gstreamer/gst-libs/gst/riff/riff-read.c

/* GStreamer RIFF I/O
 * Copyright (C) 2003 Ronald Bultje <rbultje@ronald.bitfreak.net>
 *
 * riff-read.c: RIFF input file parsing
 *
 * 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.
 */

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

#include <string.h>
#include <gst/gstutils.h>

#include "riff-ids.h"
#include "riff-read.h"

enum
{
  ARG_0,
  ARG_METADATA
      /* FILL ME */
};

static void gst_riff_read_class_init (GstRiffReadClass * klass);
static void gst_riff_read_init (GstRiffRead * riff);

static GstElementStateReturn gst_riff_read_change_state (GstElement * element);

static GstElementClass *parent_class = NULL;

GType
gst_riff_read_get_type (void)
{
  static GType gst_riff_read_type = 0;

  if (!gst_riff_read_type) {
    static const GTypeInfo gst_riff_read_info = {
      sizeof (GstRiffReadClass),
      NULL,
      NULL,
      (GClassInitFunc) gst_riff_read_class_init,
      NULL,
      NULL,
      sizeof (GstRiffRead),
      0,
      (GInstanceInitFunc) gst_riff_read_init,
    };

    gst_riff_read_type =
        g_type_register_static (GST_TYPE_ELEMENT, "GstRiffRead",
        &gst_riff_read_info, 0);
  }

  return gst_riff_read_type;
}

static void
gst_riff_read_class_init (GstRiffReadClass * klass)
{
  GstElementClass *gstelement_class = GST_ELEMENT_CLASS (klass);

  parent_class = g_type_class_ref (GST_TYPE_ELEMENT);

  gstelement_class->change_state = gst_riff_read_change_state;
}

static void
gst_riff_read_init (GstRiffRead * riff)
{
  riff->sinkpad = NULL;
  riff->bs = NULL;
  riff->level = NULL;
}

static GstElementStateReturn
gst_riff_read_change_state (GstElement * element)
{
  GstRiffRead *riff = GST_RIFF_READ (element);

  switch (GST_STATE_TRANSITION (element)) {
    case GST_STATE_READY_TO_PAUSED:
      if (!riff->sinkpad)
        return GST_STATE_FAILURE;
      riff->bs = gst_bytestream_new (riff->sinkpad);
      break;
    case GST_STATE_PAUSED_TO_READY:
      gst_bytestream_destroy (riff->bs);
      while (riff->level) {
        GstRiffLevel *level = riff->level->data;

        riff->level = g_list_remove (riff->level, level);
        g_free (level);
      }
      break;
    default:
      break;
  }

  if (GST_ELEMENT_CLASS (parent_class)->change_state)
    return GST_ELEMENT_CLASS (parent_class)->change_state (element);

  return GST_STATE_SUCCESS;
}

/*
 * Return: the amount of levels in the hierarchy that the
 * current element lies higher than the previous one.
 * The opposite isn't done - that's auto-done using list
 * element reading.
 */

static guint
gst_riff_read_element_level_up (GstRiffRead * riff)
{
  guint num = 0;
  guint64 pos = gst_bytestream_tell (riff->bs);

  while (riff->level != NULL) {
    GList *last = g_list_last (riff->level);
    GstRiffLevel *level = last->data;

    if (pos >= level->start + level->length) {
      riff->level = g_list_remove (riff->level, level);
      g_free (level);
      num++;
    } else
      break;
  }

  return num;
}

/*
 * Read the next tag plus length (may be NULL). Return
 * TRUE on success or FALSE on failure.
 */

gboolean
gst_riff_peek_head (GstRiffRead * riff,
    guint32 * tag, guint32 * length, guint * level_up)
{
  GList *last;
  guint8 *data;

