gstreamer/ext/celt/gstceltenc.c

/* GStreamer Celt Encoder
 * Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>
 * Copyright (C) <2008> Sebastian Dröge <sebastian.droege@collabora.co.uk>
 *
 * 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., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

/*
 * Based on the speexenc element
 */

/**
 * SECTION:element-celtenc
 * @see_also: celtdec, oggmux
 *
 * This element raw audio to CELT.
 *
 * <refsect2>
 * <title>Example pipelines</title>
 * |[
 * gst-launch -v audiotestsrc wave=sine num-buffers=100 ! audioconvert ! celtenc ! oggmux ! filesink location=sine.ogg
 * ]| Encode a test sine signal to Ogg/CELT.
 * </refsect2>
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <math.h>
#include <celt/celt.h>
#include <celt/celt_header.h>

#include <gst/gsttagsetter.h>
#include <gst/tag/tag.h>
#include <gst/audio/audio.h>
#include "gstceltenc.h"

GST_DEBUG_CATEGORY_STATIC (celtenc_debug);
#define GST_CAT_DEFAULT celtenc_debug

static GstStaticPadTemplate sink_factory = GST_STATIC_PAD_TEMPLATE ("sink",
    GST_PAD_SINK,
    GST_PAD_ALWAYS,
    GST_STATIC_CAPS ("audio/x-raw-int, "
        "rate = (int) [ 32000, 64000 ], "
        "channels = (int) [ 1, 2 ], "
        "endianness = (int) BYTE_ORDER, "
        "signed = (boolean) TRUE, " "width = (int) 16, " "depth = (int) 16")
    );

static GstStaticPadTemplate src_factory = GST_STATIC_PAD_TEMPLATE ("src",
    GST_PAD_SRC,
    GST_PAD_ALWAYS,
    GST_STATIC_CAPS ("audio/x-celt, "
        "rate = (int) [ 32000, 64000 ], "
        "channels = (int) [ 1, 2 ], " "frame-size = (int) [ 64, 512 ]")
    );

static const GstElementDetails celtenc_details =
GST_ELEMENT_DETAILS ("Celt audio encoder",
    "Codec/Encoder/Audio",
    "Encodes audio in Celt format",
    "Sebastian Dröge <sebastian.droege@collabora.co.uk>");

#define DEFAULT_BITRATE         64
#define DEFAULT_FRAMESIZE       480
#define DEFAULT_CBR             TRUE
#define DEFAULT_COMPLEXITY      9
#define DEFAULT_MAX_BITRATE     64

enum
{
  PROP_0,
  PROP_BITRATE,
  PROP_FRAMESIZE,
  PROP_CBR,
  PROP_COMPLEXITY,
  PROP_MAX_BITRATE
};

static void gst_celt_enc_finalize (GObject * object);

static gboolean gst_celt_enc_sinkevent (GstPad * pad, GstEvent * event);
static GstFlowReturn gst_celt_enc_chain (GstPad * pad, GstBuffer * buf);
static gboolean gst_celt_enc_setup (GstCeltEnc * enc);

static void gst_celt_enc_get_property (GObject * object, guint prop_id,
    GValue * value, GParamSpec * pspec);
static void gst_celt_enc_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec);
static GstStateChangeReturn gst_celt_enc_change_state (GstElement * element,
    GstStateChange transition);

static GstFlowReturn gst_celt_enc_encode (GstCeltEnc * enc, gboolean flush);

static void
gst_celt_enc_setup_interfaces (GType celtenc_type)
{
  static const GInterfaceInfo tag_setter_info = { NULL, NULL, NULL };
  const GInterfaceInfo preset_interface_info = {
    NULL,                       /* interface_init */
    NULL,                       /* interface_finalize */
    NULL                        /* interface_data */
  };

  g_type_add_interface_static (celtenc_type, GST_TYPE_TAG_SETTER,
      &tag_setter_info);
  g_type_add_interface_static (celtenc_type, GST_TYPE_PRESET,
      &preset_interface_info);

  GST_DEBUG_CATEGORY_INIT (celtenc_debug, "celtenc", 0, "Celt encoder");
}

GST_BOILERPLATE_FULL (GstCeltEnc, gst_celt_enc, GstElement, GST_TYPE_ELEMENT,
    gst_celt_enc_setup_interfaces);

static void
gst_celt_enc_base_init (gpointer g_class)
{
  GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);

  gst_element_class_add_pad_template (element_class,
      gst_static_pad_template_get (&src_factory));
  gst_element_class_add_pad_template (element_class,
      gst_static_pad_template_get (&sink_factory));
  gst_element_class_set_details_simple (element_class, "Celt audio encoder",
      "Codec/Encoder/Audio",
      "Encodes audio in Celt format",
      "Sebastian Dröge <sebastian.droege@collabora.co.uk>");
}

static void
gst_celt_enc_class_init (GstCeltEncClass * klass)
{
  GObjectClass *gobject_class;
  GstElementClass *gstelement_class;

