path: root/libmpdemux/demux_mkv.c

/*
 * Matroska demuxer
 * Copyright (C) 2004 Aurelien Jacobs <aurel@gnuage.org>
 * Based on the one written by Ronald Bultje for gstreamer
 * and on demux_mkv.cpp from Moritz Bunkus.
 *
 * This file is part of MPlayer.
 *
 * MPlayer is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * MPlayer 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with MPlayer; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "config.h"

#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <inttypes.h>
#include <stdbool.h>

#include "talloc.h"
#include "options.h"
#include "stream/stream.h"
#include "demuxer.h"
#include "stheader.h"
#include "ebml.h"
#include "matroska.h"

#include "mp_msg.h"
#include "help_mp.h"

#include "vobsub.h"
#include "subreader.h"
#include "libvo/sub.h"

#include "libass/ass.h"
#include "libass/ass_mp.h"

#include "libavutil/common.h"

#ifdef CONFIG_QTX_CODECS
#include "loader/qtx/qtxsdk/components.h"
#endif

#if CONFIG_ZLIB
#include <zlib.h>
#endif

#include "libavutil/lzo.h"
#include "ffmpeg_files/intreadwrite.h"
#include "libavutil/avstring.h"

static const unsigned char sipr_swaps[38][2]={
    {0,63},{1,22},{2,44},{3,90},{5,81},{7,31},{8,86},{9,58},{10,36},{12,68},
    {13,39},{14,73},{15,53},{16,69},{17,57},{19,88},{20,34},{21,71},{24,46},
    {25,94},{26,54},{28,75},{29,50},{32,70},{33,92},{35,74},{38,85},{40,56},
    {42,87},{43,65},{45,59},{48,79},{49,93},{51,89},{55,95},{61,76},{67,83},
    {77,80} };

// Map flavour to bytes per second
#define SIPR_FLAVORS 4
#define ATRC_FLAVORS 8
#define COOK_FLAVORS 34
static const int sipr_fl2bps[SIPR_FLAVORS] = {813, 1062, 625, 2000};
static const int atrc_fl2bps[ATRC_FLAVORS] = {8269, 11714, 13092, 16538, 18260, 22050, 33075, 44100};
static const int cook_fl2bps[COOK_FLAVORS] = {
    1000, 1378, 2024, 2584, 4005, 5513, 8010, 4005, 750, 2498,
    4048, 5513, 8010, 11973, 8010, 2584, 4005, 2067, 2584, 2584,
    4005, 4005, 5513, 5513, 8010, 12059, 1550, 8010, 12059, 5513,
    12016, 16408, 22911, 33506};

typedef struct
{
  uint32_t order, type, scope;
  uint32_t comp_algo;
  uint8_t *comp_settings;
  int comp_settings_len;
} mkv_content_encoding_t;

typedef struct mkv_track
{
  int tnum;
  char *name;

  char *codec_id;
  int ms_compat;
  char *language;

  int type;

  uint32_t v_width, v_height, v_dwidth, v_dheight;
  double v_frate;

  uint32_t a_formattag;
  uint32_t a_channels, a_bps;
  float a_sfreq;

  double default_duration;

  int default_track;

  unsigned char *private_data;
  unsigned int private_size;

  /* stuff for realmedia */
  int realmedia;
  int64_t rv_kf_base;
  int rv_kf_pts;
  double rv_pts;  /* previous video timestamp */
  double ra_pts;  /* previous audio timestamp */

  /** realaudio descrambling */
  int sub_packet_size; ///< sub packet size, per stream
  int sub_packet_h; ///< number of coded frames per block
  int coded_framesize; ///< coded frame size, per stream
  int audiopk_size; ///< audio packet size
  unsigned char *audio_buf; ///< place to store reordered audio data
  double *audio_timestamp; ///< timestamp for each audio packet
  int sub_packet_cnt; ///< number of subpacket already received
  int audio_filepos; ///< file position of first audio packet in block

  /* stuff for quicktime */
  int fix_i_bps;
  double qt_last_a_pts;

  int subtitle_type;

  /* The timecodes of video frames might have to be reordered if they're
     in display order (the timecodes, not the frames themselves!). In this
     case demux packets have to be cached with the help of these variables. */
  int reorder_timecodes;
  demux_packet_t **cached_dps;
  int num_cached_dps, num_allocated_dps;
  double max_pts;

  /* generic content encoding support */
  mkv_content_encoding_t *encodings;
  int num_encodings;

  /* For VobSubs and SSA/ASS */
  sh_sub_t *sh_sub;
} mkv_track_t;

typedef struct mkv_index
{
  int tnum;
  uint64_t timecode, filepos;
} mkv_index_t;

typedef struct mkv_demuxer
{
  off_t segment_start;

  double duration, last_pts;
  uint64_t last_filepos;

  mkv_track_t **tracks;
  int num_tracks;

  uint64_t tc_scale, cluster_tc;

  uint64_t cluster_size;
  uint64_t blockgroup_size;

  mkv_index_t *indexes;
  int num_indexes;

  off_t *parsed_cues;
  int parsed_cues_num;
  off_t *parsed_seekhead;
  int parsed_seekhead_num;

  uint64_t *cluster_positions;
  int num_cluster_pos;

  int64_t skip_to_timecode;
  int v_skip_to_keyframe, a_skip_to_keyframe;

  int last_aid;
  int audio_tracks[MAX_A_STREAMS];
} mkv_demuxer_t;

#define REALHEADER_SIZE    16
#define RVPROPERTIES_SIZE  34
#define RAPROPERTIES4_SIZE 56
#define RAPROPERTIES5_SIZE 70

/**
 * \brief ensures there is space for at least one additional element
 * \param array array to grow
 * \param nelem current number of elements in array
 * \param elsize size of one array element
 */
static void *grow_array(void *array, int nelem, size_t elsize) {
  if (!(nelem & 31))
    array = realloc(array, (nelem + 32) * elsize);
  return array;
}

static mkv_track_t *
demux_mkv_find_track_by_num (mkv_demuxer_t *d, int n, int type)
{
  int i, id;

  for (i=0, id=0; i < d->num_tracks; i++)
    if (d->tracks[i] != NULL && d->tracks[i]->type == type)
      if (id++ == n)
        return d->tracks[i];

  return NULL;
}

static void
add_cluster_position (mkv_demuxer_t *mkv_d, uint64_t position)
{
  int i = mkv_d->num_cluster_pos;

  while (i--)
    if (mkv_d->cluster_positions[i] == position)
      return;

  mkv_d->cluster_positions = grow_array(mkv_d->cluster_positions,
                                        mkv_d->num_cluster_pos,
                                        sizeof(uint64_t));
  mkv_d->cluster_positions[mkv_d->num_cluster_pos++] = position;
}


#define AAC_SYNC_EXTENSION_TYPE 0x02b7
static int
aac_get_sample_rate_index (uint32_t sample_rate)
{
  if (92017 <= sample_rate)
    return 0;
  else if (75132 <= sample_rate)
    return 1;
  else if (55426 <= sample_rate)
    return 2;
  else if (46009 <= sample_rate)
    return 3;
  else if (37566 <= sample_rate)
    return 4;
  else if (27713 <= sample_rate)
    return 5;
  else if (23004 <= sample_rate)
    return 6;
  else if (18783 <= sample_rate)
    return 7;
  else if (13856 <= sample_rate)
    return 8;
  else if (11502 <= sample_rate)
    return 9;
  else if (9391 <= sample_rate)
    return 10;
  else
    return 11;
}

/** \brief Free cached demux packets
 *
 * Reordering the timecodes requires caching of demux packets. This function
 * frees all these cached packets and the memory for the cached pointers
 * itself.
 *
 * \param demuxer The demuxer for which the cache is to be freed.
 */
static void
free_cached_dps (demuxer_t *demuxer)
{
  mkv_demuxer_t *mkv_d = (mkv_demuxer_t *) demuxer->priv;
  mkv_track_t *track;
  int i, k;

  for (k = 0; k < mkv_d->num_tracks; k++)
    {
      track = mkv_d->tracks[k];
      for (i = 0; i < track->num_cached_dps; i++)
        free_demux_packet (track->cached_dps[i]);
      free(track->cached_dps);
      track->cached_dps = NULL;
      track->num_cached_dps = 0;
      track->num_allocated_dps = 0;
      track->max_pts = 0;
    }
}

static int
demux_mkv_decode (mkv_track_t *track, uint8_t *src, uint8_t **dest,
                  uint32_t *size, uint32_t type)
{
  int i, result;
  int modified = 0;

  *dest = src;
  if (track->num_encodings <= 0)
    return 0;

  for (i=0; i<track->num_encodings; i++)
    {
      if (!(track->encodings[i].scope & type))
        continue;

#if CONFIG_ZLIB
      if (track->encodings[i].comp_algo == 0)
        {
          /* zlib encoded track */
          z_stream zstream;

          zstream.zalloc = (alloc_func) 0;
          zstream.zfree = (free_func) 0;
          zstream.opaque = (voidpf) 0;
          if (inflateInit (&zstream) != Z_OK)
            {
              mp_tmsg (MSGT_DEMUX, MSGL_WARN,
                      "[mkv] zlib initialization failed.\n");
              return modified;
            }
          zstream.next_in = (Bytef *) src;
          zstream.avail_in = *size;

          modified = 1;
          *dest = NULL;
          zstream.avail_out = *size;
          do {
            *size += 4000;
            *dest = realloc (*dest, *size);
            zstream.next_out = (Bytef *) (*dest + zstream.total_out);
            result = inflate (&zstream, Z_NO_FLUSH);
            if (result != Z_OK && result != Z_STREAM_END)
              {
                mp_tmsg (MSGT_DEMUX, MSGL_WARN,
                        "[mkv] zlib decompression failed.\n");
                free(*dest);
                *dest = NULL;
                inflateEnd (&zstream);
                return modified;
              }
            zstream.avail_out += 4000;
          } while (zstream.avail_out == 4000 &&
                   zstream.avail_in != 0 && result != Z_STREAM_END);

          *size = zstream.total_out;
          inflateEnd (&zstream);
        }
#endif
      if (track->encodings[i].comp_algo == 2)
        {
          /* lzo encoded track */
          int dstlen = *size * 3;

          *dest = NULL;
          while (1)
            {
              int srclen = *size;
              if (dstlen > SIZE_MAX - AV_LZO_OUTPUT_PADDING) goto lzo_fail;
              *dest = realloc (*dest, dstlen + AV_LZO_OUTPUT_PADDING);
              result = av_lzo1x_decode (*dest, &dstlen, src, &srclen);
              if (result == 0)
                break;
              if (!(result & AV_LZO_OUTPUT_FULL))
                {
lzo_fail:
                  mp_tmsg (MSGT_DEMUX, MSGL_WARN,
                          "[mkv] lzo decompression failed.\n");
                  free(*dest);
                  *dest = NULL;
                  return modified;
                }
              mp_msg (MSGT_DEMUX, MSGL_DBG2,
                      "[mkv] lzo decompression buffer too small.\n");
              dstlen *= 2;
            }
          *size = dstlen;
        }
    }

  return modified;
}


static int demux_mkv_read_info(demuxer_t *demuxer)
{
    mkv_demuxer_t *mkv_d = demuxer->priv;
    stream_t *s = demuxer->stream;
    uint64_t length, l;
    int i;
    uint64_t tc_scale = 1000000;
    long double duration = 0.;

    length = ebml_read_length(s, NULL);
    while (length > 0) {
        uint32_t id = ebml_read_id(s, &i);
        length -= i;
        switch (id) {
        case MATROSKA_ID_TIMECODESCALE:
            tc_scale = ebml_read_uint(s, &l);
            length -= l;
            if (tc_scale == EBML_UINT_INVALID)
                return 1;
            mp_msg(MSGT_DEMUX, MSGL_V, "[mkv] | + timecode scale: %"PRIu64"\n",
                    tc_scale);
            break;

        case MATROSKA_ID_DURATION:
            duration = ebml_read_float(s, &l);
            length -= l;
            if (duration == EBML_FLOAT_INVALID)
                return 1;
            break;

        case MATROSKA_ID_SEGMENTUID:;
            l = ebml_read_length(s, &i);
            length -= i;
            if (l != sizeof(demuxer->matroska_data.segment_uid)) {
                mp_msg(MSGT_DEMUX, MSGL_INFO,
                       "[mkv] segment uid invalid length %"PRIu64"\n", l);
                stream_skip(s, l);
            } else {
                stream_read(s, demuxer->matroska_data.segment_uid, l);
                mp_msg(MSGT_DEMUX, MSGL_V, "[mkv] | + segment uid");
                for (int i = 0; i < l; i++)
                    mp_msg(MSGT_DEMUX, MSGL_V, " %02x",
                           demuxer->matroska_data.segment_uid[i]);
                mp_msg(MSGT_DEMUX, MSGL_V, "\n");
            }
            length -= l;
            break;

        default:
            ebml_read_skip(s, &l);
            length -= l;
            break;
        }
    }
    mkv_d->tc_scale = tc_scale;
    mkv_d->duration = duration * tc_scale / 1000000000.0;
    if (duration)
        mp_msg(MSGT_DEMUX, MSGL_V, "[mkv] | + duration: %.3fs\n",
               mkv_d->duration);

    return 0;
}

/**
 * \brief free array of kv_content_encoding_t
 * \param encodings pointer to array
 * \param numencodings number of encodings in array
 */
static void
demux_mkv_free_encodings(mkv_content_encoding_t *encodings, int numencodings)
{
  while (numencodings-- > 0)
    free(encodings[numencodings].comp_settings);
  free(encodings);
}

static int
demux_mkv_read_trackencodings (demuxer_t *demuxer, mkv_track_t *track)
{
  stream_t *s = demuxer->stream;
  mkv_content_encoding_t *ce, e;
  uint64_t len, length, l;
  int il, n;

  ce = malloc (sizeof (*ce));
  n = 0;

  len = length = ebml_read_length (s, &il);
  len += il;
  while (length > 0)
    {
      switch (ebml_read_id (s, &il))
        {
        case MATROSKA_ID_CONTENTENCODING:
          {
            uint64_t len;
            int i;

            memset (&e, 0, sizeof (e));
            e.scope = 1;

            len = ebml_read_length (s, &i);
            l = len + i;

            while (len > 0)
              {
                uint64_t num, l;
                int il;

                switch (ebml_read_id (s, &il))
                  {
                  case MATROSKA_ID_CONTENTENCODINGORDER:
                    num = ebml_read_uint (s, &l);
                    if (num == EBML_UINT_INVALID)
                      goto err_out;
                    e.order = num;
                    break;

                  case MATROSKA_ID_CONTENTENCODINGSCOPE:
                    num = ebml_read_uint (s, &l);
                    if (num == EBML_UINT_INVALID)
                      goto err_out;
                    e.scope = num;
                    break;

                  case MATROSKA_ID_CONTENTENCODINGTYPE:
                    num = ebml_read_uint (s, &l);
                    if (num == EBML_UINT_INVALID)
                      goto err_out;
                    e.type = num;
                    break;

                  case MATROSKA_ID_CONTENTCOMPRESSION:
                    {
                      uint64_t le;

                      le = ebml_read_length (s, &i);
                      l = le + i;

                      while (le > 0)
                        {
                          uint64_t l;
                          int il;