  /* if we're at the end of a chunk, but unaligned, then re-align.
   * Those are essentially broken files, but unfortunately they
   * exist. */
  if ((last = g_list_last (riff->level)) != NULL) {
    GstRiffLevel *level = last->data;
    guint64 pos = gst_bytestream_tell (riff->bs);

    if (level->start + level->length - pos < 8) {
      if (!gst_bytestream_flush (riff->bs, level->start + level->length - pos)) {
        GST_ELEMENT_ERROR (riff, RESOURCE, READ, (NULL), (NULL));
        return FALSE;
      }
    }
  }

  /* read */
  while (gst_bytestream_peek_bytes (riff->bs, &data, 8) != 8) {
    GstEvent *event = NULL;
    guint32 remaining;

    /* Here, we might encounter EOS */
    gst_bytestream_get_status (riff->bs, &remaining, &event);
    if (GST_IS_EVENT (event)) {
      gboolean eos = (GST_EVENT_TYPE (event) == GST_EVENT_EOS);

      gst_pad_event_default (riff->sinkpad, event);
      if (eos)
        return FALSE;
    } else {
      GST_ELEMENT_ERROR (riff, RESOURCE, READ, (NULL), (NULL));
      return FALSE;
    }
  }

  /* parse tag + length (if wanted) */
  *tag = GST_READ_UINT32_LE (data);
  if (length)
    *length = GST_READ_UINT32_LE (((guint32 *) data) + 1);

  /* level */
  if (level_up)
    *level_up = gst_riff_read_element_level_up (riff);

  return TRUE;
}

/*
 * Read: the actual data (plus alignment and flush).
 * Return: the data, as a GstBuffer.
 */

GstBuffer *
gst_riff_read_element_data (GstRiffRead * riff, guint length, guint * got_bytes)
{
  GstBuffer *buf = NULL;
  guint32 got;

  while ((got = gst_bytestream_peek (riff->bs, &buf, length)) != length) {
    /*GST_ELEMENT_ERROR (riff, RESOURCE, READ, (NULL), (NULL)); */
    GstEvent *event = NULL;
    guint32 remaining;

    gst_bytestream_get_status (riff->bs, &remaining, &event);
    if (GST_IS_EVENT (event)) {
      gst_pad_event_default (riff->sinkpad, event);
      if (GST_EVENT_TYPE (event) == GST_EVENT_EOS) {

        if (buf)
          gst_buffer_unref (buf);

        if (got_bytes)
          *got_bytes = got;

        return NULL;
      }
    } else {
      GST_ELEMENT_ERROR (riff, RESOURCE, READ, (NULL), (NULL));
      if (buf)
        gst_buffer_unref (buf);

      if (got_bytes)
        *got_bytes = got;

      return NULL;
    }
  }

  /* we need 16-bit alignment */
  if (length & 1)
    length++;

  gst_bytestream_flush (riff->bs, length);

  if (got_bytes)
    *got_bytes = got;

  return buf;
}

/*
 * Seek.
 */

GstEvent *
gst_riff_read_seek (GstRiffRead * riff, guint64 offset)
{
  guint64 length = gst_bytestream_length (riff->bs);
  guint32 remaining;
  GstEvent *event = NULL;
  guchar *data;

  /* hack for AVI files with broken idx1 size chunk markers */
  if (offset > length)
    offset = length;

  /* first, flush remaining buffers */
  gst_bytestream_get_status (riff->bs, &remaining, &event);
  if (event) {
    g_warning ("Unexpected event before seek");
    gst_event_unref (event);
  }
  if (remaining)
    gst_bytestream_flush_fast (riff->bs, remaining);

  /* now seek */
  if (!gst_bytestream_seek (riff->bs, offset, GST_SEEK_METHOD_SET)) {
    GST_ELEMENT_ERROR (riff, RESOURCE, SEEK, (NULL), (NULL));
    return NULL;
  }

  /* and now, peek a new byte. This will fail because there's a
   * pending event. Then, take the event and return it. */
  while (!event) {
    if (gst_bytestream_peek_bytes (riff->bs, &data, 1)) {
      GST_WARNING ("Unexpected data after seek - this means seek failed");
      break;
    }