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

  gobject_class->set_property = gst_celt_enc_set_property;
  gobject_class->get_property = gst_celt_enc_get_property;

  g_object_class_install_property (G_OBJECT_CLASS (klass), PROP_BITRATE,
      g_param_spec_int ("bitrate", "Encoding Bit-rate",
          "Specify an encoding bit-rate (in Kbps).",
          10, 320, DEFAULT_BITRATE,
          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
  g_object_class_install_property (gobject_class, PROP_FRAMESIZE,
      g_param_spec_int ("framesize", "Frame Size",
          "The number of samples per frame", 64, 512, DEFAULT_FRAMESIZE,
          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
  g_object_class_install_property (gobject_class, PROP_CBR,
      g_param_spec_boolean ("cbr", "Constant bit rate",
          "Constant bit rate", DEFAULT_CBR,
          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
  g_object_class_install_property (gobject_class, PROP_COMPLEXITY,
      g_param_spec_int ("complexity", "Complexity",
          "Complexity", 0, 10, DEFAULT_COMPLEXITY,
          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
  g_object_class_install_property (G_OBJECT_CLASS (klass), PROP_MAX_BITRATE,
      g_param_spec_int ("max-bitrate", "Maximum Encoding Bit-rate",
          "Specify a maximum encoding bit rate (in Kbps) for variable bit rate encoding.",
          10, 320, DEFAULT_MAX_BITRATE,
          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  gobject_class->finalize = GST_DEBUG_FUNCPTR (gst_celt_enc_finalize);

  gstelement_class->change_state =
      GST_DEBUG_FUNCPTR (gst_celt_enc_change_state);
}

static void
gst_celt_enc_finalize (GObject * object)
{
  GstCeltEnc *enc;

  enc = GST_CELT_ENC (object);

  g_object_unref (enc->adapter);

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

static gboolean
gst_celt_enc_sink_setcaps (GstPad * pad, GstCaps * caps)
{
  GstCeltEnc *enc;
  GstStructure *structure;
  GstCaps *otherpadcaps;

  enc = GST_CELT_ENC (GST_PAD_PARENT (pad));
  enc->setup = FALSE;
  enc->frame_size = DEFAULT_FRAMESIZE;
  otherpadcaps = gst_pad_get_allowed_caps (pad);

  structure = gst_caps_get_structure (caps, 0);
  gst_structure_get_int (structure, "channels", &enc->channels);
  gst_structure_get_int (structure, "rate", &enc->rate);

  if (otherpadcaps) {
    if (!gst_caps_is_empty (otherpadcaps)) {
      GstStructure *ps = gst_caps_get_structure (otherpadcaps, 0);
      gst_structure_get_int (ps, "frame-size", &enc->frame_size);
    }
    gst_caps_unref (otherpadcaps);
  }

  GST_DEBUG_OBJECT (pad, "channels=%d rate=%d frame-size=%d",
      enc->channels, enc->rate, enc->frame_size);

  gst_celt_enc_setup (enc);

  return enc->setup;
}


static GstCaps *
gst_celt_enc_sink_getcaps (GstPad * pad)
{
  GstCaps *caps = gst_caps_copy (gst_pad_get_pad_template_caps (pad));
  GstCaps *peercaps = NULL;
  GstCeltEnc *enc = GST_CELT_ENC (gst_pad_get_parent_element (pad));

  peercaps = gst_pad_peer_get_caps (enc->srcpad);

  if (peercaps) {
    if (!gst_caps_is_empty (peercaps) && !gst_caps_is_any (peercaps)) {
      GstStructure *ps = gst_caps_get_structure (peercaps, 0);
      GstStructure *s = gst_caps_get_structure (caps, 0);
      gint rate, channels;

      if (gst_structure_get_int (ps, "rate", &rate)) {
        gst_structure_fixate_field_nearest_int (s, "rate", rate);
      }

      if (gst_structure_get_int (ps, "channels", &channels)) {
        gst_structure_fixate_field_nearest_int (s, "channels", channels);
      }
    }
    gst_caps_unref (peercaps);
  }

  gst_object_unref (enc);

  return caps;
}


static gboolean
gst_celt_enc_convert_src (GstPad * pad, GstFormat src_format, gint64 src_value,
    GstFormat * dest_format, gint64 * dest_value)
{
  gboolean res = TRUE;
  GstCeltEnc *enc;
  gint64 avg;

