gstreamer/gst/transcode/gsttranscodebin.c

/* GStreamer
 * Copyright (C) 2019 Thibault Saunier <tsaunier@igalia.com>
 *
 * gsttranscodebin.c:
 *
 * 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 "gsttranscoding.h"
#include <gst/gst-i18n-plugin.h>
#include <gst/pbutils/pbutils.h>

#include <gst/pbutils/missing-plugins.h>

GST_DEBUG_CATEGORY_STATIC (gst_transcodebin_debug);
#define GST_CAT_DEFAULT gst_transcodebin_debug

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

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

typedef struct
{
  GstBin parent;

  GstElement *decodebin;
  GstElement *encodebin;

  GstEncodingProfile *profile;
  gboolean avoid_reencoding;
  GstPad *sinkpad;
  GstPad *srcpad;

  GstElement *audio_filter;
  GstElement *video_filter;
} GstTranscodeBin;

typedef struct
{
  GstBinClass parent;

} GstTranscodeBinClass;

/* *INDENT-OFF* */
#define GST_TYPE_TRANSCODE_BIN (gst_transcode_bin_get_type ())
#define GST_TRANSCODE_BIN(obj) (G_TYPE_CHECK_INSTANCE_CAST ((obj), GST_TYPE_TRANSCODE_BIN, GstTranscodeBin))
#define GST_TRANSCODE_BIN_CLASS(klass) (G_TYPE_CHECK_CLASS_CAST ((klass), GST_TRANSCODE_BIN_TYPE, GstTranscodeBinClass))
#define GST_IS_TRANSCODE_BIN(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GST_TRANSCODE_BIN_TYPE))
#define GST_IS_TRANSCODE_BIN_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GST_TRANSCODE_BIN_TYPE))
#define GST_TRANSCODE_BIN_GET_CLASS(obj) (G_TYPE_INSTANCE_GET_CLASS ((obj), GST_TRANSCODE_BIN_TYPE, GstTranscodeBinClass))

#define DEFAULT_AVOID_REENCODING   FALSE

G_DEFINE_TYPE (GstTranscodeBin, gst_transcode_bin, GST_TYPE_BIN)
enum
{
 PROP_0,
 PROP_PROFILE,
 PROP_AVOID_REENCODING,
 PROP_VIDEO_FILTER,
 PROP_AUDIO_FILTER,
 LAST_PROP
};

static void
post_missing_plugin_error (GstElement * dec, const gchar * element_name)
{
  GstMessage *msg;

  msg = gst_missing_element_message_new (dec, element_name);
  gst_element_post_message (dec, msg);

  GST_ELEMENT_ERROR (dec, CORE, MISSING_PLUGIN,
      ("Missing element '%s' - check your GStreamer installation.",
          element_name), (NULL));
}
/* *INDENT-ON* */

static GstPad *
_insert_filter (GstTranscodeBin * self, GstPad * sinkpad, GstPad * pad,
    GstCaps * caps)
{
  GstPad *filter_src = NULL, *filter_sink = NULL, *convert_sink, *convert_src;
  GstElement *filter = NULL, *convert;
  GstObject *filter_parent;
  const gchar *media_type;
  gboolean audio = TRUE;

  media_type = gst_structure_get_name (gst_caps_get_structure (caps, 0));

  if (self->video_filter && g_str_has_prefix (media_type, "video")) {
    audio = FALSE;

    if (!g_strcmp0 (media_type, "video/x-raw"))
      filter = self->video_filter;
    else
      GST_ERROR_OBJECT (pad, "decodebin pad does not produce raw data (%"
          GST_PTR_FORMAT "), cannot add video filter '%s'", caps,
          GST_ELEMENT_NAME (self->video_filter));
  } else if (self->audio_filter && g_str_has_prefix (media_type, "audio")) {
    if (!g_strcmp0 (media_type, "audio/x-raw"))
      filter = self->audio_filter;
    else
      GST_ERROR_OBJECT (pad, "decodebin pad does not produce raw data (%"
          GST_PTR_FORMAT "), cannot add audio filter '%s'", caps,
          GST_ELEMENT_NAME (self->audio_filter));
  }