                          switch (ebml_read_id (s, &il))
                            {
                            case MATROSKA_ID_CONTENTCOMPALGO:
                              num = ebml_read_uint (s, &l);
                              if (num == EBML_UINT_INVALID)
                                goto err_out;
                              e.comp_algo = num;
                              break;

                            case MATROSKA_ID_CONTENTCOMPSETTINGS:
                              l = ebml_read_length (s, &i);
                              e.comp_settings = malloc (l);
                              stream_read (s, e.comp_settings, l);
                              e.comp_settings_len = l;
                              l += i;
                              break;

                            default:
                              ebml_read_skip (s, &l);
                              break;
                            }
                          le -= l + il;
                        }

                      if (e.type == 1)
                        {
                          mp_tmsg(MSGT_DEMUX, MSGL_WARN,
                                 "[mkv] Track number %u has been encrypted and decryption has not yet been\n[mkv] implemented. Skipping track.\n", track->tnum);
                        }
                      else if (e.type != 0)
                        {
                          mp_tmsg(MSGT_DEMUX, MSGL_WARN,
                                 "[mkv] Unknown content encoding type for track %u. Skipping track.\n", track->tnum);
                        }

                      if (e.comp_algo != 0 && e.comp_algo != 2)
                        {
                          mp_tmsg (MSGT_DEMUX, MSGL_WARN,
                                  "[mkv] Track %u has been compressed with an unknown/unsupported compression\n[mkv] algorithm (%u). Skipping track.\n",
                                  track->tnum, e.comp_algo);
                        }
#if !CONFIG_ZLIB
                      else if (e.comp_algo == 0)
                        {
                          mp_tmsg (MSGT_DEMUX, MSGL_WARN,
                                  "[mkv] Track %u was compressed with zlib but mplayer has not been compiled\n[mkv] with support for zlib compression. Skipping track.\n",
                                  track->tnum);
                        }
#endif

                      break;
                    }

                  default:
                    ebml_read_skip (s, &l);
                    break;
                  }
                len -= l + il;
              }
            for (i=0; i<n; i++)
              if (e.order <= ce[i].order)
                break;
            ce = realloc (ce, (n+1) *sizeof (*ce));
            memmove (ce+i+1, ce+i, (n-i) * sizeof (*ce));
            memcpy (ce+i, &e, sizeof (e));
            n++;
            break;
          }

        default:
          ebml_read_skip (s, &l);
          break;
        }

      length -= l + il;
    }

  track->encodings = ce;
  track->num_encodings = n;
  return len;

err_out:
  demux_mkv_free_encodings(ce, n);
  return 0;
}

static int
demux_mkv_read_trackaudio (demuxer_t *demuxer, mkv_track_t *track)
{
  stream_t *s = demuxer->stream;
  uint64_t len, length, l;
  int il;

  track->a_sfreq = 8000.0;
  track->a_channels = 1;

  len = length = ebml_read_length (s, &il);
  len += il;
  while (length > 0)
    {
      switch (ebml_read_id (s, &il))
        {
        case MATROSKA_ID_AUDIOSAMPLINGFREQ:
          {
            long double num = ebml_read_float (s, &l);
            if (num == EBML_FLOAT_INVALID)
              return 0;
            track->a_sfreq = num;
            mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |   + Sampling frequency: %f\n",
                    track->a_sfreq);
            break;
          }

        case MATROSKA_ID_AUDIOBITDEPTH:
          {
            uint64_t num = ebml_read_uint (s, &l);
            if (num == EBML_UINT_INVALID)
              return 0;
            track->a_bps = num;
            mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |   + Bit depth: %u\n",
                    track->a_bps);
            break;
          }

        case MATROSKA_ID_AUDIOCHANNELS:
          {
            uint64_t num = ebml_read_uint (s, &l);
            if (num == EBML_UINT_INVALID)
              return 0;
            track->a_channels = num;
            mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |   + Channels: %u\n",
                    track->a_channels);
            break;
          }

        default:
            ebml_read_skip (s, &l);
            break;
        }
      length -= l + il;
    }
  return len;
}

static int
demux_mkv_read_trackvideo (demuxer_t *demuxer, mkv_track_t *track)
{
  stream_t *s = demuxer->stream;
  uint64_t len, length, l;
  int il;

  len = length = ebml_read_length (s, &il);
  len += il;
  while (length > 0)
    {
      switch (ebml_read_id (s, &il))
        {
        case MATROSKA_ID_VIDEOFRAMERATE:
          {
            long double num = ebml_read_float (s, &l);
            if (num == EBML_FLOAT_INVALID)
              return 0;
            track->v_frate = num;
            mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |   + Frame rate: %f\n",
                    track->v_frate);
            if (track->v_frate > 0)
              track->default_duration = 1 / track->v_frate;
            break;
          }

        case MATROSKA_ID_VIDEODISPLAYWIDTH:
          {
            uint64_t num = ebml_read_uint (s, &l);
            if (num == EBML_UINT_INVALID)
              return 0;
            track->v_dwidth = num;
            mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |   + Display width: %u\n",
                    track->v_dwidth);
            break;
          }

        case MATROSKA_ID_VIDEODISPLAYHEIGHT:
          {
            uint64_t num = ebml_read_uint (s, &l);
            if (num == EBML_UINT_INVALID)
              return 0;
            track->v_dheight = num;
            mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |   + Display height: %u\n",
                    track->v_dheight);
            break;
          }

        case MATROSKA_ID_VIDEOPIXELWIDTH:
          {
            uint64_t num = ebml_read_uint (s, &l);
            if (num == EBML_UINT_INVALID)
              return 0;
            track->v_width = num;
            mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |   + Pixel width: %u\n",
                    track->v_width);
            break;
          }

        case MATROSKA_ID_VIDEOPIXELHEIGHT:
          {
            uint64_t num = ebml_read_uint (s, &l);
            if (num == EBML_UINT_INVALID)
              return 0;
            track->v_height = num;
            mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |   + Pixel height: %u\n",
                    track->v_height);
            break;
          }

        default:
            ebml_read_skip (s, &l);
            break;
        }
      length -= l + il;
    }
  return len;
}

/**
 * \brief free any data associated with given track
 * \param track track of which to free data
 */
static void
demux_mkv_free_trackentry(mkv_track_t *track) {
  free (track->name);
  free (track->codec_id);
  free (track->language);
  free (track->private_data);
  free (track->audio_buf);
  free (track->audio_timestamp);
  demux_mkv_free_encodings(track->encodings, track->num_encodings);
  free(track);
}

static int
demux_mkv_read_trackentry (demuxer_t *demuxer)
{
  mkv_demuxer_t *mkv_d = (mkv_demuxer_t *) demuxer->priv;
  stream_t *s = demuxer->stream;
  mkv_track_t *track;
  uint64_t len, length, l;
  int il;

  track = calloc (1, sizeof (*track));
  /* set default values */
  track->default_track = 1;
  track->name = 0;
  track->language = strdup("eng");

  len = length = ebml_read_length (s, &il);
  len += il;
  while (length > 0)
    {
      switch (ebml_read_id (s, &il))
        {
        case MATROSKA_ID_TRACKNUMBER:
          {
            uint64_t num = ebml_read_uint (s, &l);
            if (num == EBML_UINT_INVALID)
              goto err_out;
            track->tnum = num;
            mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |  + Track number: %u\n",
                    track->tnum);
            break;
          }

        case MATROSKA_ID_TRACKNAME:
          {
            track->name = ebml_read_utf8 (s, &l);
            if (track->name == NULL)
              goto err_out;
            mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |  + Name: %s\n",
                    track->name);
            break;
          }

        case MATROSKA_ID_TRACKTYPE:
          {
            uint64_t num = ebml_read_uint (s, &l);
            if (num == EBML_UINT_INVALID)
              return 0;
            track->type = num;
            mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |  + Track type: ");
            switch (track->type)
              {
              case MATROSKA_TRACK_AUDIO:
                mp_msg (MSGT_DEMUX, MSGL_V, "Audio\n");
                break;
              case MATROSKA_TRACK_VIDEO:
                mp_msg (MSGT_DEMUX, MSGL_V, "Video\n");
                break;
              case MATROSKA_TRACK_SUBTITLE:
                mp_msg (MSGT_DEMUX, MSGL_V, "Subtitle\n");
                break;
              default:
                mp_msg (MSGT_DEMUX, MSGL_V, "unknown\n");
                break;
            }
            break;
          }

        case MATROSKA_ID_TRACKAUDIO:
          mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |  + Audio track\n");
          l = demux_mkv_read_trackaudio (demuxer, track);
          if (l == 0)
            goto err_out;
          break;

        case MATROSKA_ID_TRACKVIDEO:
          mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |  + Video track\n");
          l = demux_mkv_read_trackvideo (demuxer, track);
          if (l == 0)
            goto err_out;
          break;

        case MATROSKA_ID_CODECID:
          track->codec_id = ebml_read_ascii (s, &l);
          if (track->codec_id == NULL)
            goto err_out;
          if (!strcmp (track->codec_id, MKV_V_MSCOMP) ||
              !strcmp (track->codec_id, MKV_A_ACM))
            track->ms_compat = 1;
          else if (!strcmp (track->codec_id, MKV_S_VOBSUB))
            track->subtitle_type = MATROSKA_SUBTYPE_VOBSUB;
          else if (!strcmp (track->codec_id, MKV_S_TEXTSSA)
                   || !strcmp (track->codec_id, MKV_S_TEXTASS)
                   || !strcmp (track->codec_id, MKV_S_SSA)
                   || !strcmp (track->codec_id, MKV_S_ASS))
            {
              track->subtitle_type = MATROSKA_SUBTYPE_SSA;
            }
          else if (!strcmp (track->codec_id, MKV_S_TEXTASCII))
            track->subtitle_type = MATROSKA_SUBTYPE_TEXT;
          if (!strcmp (track->codec_id, MKV_S_TEXTUTF8))
            {
              track->subtitle_type = MATROSKA_SUBTYPE_TEXT;
            }
          mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |  + Codec ID: %s\n",
                  track->codec_id);
          break;

        case MATROSKA_ID_CODECPRIVATE:
          {
            int x;
            uint64_t num = ebml_read_length (s, &x);
	    // audit: cheap guard against overflows later..
	    if (num > SIZE_MAX - 1000) return 0;
            l = x + num;
            track->private_data = malloc (num + AV_LZO_INPUT_PADDING);
            if (stream_read(s, track->private_data, num) != (int) num)
              goto err_out;
            track->private_size = num;
            mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |  + CodecPrivate, length "
                    "%u\n", track->private_size);
            break;
          }

        case MATROSKA_ID_TRACKLANGUAGE:
          free(track->language);
          track->language = ebml_read_utf8 (s, &l);
          if (track->language == NULL)
            goto err_out;
          mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |  + Language: %s\n",
                  track->language);
          break;

        case MATROSKA_ID_TRACKFLAGDEFAULT:
          {
            uint64_t num = ebml_read_uint (s, &l);
            if (num == EBML_UINT_INVALID)
              goto err_out;
            track->default_track = num;
            mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |  + Default flag: %u\n",
                    track->default_track);
            break;
          }

        case MATROSKA_ID_TRACKDEFAULTDURATION:
          {
            uint64_t num = ebml_read_uint (s, &l);
            if (num == EBML_UINT_INVALID)
              goto err_out;
            if (num == 0)
              mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |  + Default duration: 0");
            else
              {
                track->v_frate = 1000000000.0 / num;
                track->default_duration = num / 1000000000.0;
                mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |  + Default duration: "
                        "%.3fms ( = %.3f fps)\n",num/1000000.0,track->v_frate);
              }
            break;
          }