    /* get the discont event and return */
    gst_bytestream_get_status (riff->bs, &remaining, &event);
    if (!event) {
      GST_WARNING ("No discontinuity event after seek - seek failed");
      break;
    } else if (GST_EVENT_TYPE (event) != GST_EVENT_DISCONTINUOUS) {
      GstEventType type = GST_EVENT_TYPE (event);

      gst_pad_event_default (riff->sinkpad, event);
      if (type == GST_EVENT_EOS)
        return NULL;
      event = NULL;
    }
  }

  return event;
}

/*
 * Gives the tag of the next RIFF element.
 */

guint32
gst_riff_peek_tag (GstRiffRead * riff, guint * level_up)
{
  guint32 tag;

  if (!gst_riff_peek_head (riff, &tag, NULL, level_up))
    return 0;

  return tag;
}

/*
 * Gives the tag of the next LIST/RIFF element.
 */

guint32
gst_riff_peek_list (GstRiffRead * riff)
{
  guint32 lst;
  guint8 *data;

  if (!gst_riff_peek_head (riff, &lst, NULL, NULL))
    return FALSE;
  if (lst != GST_RIFF_TAG_LIST) {
    g_warning ("Not a LIST object");
    return 0;
  }

  if (gst_bytestream_peek_bytes (riff->bs, &data, 12) != 12) {
    GST_ELEMENT_ERROR (riff, RESOURCE, READ, (NULL), (NULL));
    return 0;
  }

  return GST_READ_UINT32_LE (((guint32 *) data) + 2);
}

/*
 * Don't read data.
 */

gboolean
gst_riff_read_skip (GstRiffRead * riff)
{
  guint32 tag, length;
  GstEvent *event;
  guint32 remaining;

  if (!gst_riff_peek_head (riff, &tag, &length, NULL))
    return FALSE;

  /* 16-bit alignment */
  if (length & 1)
    length++;

  /* header itself */
  length += 8;

  /* see if we have that much data available */
  gst_bytestream_get_status (riff->bs, &remaining, &event);
  if (event) {
    g_warning ("Unexpected event in skip");
    gst_event_unref (event);
  }

  /* yes */
  if (remaining >= length) {
    gst_bytestream_flush_fast (riff->bs, length);
    return TRUE;
  }

  /* no */
  if (!(event = gst_riff_read_seek (riff,
              gst_bytestream_tell (riff->bs) + length)))
    return FALSE;

  gst_event_unref (event);

  return TRUE;
}

/*
 * Read any type of data.
 */

gboolean
gst_riff_read_data (GstRiffRead * riff, guint32 * tag, GstBuffer ** buf)
{
  guint32 length;

  if (!gst_riff_peek_head (riff, tag, &length, NULL))
    return FALSE;
  gst_bytestream_flush_fast (riff->bs, 8);

  return ((*buf = gst_riff_read_element_data (riff, length, NULL)) != NULL);
}

/*
 * Read a string.
 */

gboolean
gst_riff_read_ascii (GstRiffRead * riff, guint32 * tag, gchar ** str)
{
  GstBuffer *buf;

  if (!gst_riff_read_data (riff, tag, &buf))
    return FALSE;

  *str = g_malloc (GST_BUFFER_SIZE (buf) + 1);
  memcpy (*str, GST_BUFFER_DATA (buf), GST_BUFFER_SIZE (buf));
  (*str)[GST_BUFFER_SIZE (buf)] = '\0';

  gst_buffer_unref (buf);

  return TRUE;
}

/*
 * Read media structs.
 */

gboolean
gst_riff_read_strh (GstRiffRead * riff, gst_riff_strh ** header)
{
  guint32 tag;
  GstBuffer *buf;
  gst_riff_strh *strh;

  if (!gst_riff_read_data (riff, &tag, &buf))
    return FALSE;

  if (tag != GST_RIFF_TAG_strh) {
    g_warning ("Not a strh chunk");
    gst_buffer_unref (buf);
    return FALSE;
  }
  if (GST_BUFFER_SIZE (buf) < sizeof (gst_riff_strh)) {
    g_warning ("Too small strh (%d available, %d needed)",
        GST_BUFFER_SIZE (buf), (int) sizeof (gst_riff_strh));
    gst_buffer_unref (buf);
    return FALSE;
  }

  strh = g_memdup (GST_BUFFER_DATA (buf), GST_BUFFER_SIZE (buf));
  gst_buffer_unref (buf);