  if (!filter)
    return pad;

  if ((filter_parent = gst_object_get_parent (GST_OBJECT (filter)))) {
    GST_WARNING_OBJECT (self,
        "Filter already in use (inside %" GST_PTR_FORMAT ").", filter_parent);
    GST_FIXME_OBJECT (self,
        "Handle transcoding several streams of a same kind.");
    gst_object_unref (filter_parent);

    return pad;
  }

  /* We are guaranteed filters only have 1 unique sinkpad and srcpad */
  GST_OBJECT_LOCK (filter);
  filter_sink = filter->sinkpads->data;
  filter_src = filter->srcpads->data;
  GST_OBJECT_UNLOCK (filter);

  if (audio)
    convert = gst_element_factory_make ("audioconvert", NULL);
  else
    convert = gst_element_factory_make ("videoconvert", NULL);

  if (!convert) {
    GST_ELEMENT_ERROR (self, CORE, MISSING_PLUGIN,
        (_("Missing element '%s' - check your GStreamer installation."),
            audio ? "audioconvert" : "videoconvert"),
        ("Cannot add filter as %s element is missing",
            audio ? "audioconvert" : "videoconvert"));
    return pad;
  }

  gst_bin_add_many (GST_BIN (self), convert, gst_object_ref (filter), NULL);

  convert_sink = gst_element_get_static_pad (convert, "sink");
  g_assert (convert_sink);

  if (G_UNLIKELY (gst_pad_link (pad, convert_sink) != GST_PAD_LINK_OK)) {
    GstCaps *othercaps = gst_pad_get_pad_template_caps (convert_sink);
    caps = gst_pad_get_current_caps (pad);

    GST_ELEMENT_ERROR (self, CORE, PAD,
        (NULL),
        ("Couldn't link pads \n\n %" GST_PTR_FORMAT ": %" GST_PTR_FORMAT
            "\n\n  and \n\n %" GST_PTR_FORMAT ": %" GST_PTR_FORMAT
            "\n\n", pad, caps, convert_sink, othercaps));

    gst_object_unref (convert_sink);
    gst_caps_unref (caps);
    gst_caps_unref (othercaps);
  }

  gst_object_unref (convert_sink);

  convert_src = gst_element_get_static_pad (convert, "src");
  g_assert (convert_src);

  if (G_UNLIKELY (gst_pad_link (convert_src, filter_sink) != GST_PAD_LINK_OK)) {
    GstCaps *othercaps = gst_pad_get_pad_template_caps (filter_sink);
    caps = gst_pad_get_pad_template_caps (convert_src);

    GST_ELEMENT_ERROR (self, CORE, PAD,
        (NULL),
        ("Couldn't link pads \n\n %" GST_PTR_FORMAT ": %" GST_PTR_FORMAT
            "\n\n  and \n\n %" GST_PTR_FORMAT ": %" GST_PTR_FORMAT
            "\n\n", convert_src, caps, filter_sink, othercaps));

    gst_object_unref (convert_src);
    gst_caps_unref (caps);
    gst_caps_unref (othercaps);
  }

  gst_object_unref (convert_src);

  gst_element_sync_state_with_parent (convert);
  gst_element_sync_state_with_parent (filter);

  GST_DEBUG_OBJECT (self, "added %s filter '%s'",
      audio ? "audio" : "video", GST_ELEMENT_NAME (filter));

  return filter_src;
}

static void
pad_added_cb (GstElement * decodebin, GstPad * pad, GstTranscodeBin * self)
{
  GstCaps *caps;
  GstPad *sinkpad = NULL;
  GstPadLinkReturn lret;

  caps = gst_pad_query_caps (pad, NULL);

  GST_DEBUG_OBJECT (decodebin, "Pad added, caps: %" GST_PTR_FORMAT, caps);

  g_signal_emit_by_name (self->encodebin, "request-pad", caps, &sinkpad);

  if (sinkpad == NULL) {
    gchar *stream_id = gst_pad_get_stream_id (pad);