        case MATROSKA_ID_TRACKENCODINGS:
          l = demux_mkv_read_trackencodings (demuxer, track);
          if (l == 0)
            goto err_out;
          break;

        default:
          ebml_read_skip (s, &l);
          break;
        }
      length -= l + il;
    }

  mkv_d->tracks[mkv_d->num_tracks++] = track;
  return len;

err_out:
  demux_mkv_free_trackentry(track);
  return 0;
}

static int
demux_mkv_read_tracks (demuxer_t *demuxer)
{
  mkv_demuxer_t *mkv_d = (mkv_demuxer_t *) demuxer->priv;
  stream_t *s = demuxer->stream;
  uint64_t length, l;
  int il;

  mkv_d->tracks = malloc (sizeof (*mkv_d->tracks));
  mkv_d->num_tracks = 0;

  length = ebml_read_length (s, NULL);
  while (length > 0)
    {
      switch (ebml_read_id (s, &il))
        {
        case MATROSKA_ID_TRACKENTRY:
          mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] | + a track...\n");
          mkv_d->tracks = realloc (mkv_d->tracks,
                                   (mkv_d->num_tracks+1)
                                   *sizeof (*mkv_d->tracks));
          l = demux_mkv_read_trackentry (demuxer);
          if (l == 0)
            return 1;
          break;

        default:
            ebml_read_skip (s, &l);
            break;
        }
      length -= l + il;
    }
  return 0;
}

static int
demux_mkv_read_cues (demuxer_t *demuxer)
{
  mkv_demuxer_t *mkv_d = (mkv_demuxer_t *) demuxer->priv;
  stream_t *s = demuxer->stream;
  uint64_t length, l, time, track, pos;
  off_t off;
  int i, il;

  if (index_mode == 0) {
    ebml_read_skip (s, NULL);
    return 0;
  }
  off = stream_tell (s);
  for (i=0; i<mkv_d->parsed_cues_num; i++)
    if (mkv_d->parsed_cues[i] == off)
      {
        ebml_read_skip (s, NULL);
        return 0;
      }
  mkv_d->parsed_cues = realloc (mkv_d->parsed_cues,
                                (mkv_d->parsed_cues_num+1)
                                * sizeof (off_t));
  mkv_d->parsed_cues[mkv_d->parsed_cues_num++] = off;

  mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] /---- [ parsing cues ] -----------\n");
  length = ebml_read_length (s, NULL);

  while (length > 0)
    {
      time = track = pos = EBML_UINT_INVALID;

      switch (ebml_read_id (s, &il))
        {
        case MATROSKA_ID_POINTENTRY:
          {
            uint64_t len;

            len = ebml_read_length (s, &i);
            l = len + i;

            while (len > 0)
              {
                uint64_t l;
                int il;

                switch (ebml_read_id (s, &il))
                  {
                  case MATROSKA_ID_CUETIME:
                    time = ebml_read_uint (s, &l);
                    break;

                  case MATROSKA_ID_CUETRACKPOSITION:
                    {
                      uint64_t le;

                      le = ebml_read_length (s, &i);
                      l = le + i;

                      while (le > 0)
                        {
                          uint64_t l;
                          int il;

                          switch (ebml_read_id (s, &il))
                            {
                            case MATROSKA_ID_CUETRACK:
                              track = ebml_read_uint (s, &l);
                              break;

                            case MATROSKA_ID_CUECLUSTERPOSITION:
                              pos = ebml_read_uint (s, &l);
                              break;

                            default:
                              ebml_read_skip (s, &l);
                              break;
                            }
                          le -= l + il;
                        }
                      break;
                    }

                  default:
                    ebml_read_skip (s, &l);
                    break;
                  }
                len -= l + il;
              }
            break;
          }

        default:
          ebml_read_skip (s, &l);
          break;
        }

      length -= l + il;

      if (time != EBML_UINT_INVALID && track != EBML_UINT_INVALID
          && pos != EBML_UINT_INVALID)
        {
          mkv_d->indexes = grow_array(mkv_d->indexes, mkv_d->num_indexes,
                                      sizeof(mkv_index_t));
          mkv_d->indexes[mkv_d->num_indexes].tnum = track;
          mkv_d->indexes[mkv_d->num_indexes].timecode = time;
          mkv_d->indexes[mkv_d->num_indexes].filepos =mkv_d->segment_start+pos;
          mp_msg (MSGT_DEMUX, MSGL_DBG2, "[mkv] |+ found cue point "
                  "for track %"PRIu64": timecode %"PRIu64", filepos: %"PRIu64"\n",
                  track, time, mkv_d->segment_start + pos);
          mkv_d->num_indexes++;
        }
    }

  mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] \\---- [ parsing cues ] -----------\n");
  return 0;
}

static uint64_t read_one_chapter(struct demuxer *demuxer, stream_t *s)
{
    uint64_t len, l;
    uint64_t start = 0, end = 0;
    struct matroska_chapter chapter = {};
    char *name = 0;
    int i;
    uint32_t id;

    len = ebml_read_length(s, &i);
    uint64_t bytes_read = len + i;

    while (len > 0) {
        id = ebml_read_id(s, &i);
        len -= i;
        switch (id) {
        case MATROSKA_ID_CHAPTERTIMESTART:
            start = ebml_read_uint(s, &l) / 1000000;
            len -= l;
            break;

        case MATROSKA_ID_CHAPTERTIMEEND:
            end = ebml_read_uint(s, &l) / 1000000;
            len -= l;
            break;

        case MATROSKA_ID_CHAPTERDISPLAY:;
            uint64_t displaylen = ebml_read_length(s, &i);
            len -= displaylen + i;
            while (displaylen > 0) {
                id = ebml_read_id(s, &i);
                displaylen -= i;
                switch (id) {
                case MATROSKA_ID_CHAPSTRING:
                    name = ebml_read_utf8(s, &l);
                    break;
                default:
                    ebml_read_skip(s, &l);
                    break;
                }
                displaylen -= l;
            }
            break;

        case MATROSKA_ID_CHAPTERSEGMENTUID:
            l = ebml_read_length(s, &i);
            len -= l + i;
            if (l != sizeof(chapter.segment_uid)) {
                mp_msg(MSGT_DEMUX, MSGL_INFO,
                       "[mkv] chapter segment uid invalid length %"PRIu64"\n",
                       l);
                stream_skip(s, l);
            } else {
                stream_read(s, chapter.segment_uid, l);
                chapter.has_segment_uid = true;
                mp_msg(MSGT_DEMUX, MSGL_V, "[mkv] Chapter segment uid ");
                for (int i = 0; i < l; i++)
                    mp_msg(MSGT_DEMUX, MSGL_V, "%02x ", chapter.segment_uid[i]);
                mp_msg(MSGT_DEMUX, MSGL_V, "\n");
            }
            break;

        default:
            ebml_read_skip(s, &l);
            len -= l;
            break;
        }
    }

    if (!name)
        name = strdup("(unnamed)");

    int cid = demuxer_add_chapter(demuxer, name, start, end);
    struct matroska_data *m = &demuxer->matroska_data;
    m->ordered_chapters = talloc_realloc(demuxer, m->ordered_chapters,
                                         struct matroska_chapter,
                                         m->num_ordered_chapters + 1);
    chapter.start = start;
    chapter.end = end;
    chapter.name = talloc_strdup(m->ordered_chapters, name);
    // Will be undone later if this is a normal chapter rather than ordered
    m->ordered_chapters[m->num_ordered_chapters] = chapter;
    m->num_ordered_chapters++;

    mp_msg(MSGT_DEMUX, MSGL_V, "[mkv] Chapter %u from %02d:%02d:%02d."
           "%03d to %02d:%02d:%02d.%03d, %s\n",
           cid,
           (int) (start / 60 / 60 / 1000),
           (int) ((start / 60 / 1000) % 60),
           (int) ((start / 1000) % 60),
           (int) (start % 1000),
           (int) (end / 60 / 60 / 1000),
           (int) ((end / 60 / 1000) % 60),
           (int) ((end / 1000) % 60),
           (int) (end % 1000), name);

    free(name);
    return bytes_read;
}

static int demux_mkv_read_chapters(struct demuxer *demuxer)
{
    stream_t *s = demuxer->stream;
    uint64_t length, l;
    int i;
    uint32_t id;

    if (demuxer->chapters) {
        ebml_read_skip(s, NULL);
        return 0;
    }

    mp_msg(MSGT_DEMUX, MSGL_V, "[mkv] /---- [ parsing chapters ] ---------\n");
    length = ebml_read_length(s, NULL);

    bool have_edition = false;
    while (length > 0) {
        id = ebml_read_id(s, &i);
        length -= i;
        switch (id) {
        case MATROSKA_ID_EDITIONENTRY:
            if (have_edition) {
                mp_msg(MSGT_DEMUX, MSGL_WARN, "[mkv] Multiple edition entries"
                       " - ignoring all but first!\n");
                ebml_read_skip(s, &l);
                length -= l;
                break;
            }
            have_edition = true;
            uint64_t editionlen = ebml_read_length(s, &i);
            length -= editionlen + i;
            bool ordered = false;
            while (editionlen > 0) {
                id = ebml_read_id(s, &i);
                editionlen -= i;
                switch (id) {
                case MATROSKA_ID_CHAPTERATOM:
                    l = read_one_chapter(demuxer, s);
                    break;
                case MATROSKA_ID_EDITIONFLAGORDERED:
                    ordered = ebml_read_uint(s, &l);
                    mp_msg(MSGT_DEMUX, MSGL_V,
                           "[mkv] Ordered chapter flag: %d\n", ordered);
                    break;

                default:
                    ebml_read_skip(s, &l);
                    break;
                }
                editionlen -= l;
            }
            if (!ordered) {
                // The chapters should be interpreted as normal ones,
                // so undo the addition of this information.
                talloc_free(demuxer->matroska_data.ordered_chapters);
                demuxer->matroska_data.ordered_chapters = NULL;
                demuxer->matroska_data.num_ordered_chapters = 0;
            }
            break;

        default:
            ebml_read_skip(s, &l);
            length -= l;
            break;
        }
    }

    mp_msg(MSGT_DEMUX, MSGL_V, "[mkv] \\---- [ parsing chapters ] ---------\n");
    return 0;
}

static int
demux_mkv_read_tags (demuxer_t *demuxer)
{
  ebml_read_skip (demuxer->stream, NULL);
  return 0;
}

static int
demux_mkv_read_attachments (demuxer_t *demuxer)
{
  stream_t *s = demuxer->stream;
  uint64_t length, l;
  int il;

  mp_msg(MSGT_DEMUX, MSGL_V, "[mkv] /---- [ parsing attachments ] ---------\n");
  length = ebml_read_length (s, NULL);

  while (length > 0)
    {
      switch (ebml_read_id (s, &il))
        {
          case MATROSKA_ID_ATTACHEDFILE:
            {
              uint64_t len;
              int i;
              char* name = NULL;
              char* mime = NULL;
              char* data = NULL;
              int data_size = 0;

              len = ebml_read_length (s, &i);
              l = len + i;

              mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] | + an attachment...\n");

              while (len > 0)
                {
                  uint64_t l;
                  int il;

                  switch (ebml_read_id (s, &il))
                    {
                    case MATROSKA_ID_FILENAME:
                      name = ebml_read_utf8 (s, &l);
                      if (name == NULL)
                        return 0;
                      mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |  + FileName: %s\n",
                        name);
                      break;

                    case MATROSKA_ID_FILEMIMETYPE:
                      mime = ebml_read_ascii (s, &l);
                      if (mime == NULL)
                        return 0;
                      mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |  + FileMimeType: %s\n",
                        mime);
                      break;

                    case MATROSKA_ID_FILEDATA:
                      {
                        int x;
                        uint64_t num = ebml_read_length (s, &x);
                        l = x + num;
                        free(data);
                        data = malloc (num);
                        if (stream_read(s, data, num) != (int) num)
                        {
                          free(data);
                          return 0;
                        }
                        data_size = num;
                        mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |  + FileData, length "
                                "%u\n", data_size);
                        break;
                      }

                    default:
                      ebml_read_skip (s, &l);
                      break;
                    }
                  len -= l + il;
                }

              demuxer_add_attachment(demuxer, name, mime, data, data_size);
              mp_msg(MSGT_DEMUX, MSGL_V,
                     "[mkv] Attachment: %s, %s, %u bytes\n",
                     name, mime, data_size);
              break;
            }

          default:
            ebml_read_skip (s, &l);
            break;
        }
      length -= l + il;
    }

  mp_msg(MSGT_DEMUX, MSGL_V, "[mkv] \\---- [ parsing attachments ] ---------\n");
  return 0;
}

static int
demux_mkv_read_seekhead (demuxer_t *demuxer)
{
  mkv_demuxer_t *mkv_d = (mkv_demuxer_t *) demuxer->priv;
  stream_t *s = demuxer->stream;
  uint64_t length, l, seek_pos, saved_pos, num;
  uint32_t seek_id;
  int i, il, res = 0;
  off_t off;