  enc = GST_CELT_ENC (GST_PAD_PARENT (pad));

  if (enc->samples_in == 0 || enc->bytes_out == 0 || enc->rate == 0)
    return FALSE;

  avg = (enc->bytes_out * enc->rate) / (enc->samples_in);

  switch (src_format) {
    case GST_FORMAT_BYTES:
      switch (*dest_format) {
        case GST_FORMAT_TIME:
          *dest_value = src_value * GST_SECOND / avg;
          break;
        default:
          res = FALSE;
      }
      break;
    case GST_FORMAT_TIME:
      switch (*dest_format) {
        case GST_FORMAT_BYTES:
          *dest_value = src_value * avg / GST_SECOND;
          break;
        default:
          res = FALSE;
      }
      break;
    default:
      res = FALSE;
  }
  return res;
}

static gboolean
gst_celt_enc_convert_sink (GstPad * pad, GstFormat src_format,
    gint64 src_value, GstFormat * dest_format, gint64 * dest_value)
{
  gboolean res = TRUE;
  guint scale = 1;
  gint bytes_per_sample;
  GstCeltEnc *enc;

  enc = GST_CELT_ENC (GST_PAD_PARENT (pad));

  bytes_per_sample = enc->channels * 2;

  switch (src_format) {
    case GST_FORMAT_BYTES:
      switch (*dest_format) {
        case GST_FORMAT_DEFAULT:
          if (bytes_per_sample == 0)
            return FALSE;
          *dest_value = src_value / bytes_per_sample;
          break;
        case GST_FORMAT_TIME:
        {
          gint byterate = bytes_per_sample * enc->rate;

          if (byterate == 0)
            return FALSE;
          *dest_value = src_value * GST_SECOND / byterate;
          break;
        }
        default:
          res = FALSE;
      }
      break;
    case GST_FORMAT_DEFAULT:
      switch (*dest_format) {
        case GST_FORMAT_BYTES:
          *dest_value = src_value * bytes_per_sample;
          break;
        case GST_FORMAT_TIME:
          if (enc->rate == 0)
            return FALSE;
          *dest_value = src_value * GST_SECOND / enc->rate;
          break;
        default:
          res = FALSE;
      }
      break;
    case GST_FORMAT_TIME:
      switch (*dest_format) {
        case GST_FORMAT_BYTES:
          scale = bytes_per_sample;
          /* fallthrough */
        case GST_FORMAT_DEFAULT:
          *dest_value = src_value * scale * enc->rate / GST_SECOND;
          break;
        default:
          res = FALSE;
      }
      break;
    default:
      res = FALSE;
  }
  return res;
}

static gint64
gst_celt_enc_get_latency (GstCeltEnc * enc)
{
  return gst_util_uint64_scale (enc->frame_size, GST_SECOND, enc->rate);
}

static const GstQueryType *
gst_celt_enc_get_query_types (GstPad * pad)
{
  static const GstQueryType gst_celt_enc_src_query_types[] = {
    GST_QUERY_POSITION,
    GST_QUERY_DURATION,
    GST_QUERY_CONVERT,
    GST_QUERY_LATENCY,
    0
  };

  return gst_celt_enc_src_query_types;
}

static gboolean
gst_celt_enc_src_query (GstPad * pad, GstQuery * query)
{
  gboolean res = TRUE;
  GstCeltEnc *enc;

  enc = GST_CELT_ENC (gst_pad_get_parent (pad));

  switch (GST_QUERY_TYPE (query)) {
    case GST_QUERY_POSITION:
    {
      GstFormat fmt, req_fmt;
      gint64 pos, val;

      gst_query_parse_position (query, &req_fmt, NULL);
      if ((res = gst_pad_query_peer_position (enc->sinkpad, &req_fmt, &val))) {
        gst_query_set_position (query, req_fmt, val);
        break;
      }

      fmt = GST_FORMAT_TIME;
      if (!(res = gst_pad_query_peer_position (enc->sinkpad, &fmt, &pos)))
        break;

      if ((res =
              gst_pad_query_peer_convert (enc->sinkpad, fmt, pos, &req_fmt,
                  &val)))
        gst_query_set_position (query, req_fmt, val);

      break;
    }
    case GST_QUERY_DURATION:
    {
      GstFormat fmt, req_fmt;
      gint64 dur, val;

      gst_query_parse_duration (query, &req_fmt, NULL);
      if ((res = gst_pad_query_peer_duration (enc->sinkpad, &req_fmt, &val))) {
        gst_query_set_duration (query, req_fmt, val);
        break;
      }

      fmt = GST_FORMAT_TIME;
      if (!(res = gst_pad_query_peer_duration (enc->sinkpad, &fmt, &dur)))
        break;