    GST_ELEMENT_WARNING_WITH_DETAILS (self, STREAM, FORMAT,
        (NULL), ("Stream with caps: %" GST_PTR_FORMAT " can not be"
            " encoded in the defined encoding formats",
            caps),
        ("can-t-encode-stream", G_TYPE_BOOLEAN, TRUE,
            "stream-caps", GST_TYPE_CAPS, caps,
            "stream-id", G_TYPE_STRING, stream_id, NULL));

    g_free (stream_id);
    return;
  }

  if (caps)
    gst_caps_unref (caps);

  pad = _insert_filter (self, sinkpad, pad, caps);
  lret = gst_pad_link (pad, sinkpad);
  switch (lret) {
    case GST_PAD_LINK_OK:
      break;
    case GST_PAD_LINK_WAS_LINKED:
      GST_FIXME_OBJECT (self, "Pad %" GST_PTR_FORMAT " was already linked",
          sinkpad);
      break;
    default:
    {
      GstCaps *othercaps = gst_pad_query_caps (sinkpad, NULL);
      caps = gst_pad_get_current_caps (pad);

      GST_ELEMENT_ERROR_WITH_DETAILS (self, CORE, PAD,
          (NULL),
          ("Couldn't link pads:\n    %" GST_PTR_FORMAT ": %" GST_PTR_FORMAT
              "\nand:\n"
              "    %" GST_PTR_FORMAT ": %" GST_PTR_FORMAT "\n\n",
              pad, caps, sinkpad, othercaps),
          ("linking-error", GST_TYPE_PAD_LINK_RETURN, lret,
              "source-pad", GST_TYPE_PAD, pad,
              "source-caps", GST_TYPE_CAPS, caps,
              "sink-pad", GST_TYPE_PAD, sinkpad,
              "sink-caps", GST_TYPE_CAPS, othercaps, NULL));

      gst_clear_caps (&caps);
      if (othercaps)
        gst_caps_unref (othercaps);
    }
  }

  gst_object_unref (sinkpad);
}

static gboolean
make_encodebin (GstTranscodeBin * self)
{
  GstPad *pad;
  GST_INFO_OBJECT (self, "making new encodebin");

  if (!self->profile)
    goto no_profile;

  self->encodebin = gst_element_factory_make ("encodebin", NULL);
  if (!self->encodebin)
    goto no_encodebin;

  gst_bin_add (GST_BIN (self), self->encodebin);
  g_object_set (self->encodebin, "profile", self->profile, NULL);

  pad = gst_element_get_static_pad (self->encodebin, "src");
  if (!gst_ghost_pad_set_target (GST_GHOST_PAD_CAST (self->srcpad), pad)) {

    gst_object_unref (pad);
    GST_ERROR_OBJECT (self, "Could not ghost %" GST_PTR_FORMAT " srcpad",
        self->encodebin);

    return FALSE;
  }
  gst_object_unref (pad);

  return gst_element_sync_state_with_parent (self->encodebin);

  /* ERRORS */
no_encodebin:
  {
    post_missing_plugin_error (GST_ELEMENT_CAST (self), "encodebin");

    GST_ELEMENT_ERROR (self, CORE, MISSING_PLUGIN, (NULL),
        ("No encodebin element, check your installation"));

    return FALSE;
  }
  /* ERRORS */
no_profile:
  {
    GST_ELEMENT_ERROR (self, CORE, MISSING_PLUGIN, (NULL),
        ("No GstEncodingProfile set, can not run."));

    return FALSE;
  }
}

static gboolean
make_decodebin (GstTranscodeBin * self)
{
  GstPad *pad;
  GST_INFO_OBJECT (self, "making new decodebin");

  self->decodebin = gst_element_factory_make ("decodebin", NULL);

  if (!self->decodebin)
    goto no_decodebin;

  if (self->avoid_reencoding) {
    GstCaps *decodecaps;