  off = stream_tell (s);
  for (i=0; i<mkv_d->parsed_seekhead_num; i++)
    if (mkv_d->parsed_seekhead[i] == off)
      {
        ebml_read_skip (s, NULL);
        return 0;
      }
  mkv_d->parsed_seekhead = realloc (mkv_d->parsed_seekhead,
                                    (mkv_d->parsed_seekhead_num+1)
                                    * sizeof (off_t));
  mkv_d->parsed_seekhead[mkv_d->parsed_seekhead_num++] = off;

  mp_msg(MSGT_DEMUX, MSGL_V, "[mkv] /---- [ parsing seek head ] ---------\n");
  length = ebml_read_length (s, NULL);
  /* off now holds the position of the next element after the seek head. */
  off = stream_tell (s) + length;
  while (length > 0 && !res)
    {

      seek_id = 0;
      seek_pos = EBML_UINT_INVALID;

      switch (ebml_read_id (s, &il))
        {
        case MATROSKA_ID_SEEKENTRY:
          {
            uint64_t len;

            len = ebml_read_length (s, &i);
            l = len + i;

            while (len > 0)
              {
                uint64_t l;
                int il;

                switch (ebml_read_id (s, &il))
                  {
                  case MATROSKA_ID_SEEKID:
                    num = ebml_read_uint (s, &l);
                    if (num != EBML_UINT_INVALID)
                      seek_id = num;
                    break;

                  case MATROSKA_ID_SEEKPOSITION:
                    seek_pos = ebml_read_uint (s, &l);
                    break;

                  default:
                    ebml_read_skip (s, &l);
                    break;
                  }
                len -= l + il;
              }

            break;
          }

        default:
            ebml_read_skip (s, &l);
            break;
        }
      length -= l + il;

      if (seek_id == 0 || seek_id == MATROSKA_ID_CLUSTER
          || seek_pos == EBML_UINT_INVALID ||
          ((mkv_d->segment_start + seek_pos) >= (uint64_t)demuxer->movi_end))
        continue;

      saved_pos = stream_tell (s);
      if (!stream_seek (s, mkv_d->segment_start + seek_pos))
        res = 1;
      else
        {
          if (ebml_read_id (s, &il) != seek_id)
            res = 1;
          else
            switch (seek_id)
              {
              case MATROSKA_ID_CUES:
                if (demux_mkv_read_cues (demuxer))
                  res = 1;
                break;

              case MATROSKA_ID_TAGS:
                if (demux_mkv_read_tags (demuxer))
                  res = 1;
                break;

              case MATROSKA_ID_SEEKHEAD:
                if (demux_mkv_read_seekhead (demuxer))
                  res = 1;
                break;

              case MATROSKA_ID_CHAPTERS:
                if (demux_mkv_read_chapters (demuxer))
                  res = 1;
                break;
              }
        }

      stream_seek (s, saved_pos);
    }
  if (res)
    {
      /* If there was an error then try to skip this seek head. */
      if (stream_seek (s, off))
        res = 0;
    }
  else
  if (length > 0)
     stream_seek (s, stream_tell (s) + length);
  mp_msg(MSGT_DEMUX, MSGL_V, "[mkv] \\---- [ parsing seek head ] ---------\n");
  return res;
}

static int
demux_mkv_open_video (demuxer_t *demuxer, mkv_track_t *track, int vid);
static int
demux_mkv_open_audio (demuxer_t *demuxer, mkv_track_t *track, int aid);
static int
demux_mkv_open_sub (demuxer_t *demuxer, mkv_track_t *track, int sid);

static void
display_create_tracks (demuxer_t *demuxer)
{
  mkv_demuxer_t *mkv_d = (mkv_demuxer_t *)demuxer->priv;
  int i, vid=0, aid=0, sid=0;

  for (i=0; i<mkv_d->num_tracks; i++)
    {
      char *type = "unknown", str[32];
      *str = '\0';
      switch (mkv_d->tracks[i]->type)
        {
        case MATROSKA_TRACK_VIDEO:
          type = "video";
          demux_mkv_open_video(demuxer, mkv_d->tracks[i], vid);
          if (mkv_d->tracks[i]->name)
            mp_msg(MSGT_IDENTIFY, MSGL_INFO, "ID_VID_%d_NAME=%s\n", vid, mkv_d->tracks[i]->name);
          sprintf (str, "-vid %u", vid++);
          break;
        case MATROSKA_TRACK_AUDIO:
          type = "audio";
          demux_mkv_open_audio(demuxer, mkv_d->tracks[i], aid);
          if (mkv_d->tracks[i]->name)
            mp_msg(MSGT_IDENTIFY, MSGL_INFO, "ID_AID_%d_NAME=%s\n", aid, mkv_d->tracks[i]->name);
          mp_msg(MSGT_IDENTIFY, MSGL_INFO, "ID_AID_%d_LANG=%s\n", aid, mkv_d->tracks[i]->language);
          sprintf (str, "-aid %u, -alang %.5s",aid++,mkv_d->tracks[i]->language);
          break;
        case MATROSKA_TRACK_SUBTITLE:
          type = "subtitles";
          demux_mkv_open_sub(demuxer, mkv_d->tracks[i], sid);
          if (mkv_d->tracks[i]->name)
            mp_msg(MSGT_IDENTIFY, MSGL_INFO, "ID_SID_%d_NAME=%s\n", sid, mkv_d->tracks[i]->name);
          mp_msg(MSGT_IDENTIFY, MSGL_INFO, "ID_SID_%d_LANG=%s\n", sid, mkv_d->tracks[i]->language);
          sprintf (str, "-sid %u, -slang %.5s",sid++,mkv_d->tracks[i]->language);
          break;
        }
      if (mkv_d->tracks[i]->name)
        mp_tmsg(MSGT_DEMUX, MSGL_INFO, "[mkv] Track ID %u: %s (%s) \"%s\", %s\n",
             mkv_d->tracks[i]->tnum, type, mkv_d->tracks[i]->codec_id, mkv_d->tracks[i]->name, str);
      else
        mp_tmsg(MSGT_DEMUX, MSGL_INFO, "[mkv] Track ID %u: %s (%s), %s\n",
             mkv_d->tracks[i]->tnum, type, mkv_d->tracks[i]->codec_id, str);
    }
}

typedef struct {
  char *id;
  int fourcc;
  int extradata;
} videocodec_info_t;

static const videocodec_info_t vinfo[] = {
  { MKV_V_MPEG1,     mmioFOURCC('m', 'p', 'g', '1'), 0 },
  { MKV_V_MPEG2,     mmioFOURCC('m', 'p', 'g', '2'), 0 },
  { MKV_V_MPEG4_SP,  mmioFOURCC('m', 'p', '4', 'v'), 1 },
  { MKV_V_MPEG4_ASP, mmioFOURCC('m', 'p', '4', 'v'), 1 },
  { MKV_V_MPEG4_AP,  mmioFOURCC('m', 'p', '4', 'v'), 1 },
  { MKV_V_MPEG4_AVC, mmioFOURCC('a', 'v', 'c', '1'), 1 },
  { MKV_V_THEORA,    mmioFOURCC('t', 'h', 'e', 'o'), 1 },
  { NULL, 0, 0 }
};

static int
demux_mkv_open_video (demuxer_t *demuxer, mkv_track_t *track, int vid)
{
  struct MPOpts *opts = demuxer->opts;
  BITMAPINFOHEADER *bih;
  void *ImageDesc = NULL;
  sh_video_t *sh_v;

  if (track->ms_compat)  /* MS compatibility mode */
    {
      BITMAPINFOHEADER *src;

      if (track->private_data == NULL
          || track->private_size < sizeof (BITMAPINFOHEADER))
        return 1;

      src = (BITMAPINFOHEADER *) track->private_data;
      bih = calloc (1, track->private_size);
      bih->biSize = le2me_32 (src->biSize);
      bih->biWidth = le2me_32 (src->biWidth);
      bih->biHeight = le2me_32 (src->biHeight);
      bih->biPlanes = le2me_16 (src->biPlanes);
      bih->biBitCount = le2me_16 (src->biBitCount);
      bih->biCompression = le2me_32 (src->biCompression);
      bih->biSizeImage = le2me_32 (src->biSizeImage);
      bih->biXPelsPerMeter = le2me_32 (src->biXPelsPerMeter);
      bih->biYPelsPerMeter = le2me_32 (src->biYPelsPerMeter);
      bih->biClrUsed = le2me_32 (src->biClrUsed);
      bih->biClrImportant = le2me_32 (src->biClrImportant);
      memcpy((char *) bih + sizeof (BITMAPINFOHEADER),
             (char *) src + sizeof (BITMAPINFOHEADER),
             track->private_size - sizeof (BITMAPINFOHEADER));

      if (track->v_width == 0)
        track->v_width = bih->biWidth;
      if (track->v_height == 0)
        track->v_height = bih->biHeight;
    }
  else
    {
      bih = calloc (1, sizeof (BITMAPINFOHEADER));
      bih->biSize = sizeof (BITMAPINFOHEADER);
      bih->biWidth = track->v_width;
      bih->biHeight = track->v_height;
      bih->biBitCount = 24;
      bih->biSizeImage = bih->biWidth * bih->biHeight * bih->biBitCount/8;

      if (track->private_size >= RVPROPERTIES_SIZE
          && (!strcmp (track->codec_id, MKV_V_REALV10)
              || !strcmp (track->codec_id, MKV_V_REALV20)
              || !strcmp (track->codec_id, MKV_V_REALV30)
              || !strcmp (track->codec_id, MKV_V_REALV40)))
        {
          unsigned char *dst, *src;
          uint32_t type2;
          unsigned int cnt;

          src = track->private_data + RVPROPERTIES_SIZE;

          cnt = track->private_size - RVPROPERTIES_SIZE;
          bih = realloc(bih, sizeof (BITMAPINFOHEADER)+8+cnt);
          bih->biSize = 48+cnt;
          bih->biPlanes = 1;
          type2 = AV_RB32(src - 4);
          if (type2 == 0x10003000 || type2 == 0x10003001)
            bih->biCompression=mmioFOURCC('R','V','1','3');
          else
            bih->biCompression=mmioFOURCC('R','V',track->codec_id[9],'0');
          dst = (unsigned char *) (bih + 1);
          // copy type1 and type2 info from rv properties
          memcpy(dst, src - 8, 8);
          stream_read(demuxer->stream, dst+8, cnt);
          track->realmedia = 1;

#ifdef CONFIG_QTX_CODECS
        }
      else if (track->private_size >= sizeof (ImageDescription)
               && !strcmp(track->codec_id, MKV_V_QUICKTIME))
        {
          ImageDescriptionPtr idesc;

          idesc = (ImageDescriptionPtr) track->private_data;
          idesc->idSize = be2me_32 (idesc->idSize);
          idesc->cType = be2me_32 (idesc->cType);
          idesc->version = be2me_16 (idesc->version);
          idesc->revisionLevel = be2me_16 (idesc->revisionLevel);
          idesc->vendor = be2me_32 (idesc->vendor);
          idesc->temporalQuality = be2me_32 (idesc->temporalQuality);
          idesc->spatialQuality = be2me_32 (idesc->spatialQuality);
          idesc->width = be2me_16 (idesc->width);
          idesc->height = be2me_16 (idesc->height);
          idesc->hRes = be2me_32 (idesc->hRes);
          idesc->vRes = be2me_32 (idesc->vRes);
          idesc->dataSize = be2me_32 (idesc->dataSize);
          idesc->frameCount = be2me_16 (idesc->frameCount);
          idesc->depth = be2me_16 (idesc->depth);
          idesc->clutID = be2me_16 (idesc->clutID);
          bih->biPlanes = 1;
          bih->biCompression = idesc->cType;
          ImageDesc = idesc;
#endif /* CONFIG_QTX_CODECS */

