split some common code from the mkv demuxer that will be useful to the muxer

patch by David Conrad  umovimus _at_ gmail.com

Originally committed as revision 9215 to svn://svn.ffmpeg.org/ffmpeg/trunk

4 files changed, 2842 insertions, 2790 deletions

diff --git a/libavformat/Makefile b/libavformat/Makefile
index a2de37d425..7c837ce46b 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -71,7 +71,7 @@ OBJS-$(CONFIG_INGENIENT_DEMUXER)         += raw.o
 OBJS-$(CONFIG_IPMOVIE_DEMUXER)           += ipmovie.o
 OBJS-$(CONFIG_M4V_DEMUXER)               += raw.o
 OBJS-$(CONFIG_M4V_MUXER)                 += raw.o
-OBJS-$(CONFIG_MATROSKA_DEMUXER)          += matroska.o riff.o
+OBJS-$(CONFIG_MATROSKA_DEMUXER)          += matroskadec.o matroska.o riff.o
 OBJS-$(CONFIG_MJPEG_DEMUXER)             += raw.o
 OBJS-$(CONFIG_MJPEG_MUXER)               += raw.o
 OBJS-$(CONFIG_MM_DEMUXER)                += mm.o
diff --git a/libavformat/matroska.c b/libavformat/matroska.c
index eaf4ceb953..3748a59ea2 100644
--- a/libavformat/matroska.c
+++ b/libavformat/matroska.c
@@ -1,5 +1,5 @@
 /*
- * Matroska file demuxer (no muxer yet)
+ * Matroska common data
  * Copyright (c) 2003-2004 The ffmpeg Project
  *
  * This file is part of FFmpeg.
@@ -19,185 +19,9 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-/**
- * @file matroska.c
- * Matroska file demuxer
- * by Ronald Bultje <rbultje@ronald.bitfreak.net>
- * with a little help from Moritz Bunkus <moritz@bunkus.org>
- * Specs available on the matroska project page:
- * http://www.matroska.org/.
- */
-
-#include "avformat.h"
-/* For codec_get_id(). */
-#include "riff.h"
-#include "intfloat_readwrite.h"
-
-/* EBML version supported */
-#define EBML_VERSION 1
-
-/* top-level master-IDs */
-#define EBML_ID_HEADER             0x1A45DFA3
-
-/* IDs in the HEADER master */
-#define EBML_ID_EBMLVERSION        0x4286
-#define EBML_ID_EBMLREADVERSION    0x42F7
-#define EBML_ID_EBMLMAXIDLENGTH    0x42F2
-#define EBML_ID_EBMLMAXSIZELENGTH  0x42F3
-#define EBML_ID_DOCTYPE            0x4282
-#define EBML_ID_DOCTYPEVERSION     0x4287
-#define EBML_ID_DOCTYPEREADVERSION 0x4285
-
-/* general EBML types */
-#define EBML_ID_VOID               0xEC
-
-/*
- * Matroska element IDs. max. 32-bit.
- */
-
-/* toplevel segment */
-#define MATROSKA_ID_SEGMENT    0x18538067
-
-/* matroska top-level master IDs */
-#define MATROSKA_ID_INFO       0x1549A966
-#define MATROSKA_ID_TRACKS     0x1654AE6B
-#define MATROSKA_ID_CUES       0x1C53BB6B
-#define MATROSKA_ID_TAGS       0x1254C367
-#define MATROSKA_ID_SEEKHEAD   0x114D9B74
-#define MATROSKA_ID_CLUSTER    0x1F43B675
-
-/* IDs in the info master */
-#define MATROSKA_ID_TIMECODESCALE 0x2AD7B1
-#define MATROSKA_ID_DURATION   0x4489
-#define MATROSKA_ID_TITLE      0x7BA9
-#define MATROSKA_ID_WRITINGAPP 0x5741
-#define MATROSKA_ID_MUXINGAPP  0x4D80
-#define MATROSKA_ID_DATEUTC    0x4461
-
-/* ID in the tracks master */
-#define MATROSKA_ID_TRACKENTRY 0xAE
-
-/* IDs in the trackentry master */
-#define MATROSKA_ID_TRACKNUMBER 0xD7
-#define MATROSKA_ID_TRACKUID   0x73C5
-#define MATROSKA_ID_TRACKTYPE  0x83
-#define MATROSKA_ID_TRACKAUDIO 0xE1
-#define MATROSKA_ID_TRACKVIDEO 0xE0
-#define MATROSKA_ID_CODECID    0x86
-#define MATROSKA_ID_CODECPRIVATE 0x63A2
-#define MATROSKA_ID_CODECNAME  0x258688
-#define MATROSKA_ID_CODECINFOURL 0x3B4040
-#define MATROSKA_ID_CODECDOWNLOADURL 0x26B240
-#define MATROSKA_ID_TRACKNAME  0x536E
-#define MATROSKA_ID_TRACKLANGUAGE 0x22B59C
-#define MATROSKA_ID_TRACKFLAGENABLED 0xB9
-#define MATROSKA_ID_TRACKFLAGDEFAULT 0x88
-#define MATROSKA_ID_TRACKFLAGLACING 0x9C
-#define MATROSKA_ID_TRACKMINCACHE 0x6DE7
-#define MATROSKA_ID_TRACKMAXCACHE 0x6DF8
-#define MATROSKA_ID_TRACKDEFAULTDURATION 0x23E383
-
-/* IDs in the trackvideo master */
-#define MATROSKA_ID_VIDEOFRAMERATE 0x2383E3
-#define MATROSKA_ID_VIDEODISPLAYWIDTH 0x54B0
-#define MATROSKA_ID_VIDEODISPLAYHEIGHT 0x54BA
-#define MATROSKA_ID_VIDEOPIXELWIDTH 0xB0
-#define MATROSKA_ID_VIDEOPIXELHEIGHT 0xBA
-#define MATROSKA_ID_VIDEOFLAGINTERLACED 0x9A
-#define MATROSKA_ID_VIDEOSTEREOMODE 0x53B9
-#define MATROSKA_ID_VIDEOASPECTRATIO 0x54B3
-#define MATROSKA_ID_VIDEOCOLOURSPACE 0x2EB524
+#include "matroska.h"
 