    g_object_get (self->decodebin, "caps", &decodecaps, NULL);
    if (GST_IS_ENCODING_CONTAINER_PROFILE (self->profile)) {
      GList *tmp;

      decodecaps = gst_caps_make_writable (decodecaps);
      for (tmp = (GList *)
          gst_encoding_container_profile_get_profiles
          (GST_ENCODING_CONTAINER_PROFILE (self->profile)); tmp;
          tmp = tmp->next) {
        GstEncodingProfile *profile = tmp->data;
        GstCaps *restrictions;

        restrictions = gst_encoding_profile_get_restriction (profile);

        if (!restrictions || gst_caps_is_any (restrictions)) {
          GstCaps *encodecaps = gst_encoding_profile_get_format (profile);
          GstElement *filter = NULL;

          /* Filter operates on raw data so don't allow decodebin to produce
           * encoded data if one is defined. */
          if (GST_IS_ENCODING_VIDEO_PROFILE (profile) && self->video_filter)
            filter = self->video_filter;
          else if (GST_IS_ENCODING_AUDIO_PROFILE (profile)
              && self->audio_filter)
            filter = self->audio_filter;

          if (!filter) {
            GST_DEBUG_OBJECT (self,
                "adding %" GST_PTR_FORMAT " as output caps to decodebin",
                encodecaps);
            gst_caps_append (decodecaps, encodecaps);
          }
        } else {
          gst_caps_unref (restrictions);
        }
      }
    }
    g_object_set (self->decodebin, "caps", decodecaps, NULL);
    gst_caps_unref (decodecaps);
  }

  g_signal_connect (self->decodebin, "pad-added", G_CALLBACK (pad_added_cb),
      self);

  gst_bin_add (GST_BIN (self), self->decodebin);
  pad = gst_element_get_static_pad (self->decodebin, "sink");
  if (!gst_ghost_pad_set_target (GST_GHOST_PAD_CAST (self->sinkpad), pad)) {

    gst_object_unref (pad);
    GST_ERROR_OBJECT (self, "Could not ghost %" GST_PTR_FORMAT " sinkpad",
        self->decodebin);

    return FALSE;
  }

  gst_object_unref (pad);
  return TRUE;

  /* ERRORS */
no_decodebin:
  {
    post_missing_plugin_error (GST_ELEMENT_CAST (self), "decodebin");
    GST_ELEMENT_ERROR (self, CORE, MISSING_PLUGIN, (NULL),
        ("No decodebin element, check your installation"));

    return FALSE;
  }
}

static void
remove_all_children (GstTranscodeBin * self)
{
  if (self->encodebin) {
    gst_element_set_state (self->encodebin, GST_STATE_NULL);
    gst_bin_remove (GST_BIN (self), self->encodebin);
    self->encodebin = NULL;
  }

  if (self->video_filter && GST_OBJECT_PARENT (self->video_filter)) {
    gst_element_set_state (self->video_filter, GST_STATE_NULL);
    gst_bin_remove (GST_BIN (self), self->video_filter);
  }

  if (self->audio_filter && GST_OBJECT_PARENT (self->audio_filter)) {
    gst_element_set_state (self->audio_filter, GST_STATE_NULL);
    gst_bin_remove (GST_BIN (self), self->audio_filter);
  }

  if (self->decodebin) {
    gst_element_set_state (self->decodebin, GST_STATE_NULL);
    gst_bin_remove (GST_BIN (self), self->decodebin);
    self->decodebin = NULL;
  }
}

static GstStateChangeReturn
gst_transcode_bin_change_state (GstElement * element, GstStateChange transition)
{
  GstStateChangeReturn ret;
  GstTranscodeBin *self = GST_TRANSCODE_BIN (element);

  switch (transition) {
    case GST_STATE_CHANGE_READY_TO_PAUSED:

      if (!make_encodebin (self))
        goto setup_failed;

      if (!make_decodebin (self))
        goto setup_failed;