        }
      else
        {
          const videocodec_info_t *vi = vinfo;
          while (vi->id && strcmp(vi->id, track->codec_id)) vi++;
          bih->biCompression = vi->fourcc;
          if (vi->extradata && track->private_data && (track->private_size > 0))
            {
              bih->biSize += track->private_size;
              bih = realloc (bih, bih->biSize);
              memcpy (bih + 1, track->private_data, track->private_size);
            }
          track->reorder_timecodes = opts->user_correct_pts == 0;
          if (!vi->id) {
              mp_tmsg (MSGT_DEMUX,MSGL_WARN, "[mkv] Unknown/unsupported CodecID (%s) or missing/bad CodecPrivate\n[mkv] data (track %u).\n",
                      track->codec_id, track->tnum);
              free(bih);
              return 1;
          }
        }
    }

  sh_v = new_sh_video_vid (demuxer, track->tnum, vid);
  sh_v->bih = bih;
  sh_v->format = sh_v->bih->biCompression;
  if (track->v_frate == 0.0)
    track->v_frate = 25.0;
  sh_v->fps = track->v_frate;
  sh_v->frametime = 1 / track->v_frate;
  sh_v->aspect = 0;
  if (!track->realmedia)
    {
      sh_v->disp_w = track->v_width;
      sh_v->disp_h = track->v_height;
      if (track->v_dheight)
      sh_v->aspect = (double)track->v_dwidth / track->v_dheight;
    }
  else
    {
      // vd_realvid.c will set aspect to disp_w/disp_h and rederive
      // disp_w and disp_h from the RealVideo stream contents returned
      // by the Real DLLs. If DisplayWidth/DisplayHeight was not set in
      // the Matroska file then it has already been set to PixelWidth/Height
      // by check_track_information.
      sh_v->disp_w = track->v_dwidth;
      sh_v->disp_h = track->v_dheight;
    }
  sh_v->ImageDesc = ImageDesc;
  mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] Aspect: %f\n", sh_v->aspect);

  sh_v->ds = demuxer->video;
  return 0;
}

static int
demux_mkv_open_audio (demuxer_t *demuxer, mkv_track_t *track, int aid)
{
  mkv_demuxer_t *mkv_d = (mkv_demuxer_t *) demuxer->priv;
  sh_audio_t *sh_a = new_sh_audio_aid(demuxer, track->tnum, aid);
  demux_packet_t *dp;
  if(!sh_a) return 1;
  mkv_d->audio_tracks[mkv_d->last_aid] = track->tnum;

  if (track->language && (strcmp(track->language, "und") != 0))
    sh_a->lang = strdup(track->language);
  sh_a->default_track = track->default_track;
  sh_a->ds = demuxer->audio;
  sh_a->wf = malloc (sizeof (WAVEFORMATEX));
  if (track->ms_compat && (track->private_size >= sizeof(WAVEFORMATEX)))
    {
      WAVEFORMATEX *wf = (WAVEFORMATEX *)track->private_data;
      sh_a->wf = realloc(sh_a->wf, track->private_size);
      sh_a->wf->wFormatTag = le2me_16 (wf->wFormatTag);
      sh_a->wf->nChannels = le2me_16 (wf->nChannels);
      sh_a->wf->nSamplesPerSec = le2me_32 (wf->nSamplesPerSec);
      sh_a->wf->nAvgBytesPerSec = le2me_32 (wf->nAvgBytesPerSec);
      sh_a->wf->nBlockAlign = le2me_16 (wf->nBlockAlign);
      sh_a->wf->wBitsPerSample = le2me_16 (wf->wBitsPerSample);
      sh_a->wf->cbSize = track->private_size - sizeof(WAVEFORMATEX);
      memcpy(sh_a->wf + 1, wf + 1, track->private_size - sizeof(WAVEFORMATEX));
      if (track->a_sfreq == 0.0)
        track->a_sfreq = sh_a->wf->nSamplesPerSec;
      if (track->a_channels == 0)
        track->a_channels = sh_a->wf->nChannels;
      if (track->a_bps == 0)
        track->a_bps = sh_a->wf->wBitsPerSample;
      track->a_formattag = sh_a->wf->wFormatTag;
    }
  else
    {
      memset(sh_a->wf, 0, sizeof (WAVEFORMATEX));
      if (!strcmp(track->codec_id, MKV_A_MP3) ||
          !strcmp(track->codec_id, MKV_A_MP2))
        track->a_formattag = 0x0055;
      else if (!strncmp(track->codec_id, MKV_A_AC3, strlen(MKV_A_AC3)))
        track->a_formattag = 0x2000;
      else if (!strcmp(track->codec_id, MKV_A_DTS))
        track->a_formattag = 0x2001;
      else if (!strcmp(track->codec_id, MKV_A_PCM) ||
               !strcmp(track->codec_id, MKV_A_PCM_BE))
        track->a_formattag = 0x0001;
      else if (!strcmp(track->codec_id, MKV_A_AAC_2MAIN) ||
               !strncmp(track->codec_id, MKV_A_AAC_2LC,
                        strlen(MKV_A_AAC_2LC)) ||
               !strcmp(track->codec_id, MKV_A_AAC_2SSR) ||
               !strcmp(track->codec_id, MKV_A_AAC_4MAIN) ||
               !strncmp(track->codec_id, MKV_A_AAC_4LC,
                        strlen(MKV_A_AAC_4LC)) ||
               !strcmp(track->codec_id, MKV_A_AAC_4SSR) ||
               !strcmp(track->codec_id, MKV_A_AAC_4LTP) ||
               !strcmp(track->codec_id, MKV_A_AAC))
        track->a_formattag = mmioFOURCC('M', 'P', '4', 'A');
      else if (!strcmp(track->codec_id, MKV_A_VORBIS))
        {
          if (track->private_data == NULL)
            return 1;
          track->a_formattag = mmioFOURCC('v', 'r', 'b', 's');
        }
      else if (!strcmp(track->codec_id, MKV_A_QDMC))
        track->a_formattag = mmioFOURCC('Q', 'D', 'M', 'C');
      else if (!strcmp(track->codec_id, MKV_A_QDMC2))
        track->a_formattag = mmioFOURCC('Q', 'D', 'M', '2');
      else if (!strcmp(track->codec_id, MKV_A_WAVPACK))
        track->a_formattag = mmioFOURCC('W', 'V', 'P', 'K');
      else if (!strcmp(track->codec_id, MKV_A_FLAC))
        {
          if (track->private_data == NULL || track->private_size == 0)
            {
              mp_tmsg (MSGT_DEMUX, MSGL_WARN,
                      "[mkv] FLAC track does not contain valid headers.\n");
              return 1;
            }
          track->a_formattag = mmioFOURCC ('f', 'L', 'a', 'C');
        }
      else if (track->private_size >= RAPROPERTIES4_SIZE)
        {
          if (!strcmp(track->codec_id, MKV_A_REAL28))
            track->a_formattag = mmioFOURCC('2', '8', '_', '8');
          else if (!strcmp(track->codec_id, MKV_A_REALATRC))
            track->a_formattag = mmioFOURCC('a', 't', 'r', 'c');
          else if (!strcmp(track->codec_id, MKV_A_REALCOOK))
            track->a_formattag = mmioFOURCC('c', 'o', 'o', 'k');
          else if (!strcmp(track->codec_id, MKV_A_REALDNET))
            track->a_formattag = mmioFOURCC('d', 'n', 'e', 't');
          else if (!strcmp(track->codec_id, MKV_A_REALSIPR))
            track->a_formattag = mmioFOURCC('s', 'i', 'p', 'r');
        }
      else
        {
          mp_tmsg (MSGT_DEMUX, MSGL_WARN, "[mkv] Unknown/unsupported audio codec ID '%s' for track %u or missing/faulty\n[mkv] private codec data.\n",
                  track->codec_id, track->tnum);
          free_sh_audio(demuxer, track->tnum);
          return 1;
        }
    }

  sh_a->format = track->a_formattag;
  sh_a->wf->wFormatTag = track->a_formattag;
  sh_a->channels = track->a_channels;
  sh_a->wf->nChannels = track->a_channels;
  sh_a->samplerate = (uint32_t) track->a_sfreq;
  sh_a->wf->nSamplesPerSec = (uint32_t) track->a_sfreq;
  if (track->a_bps == 0)
    {
      sh_a->samplesize = 2;
      sh_a->wf->wBitsPerSample = 16;
    }
  else
    {
      sh_a->samplesize = track->a_bps / 8;
      sh_a->wf->wBitsPerSample = track->a_bps;
    }
  if (track->a_formattag == 0x0055)  /* MP3 || MP2 */
    {
      sh_a->wf->nAvgBytesPerSec = 16000;
      sh_a->wf->nBlockAlign = 1152;
    }
  else if ((track->a_formattag == 0x2000) || /* AC3 */
           (track->a_formattag == 0x2001)) /* DTS */
    {
      free(sh_a->wf);
      sh_a->wf = NULL;
    }
  else if (track->a_formattag == 0x0001)  /* PCM || PCM_BE */
    {
      sh_a->wf->nAvgBytesPerSec = sh_a->channels * sh_a->samplerate*2;
      sh_a->wf->nBlockAlign = sh_a->wf->nAvgBytesPerSec;
      if (!strcmp(track->codec_id, MKV_A_PCM_BE))
        sh_a->format = mmioFOURCC('t', 'w', 'o', 's');
    }
  else if (!strcmp(track->codec_id, MKV_A_QDMC) ||
           !strcmp(track->codec_id, MKV_A_QDMC2))
    {
      sh_a->wf->nAvgBytesPerSec = 16000;
      sh_a->wf->nBlockAlign = 1486;
      track->fix_i_bps = 1;
      track->qt_last_a_pts = 0.0;
      if (track->private_data != NULL)
        {
          sh_a->codecdata=malloc(track->private_size);
          memcpy (sh_a->codecdata, track->private_data,
                  track->private_size);
          sh_a->codecdata_len = track->private_size;
        }
    }
  else if (track->a_formattag == mmioFOURCC('M', 'P', '4', 'A'))
    {
      int profile, srate_idx;

      sh_a->wf->nAvgBytesPerSec = 16000;
      sh_a->wf->nBlockAlign = 1024;

      if (!strcmp (track->codec_id, MKV_A_AAC) &&
          (NULL != track->private_data))
        {
          sh_a->codecdata=malloc(track->private_size);
          memcpy (sh_a->codecdata, track->private_data,
                  track->private_size);
          sh_a->codecdata_len = track->private_size;
          return 0;
        }

      /* Recreate the 'private data' */
      /* which faad2 uses in its initialization */
      srate_idx = aac_get_sample_rate_index (sh_a->samplerate);
      if (!strncmp (&track->codec_id[12], "MAIN", 4))
        profile = 0;
      else if (!strncmp (&track->codec_id[12], "LC", 2))
        profile = 1;
      else if (!strncmp (&track->codec_id[12], "SSR", 3))
        profile = 2;
      else
        profile = 3;
      sh_a->codecdata = malloc (5);
      sh_a->codecdata[0] = ((profile+1) << 3) | ((srate_idx&0xE) >> 1);
      sh_a->codecdata[1] = ((srate_idx&0x1)<<7)|(track->a_channels<<3);

      if (strstr(track->codec_id, "SBR") != NULL)
        {
          /* HE-AAC (aka SBR AAC) */
          sh_a->codecdata_len = 5;

          sh_a->samplerate *= 2;
          sh_a->wf->nSamplesPerSec *= 2;
          srate_idx = aac_get_sample_rate_index(sh_a->samplerate);
          sh_a->codecdata[2] = AAC_SYNC_EXTENSION_TYPE >> 3;
          sh_a->codecdata[3] = ((AAC_SYNC_EXTENSION_TYPE&0x07)<<5) | 5;
          sh_a->codecdata[4] = (1 << 7) | (srate_idx << 3);
          track->default_duration = 1024.0 / (sh_a->samplerate / 2);
        }
      else
        {
          sh_a->codecdata_len = 2;
          track->default_duration = 1024.0 / sh_a->samplerate;
        }
    }
  else if (track->a_formattag == mmioFOURCC('v', 'r', 'b', 's'))  /* VORBIS */
    {
      sh_a->wf->cbSize = track->private_size;
      sh_a->wf = realloc(sh_a->wf, sizeof(WAVEFORMATEX) + sh_a->wf->cbSize);
      memcpy((unsigned char *) (sh_a->wf+1), track->private_data, sh_a->wf->cbSize);
    }
  else if (track->private_size >= RAPROPERTIES4_SIZE
           && !strncmp (track->codec_id, MKV_A_REALATRC, 7))
    {
      /* Common initialization for all RealAudio codecs */
      unsigned char *src = track->private_data;
      int codecdata_length, version;
      int flavor;

      sh_a->wf->nAvgBytesPerSec = 0;  /* FIXME !? */

      version = AV_RB16(src + 4);
      flavor = AV_RB16(src + 22);
      track->coded_framesize = AV_RB32(src + 24);
      track->sub_packet_h = AV_RB16(src + 40);
      sh_a->wf->nBlockAlign =
      track->audiopk_size = AV_RB16(src + 42);
      track->sub_packet_size = AV_RB16(src + 44);
      if (version == 4)
        {
          src += RAPROPERTIES4_SIZE;
          src += src[0] + 1;
          src += src[0] + 1;
        }
      else
        src += RAPROPERTIES5_SIZE;

      src += 3;
      if (version == 5)
        src++;
      codecdata_length = AV_RB32(src);
      src += 4;
      sh_a->wf->cbSize = codecdata_length;
      sh_a->wf = realloc (sh_a->wf,
                          sizeof (WAVEFORMATEX) +
                          sh_a->wf->cbSize);
      memcpy(((char *)(sh_a->wf + 1)), src, codecdata_length);

      switch (track->a_formattag) {
        case mmioFOURCC('a', 't', 'r', 'c'):
          sh_a->wf->nAvgBytesPerSec = atrc_fl2bps[flavor];
          sh_a->wf->nBlockAlign = track->sub_packet_size;
          track->audio_buf = malloc(track->sub_packet_h * track->audiopk_size);
          track->audio_timestamp = malloc(track->sub_packet_h * sizeof(double));
          break;
        case mmioFOURCC('c', 'o', 'o', 'k'):
          sh_a->wf->nAvgBytesPerSec = cook_fl2bps[flavor];
          sh_a->wf->nBlockAlign = track->sub_packet_size;
          track->audio_buf = malloc(track->sub_packet_h * track->audiopk_size);
          track->audio_timestamp = malloc(track->sub_packet_h * sizeof(double));
          break;
        case mmioFOURCC('s', 'i', 'p', 'r'):
          sh_a->wf->nAvgBytesPerSec = sipr_fl2bps[flavor];
          sh_a->wf->nBlockAlign = track->coded_framesize;
          track->audio_buf = malloc(track->sub_packet_h * track->audiopk_size);
          track->audio_timestamp = malloc(track->sub_packet_h * sizeof(double));
          break;
        case mmioFOURCC('2', '8', '_', '8'):
          sh_a->wf->nAvgBytesPerSec = 3600;
          sh_a->wf->nBlockAlign = track->coded_framesize;
          track->audio_buf = malloc(track->sub_packet_h * track->audiopk_size);
          track->audio_timestamp = malloc(track->sub_packet_h * sizeof(double));
          break;
      }