#if (G_BYTE_ORDER == G_BIG_ENDIAN)
  strh->type = GUINT32_FROM_LE (strh->type);
  strh->fcc_handler = GUINT32_FROM_LE (strh->fcc_handler);
  strh->flags = GUINT32_FROM_LE (strh->flags);
  strh->priority = GUINT32_FROM_LE (strh->priority);
  strh->init_frames = GUINT32_FROM_LE (strh->init_frames);
  strh->scale = GUINT32_FROM_LE (strh->scale);
  strh->rate = GUINT32_FROM_LE (strh->rate);
  strh->start = GUINT32_FROM_LE (strh->start);
  strh->length = GUINT32_FROM_LE (strh->length);
  strh->bufsize = GUINT32_FROM_LE (strh->bufsize);
  strh->quality = GUINT32_FROM_LE (strh->quality);
  strh->samplesize = GUINT32_FROM_LE (strh->samplesize);
#endif

  /* avoid divisions by zero */
  if (!strh->scale)
    strh->scale = 1;
  if (!strh->rate)
    strh->rate = 1;

  /* debug */
  GST_INFO ("strh tag found");
  GST_INFO (" type        " GST_FOURCC_FORMAT, GST_FOURCC_ARGS (strh->type));
  GST_INFO (" fcc_handler " GST_FOURCC_FORMAT,
      GST_FOURCC_ARGS (strh->fcc_handler));
  GST_INFO (" flags       0x%08x", strh->flags);
  GST_INFO (" priority    %d", strh->priority);
  GST_INFO (" init_frames %d", strh->init_frames);
  GST_INFO (" scale       %d", strh->scale);
  GST_INFO (" rate        %d", strh->rate);
  GST_INFO (" start       %d", strh->start);
  GST_INFO (" length      %d", strh->length);
  GST_INFO (" bufsize     %d", strh->bufsize);
  GST_INFO (" quality     %d", strh->quality);
  GST_INFO (" samplesize  %d", strh->samplesize);

  *header = strh;

  return TRUE;
}

gboolean
gst_riff_read_strf_vids_with_data (GstRiffRead * riff,
    gst_riff_strf_vids ** header, GstBuffer ** extradata)
{
  guint32 tag;
  GstBuffer *buf;
  gst_riff_strf_vids *strf;

  if (!gst_riff_read_data (riff, &tag, &buf))
    return FALSE;

  if (tag != GST_RIFF_TAG_strf) {
    g_warning ("Not a strf chunk");
    gst_buffer_unref (buf);
    return FALSE;
  }
  if (GST_BUFFER_SIZE (buf) < sizeof (gst_riff_strf_vids)) {
    g_warning ("Too small strf_vids (%d available, %d needed)",
        GST_BUFFER_SIZE (buf), (int) sizeof (gst_riff_strf_vids));
    gst_buffer_unref (buf);
    return FALSE;
  }

  strf = g_memdup (GST_BUFFER_DATA (buf), GST_BUFFER_SIZE (buf));