      break;
    default:
      break;
  }

  ret =
      GST_ELEMENT_CLASS (gst_transcode_bin_parent_class)->change_state (element,
      transition);
  if (ret == GST_STATE_CHANGE_FAILURE)
    goto beach;

  switch (transition) {
    case GST_STATE_CHANGE_PAUSED_TO_READY:
      remove_all_children (self);
      break;
    default:
      break;
  }

beach:
  return ret;

setup_failed:
  remove_all_children (self);
  return GST_STATE_CHANGE_FAILURE;
}

static void
gst_transcode_bin_dispose (GObject * object)
{
  GstTranscodeBin *self = (GstTranscodeBin *) object;

  g_clear_object (&self->video_filter);
  g_clear_object (&self->audio_filter);

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

static void
gst_transcode_bin_get_property (GObject * object,
    guint prop_id, GValue * value, GParamSpec * pspec)
{
  GstTranscodeBin *self = GST_TRANSCODE_BIN (object);

  switch (prop_id) {
    case PROP_PROFILE:
      GST_OBJECT_LOCK (self);
      g_value_set_object (value, self->profile);
      GST_OBJECT_UNLOCK (self);
      break;
    case PROP_AVOID_REENCODING:
      GST_OBJECT_LOCK (self);
      g_value_set_boolean (value, self->avoid_reencoding);
      GST_OBJECT_UNLOCK (self);
      break;
    case PROP_AUDIO_FILTER:
      GST_OBJECT_LOCK (self);
      g_value_set_object (value, self->audio_filter);
      GST_OBJECT_UNLOCK (self);
      break;
    case PROP_VIDEO_FILTER:
      GST_OBJECT_LOCK (self);
      g_value_set_object (value, self->video_filter);
      GST_OBJECT_UNLOCK (self);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
  }
}

static void
_set_filter (GstTranscodeBin * self, GstElement * filter, GstElement ** mfilter)
{
  if (filter) {
    GST_OBJECT_LOCK (filter);
    if (filter->numsinkpads != 1) {
      GST_ERROR_OBJECT (self, "Can not use %" GST_PTR_FORMAT
          " as filter as it does not have "
          " one and only one sinkpad", filter);
      goto bail_out;
    } else if (filter->numsrcpads != 1) {
      GST_ERROR_OBJECT (self, "Can not use %" GST_PTR_FORMAT
          " as filter as it does not have " " one and only one srcpad", filter);
      goto bail_out;
    }
    GST_OBJECT_UNLOCK (filter);
  }

  GST_OBJECT_LOCK (self);
  *mfilter = filter;
  GST_OBJECT_UNLOCK (self);

  return;

bail_out:
  GST_OBJECT_UNLOCK (filter);
}

static void
gst_transcode_bin_set_property (GObject * object,
    guint prop_id, const GValue * value, GParamSpec * pspec)
{
  GstTranscodeBin *self = GST_TRANSCODE_BIN (object);

  switch (prop_id) {
    case PROP_PROFILE:
      GST_OBJECT_LOCK (self);
      self->profile = g_value_dup_object (value);
      GST_OBJECT_UNLOCK (self);
      break;
    case PROP_AVOID_REENCODING:
      GST_OBJECT_LOCK (self);
      self->avoid_reencoding = g_value_get_boolean (value);
      GST_OBJECT_UNLOCK (self);
      break;
    case PROP_AUDIO_FILTER:
      _set_filter (self, g_value_dup_object (value), &self->audio_filter);
      break;
    case PROP_VIDEO_FILTER:
      _set_filter (self, g_value_dup_object (value), &self->video_filter);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
  }
}

static void
gst_transcode_bin_class_init (GstTranscodeBinClass * klass)
{
  GObjectClass *object_class = G_OBJECT_CLASS (klass);
  GstElementClass *gstelement_klass;

  object_class->dispose = gst_transcode_bin_dispose;
  object_class->get_property = gst_transcode_bin_get_property;
  object_class->set_property = gst_transcode_bin_set_property;

  gstelement_klass = (GstElementClass *) klass;
  gstelement_klass->change_state =
      GST_DEBUG_FUNCPTR (gst_transcode_bin_change_state);

  gst_element_class_add_pad_template (gstelement_klass,
      gst_static_pad_template_get (&transcode_bin_sink_template));
  gst_element_class_add_pad_template (gstelement_klass,
      gst_static_pad_template_get (&transcode_bin_src_template));

  gst_element_class_set_static_metadata (gstelement_klass,
      "Transcode Bin", "Generic/Bin/Encoding",
      "Autoplug and transcoder a stream",
      "Thibault Saunier <tsaunier@igalia.com>");