      track->realmedia = 1;
    }
  else if (!strcmp(track->codec_id, MKV_A_FLAC) ||
           (track->a_formattag == 0xf1ac))
    {
      unsigned char *ptr;
      int size;
      free(sh_a->wf);
      sh_a->wf = NULL;

      if (track->a_formattag == mmioFOURCC('f', 'L', 'a', 'C'))
        {
          ptr = track->private_data;
          size = track->private_size;
        }
      else
        {
          sh_a->format = mmioFOURCC('f', 'L', 'a', 'C');
          ptr = track->private_data
            + sizeof (WAVEFORMATEX);
          size = track->private_size - sizeof (WAVEFORMATEX);
        }
      if (size < 4 || ptr[0] != 'f' || ptr[1] != 'L' ||
          ptr[2] != 'a' || ptr[3] != 'C')
        {
          dp = new_demux_packet (4);
          memcpy (dp->buffer, "fLaC", 4);
        }
      else
        {
          dp = new_demux_packet (size);
          memcpy (dp->buffer, ptr, size);
        }
      dp->pts = 0;
      dp->flags = 0;
      ds_add_packet (demuxer->audio, dp);
    }
  else if (track->a_formattag == mmioFOURCC('W', 'V', 'P', 'K'))
    {  /* do nothing, still works */  }
  else if (!track->ms_compat || (track->private_size < sizeof(WAVEFORMATEX)))
    {
      free_sh_audio(demuxer, track->tnum);
      return 1;
    }

  return 0;
}

static int
demux_mkv_open_sub (demuxer_t *demuxer, mkv_track_t *track, int sid)
{
  if (track->subtitle_type != MATROSKA_SUBTYPE_UNKNOWN)
    {
      int size, m;
      uint8_t *buffer;
      sh_sub_t *sh = new_sh_sub_sid(demuxer, track->tnum, sid);
      track->sh_sub = sh;
      sh->type = 't';
      if (track->subtitle_type == MATROSKA_SUBTYPE_VOBSUB)
        sh->type = 'v';
      if (track->subtitle_type == MATROSKA_SUBTYPE_SSA)
        sh->type = 'a';
      size = track->private_size;
      m = demux_mkv_decode (track,track->private_data,&buffer,&size,2);
      if (buffer && m)
        {
          free (track->private_data);
          track->private_data = buffer;
          track->private_size = size;
        }
      sh->extradata=malloc(track->private_size);
      memcpy (sh->extradata, track->private_data,
              track->private_size);
      sh->extradata_len = track->private_size;
      if (track->language && (strcmp(track->language, "und") != 0))
        sh->lang = strdup(track->language);
      sh->default_track = track->default_track;
    }
  else
    {
      mp_tmsg (MSGT_DEMUX, MSGL_ERR, "[mkv] Subtitle type '%s' is not supported.\n",
              track->codec_id);
      return 1;
    }

  return 0;
}

static int
demux_mkv_open (demuxer_t *demuxer)
{
  stream_t *s = demuxer->stream;
  mkv_demuxer_t *mkv_d;
  mkv_track_t *track;
  int i, version, cont = 0;
  char *str;

  stream_seek(s, s->start_pos);
  str = ebml_read_header (s, &version);
  if (str == NULL || strcmp (str, "matroska") || version > 2)
    {
      mp_msg (MSGT_DEMUX, MSGL_DBG2, "[mkv] no head found\n");
      return 0;
    }
  free (str);

  mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] Found the head...\n");

  if (ebml_read_id (s, NULL) != MATROSKA_ID_SEGMENT)
    {
      mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] but no segment :(\n");
      return 0;
    }
  ebml_read_length (s, NULL);  /* return bytes number until EOF */

  mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] + a segment...\n");

  mkv_d = calloc (1, sizeof (mkv_demuxer_t));
  demuxer->priv = mkv_d;
  mkv_d->tc_scale = 1000000;
  mkv_d->segment_start = stream_tell (s);
  mkv_d->parsed_cues = malloc (sizeof (off_t));
  mkv_d->parsed_seekhead = malloc (sizeof (off_t));

  while (!cont)
    {
      switch (ebml_read_id (s, NULL))
        {
        case MATROSKA_ID_INFO:
          mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |+ segment information...\n");
          cont = demux_mkv_read_info (demuxer);
          break;

        case MATROSKA_ID_TRACKS:
          mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |+ segment tracks...\n");
          cont = demux_mkv_read_tracks (demuxer);
          break;

        case MATROSKA_ID_CUES:
          cont = demux_mkv_read_cues (demuxer);
          break;

        case MATROSKA_ID_TAGS:
          cont = demux_mkv_read_tags (demuxer);
          break;

        case MATROSKA_ID_SEEKHEAD:
          cont = demux_mkv_read_seekhead (demuxer);
          break;

        case MATROSKA_ID_CHAPTERS:
          cont = demux_mkv_read_chapters (demuxer);
          break;

        case MATROSKA_ID_ATTACHMENTS:
          cont = demux_mkv_read_attachments (demuxer);
          break;

        case MATROSKA_ID_CLUSTER:
          {
            int p, l;
            mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] |+ found cluster, headers are "
                    "parsed completely :)\n");
            /* get the first cluster timecode */
            p = stream_tell(s);
            l = ebml_read_length (s, NULL);
            while (ebml_read_id (s, NULL) != MATROSKA_ID_CLUSTERTIMECODE)
              {
                ebml_read_skip (s, NULL);
                if (stream_tell (s) >= p + l)
                  break;
              }
            if (stream_tell (s) < p + l)
              {
                uint64_t num = ebml_read_uint (s, NULL);
                if (num == EBML_UINT_INVALID)
                  return 0;
              }
            stream_seek (s, p - 4);
            cont = 1;
            break;
          }

        default:
          cont = 1;
        case EBML_ID_VOID:
          ebml_read_skip (s, NULL);
          break;
        }
    }

  display_create_tracks (demuxer);

  /* select video track */
  track = NULL;
  if (demuxer->video->id == -1)  /* automatically select a video track */
    {
      /* search for a video track that has the 'default' flag set */
      for (i=0; i<mkv_d->num_tracks; i++)
        if (mkv_d->tracks[i]->type == MATROSKA_TRACK_VIDEO
            && mkv_d->tracks[i]->default_track)
          {
            track = mkv_d->tracks[i];
            break;
          }

      if (track == NULL)
        /* no track has the 'default' flag set */
        /* let's take the first video track */
        for (i=0; i<mkv_d->num_tracks; i++)
          if (mkv_d->tracks[i]->type == MATROSKA_TRACK_VIDEO)
            {
              track = mkv_d->tracks[i];
              break;
            }
    }
  else if (demuxer->video->id != -2)  /* -2 = no video at all */
    track = demux_mkv_find_track_by_num (mkv_d, demuxer->video->id,
                                         MATROSKA_TRACK_VIDEO);

  if (track && demuxer->v_streams[track->tnum])
              {
                mp_tmsg (MSGT_DEMUX, MSGL_INFO,
                        "[mkv] Will play video track %u.\n", track->tnum);
                demuxer->video->id = track->tnum;
                demuxer->video->sh = demuxer->v_streams[track->tnum];
              }
  else
    {
      mp_tmsg (MSGT_DEMUX, MSGL_INFO, "[mkv] No video track found/wanted.\n");
      demuxer->video->id = -2;
    }

  /* select audio track */
  track = NULL;
  if (track == NULL)
    /* search for an audio track that has the 'default' flag set */
    for (i=0; i < mkv_d->num_tracks; i++)
      if (mkv_d->tracks[i]->type == MATROSKA_TRACK_AUDIO
          && mkv_d->tracks[i]->default_track)
        {
          track = mkv_d->tracks[i];
          break;
        }

  if (track == NULL)
    /* no track has the 'default' flag set */
    /* let's take the first audio track */
    for (i=0; i < mkv_d->num_tracks; i++)
      if (mkv_d->tracks[i]->type == MATROSKA_TRACK_AUDIO)
        {
          track = mkv_d->tracks[i];
          break;
        }

  if (track && demuxer->a_streams[track->tnum])
    {
      demuxer->audio->id = track->tnum;
      demuxer->audio->sh = demuxer->a_streams[track->tnum];
    }
  else
    {
      mp_tmsg (MSGT_DEMUX, MSGL_INFO, "[mkv] No audio track found/wanted.\n");
      demuxer->audio->id = -2;
    }


  if(demuxer->audio->id != -2)
  for (i=0; i < mkv_d->num_tracks; i++)
    {
      if(mkv_d->tracks[i]->type != MATROSKA_TRACK_AUDIO)
          continue;
      if(demuxer->a_streams[track->tnum])
        {
          mkv_d->last_aid++;
          if(mkv_d->last_aid == MAX_A_STREAMS)
            break;
        }
    }

  if (s->end_pos == 0 || (mkv_d->indexes == NULL && index_mode < 0))
    demuxer->seekable = 0;
  else
    {
      demuxer->movi_start = s->start_pos;
      demuxer->movi_end = s->end_pos;
      demuxer->seekable = 1;
    }

  demuxer->accurate_seek = true;

  return DEMUXER_TYPE_MATROSKA;
}

static void
demux_close_mkv (demuxer_t *demuxer)
{
  mkv_demuxer_t *mkv_d = (mkv_demuxer_t *) demuxer->priv;

  if (mkv_d)
    {
      int i;
      free_cached_dps (demuxer);
      if (mkv_d->tracks)
        {
          for (i=0; i<mkv_d->num_tracks; i++)
            demux_mkv_free_trackentry(mkv_d->tracks[i]);
          free (mkv_d->tracks);
        }
      free (mkv_d->indexes);
      free (mkv_d->cluster_positions);
      free (mkv_d->parsed_cues);
      free (mkv_d->parsed_seekhead);
      free (mkv_d);
    }
}

static int
demux_mkv_read_block_lacing (uint8_t *buffer, uint64_t *size,
                             uint8_t *laces, uint32_t **all_lace_sizes)
{
  uint32_t total = 0, *lace_size;
  uint8_t flags;
  int i;

  *all_lace_sizes = NULL;
  lace_size = NULL;
  /* lacing flags */
  flags = *buffer++;
  (*size)--;

  switch ((flags & 0x06) >> 1)
    {
    case 0:  /* no lacing */
      *laces = 1;
      lace_size = calloc(*laces, sizeof(uint32_t));
      lace_size[0] = *size;
      break;

    case 1:  /* xiph lacing */
    case 2:  /* fixed-size lacing */
    case 3:  /* EBML lacing */
      *laces = *buffer++;
      (*size)--;
      (*laces)++;
      lace_size = calloc(*laces, sizeof(uint32_t));

      switch ((flags & 0x06) >> 1)
        {
        case 1:  /* xiph lacing */
          for (i=0; i < *laces-1; i++)
            {
              lace_size[i] = 0;
              do
                {
                  lace_size[i] += *buffer;
                  (*size)--;
                } while (*buffer++ == 0xFF);
              total += lace_size[i];
            }
          lace_size[i] = *size - total;
          break;

        case 2:  /* fixed-size lacing */
          for (i=0; i < *laces; i++)
            lace_size[i] = *size / *laces;
          break;

        case 3:  /* EBML lacing */
          {
            int l;
            uint64_t num = ebml_read_vlen_uint (buffer, &l);
            if (num == EBML_UINT_INVALID) {
              free(lace_size);
              return 1;
            }
            buffer += l;
            *size -= l;

            total = lace_size[0] = num;
            for (i=1; i < *laces-1; i++)
              {
                int64_t snum;
                snum = ebml_read_vlen_int (buffer, &l);
                if (snum == EBML_INT_INVALID) {
                  free(lace_size);
                  return 1;
                }
                buffer += l;
                *size -= l;
                lace_size[i] = lace_size[i-1] + snum;
                total += lace_size[i];
              }
            lace_size[i] = *size - total;
            break;
          }
        }
      break;
    }
  *all_lace_sizes = lace_size;
  return 0;
}

static void
handle_subtitles(demuxer_t *demuxer, mkv_track_t *track, char *block,
                 int64_t size, uint64_t block_duration, uint64_t timecode)
{
  demux_packet_t *dp;

  if (block_duration == 0)
    {
      mp_msg (MSGT_DEMUX, MSGL_WARN,
              "[mkv] Warning: No BlockDuration for subtitle track found.\n");
      return;
    }

  sub_utf8 = 1;
  dp = new_demux_packet(size);
  memcpy(dp->buffer, block, size);
  dp->pts = timecode / 1000.0;
  dp->endpts = (timecode + block_duration) / 1000.0;
  ds_add_packet(demuxer->sub, dp);
}

double real_fix_timestamp(unsigned char *buf, unsigned int timestamp, unsigned int format, int64_t *kf_base, int *kf_pts, double *pts);

static void
handle_realvideo (demuxer_t *demuxer, mkv_track_t *track, uint8_t *buffer,
                  uint32_t size, int block_bref)
{
  mkv_demuxer_t *mkv_d = (mkv_demuxer_t *) demuxer->priv;
  demux_packet_t *dp;
  uint32_t timestamp = mkv_d->last_pts * 1000;