#if (G_BYTE_ORDER == G_BIG_ENDIAN)
  strf->size = GUINT32_FROM_LE (strf->size);
  strf->width = GUINT32_FROM_LE (strf->width);
  strf->height = GUINT32_FROM_LE (strf->height);
  strf->planes = GUINT16_FROM_LE (strf->planes);
  strf->bit_cnt = GUINT16_FROM_LE (strf->bit_cnt);
  strf->compression = GUINT32_FROM_LE (strf->compression);
  strf->image_size = GUINT32_FROM_LE (strf->image_size);
  strf->xpels_meter = GUINT32_FROM_LE (strf->xpels_meter);
  strf->ypels_meter = GUINT32_FROM_LE (strf->ypels_meter);
  strf->num_colors = GUINT32_FROM_LE (strf->num_colors);
  strf->imp_colors = GUINT32_FROM_LE (strf->imp_colors);
#endif

  /* size checking */
  *extradata = NULL;
  if (strf->size > GST_BUFFER_SIZE (buf)) {
    g_warning ("strf_vids header gave %d bytes data, only %d available",
        strf->size, GST_BUFFER_SIZE (buf));
    strf->size = GST_BUFFER_SIZE (buf);
  } else if (strf->size < GST_BUFFER_SIZE (buf)) {
    gint len;

    len = GST_BUFFER_SIZE (buf) - strf->size - 2;
    if (len > 0) {
      *extradata = gst_buffer_create_sub (buf, strf->size + 2, len);
    }
  }

  /* debug */
  GST_INFO ("strf tag found in context vids:");
  GST_INFO (" size        %d", strf->size);
  GST_INFO (" width       %d", strf->width);
  GST_INFO (" height      %d", strf->height);
  GST_INFO (" planes      %d", strf->planes);
  GST_INFO (" bit_cnt     %d", strf->bit_cnt);
  GST_INFO (" compression " GST_FOURCC_FORMAT,
      GST_FOURCC_ARGS (strf->compression));
  GST_INFO (" image_size  %d", strf->image_size);
  GST_INFO (" xpels_meter %d", strf->xpels_meter);
  GST_INFO (" ypels_meter %d", strf->ypels_meter);
  GST_INFO (" num_colors  %d", strf->num_colors);
  GST_INFO (" imp_colors  %d", strf->imp_colors);
  if (*extradata)
    GST_INFO (" %d bytes extra_data", GST_BUFFER_SIZE (*extradata));

  gst_buffer_unref (buf);

  *header = strf;

  return TRUE;
}

/*
 * Obsolete, use gst_riff_read_strf_vids_with_data ().
 */
gboolean
gst_riff_read_strf_vids (GstRiffRead * riff, gst_riff_strf_vids ** header)
{
  GstBuffer *data = NULL;
  gboolean ret;

  ret = gst_riff_read_strf_vids_with_data (riff, header, &data);
  if (data)
    gst_buffer_unref (data);

  return ret;
}

gboolean
gst_riff_read_strf_auds_with_data (GstRiffRead * riff,
    gst_riff_strf_auds ** header, GstBuffer ** extradata)
{
  guint32 tag;
  GstBuffer *buf;
  gst_riff_strf_auds *strf;

  if (!gst_riff_read_data (riff, &tag, &buf))
    return FALSE;

  if (tag != GST_RIFF_TAG_strf && tag != GST_RIFF_TAG_fmt) {
    g_warning ("Not a strf chunk");
    gst_buffer_unref (buf);
    return FALSE;
  }
  if (GST_BUFFER_SIZE (buf) < sizeof (gst_riff_strf_auds)) {
    g_warning ("Too small strf_auds (%d available, %d needed)",
        GST_BUFFER_SIZE (buf), (int) sizeof (gst_riff_strf_auds));
    gst_buffer_unref (buf);
    return FALSE;
  }

  strf = g_memdup (GST_BUFFER_DATA (buf), GST_BUFFER_SIZE (buf));

#if (G_BYTE_ORDER == G_BIG_ENDIAN)
  strf->format = GUINT16_FROM_LE (strf->format);
  strf->channels = GUINT16_FROM_LE (strf->channels);
  strf->rate = GUINT32_FROM_LE (strf->rate);
  strf->av_bps = GUINT32_FROM_LE (strf->av_bps);
  strf->blockalign = GUINT16_FROM_LE (strf->blockalign);
  strf->size = GUINT16_FROM_LE (strf->size);
#endif