  /**
   * GstTranscodeBin:profile:
   *
   * The #GstEncodingProfile to use. This property must be set before going
   * to %GST_STATE_PAUSED or higher.
   */
  g_object_class_install_property (object_class, PROP_PROFILE,
      g_param_spec_object ("profile", "Profile",
          "The GstEncodingProfile to use", GST_TYPE_ENCODING_PROFILE,
          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS |
          GST_PARAM_MUTABLE_READY));

  /**
   * GstTranscodeBin:avoid-reencoding:
   *
   * See #encodebin:avoid-reencoding
   */
  g_object_class_install_property (object_class, PROP_AVOID_REENCODING,
      g_param_spec_boolean ("avoid-reencoding", "Avoid re-encoding",
          "Whether to re-encode portions of compatible video streams that lay on segment boundaries",
          DEFAULT_AVOID_REENCODING,
          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS |
          GST_PARAM_MUTABLE_READY));

  /**
   * GstTranscodeBin:video-filter:
   *
   * Set the video filter element/bin to use.
   */
  g_object_class_install_property (object_class, PROP_VIDEO_FILTER,
      g_param_spec_object ("video-filter", "Video filter",
          "the video filter(s) to apply, if possible",
          GST_TYPE_ELEMENT, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS |
          GST_PARAM_MUTABLE_READY));
  /**
   * GstTranscodeBin:audio-filter:
   *
   * Set the audio filter element/bin to use.
   */
  g_object_class_install_property (object_class, PROP_AUDIO_FILTER,
      g_param_spec_object ("audio-filter", "Audio filter",
          "the audio filter(s) to apply, if possible",
          GST_TYPE_ELEMENT, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS |
          GST_PARAM_MUTABLE_READY));
}

static void
gst_transcode_bin_init (GstTranscodeBin * self)
{
  GstPadTemplate *pad_tmpl;

  pad_tmpl = gst_static_pad_template_get (&transcode_bin_sink_template);
  self->sinkpad = gst_ghost_pad_new_no_target_from_template ("sink", pad_tmpl);
  gst_pad_set_active (self->sinkpad, TRUE);
  gst_element_add_pad (GST_ELEMENT (self), self->sinkpad);

  gst_object_unref (pad_tmpl);

  pad_tmpl = gst_static_pad_template_get (&transcode_bin_src_template);

  self->srcpad = gst_ghost_pad_new_no_target_from_template ("src", pad_tmpl);
  gst_pad_set_active (self->srcpad, TRUE);
  gst_element_add_pad (GST_ELEMENT (self), self->srcpad);

  gst_object_unref (pad_tmpl);
}

static gboolean
plugin_init (GstPlugin * plugin)
{
  gboolean res = TRUE;
  gst_pb_utils_init ();

  GST_DEBUG_CATEGORY_INIT (gst_transcodebin_debug, "transcodebin", 0,
      "Transcodebin element");

  res &= gst_element_register (plugin, "transcodebin", GST_RANK_NONE,
      GST_TYPE_TRANSCODE_BIN);

  res &= gst_element_register (plugin, "uritranscodebin", GST_RANK_NONE,
      gst_uri_transcode_bin_get_type ());

  return res;
}

GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
    GST_VERSION_MINOR,
    transcode,
    "A plugin containing elements for transcoding", plugin_init, VERSION,
    GST_LICENSE, GST_PACKAGE_NAME, GST_PACKAGE_ORIGIN)