  dp = new_demux_packet (size);
  memcpy (dp->buffer, buffer, size);

  if (mkv_d->v_skip_to_keyframe)
    {
      dp->pts = mkv_d->last_pts;
      track->rv_kf_base = 0;
      track->rv_kf_pts = timestamp;
    }
  else
    dp->pts = real_fix_timestamp (dp->buffer, timestamp,
                                  ((sh_video_t*)demuxer->video->sh)->bih->biCompression,
                                  &track->rv_kf_base, &track->rv_kf_pts, NULL);
  dp->pos = demuxer->filepos;
  dp->flags = block_bref ? 0 : 0x10;

  ds_add_packet(demuxer->video, dp);
}

static void
handle_realaudio (demuxer_t *demuxer, mkv_track_t *track, uint8_t *buffer,
                  uint32_t size, int block_bref)
{
  mkv_demuxer_t *mkv_d = (mkv_demuxer_t *) demuxer->priv;
  int sps = track->sub_packet_size;
  int sph = track->sub_packet_h;
  int cfs = track->coded_framesize;
  int w = track->audiopk_size;
  int spc = track->sub_packet_cnt;
  demux_packet_t *dp;
  int x;

  if ((track->a_formattag == mmioFOURCC('2', '8', '_', '8')) ||
      (track->a_formattag == mmioFOURCC('c', 'o', 'o', 'k')) ||
      (track->a_formattag == mmioFOURCC('a', 't', 'r', 'c')) ||
      (track->a_formattag == mmioFOURCC('s', 'i', 'p', 'r')))
    {
//      if(!block_bref)
//        spc = track->sub_packet_cnt = 0;
      switch (track->a_formattag) {
        case mmioFOURCC('2', '8', '_', '8'):
          for (x = 0; x < sph / 2; x++)
            memcpy(track->audio_buf + x * 2 * w + spc * cfs, buffer + cfs * x, cfs);
          break;
        case mmioFOURCC('c', 'o', 'o', 'k'):
        case mmioFOURCC('a', 't', 'r', 'c'):
          for (x = 0; x < w / sps; x++)
            memcpy(track->audio_buf + sps * (sph * x + ((sph + 1) / 2) * (spc & 1) + (spc >> 1)), buffer + sps * x, sps);
          break;
        case mmioFOURCC('s', 'i', 'p', 'r'):
          memcpy(track->audio_buf + spc * w, buffer, w);
          if (spc == sph - 1)
            {
              int n;
              int bs = sph * w * 2 / 96;  // nibbles per subpacket
              // Perform reordering
              for(n=0; n < 38; n++)
                {
                  int j;
                  int i = bs * sipr_swaps[n][0];
                  int o = bs * sipr_swaps[n][1];
                  // swap nibbles of block 'i' with 'o'      TODO: optimize
                  for(j = 0;j < bs; j++)
                    {
                      int x = (i & 1) ? (track->audio_buf[i >> 1] >> 4) : (track->audio_buf[i >> 1] & 0x0F);
                      int y = (o & 1) ? (track->audio_buf[o >> 1] >> 4) : (track->audio_buf[o >> 1] & 0x0F);
                      if(o & 1)
                        track->audio_buf[o >> 1] = (track->audio_buf[o >> 1] & 0x0F) | (x << 4);
                      else
                        track->audio_buf[o >> 1] = (track->audio_buf[o >> 1] & 0xF0) | x;
                      if(i & 1)
                        track->audio_buf[i >> 1] = (track->audio_buf[i >> 1] & 0x0F) | (y << 4);
                      else
                        track->audio_buf[i >> 1] = (track->audio_buf[i >> 1] & 0xF0) | y;
                      ++i; ++o;
                    }
                }
            }
          break;
      }
      track->audio_timestamp[track->sub_packet_cnt] = (track->ra_pts == mkv_d->last_pts) ? 0 : (mkv_d->last_pts);
      track->ra_pts = mkv_d->last_pts;
      if (track->sub_packet_cnt == 0)
        track->audio_filepos = demuxer->filepos;
      if (++(track->sub_packet_cnt) == sph)
        {
           int apk_usize = ((WAVEFORMATEX*)((sh_audio_t*)demuxer->audio->sh)->wf)->nBlockAlign;
           track->sub_packet_cnt = 0;
           // Release all the audio packets
           for (x = 0; x < sph*w/apk_usize; x++)
             {
               dp = new_demux_packet(apk_usize);
               memcpy(dp->buffer, track->audio_buf + x * apk_usize, apk_usize);
               /* Put timestamp only on packets that correspond to original audio packets in file */
               dp->pts = (x * apk_usize % w) ? 0 : track->audio_timestamp[x * apk_usize / w];
               dp->pos = track->audio_filepos; // all equal
               dp->flags = x ? 0 : 0x10; // Mark first packet as keyframe
               ds_add_packet(demuxer->audio, dp);
             }
        }
   } else { // Not a codec that require reordering
  dp = new_demux_packet (size);
  memcpy(dp->buffer, buffer, size);
  if (track->ra_pts == mkv_d->last_pts && !mkv_d->a_skip_to_keyframe)
    dp->pts = 0;
  else
    dp->pts = mkv_d->last_pts;
  track->ra_pts = mkv_d->last_pts;

  dp->pos = demuxer->filepos;
  dp->flags = block_bref ? 0 : 0x10;
  ds_add_packet (demuxer->audio, dp);
  }
}

/** Reorder timecodes and add cached demux packets to the queues.
 *
 * Timecode reordering is needed if a video track contains B frames that
 * are timestamped in display order (e.g. MPEG-1, MPEG-2 or "native" MPEG-4).
 * MPlayer doesn't like timestamps in display order. This function adjusts
 * the timestamp of cached frames (which are exactly one I/P frame followed
 * by one or more B frames) so that they are in coding order again.
 *
 * Example: The track with 25 FPS contains four frames with the timecodes
 * I at 0ms, P at 120ms, B at 40ms and B at 80ms. As soon as the next I
 * or P frame arrives these timecodes can be changed to I at 0ms, P at 40ms,
 * B at 80ms and B at 120ms.
 *
 * This works for simple H.264 B-frame pyramids, but not for arbitrary orders.
 *
 * \param demuxer The Matroska demuxer struct for this instance.
 * \param track The track structure whose cache should be handled.
 */
static void
flush_cached_dps (demuxer_t *demuxer, mkv_track_t *track)
{
  int i, ok;

  if (track->num_cached_dps == 0)
    return;

  do {
    ok = 1;
    for (i = 1; i < track->num_cached_dps; i++)
      if (track->cached_dps[i - 1]->pts > track->cached_dps[i]->pts) {
        double tmp_pts = track->cached_dps[i - 1]->pts;
        track->cached_dps[i - 1]->pts = track->cached_dps[i]->pts;
        track->cached_dps[i]->pts = tmp_pts;
        ok = 0;
      }
  } while (!ok);

  for (i = 0; i < track->num_cached_dps; i++)
    ds_add_packet (demuxer->video, track->cached_dps[i]);
  track->num_cached_dps = 0;
}

/** Cache video frames if timecodes have to be reordered.
 *
 * Timecode reordering is needed if a video track contains B frames that
 * are timestamped in display order (e.g. MPEG-1, MPEG-2 or "native" MPEG-4).
 * This function takes in a Matroska block read from the file, allocates a
 * demux packet for it, fills in its values, allocates space for storing
 * pointers to the cached demux packets and adds the packet to it. If
 * the packet contains an I or a P frame then ::flush_cached_dps is called
 * in order to send the old cached frames downstream.
 *
 * \param demuxer The Matroska demuxer struct for this instance.
 * \param track The packet is meant for this track.
 * \param buffer The actual frame contents.
 * \param size The frame size in bytes.
 * \param block_bref A relative timecode (backward reference). If it is \c 0
 *   then the frame is an I frame.
 * \param block_fref A relative timecode (forward reference). If it is \c 0
 *   then the frame is either an I frame or a P frame depending on the value
 *   of \a block_bref. Otherwise it's a B frame.
 */
static void
handle_video_bframes (demuxer_t *demuxer, mkv_track_t *track, uint8_t *buffer,
                      uint32_t size, int block_bref, int block_fref)
{
  mkv_demuxer_t *mkv_d = (mkv_demuxer_t *) demuxer->priv;
  demux_packet_t *dp;

  dp = new_demux_packet (size);
  memcpy(dp->buffer, buffer, size);
  dp->pos = demuxer->filepos;
  dp->pts = mkv_d->last_pts;
  if ((track->num_cached_dps > 0) && (dp->pts < track->max_pts))
    block_fref = 1;
  if (block_fref == 0)          /* I or P frame */
    flush_cached_dps (demuxer, track);
  if (block_bref != 0)          /* I frame, don't cache it */
    dp->flags = 0x10;
  if ((track->num_cached_dps + 1) > track->num_allocated_dps)
    {
      track->cached_dps = (demux_packet_t **)
        realloc(track->cached_dps, (track->num_cached_dps + 10) *
                sizeof(demux_packet_t *));
      track->num_allocated_dps += 10;
    }
  track->cached_dps[track->num_cached_dps] = dp;
  track->num_cached_dps++;
  if (dp->pts > track->max_pts)
    track->max_pts = dp->pts;
}

static int
handle_block (demuxer_t *demuxer, uint8_t *block, uint64_t length,
              uint64_t block_duration, int64_t block_bref, int64_t block_fref, uint8_t simpleblock)
{
  mkv_demuxer_t *mkv_d = (mkv_demuxer_t *) demuxer->priv;
  mkv_track_t *track = NULL;
  demux_stream_t *ds = NULL;
  uint64_t old_length;
  int64_t tc;
  uint32_t *lace_size;
  uint8_t laces, flags;
  int i, num, tmp, use_this_block = 1;
  double current_pts;
  int16_t time;

  /* first byte(s): track num */
  num = ebml_read_vlen_uint (block, &tmp);
  block += tmp;
  /* time (relative to cluster time) */
  time = block[0] << 8 | block[1];
  block += 2;
  length -= tmp + 2;
  old_length = length;
  flags = block[0];
  if (demux_mkv_read_block_lacing (block, &length, &laces, &lace_size))
    return 0;
  block += old_length - length;

  tc = (time*mkv_d->tc_scale+mkv_d->cluster_tc) / 1000000.0 + 0.5;
  if (tc < 0)
    tc = 0;
  current_pts = tc / 1000.0;

  for (i=0; i<mkv_d->num_tracks; i++)
    if (mkv_d->tracks[i]->tnum == num) {
      track = mkv_d->tracks[i];
      break;
    }
  if (track == NULL)
    {
      free(lace_size);
      return 1;
    }
  if (num == demuxer->audio->id)
    {
      ds = demuxer->audio;

      if (mkv_d->a_skip_to_keyframe)
        {
          if (simpleblock)
            {
               if (!(flags&0x80))   /*current frame isn't a keyframe*/
                 use_this_block = 0;
            }
          else if (block_bref != 0)
            use_this_block = 0;
        }
      else if (mkv_d->v_skip_to_keyframe)
        use_this_block = 0;

      if (track->fix_i_bps && use_this_block)
        {
          sh_audio_t *sh = (sh_audio_t *) ds->sh;

          if (block_duration != 0)
            {
              sh->i_bps = length * 1000 / block_duration;
              track->fix_i_bps = 0;
            }
          else if (track->qt_last_a_pts == 0.0)
            track->qt_last_a_pts = current_pts;
          else if(track->qt_last_a_pts != current_pts)
            {
              sh->i_bps = length / (current_pts - track->qt_last_a_pts);
              track->fix_i_bps = 0;
            }
        }
    }
  else if (tc < mkv_d->skip_to_timecode)
    use_this_block = 0;
  else if (num == demuxer->video->id)
    {
      ds = demuxer->video;
      if (mkv_d->v_skip_to_keyframe)
        {
          if (simpleblock)
            {
              if (!(flags&0x80))   /*current frame isn't a keyframe*/
                use_this_block = 0;
            }
          else if (block_bref != 0 || block_fref != 0)
            use_this_block = 0;
        }
    }
  else if (num == demuxer->sub->id)
    {
      ds = demuxer->sub;
      if (track->subtitle_type != MATROSKA_SUBTYPE_VOBSUB)
        {
          if (!mkv_d->v_skip_to_keyframe)
            handle_subtitles (demuxer, track, block, length,
                              block_duration, tc);
          use_this_block = 0;
        }
    }
  else
    use_this_block = 0;

  if (use_this_block)
    {
      mkv_d->last_pts = current_pts;
      mkv_d->last_filepos = demuxer->filepos;

      for (i=0; i < laces; i++)
        {
          if (ds == demuxer->video && track->realmedia)
            handle_realvideo (demuxer, track, block, lace_size[i], block_bref);
          else if (ds == demuxer->audio && track->realmedia)
            handle_realaudio (demuxer, track, block, lace_size[i], block_bref);
          else if (ds == demuxer->video && track->reorder_timecodes)
            handle_video_bframes (demuxer, track, block, lace_size[i],
                                  block_bref, block_fref);
          else
            {
              int modified, size = lace_size[i];
              demux_packet_t *dp;
              uint8_t *buffer;
              modified = demux_mkv_decode (track, block, &buffer, &size, 1);
              if (buffer)
                {
                  dp = new_demux_packet (size);
                  memcpy (dp->buffer, buffer, size);
                  if (modified)
                    free (buffer);
                  dp->flags = (block_bref == 0 && block_fref == 0) ? 0x10 : 0;
                  /* If default_duration is 0, assume no pts value is known
                   * for packets after the first one (rather than all pts
                   * values being the same) */
                  if (i == 0 || track->default_duration)
                  dp->pts = mkv_d->last_pts + i * track->default_duration;
                  ds_add_packet (ds, dp);
                }
            }
          block += lace_size[i];
        }