      if ((res =
              gst_pad_query_peer_convert (enc->sinkpad, fmt, dur, &req_fmt,
                  &val))) {
        gst_query_set_duration (query, req_fmt, val);
      }
      break;
    }
    case GST_QUERY_CONVERT:
    {
      GstFormat src_fmt, dest_fmt;
      gint64 src_val, dest_val;

      gst_query_parse_convert (query, &src_fmt, &src_val, &dest_fmt, &dest_val);
      if (!(res = gst_celt_enc_convert_src (pad, src_fmt, src_val, &dest_fmt,
                  &dest_val)))
        goto error;
      gst_query_set_convert (query, src_fmt, src_val, dest_fmt, dest_val);
      break;
    }
    case GST_QUERY_LATENCY:
    {
      gboolean live;
      GstClockTime min_latency, max_latency;
      gint64 latency;

      if ((res = gst_pad_peer_query (pad, query))) {
        gst_query_parse_latency (query, &live, &min_latency, &max_latency);

        latency = gst_celt_enc_get_latency (enc);

        /* add our latency */
        min_latency += latency;
        if (max_latency != -1)
          max_latency += latency;

        gst_query_set_latency (query, live, min_latency, max_latency);
      }
      break;
    }
    default:
      res = gst_pad_peer_query (pad, query);
      break;
  }

error:

  gst_object_unref (enc);

  return res;
}

static gboolean
gst_celt_enc_sink_query (GstPad * pad, GstQuery * query)
{
  gboolean res = TRUE;
  GstCeltEnc *enc;

  enc = GST_CELT_ENC (GST_PAD_PARENT (pad));

  switch (GST_QUERY_TYPE (query)) {
    case GST_QUERY_CONVERT:
    {
      GstFormat src_fmt, dest_fmt;
      gint64 src_val, dest_val;

      gst_query_parse_convert (query, &src_fmt, &src_val, &dest_fmt, &dest_val);
      if (!(res =
              gst_celt_enc_convert_sink (pad, src_fmt, src_val, &dest_fmt,
                  &dest_val)))
        goto error;
      gst_query_set_convert (query, src_fmt, src_val, dest_fmt, dest_val);
      break;
    }
    default:
      res = gst_pad_query_default (pad, query);
      break;
  }

error:
  return res;
}

static void
gst_celt_enc_init (GstCeltEnc * enc, GstCeltEncClass * klass)
{
  enc->sinkpad = gst_pad_new_from_static_template (&sink_factory, "sink");
  gst_element_add_pad (GST_ELEMENT (enc), enc->sinkpad);
  gst_pad_set_event_function (enc->sinkpad,
      GST_DEBUG_FUNCPTR (gst_celt_enc_sinkevent));
  gst_pad_set_chain_function (enc->sinkpad,
      GST_DEBUG_FUNCPTR (gst_celt_enc_chain));
  gst_pad_set_setcaps_function (enc->sinkpad,
      GST_DEBUG_FUNCPTR (gst_celt_enc_sink_setcaps));
  gst_pad_set_getcaps_function (enc->sinkpad,
      GST_DEBUG_FUNCPTR (gst_celt_enc_sink_getcaps));
  gst_pad_set_query_function (enc->sinkpad,
      GST_DEBUG_FUNCPTR (gst_celt_enc_sink_query));

  enc->srcpad = gst_pad_new_from_static_template (&src_factory, "src");
  gst_pad_set_query_function (enc->srcpad,
      GST_DEBUG_FUNCPTR (gst_celt_enc_src_query));
  gst_pad_set_query_type_function (enc->srcpad,
      GST_DEBUG_FUNCPTR (gst_celt_enc_get_query_types));
  gst_element_add_pad (GST_ELEMENT (enc), enc->srcpad);

  enc->channels = -1;
  enc->rate = -1;

  enc->bitrate = DEFAULT_BITRATE;
  enc->frame_size = DEFAULT_FRAMESIZE;
  enc->cbr = DEFAULT_CBR;
  enc->complexity = DEFAULT_COMPLEXITY;
  enc->max_bitrate = DEFAULT_MAX_BITRATE;

  enc->setup = FALSE;
  enc->header_sent = FALSE;

  enc->adapter = gst_adapter_new ();
}

static GstBuffer *
gst_celt_enc_create_metadata_buffer (GstCeltEnc * enc)
{
  const GstTagList *tags;
  GstTagList *empty_tags;
  GstBuffer *comments = NULL;

  tags = gst_tag_setter_get_tag_list (GST_TAG_SETTER (enc));