  /* size checking */
  *extradata = NULL;
  if (strf->size > GST_BUFFER_SIZE (buf)) {
    g_warning ("strf_auds header gave %d bytes data, only %d available",
        strf->size, GST_BUFFER_SIZE (buf));
    strf->size = GST_BUFFER_SIZE (buf);
  } else if (strf->size < GST_BUFFER_SIZE (buf)) {
    gint len;

    len = GST_BUFFER_SIZE (buf) - strf->size - 2;
    if (len > 0) {
      *extradata = gst_buffer_create_sub (buf, strf->size + 2, len);
    }
  }

  /* debug */
  GST_INFO ("strf tag found in context auds:");
  GST_INFO (" format      %d", strf->format);
  GST_INFO (" channels    %d", strf->channels);
  GST_INFO (" rate        %d", strf->rate);
  GST_INFO (" av_bps      %d", strf->av_bps);
  GST_INFO (" blockalign  %d", strf->blockalign);
  GST_INFO (" size        %d", strf->size);     /* wordsize, not extrasize! */
  if (*extradata)
    GST_INFO (" %d bytes extra_data", GST_BUFFER_SIZE (*extradata));

  gst_buffer_unref (buf);

  *header = strf;

  return TRUE;
}

/*
 * Obsolete, use gst_riff_read_strf_auds_with_data ().
 */
gboolean
gst_riff_read_strf_auds (GstRiffRead * riff, gst_riff_strf_auds ** header)
{
  GstBuffer *data = NULL;
  gboolean ret;

  ret = gst_riff_read_strf_auds_with_data (riff, header, &data);
  if (data)
    gst_buffer_unref (data);

  return ret;
}

gboolean
gst_riff_read_strf_iavs (GstRiffRead * riff, gst_riff_strf_iavs ** header)
{
  guint32 tag;
  GstBuffer *buf;
  gst_riff_strf_iavs *strf;

  if (!gst_riff_read_data (riff, &tag, &buf))
    return FALSE;

  if (tag != GST_RIFF_TAG_strf) {
    g_warning ("Not a strf chunk");
    gst_buffer_unref (buf);
    return FALSE;
  }
  if (GST_BUFFER_SIZE (buf) < sizeof (gst_riff_strf_iavs)) {
    g_warning ("Too small strf_iavs (%d available, %d needed)",
        GST_BUFFER_SIZE (buf), (int) sizeof (gst_riff_strf_iavs));
    gst_buffer_unref (buf);
    return FALSE;
  }

  strf = g_memdup (GST_BUFFER_DATA (buf), GST_BUFFER_SIZE (buf));
  gst_buffer_unref (buf);

#if (G_BYTE_ORDER == G_BIG_ENDIAN)
  strf->DVAAuxSrc = GUINT32_FROM_LE (strf->DVAAuxSrc);
  strf->DVAAuxCtl = GUINT32_FROM_LE (strf->DVAAuxCtl);
  strf->DVAAuxSrc1 = GUINT32_FROM_LE (strf->DVAAuxSrc1);
  strf->DVAAuxCtl1 = GUINT32_FROM_LE (strf->DVAAuxCtl1);
  strf->DVVAuxSrc = GUINT32_FROM_LE (strf->DVVAuxSrc);
  strf->DVVAuxCtl = GUINT32_FROM_LE (strf->DVVAuxCtl);
  strf->DVReserved1 = GUINT32_FROM_LE (strf->DVReserved1);
  strf->DVReserved2 = GUINT32_FROM_LE (strf->DVReserved2);
#endif

