps, 0), "payload",

        &caps_pt);

    if (self->have_caps_ssrc != have_caps_ssrc || self->caps_ssrc != caps_ssrc)

      GST_DEBUG_OBJECT (self, "SSRC changed %u, 0x%08x -> %u, 0x%08x",

          self->have_caps_ssrc, self->caps_ssrc, have_caps_ssrc, caps_ssrc);

    if (self->have_caps_pt != have_caps_pt || self->caps_pt != caps_pt)

      GST_DEBUG_OBJECT (self, "PT changed %u, %u -> %u, %u",

          self->have_caps_pt, self->caps_pt, have_caps_pt, caps_pt);

    self->have_caps_ssrc = have_caps_ssrc;

    self->have_caps_pt = have_caps_pt;

    self->caps_ssrc = caps_ssrc;

    self->caps_pt = caps_pt;

  }

  if (forward)

    return gst_pad_push_event (self->srcpad, event);

  gst_event_unref (event);

  return TRUE;

}

static void

gst_rtp_ulpfec_dec_init (GstRtpUlpFecDec * self)

{

  self->srcpad = gst_pad_new_from_static_template (&srctemplate, "src");

  self->sinkpad = gst_pad_new_from_static_template (&sinktemplate, "sink");

  GST_PAD_SET_PROXY_CAPS (self->sinkpad);

  GST_PAD_SET_PROXY_ALLOCATION (self->sinkpad);

  gst_pad_set_chain_function (self->sinkpad,

      GST_DEBUG_FUNCPTR (gst_rtp_ulpfec_dec_chain));

  gst_pad_set_event_function (self->sinkpad,

      GST_DEBUG_FUNCPTR (gst_rtp_ulpfec_dec_handle_sink_event));

  gst_element_add_pad (GST_ELEMENT (self), self->srcpad);

  gst_element_add_pad (GST_ELEMENT (self), self->sinkpad);

  self->fec_pt = DEFAULT_FEC_PT;

  self->chain_return_val = GST_FLOW_OK;

  self->have_caps_ssrc = FALSE;

  self->caps_ssrc = 0;

  self->info_fec = g_ptr_array_new ();

  self->info_arr = g_array_new (FALSE, TRUE, sizeof (RtpUlpFecMapInfo));

  g_array_set_clear_func (self->info_arr,

      (GDestroyNotify) rtp_ulpfec_map_info_unmap);

  self->scratch_buf = g_array_new (FALSE, TRUE, sizeof (guint8));

}

static void

gst_rtp_ulpfec_dec_dispose (GObject * obj)

{

  GstRtpUlpFecDec *self = GST_RTP_ULPFEC_DEC (obj);

  GST_INFO_OBJECT (self,

      " ssrc=0x%08x pt=%u"

      " packets_recovered=%" G_GSIZE_FORMAT

      " packets_unrecovered=%" G_GSIZE_FORMAT,

      self->caps_ssrc, self->caps_pt,

      self->packets_recovered, self->packets_unrecovered);

  if (self->storage)

    g_object_unref (self->storage);

  g_assert (NULL == self->info_media);

  g_assert (0 == self->info_fec->len);

  g_assert (0 == self->info_arr->len);

  if (self->fec_packets_received) {

    GST_INFO_OBJECT (self,

        " fec_packets_received=%" G_GSIZE_FORMAT

        " fec_packets_rejected=%" G_GSIZE_FORMAT

        " packets_rejected=%" G_GSIZE_FORMAT,

        self->fec_packets_received,

        self->fec_packets_rejected, self->packets_rejected);

  }

  g_ptr_array_free (self->info_fec, TRUE);

  g_array_free (self->info_arr, TRUE);

  g_array_free (self->scratch_buf, TRUE);

  G_OBJECT_CLASS (gst_rtp_ulpfec_dec_parent_class)->dispose (obj);

}

static void

gst_rtp_ulpfec_dec_set_property (GObject * object, guint prop_id,

    const GValue * value, GParamSpec * pspec)

{

  GstRtpUlpFecDec *self = GST_RTP_ULPFEC_DEC (object);

  switch (prop_id) {

    case PROP_PT:

      self->fec_pt = g_value_get_uint (value);

      break;

    case PROP_STORAGE:

      if (self->storage)

        g_object_unref (self->storage);

      self->storage = g_value_get_object (value);

      if (self->storage)

        g_object_ref (self->storage);

      break;

    default:

      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);

      break;

  }

}

static void

gst_rtp_ulpfec_dec_get_property (GObject * object, guint prop_id,

    GValue * value, GParamSpec * pspec)

{

  GstRtpUlpFecDec *self = GST_RTP_ULPFEC_DEC (object);

  switch (prop_id) {

    case PROP_PT:

      g_value_set_uint (value, self->fec_pt);

      break;

    case PROP_STORAGE:

      g_value_set_object (value, self->storage);

      break;

    case PROP_RECOVERED:

      g_value_set_uint (value, (guint) self->packets_recovered);

      break;

    case PROP_UNRECOVERED:

      g_value_set_uint (value, (guint) self->packets_unrecovered);

      break;

    default:

      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);

      break;

  }

}

static void

gst_rtp_ulpfec_dec_class_init (GstRtpUlpFecDecClass * klass)

{

  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);

  GstElementClass *element_class = GST_ELEMENT_CLASS (klass);

  GST_DEBUG_CATEGORY_INIT (gst_rtp_ulpfec_dec_debug,

      "rtpulpfecdec", 0, "RTP FEC Decoder");

  gst_element_class_add_pad_template (element_class,

      gst_static_pad_template_get (&srctemplate));

  gst_element_class_add_pad_template (element_class,

      gst_static_pad_template_get (&sinktemplate));

  gst_element_class_set_static_metadata (element_class,

      "RTP FEC Decoder",

      "Codec/Depayloader/Network/RTP",

      "Decodes RTP FEC (RFC5109)", "Mikhail Fludkov <misha@pexip.com>");

  gobject_class->set_property =

      GST_DEBUG_FUNCPTR (gst_rtp_ulpfec_dec_set_property);

  gobject_class->get_property =

      GST_DEBUG_FUNCPTR (gst_rtp_ulpfec_dec_get_property);

  gobject_class->dispose = GST_DEBUG_FUNCPTR (gst_rtp_ulpfec_dec_dispose);

  klass_properties[PROP_PT] = g_param_spec_uint ("pt", "pt",

      "FEC packets payload type", 0, 127,

      DEFAULT_FEC_PT, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);

  klass_properties[PROP_STORAGE] =

      g_param_spec_object ("storage", "RTP storage", "RTP storage",

      G_TYPE_OBJECT, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);

  klass_properties[PROP_RECOVERED] =

      g_param_spec_uint ("recovered", "recovered",

      "The number of recovered packets", 0, G_MAXUINT, 0,

      G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);

  klass_properties[PROP_UNRECOVERED] =

      g_param_spec_uint ("unrecovered", "unrecovered",

      "The number of unrecovered packets", 0, G_MAXUINT, 0,

      G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);

  g_object_class_install_properties (gobject_class, N_PROPERTIES,

      klass_properties);

  g_assert (rtp_ulpfec_ctz64 (G_GUINT64_CONSTANT (0x1)) == 0);

  g_assert (rtp_ulpfec_ctz64 (G_GUINT64_CONSTANT (0x8000000000000000)) == 63);

}