  GST_DEBUG_OBJECT (enc, "tags = %" GST_PTR_FORMAT, tags);

  if (tags == NULL) {
    /* FIXME: better fix chain of callers to not write metadata at all,
     * if there is none */
    empty_tags = gst_tag_list_new ();
    tags = empty_tags;
  }
  comments = gst_tag_list_to_vorbiscomment_buffer (tags, NULL,
      0, "Encoded with GStreamer Celtenc");

  GST_BUFFER_OFFSET (comments) = enc->bytes_out;
  GST_BUFFER_OFFSET_END (comments) = 0;

  if (empty_tags)
    gst_tag_list_free (empty_tags);

  return comments;
}

static gboolean
gst_celt_enc_setup (GstCeltEnc * enc)
{
  gint error = CELT_OK;

  enc->setup = FALSE;

#ifdef HAVE_CELT_0_7
  enc->mode = celt_mode_create (enc->rate, enc->frame_size, &error);
#else
  enc->mode =
      celt_mode_create (enc->rate, enc->channels, enc->frame_size, &error);
#endif
  if (!enc->mode)
    goto mode_initialization_failed;

  celt_mode_info (enc->mode, CELT_GET_FRAME_SIZE, &enc->frame_size);

#ifdef HAVE_CELT_0_7
  celt_header_init (&enc->header, enc->mode, enc->channels);
#else
  celt_header_init (&enc->header, enc->mode);
#endif
  enc->header.nb_channels = enc->channels;

#ifdef HAVE_CELT_0_7
  enc->state = celt_encoder_create (enc->mode, enc->channels, &error);
#else
  enc->state = celt_encoder_create (enc->mode);
#endif
  if (!enc->state)
    goto encoder_creation_failed;

#ifdef CELT_SET_VBR_RATE
  if (!enc->cbr) {
    GST_ERROR ("setting vbr");
    celt_encoder_ctl (enc->state, CELT_SET_VBR_RATE (enc->bitrate), 0);
  }
#endif
#ifdef CELT_SET_COMPLEXITY
  celt_encoder_ctl (enc->state, CELT_SET_COMPLEXITY (enc->complexity), 0);
#endif

  GST_LOG_OBJECT (enc, "we have frame size %d", enc->frame_size);

  enc->setup = TRUE;

  return TRUE;

mode_initialization_failed:
  GST_ERROR_OBJECT (enc, "Mode initialization failed: %d", error);
  return FALSE;

encoder_creation_failed:
#ifdef HAVE_CELT_0_7
  GST_ERROR_OBJECT (enc, "Encoder creation failed: %d", error);
#else
  GST_ERROR_OBJECT (enc, "Encoder creation failed");
#endif
  return FALSE;
}

/* prepare a buffer for transmission */
static GstBuffer *
gst_celt_enc_buffer_from_data (GstCeltEnc * enc, guchar * data,
    gint data_len, guint64 granulepos)
{
  GstBuffer *outbuf;

  outbuf = gst_buffer_new_and_alloc (data_len);
  memcpy (GST_BUFFER_DATA (outbuf), data, data_len);
  GST_BUFFER_OFFSET (outbuf) = enc->bytes_out;
  GST_BUFFER_OFFSET_END (outbuf) = granulepos;

  GST_LOG_OBJECT (enc, "encoded buffer of %d bytes", GST_BUFFER_SIZE (outbuf));
  return outbuf;
}


/* push out the buffer and do internal bookkeeping */
static GstFlowReturn
gst_celt_enc_push_buffer (GstCeltEnc * enc, GstBuffer * buffer)
{
  guint size;

  size = GST_BUFFER_SIZE (buffer);

  enc->bytes_out += size;

  GST_DEBUG_OBJECT (enc, "pushing output buffer of size %u", size);

  return gst_pad_push (enc->srcpad, buffer);
}

static GstCaps *
gst_celt_enc_set_header_on_caps (GstCaps * caps, GstBuffer * buf1,
    GstBuffer * buf2)
{
  GstStructure *structure = NULL;
  GstBuffer *buf;
  GValue array = { 0 };
  GValue value = { 0 };

  caps = gst_caps_make_writable (caps);
  structure = gst_caps_get_structure (caps, 0);

  g_assert (gst_buffer_is_metadata_writable (buf1));
  g_assert (gst_buffer_is_metadata_writable (buf2));

  /* mark buffers */
  GST_BUFFER_FLAG_SET (buf1, GST_BUFFER_FLAG_IN_CAPS);
  GST_BUFFER_FLAG_SET (buf2, GST_BUFFER_FLAG_IN_CAPS);