  /* debug */
  GST_INFO ("strf tag found in context iavs");
  GST_INFO (" DVAAuxSrc   %08x", strf->DVAAuxSrc);
  GST_INFO (" DVAAuxCtl   %08x", strf->DVAAuxCtl);
  GST_INFO (" DVAAuxSrc1  %08x", strf->DVAAuxSrc1);
  GST_INFO (" DVAAuxCtl1  %08x", strf->DVAAuxCtl1);
  GST_INFO (" DVVAuxSrc   %08x", strf->DVVAuxSrc);
  GST_INFO (" DVVAuxCtl   %08x", strf->DVVAuxCtl);
  GST_INFO (" DVReserved1 %08x", strf->DVReserved1);
  GST_INFO (" DVReserved2 %08x", strf->DVReserved2);

  *header = strf;

  return TRUE;
}

/*
 * Read a list.
 */

gboolean
gst_riff_read_list (GstRiffRead * riff, guint32 * tag)
{
  guint32 length, lst;
  GstRiffLevel *level;
  guint8 *data;

  if (!gst_riff_peek_head (riff, &lst, &length, NULL))
    return FALSE;
  if (lst != GST_RIFF_TAG_LIST) {
    g_warning ("Not a LIST object");
    return FALSE;
  }
  gst_bytestream_flush_fast (riff->bs, 8);
  if (gst_bytestream_peek_bytes (riff->bs, &data, 4) != 4) {
    GST_ELEMENT_ERROR (riff, RESOURCE, READ, (NULL), (NULL));
    return FALSE;
  }
  gst_bytestream_flush_fast (riff->bs, 4);
  *tag = GST_READ_UINT32_LE (data);

  /* remember level */
  level = g_new (GstRiffLevel, 1);
  level->start = gst_bytestream_tell (riff->bs);
  level->length = length - 4;
  riff->level = g_list_append (riff->level, level);

  return TRUE;
}

/*
 * Utility function for reading metadata in a RIFF file.
 */

gboolean
gst_riff_read_info (GstRiffRead * riff)
{
  guint32 tag;
  guint64 end;
  GstRiffLevel *level;
  GList *last;
  gchar *name, *type;
  GstTagList *taglist;
  gboolean have_tags = FALSE;

  /* What we're doing here is ugly (oh no!); we look
   * at our LIST tag size and assure that we do not
   * cross boundaries. This is to maintain the level
   * counter for the client app. */
  last = g_list_last (riff->level);
  level = last->data;
  riff->level = g_list_remove (riff->level, level);
  end = level->start + level->length;
  g_free (level);

  taglist = gst_tag_list_new ();

  while (gst_bytestream_tell (riff->bs) < end) {
    if (!gst_riff_peek_head (riff, &tag, NULL, NULL)) {
      return FALSE;
    }

    /* find out the type of metadata */
    switch (tag) {
      case GST_RIFF_INFO_IARL:
        type = GST_TAG_LOCATION;
        break;
      case GST_RIFF_INFO_IART:
        type = GST_TAG_ARTIST;
        break;
      case GST_RIFF_INFO_ICMS:
        type = NULL;            /*"Commissioner"; */
        break;
      case GST_RIFF_INFO_ICMT:
        type = GST_TAG_COMMENT;
        break;
      case GST_RIFF_INFO_ICOP:
        type = GST_TAG_COPYRIGHT;
        break;
      case GST_RIFF_INFO_ICRD:
        type = GST_TAG_DATE;
        break;
      case GST_RIFF_INFO_ICRP:
        type = NULL;            /*"Cropped"; */
        break;
      case GST_RIFF_INFO_IDIM:
        type = NULL;            /*"Dimensions"; */
        break;
      case GST_RIFF_INFO_IDPI:
        type = NULL;            /*"Dots per Inch"; */
        break;
      case GST_RIFF_INFO_IENG:
        type = NULL;            /*"Engineer"; */
        break;
      case GST_RIFF_INFO_IGNR:
        type = GST_TAG_GENRE;
        break;
      case GST_RIFF_INFO_IKEY:
        type = NULL; /*"Keywords"; */ ;
        break;
      case GST_RIFF_INFO_ILGT:
        type = NULL;            /*"Lightness"; */
        break;
      case GST_RIFF_INFO_IMED:
        type = NULL;            /*"Medium"; */
        break;
      case GST_RIFF_INFO_INAM:
        type = GST_TAG_TITLE;
        break;
      case GST_RIFF_INFO_IPLT:
        type = NULL;            /*"Palette"; */
        break;
      case GST_RIFF_INFO_IPRD:
        type = NULL;            /*"Product"; */
        break;
      case GST_RIFF_INFO_ISBJ:
        type = NULL;            /*"Subject"; */
        break;
      case GST_RIFF_INFO_ISFT:
        type = GST_TAG_ENCODER;
        break;
      case GST_RIFF_INFO_ISHP:
        type = NULL;            /*"Sharpness"; */
        break;
      case GST_RIFF_INFO_ISRC:
        type = GST_TAG_ISRC;
        break;
      case GST_RIFF_INFO_ISRF:
        type = NULL;            /*"Source Form"; */
        break;
      case GST_RIFF_INFO_ITCH:
        type = NULL;            /*"Technician"; */
        break;
      default:
        type = NULL;
        GST_WARNING ("Unknown INFO (metadata) tag entry " GST_FOURCC_FORMAT,
            GST_FOURCC_ARGS (tag));
        break;
    }