      if (ds == demuxer->video)
        {
          mkv_d->v_skip_to_keyframe = 0;
          mkv_d->skip_to_timecode = 0;
        }
      else if (ds == demuxer->audio)
        mkv_d->a_skip_to_keyframe = 0;

      free(lace_size);
      return 1;
    }

  free(lace_size);
  return 0;
}

static int
demux_mkv_fill_buffer (demuxer_t *demuxer, demux_stream_t *ds)
{
  mkv_demuxer_t *mkv_d = (mkv_demuxer_t *) demuxer->priv;
  stream_t *s = demuxer->stream;
  uint64_t l;
  int il, tmp;

  while (1)
    {
      while (mkv_d->cluster_size > 0)
        {
          uint64_t block_duration = 0,  block_length = 0;
          int64_t block_bref = 0, block_fref = 0;
          uint8_t *block = NULL;

          while (mkv_d->blockgroup_size > 0)
            {
              switch (ebml_read_id (s, &il))
                {
                case MATROSKA_ID_BLOCKDURATION:
                  {
                    block_duration = ebml_read_uint (s, &l);
                    if (block_duration == EBML_UINT_INVALID) {
                      free(block);
                      return 0;
                    }
                    block_duration *= mkv_d->tc_scale / 1000000.0;
                    break;
                  }

                case MATROSKA_ID_BLOCK:
                  block_length = ebml_read_length (s, &tmp);
                  free(block);
                  if (block_length > SIZE_MAX - AV_LZO_INPUT_PADDING) return 0;
                  block = malloc (block_length + AV_LZO_INPUT_PADDING);
                  demuxer->filepos = stream_tell (s);
                  if (stream_read (s,block,block_length) != (int) block_length)
                  {
                    free(block);
                    return 0;
                  }
                  l = tmp + block_length;
                  break;

                case MATROSKA_ID_REFERENCEBLOCK:
                  {
                    int64_t num = ebml_read_int (s, &l);
                    if (num == EBML_INT_INVALID) {
                      free(block);
                      return 0;
                    }
                    if (num <= 0)
                      block_bref = num;
                    else
                      block_fref = num;
                    break;
                  }

                case EBML_ID_INVALID:
                  free(block);
                  return 0;

                default:
                  ebml_read_skip (s, &l);
                  break;
                }
              mkv_d->blockgroup_size -= l + il;
              mkv_d->cluster_size -= l + il;
            }

          if (block)
            {
              int res = handle_block (demuxer, block, block_length,
                                      block_duration, block_bref, block_fref, 0);
              free (block);
              if (res < 0)
                return 0;
              if (res)
                return 1;
            }

          if (mkv_d->cluster_size > 0)
            {
              switch (ebml_read_id (s, &il))
                {
                case MATROSKA_ID_CLUSTERTIMECODE:
                  {
                    uint64_t num = ebml_read_uint (s, &l);
                    if (num == EBML_UINT_INVALID)
                      return 0;
                    mkv_d->cluster_tc = num * mkv_d->tc_scale;
                    break;
                  }

                case MATROSKA_ID_BLOCKGROUP:
                  mkv_d->blockgroup_size = ebml_read_length (s, &tmp);
                  l = tmp;
                  break;

                case MATROSKA_ID_SIMPLEBLOCK:
                  {
                    int res;
                    block_length = ebml_read_length (s, &tmp);
                    block = malloc (block_length);
                    demuxer->filepos = stream_tell (s);
                    if (stream_read (s,block,block_length) != (int) block_length)
                    {
                      free(block);
                      return 0;
                    }
                    l = tmp + block_length;
                    res = handle_block (demuxer, block, block_length,
                                        block_duration, block_bref, block_fref, 1);
                    free (block);
                    mkv_d->cluster_size -= l + il;
                    if (res < 0)
                      return 0;
                    else if (res)
                      return 1;
                    else mkv_d->cluster_size += l + il;
                    break;
                  }
                case EBML_ID_INVALID:
                  return 0;

                default:
                  ebml_read_skip (s, &l);
                  break;
                }
              mkv_d->cluster_size -= l + il;
            }
        }

      if (ebml_read_id (s, &il) != MATROSKA_ID_CLUSTER)
        return 0;
      add_cluster_position(mkv_d, stream_tell(s)-il);
      mkv_d->cluster_size = ebml_read_length (s, NULL);
    }

  return 0;
}

static void
demux_mkv_seek (demuxer_t *demuxer, float rel_seek_secs, float audio_delay, int flags)
{
    if (!(flags & (SEEK_BACKWARD | SEEK_FORWARD))) {
        if (flags & SEEK_ABSOLUTE || rel_seek_secs < 0)
            flags |= SEEK_BACKWARD;
        else
            flags |= SEEK_FORWARD;
    }
    // Adjust the target a little bit to catch cases where the target position
    // specifies a keyframe with high, but not perfect, precision.
    rel_seek_secs += flags & SEEK_FORWARD ? -0.005 : 0.005;

  free_cached_dps (demuxer);
  if (!(flags & SEEK_FACTOR))  /* time in secs */
    {
      mkv_index_t *index = NULL;
      mkv_demuxer_t *mkv_d = (mkv_demuxer_t *) demuxer->priv;
      stream_t *s = demuxer->stream;
      int64_t target_timecode = 0, diff, min_diff=0xFFFFFFFFFFFFFFFLL;
      int i;

      if (!(flags & SEEK_ABSOLUTE))  /* relative seek */
        target_timecode = (int64_t) (mkv_d->last_pts * 1000.0);
      target_timecode += (int64_t)(rel_seek_secs * 1000.0);
      if (target_timecode < 0)
        target_timecode = 0;

      if (mkv_d->indexes == NULL)  /* no index was found */
        {
          uint64_t target_filepos, cluster_pos, max_pos;

          target_filepos = (uint64_t) (target_timecode * mkv_d->last_filepos
                                       / (mkv_d->last_pts * 1000.0));

          max_pos = mkv_d->cluster_positions[mkv_d->num_cluster_pos-1];
          if (target_filepos > max_pos)
            {
              if ((off_t) max_pos > stream_tell (s))
                stream_seek (s, max_pos);
              else
                stream_seek (s, stream_tell (s) + mkv_d->cluster_size);
              /* parse all the clusters upto target_filepos */
              while (!s->eof && stream_tell(s) < (off_t) target_filepos)
                {
                  switch (ebml_read_id (s, &i))
                    {
                    case MATROSKA_ID_CLUSTER:
                      add_cluster_position(mkv_d, (uint64_t) stream_tell(s)-i);
                      break;

                    case MATROSKA_ID_CUES:
                      demux_mkv_read_cues (demuxer);
                      break;
                    }
                  ebml_read_skip (s, NULL);
                }
              if (s->eof)
                stream_reset(s);
            }

          if (mkv_d->indexes == NULL)
            {
              cluster_pos = mkv_d->cluster_positions[0];
              /* Let's find the nearest cluster */
              for (i=0; i < mkv_d->num_cluster_pos; i++)
                {
                  diff = mkv_d->cluster_positions[i] - target_filepos;
                  if (flags & SEEK_BACKWARD && diff < 0 && -diff < min_diff)
                    {
                      cluster_pos = mkv_d->cluster_positions[i];
                      min_diff = -diff;
                    }
                  else if (flags & SEEK_FORWARD
                           && (diff < 0 ? -1 * diff : diff) < min_diff)
                    {
                      cluster_pos = mkv_d->cluster_positions[i];
                      min_diff = diff < 0 ? -1 * diff : diff;
                    }
                }
              mkv_d->cluster_size = mkv_d->blockgroup_size = 0;
              stream_seek (s, cluster_pos);
            }
        }
      else
        {
          int seek_id = (demuxer->video->id < 0) ? demuxer->audio->id : demuxer->video->id;

          /* let's find the entry in the indexes with the smallest */
          /* difference to the wanted timecode. */
          for (i=0; i < mkv_d->num_indexes; i++)
            if (mkv_d->indexes[i].tnum == seek_id)
              {
                diff = target_timecode -
                       (int64_t)(mkv_d->indexes[i].timecode * mkv_d->tc_scale
                                 / 1000000.0 + 0.5);

                if (flags & SEEK_BACKWARD) {
                    // Seek backward: find the last index position
                    // before target time
                    if (diff < 0 || diff >= min_diff)
                        continue;
                }
                else {
                    // Seek forward: find the first index position
                    // after target time. If no such index exists, find last
                    // position between current position and target time.
                    if (diff <= 0) {
                        if (min_diff <= 0 && diff <= min_diff)
                            continue;
                    }
                    else if (diff >= FFMIN(target_timecode - mkv_d->last_pts,
                                           min_diff))
                        continue;
                }
                min_diff = diff;
                index = mkv_d->indexes + i;
              }

          if (index)  /* We've found an entry. */
            {
              mkv_d->cluster_size = mkv_d->blockgroup_size = 0;
              stream_seek (s, index->filepos);
            }
        }

      if (demuxer->video->id >= 0)
        mkv_d->v_skip_to_keyframe = 1;
      if (flags & SEEK_FORWARD)
        mkv_d->skip_to_timecode = target_timecode;
      else
          mkv_d->skip_to_timecode = index ? index->timecode : 0;
      mkv_d->a_skip_to_keyframe = 1;

      demux_mkv_fill_buffer(demuxer, NULL);
    }
  else if ((demuxer->movi_end <= 0) || !(flags & SEEK_ABSOLUTE))
    mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] seek unsupported flags\n");
  else
    {
      mkv_demuxer_t *mkv_d = (mkv_demuxer_t *) demuxer->priv;
      stream_t *s = demuxer->stream;
      uint64_t target_filepos;
      mkv_index_t *index = NULL;
      int i;

      if (mkv_d->indexes == NULL)  /* no index was found */
        {                       /* I'm lazy... */
          mp_msg (MSGT_DEMUX, MSGL_V, "[mkv] seek unsupported flags\n");
          return;
        }

      target_filepos = (uint64_t)(demuxer->movi_end * rel_seek_secs);
      for (i=0; i < mkv_d->num_indexes; i++)
        if (mkv_d->indexes[i].tnum == demuxer->video->id)
          if ((index == NULL) ||
              ((mkv_d->indexes[i].filepos >= target_filepos) &&
               ((index->filepos < target_filepos) ||
                (mkv_d->indexes[i].filepos < index->filepos))))
            index = &mkv_d->indexes[i];

      if (!index)
        return;

      mkv_d->cluster_size = mkv_d->blockgroup_size = 0;
      stream_seek (s, index->filepos);

      if (demuxer->video->id >= 0)
        mkv_d->v_skip_to_keyframe = 1;
      mkv_d->skip_to_timecode = index->timecode;
      mkv_d->a_skip_to_keyframe = 1;

      demux_mkv_fill_buffer(demuxer, NULL);
    }
}

static int
demux_mkv_control (demuxer_t *demuxer, int cmd, void *arg)
{
  mkv_demuxer_t *mkv_d = (mkv_demuxer_t *) demuxer->priv;

  switch (cmd)
    {
    case DEMUXER_CTRL_CORRECT_PTS:
      return DEMUXER_CTRL_OK;
    case DEMUXER_CTRL_GET_TIME_LENGTH:
      if (mkv_d->duration == 0)
        return DEMUXER_CTRL_DONTKNOW;

      *((double *)arg) = (double)mkv_d->duration;
      return DEMUXER_CTRL_OK;

    case DEMUXER_CTRL_GET_PERCENT_POS:
      if (mkv_d->duration == 0)
        {
            return DEMUXER_CTRL_DONTKNOW;
        }

      *((int *) arg) = (int) (100 * mkv_d->last_pts / mkv_d->duration);
      return DEMUXER_CTRL_OK;

    case DEMUXER_CTRL_SWITCH_AUDIO:
      if (demuxer->audio && demuxer->audio->sh) {
        sh_audio_t *sh = demuxer->a_streams[demuxer->audio->id];
        int aid = *(int*)arg;
        if (aid < 0)
          aid = (sh->aid + 1) % mkv_d->last_aid;
        if (aid != sh->aid) {
          mkv_track_t *track = demux_mkv_find_track_by_num (mkv_d, aid, MATROSKA_TRACK_AUDIO);
          if (track) {
            demuxer->audio->id = track->tnum;
            sh = demuxer->a_streams[demuxer->audio->id];
            ds_free_packs(demuxer->audio);
          }
        }
        *(int*)arg = sh->aid;
      } else
        *(int*)arg = -2;
      return DEMUXER_CTRL_OK;

    default:
      return DEMUXER_CTRL_NOTIMPL;
    }
}

const demuxer_desc_t demuxer_desc_matroska = {
  "Matroska demuxer",
  "mkv",
  "Matroska",
  "Aurelien Jacobs",
  "",
  DEMUXER_TYPE_MATROSKA,
  1, // safe autodetect
  demux_mkv_open,
  demux_mkv_fill_buffer,
  NULL,
  demux_close_mkv,
  demux_mkv_seek,
  demux_mkv_control
};