  /* put buffers in a fixed list */
  g_value_init (&array, GST_TYPE_ARRAY);
  g_value_init (&value, GST_TYPE_BUFFER);
  buf = gst_buffer_copy (buf1);
  gst_value_set_buffer (&value, buf);
  gst_buffer_unref (buf);
  gst_value_array_append_value (&array, &value);
  g_value_unset (&value);
  g_value_init (&value, GST_TYPE_BUFFER);
  buf = gst_buffer_copy (buf2);
  gst_value_set_buffer (&value, buf);
  gst_buffer_unref (buf);
  gst_value_array_append_value (&array, &value);
  gst_structure_set_value (structure, "streamheader", &array);
  g_value_unset (&value);
  g_value_unset (&array);

  return caps;
}


static gboolean
gst_celt_enc_sinkevent (GstPad * pad, GstEvent * event)
{
  gboolean res = TRUE;
  GstCeltEnc *enc;

  enc = GST_CELT_ENC (gst_pad_get_parent (pad));

  switch (GST_EVENT_TYPE (event)) {
    case GST_EVENT_EOS:
      gst_celt_enc_encode (enc, TRUE);
      res = gst_pad_event_default (pad, event);
      break;
    case GST_EVENT_TAG:
    {
      GstTagList *list;
      GstTagSetter *setter = GST_TAG_SETTER (enc);
      const GstTagMergeMode mode = gst_tag_setter_get_tag_merge_mode (setter);

      gst_event_parse_tag (event, &list);
      gst_tag_setter_merge_tags (setter, list, mode);
      res = gst_pad_event_default (pad, event);
      break;
    }
    default:
      res = gst_pad_event_default (pad, event);
      break;
  }

  gst_object_unref (enc);

  return res;
}

static GstFlowReturn
gst_celt_enc_encode (GstCeltEnc * enc, gboolean flush)
{

  GstFlowReturn ret = GST_FLOW_OK;
  gint frame_size = enc->frame_size;
  gint bytes = frame_size * 2 * enc->channels;
  gint bytes_per_packet;

  if (enc->cbr) {
    bytes_per_packet =
        (enc->bitrate * 1000 * enc->frame_size / enc->rate + 4) / 8;
  } else {
    bytes_per_packet =
        (enc->max_bitrate * 1000 * enc->frame_size / enc->rate + 4) / 8;
  }

  if (flush && gst_adapter_available (enc->adapter) % bytes != 0) {
    guint diff = gst_adapter_available (enc->adapter) % bytes;
    GstBuffer *buf = gst_buffer_new_and_alloc (diff);

    memset (GST_BUFFER_DATA (buf), 0, diff);
    gst_adapter_push (enc->adapter, buf);
  }


  while (gst_adapter_available (enc->adapter) >= bytes) {
    gint16 *data;
    gint outsize;
    GstBuffer *outbuf;

    ret = gst_pad_alloc_buffer_and_set_caps (enc->srcpad,
        GST_BUFFER_OFFSET_NONE, bytes_per_packet, GST_PAD_CAPS (enc->srcpad),
        &outbuf);

    if (GST_FLOW_OK != ret)
      goto done;

    data = (gint16 *) gst_adapter_take (enc->adapter, bytes);
    enc->samples_in += frame_size;

    GST_DEBUG_OBJECT (enc, "encoding %d samples (%d bytes)", frame_size, bytes);

#ifdef HAVE_CELT_0_5
    outsize =
        celt_encode (enc->state, data, NULL,
        GST_BUFFER_DATA (outbuf), bytes_per_packet);
#else
    outsize =
        celt_encode (enc->state, data,
        GST_BUFFER_DATA (outbuf), bytes_per_packet);
#endif

    g_free (data);

    if (outsize < 0) {
      GST_ERROR_OBJECT (enc, "Encoding failed: %d", outsize);
      ret = GST_FLOW_ERROR;
      goto done;
    }

    GST_BUFFER_TIMESTAMP (outbuf) = enc->start_ts +
        gst_util_uint64_scale_int (enc->frameno_out * frame_size, GST_SECOND,
        enc->rate);
    GST_BUFFER_DURATION (outbuf) =
        gst_util_uint64_scale_int (frame_size, GST_SECOND, enc->rate);
    /* set gp time and granulepos; see gst-plugins-base/ext/ogg/README */
    GST_BUFFER_OFFSET_END (outbuf) = enc->granulepos_offset +
        ((enc->frameno + 1) * frame_size);
    GST_BUFFER_OFFSET (outbuf) =
        gst_util_uint64_scale_int (GST_BUFFER_OFFSET_END (outbuf), GST_SECOND,
        enc->rate);

    enc->frameno++;
    enc->frameno_out++;

    ret = gst_celt_enc_push_buffer (enc, outbuf);

    if ((GST_FLOW_OK != ret) && (GST_FLOW_NOT_LINKED != ret))
      goto done;
  }

done:

  return ret;
}

static GstFlowReturn
gst_celt_enc_chain (GstPad * pad, GstBuffer * buf)
{
  GstCeltEnc *enc;
  GstFlowReturn ret = GST_FLOW_OK;

  enc = GST_CELT_ENC (GST_PAD_PARENT (pad));

  if (!enc->setup)
    goto not_setup;

  if (!enc->header_sent) {
    /* Celt streams begin with two headers; the initial header (with
       most of the codec setup parameters) which is mandated by the Ogg
       bitstream spec.  The second header holds any comment fields.
       We merely need to make the headers, then pass them to libcelt 
       one at a time; libcelt handles the additional Ogg bitstream 
       constraints */
    GstBuffer *buf1, *buf2;
    GstCaps *caps;
    guchar data[100];

    /* create header buffer */
    celt_header_to_packet (&enc->header, data, 100);
    buf1 = gst_celt_enc_buffer_from_data (enc, data, 100, 0);

    /* create comment buffer */
    buf2 = gst_celt_enc_create_metadata_buffer (enc);

    /* mark and put on caps */
    caps = gst_pad_get_caps (enc->srcpad);
    caps = gst_celt_enc_set_header_on_caps (caps, buf1, buf2);

    gst_caps_set_simple (caps,
        "rate", G_TYPE_INT, enc->rate,
        "channels", G_TYPE_INT, enc->channels,
        "frame-size", G_TYPE_INT, enc->frame_size, NULL);

    /* negotiate with these caps */
    GST_DEBUG_OBJECT (enc, "here are the caps: %" GST_PTR_FORMAT, caps);
    GST_LOG_OBJECT (enc, "rate=%d channels=%d frame-size=%d",
        enc->rate, enc->channels, enc->frame_size);
    gst_pad_set_caps (enc->srcpad, caps);

    gst_buffer_set_caps (buf1, caps);
    gst_buffer_set_caps (buf2, caps);
    gst_caps_unref (caps);

    /* push out buffers */
    ret = gst_celt_enc_push_buffer (enc, buf1);

    if (ret != GST_FLOW_OK) {
      gst_buffer_unref (buf2);
      goto done;
    }

    ret = gst_celt_enc_push_buffer (enc, buf2);

    if (ret != GST_FLOW_OK)
      goto done;

    enc->header_sent = TRUE;
  }

  GST_DEBUG_OBJECT (enc, "received buffer of %u bytes", GST_BUFFER_SIZE (buf));

  /* Save the timestamp of the first buffer. This will be later
   * used as offset for all following buffers */
  if (enc->start_ts == GST_CLOCK_TIME_NONE) {
    if (GST_BUFFER_TIMESTAMP_IS_VALID (buf)) {
      enc->start_ts = GST_BUFFER_TIMESTAMP (buf);
      enc->granulepos_offset = gst_util_uint64_scale
          (GST_BUFFER_TIMESTAMP (buf), enc->rate, GST_SECOND);
    } else {
      enc->start_ts = 0;
      enc->granulepos_offset = 0;
    }
  }


  /* Check if we have a continous stream, if not drop some samples or the buffer or
   * insert some silence samples */
  if (enc->next_ts != GST_CLOCK_TIME_NONE &&
      GST_BUFFER_TIMESTAMP (buf) < enc->next_ts) {
    guint64 diff = enc->next_ts - GST_BUFFER_TIMESTAMP (buf);
    guint64 diff_bytes;

    GST_WARNING_OBJECT (enc, "Buffer is older than previous "
        "timestamp + duration (%" GST_TIME_FORMAT "< %" GST_TIME_FORMAT
        "), cannot handle. Clipping buffer.",
        GST_TIME_ARGS (GST_BUFFER_TIMESTAMP (buf)),
        GST_TIME_ARGS (enc->next_ts));

    diff_bytes = GST_CLOCK_TIME_TO_FRAMES (diff, enc->rate) * enc->channels * 2;
    if (diff_bytes >= GST_BUFFER_SIZE (buf)) {
      gst_buffer_unref (buf);
      return GST_FLOW_OK;
    }
    buf = gst_buffer_make_metadata_writable (buf);
    GST_BUFFER_DATA (buf) += diff_bytes;
    GST_BUFFER_SIZE (buf) -= diff_bytes;