    if (type) {
      name = NULL;
      if (!gst_riff_read_ascii (riff, &tag, &name)) {
        return FALSE;
      }

      if (name && name[0] != '\0') {
        GValue src = { 0 }
        , dest =
        {
        0};
        GType dest_type = gst_tag_get_type (type);

        have_tags = TRUE;
        g_value_init (&src, G_TYPE_STRING);
        g_value_set_string (&src, name);
        g_value_init (&dest, dest_type);
        g_value_transform (&src, &dest);
        g_value_unset (&src);
        gst_tag_list_add_values (taglist, GST_TAG_MERGE_APPEND,
            type, &dest, NULL);
        g_value_unset (&dest);
      }
      g_free (name);
    } else {
      gst_riff_read_skip (riff);
    }
  }

  if (have_tags) {
    GstElement *element = GST_ELEMENT (riff);
    GstEvent *event = gst_event_new_tag (taglist);
    const GList *padlist;

    /* let the world know about this wonderful thing */
    for (padlist = gst_element_get_pad_list (element);
        padlist != NULL; padlist = padlist->next) {
      if (GST_PAD_IS_SRC (padlist->data) && GST_PAD_IS_USABLE (padlist->data)) {
        gst_event_ref (event);
        gst_pad_push (GST_PAD (padlist->data), GST_DATA (event));
      }
    }

    gst_element_found_tags (element, taglist);

    gst_event_unref (event);
  } else {
    gst_tag_list_free (taglist);
  }

  return TRUE;
}

/*
 * Read RIFF header and document type.
 */

gboolean
gst_riff_read_header (GstRiffRead * riff, guint32 * doctype)
{
  GstRiffLevel *level;
  guint32 tag, length;
  guint8 *data;

  /* We ignore size for openDML-2.0 support */
  if (!gst_riff_peek_head (riff, &tag, &length, NULL))
    return FALSE;
  if (tag != GST_RIFF_TAG_RIFF) {
    GST_ELEMENT_ERROR (riff, STREAM, WRONG_TYPE, (NULL), (NULL));
    return FALSE;
  }
  gst_bytestream_flush_fast (riff->bs, 8);

  /* doctype */
  if (gst_bytestream_peek_bytes (riff->bs, &data, 4) != 4) {
    GST_ELEMENT_ERROR (riff, RESOURCE, READ, (NULL), (NULL));
    return FALSE;
  }
  gst_bytestream_flush_fast (riff->bs, 4);
  *doctype = GST_READ_UINT32_LE (data);

  /* remember level */
  level = g_new (GstRiffLevel, 1);
  level->start = gst_bytestream_tell (riff->bs);
  level->length = length - 4;
  riff->level = g_list_append (riff->level, level);

  return TRUE;
}