    GST_BUFFER_TIMESTAMP (buf) += diff;
    if (GST_BUFFER_DURATION_IS_VALID (buf))
      GST_BUFFER_DURATION (buf) -= diff;
  }

  if (enc->next_ts != GST_CLOCK_TIME_NONE
      && GST_BUFFER_TIMESTAMP_IS_VALID (buf)) {
    guint64 max_diff =
        gst_util_uint64_scale (enc->frame_size, GST_SECOND, enc->rate);

    if (GST_BUFFER_TIMESTAMP (buf) != enc->next_ts &&
        GST_BUFFER_TIMESTAMP (buf) - enc->next_ts > max_diff) {
      GST_WARNING_OBJECT (enc,
          "Discontinuity detected: %" G_GUINT64_FORMAT " > %" G_GUINT64_FORMAT,
          GST_BUFFER_TIMESTAMP (buf) - enc->next_ts, max_diff);

      gst_celt_enc_encode (enc, TRUE);

      enc->frameno_out = 0;
      enc->start_ts = GST_BUFFER_TIMESTAMP (buf);
      enc->granulepos_offset = gst_util_uint64_scale
          (GST_BUFFER_TIMESTAMP (buf), enc->rate, GST_SECOND);
    }
  }

  if (GST_BUFFER_TIMESTAMP_IS_VALID (buf)
      && GST_BUFFER_DURATION_IS_VALID (buf))
    enc->next_ts = GST_BUFFER_TIMESTAMP (buf) + GST_BUFFER_DURATION (buf);
  else
    enc->next_ts = GST_CLOCK_TIME_NONE;

  /* push buffer to adapter */
  gst_adapter_push (enc->adapter, buf);
  buf = NULL;

  ret = gst_celt_enc_encode (enc, FALSE);

done:

  if (buf)
    gst_buffer_unref (buf);

  return ret;

  /* ERRORS */
not_setup:
  {
    GST_ELEMENT_ERROR (enc, CORE, NEGOTIATION, (NULL),
        ("encoder not initialized (input is not audio?)"));
    ret = GST_FLOW_NOT_NEGOTIATED;
    goto done;
  }

}


static void
gst_celt_enc_get_property (GObject * object, guint prop_id, GValue * value,
    GParamSpec * pspec)
{
  GstCeltEnc *enc;

  enc = GST_CELT_ENC (object);

  switch (prop_id) {
    case PROP_BITRATE:
      g_value_set_int (value, enc->bitrate);
      break;
    case PROP_FRAMESIZE:
      g_value_set_int (value, enc->frame_size);
      break;
    case PROP_CBR:
#ifdef CELT_SET_VBR_RATE
      g_value_set_boolean (value, enc->cbr);
#endif
      break;
    case PROP_COMPLEXITY:
      g_value_set_int (value, enc->complexity);
      break;
    case PROP_MAX_BITRATE:
      g_value_set_int (value, enc->max_bitrate);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_celt_enc_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec)
{
  GstCeltEnc *enc;

  enc = GST_CELT_ENC (object);

  switch (prop_id) {
    case PROP_BITRATE:
      enc->bitrate = g_value_get_int (value);
      break;
    case PROP_FRAMESIZE:
      enc->frame_size = g_value_get_int (value);
      break;
    case PROP_CBR:
      enc->cbr = g_value_get_boolean (value);
      break;
    case PROP_COMPLEXITY:
      enc->complexity = g_value_get_int (value);
      break;
    case PROP_MAX_BITRATE:
      enc->max_bitrate = g_value_get_int (value);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static GstStateChangeReturn
gst_celt_enc_change_state (GstElement * element, GstStateChange transition)
{
  GstCeltEnc *enc = GST_CELT_ENC (element);
  GstStateChangeReturn res;

  switch (transition) {
    case GST_STATE_CHANGE_NULL_TO_READY:
      break;
    case GST_STATE_CHANGE_READY_TO_PAUSED:
      enc->frameno = 0;
      enc->samples_in = 0;
      enc->frameno_out = 0;
      enc->start_ts = GST_CLOCK_TIME_NONE;
      enc->next_ts = GST_CLOCK_TIME_NONE;
      enc->granulepos_offset = 0;
      break;
    case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
      /* fall through */
    default:
      break;
  }

  res = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
  if (res == GST_STATE_CHANGE_FAILURE)
    return res;

  switch (transition) {
    case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
      break;
    case GST_STATE_CHANGE_PAUSED_TO_READY:
      enc->setup = FALSE;
      enc->header_sent = FALSE;
      if (enc->state) {
        celt_encoder_destroy (enc->state);
        enc->state = NULL;
      }
      if (enc->mode) {
        celt_mode_destroy (enc->mode);
        enc->mode = NULL;
      }
      memset (&enc->header, 0, sizeof (enc->header));
      break;
    case GST_STATE_CHANGE_READY_TO_NULL:
      gst_tag_setter_reset_tags (GST_TAG_SETTER (enc));
    default:
      break;
  }

  return res;
}