-/* IDs in the trackaudio master */
-#define MATROSKA_ID_AUDIOSAMPLINGFREQ 0xB5
-#define MATROSKA_ID_AUDIOOUTSAMPLINGFREQ 0x78B5
-
-#define MATROSKA_ID_AUDIOBITDEPTH 0x6264
-#define MATROSKA_ID_AUDIOCHANNELS 0x9F
-
-/* ID in the cues master */
-#define MATROSKA_ID_POINTENTRY 0xBB
-
-/* IDs in the pointentry master */
-#define MATROSKA_ID_CUETIME    0xB3
-#define MATROSKA_ID_CUETRACKPOSITION 0xB7
-
-/* IDs in the cuetrackposition master */
-#define MATROSKA_ID_CUETRACK   0xF7
-#define MATROSKA_ID_CUECLUSTERPOSITION 0xF1
-
-/* IDs in the tags master */
-/* TODO */
-
-/* IDs in the seekhead master */
-#define MATROSKA_ID_SEEKENTRY  0x4DBB
-
-/* IDs in the seekpoint master */
-#define MATROSKA_ID_SEEKID     0x53AB
-#define MATROSKA_ID_SEEKPOSITION 0x53AC
-
-/* IDs in the cluster master */
-#define MATROSKA_ID_CLUSTERTIMECODE 0xE7
-#define MATROSKA_ID_BLOCKGROUP 0xA0
-#define MATROSKA_ID_SIMPLEBLOCK 0xA3
-
-/* IDs in the blockgroup master */
-#define MATROSKA_ID_BLOCK      0xA1
-#define MATROSKA_ID_BLOCKDURATION 0x9B
-#define MATROSKA_ID_BLOCKREFERENCE 0xFB
-
-typedef enum {
-  MATROSKA_TRACK_TYPE_VIDEO    = 0x1,
-  MATROSKA_TRACK_TYPE_AUDIO    = 0x2,
-  MATROSKA_TRACK_TYPE_COMPLEX  = 0x3,
-  MATROSKA_TRACK_TYPE_LOGO     = 0x10,
-  MATROSKA_TRACK_TYPE_SUBTITLE = 0x11,
-  MATROSKA_TRACK_TYPE_CONTROL  = 0x20,
-} MatroskaTrackType;
-
-typedef enum {
-  MATROSKA_EYE_MODE_MONO  = 0x0,
-  MATROSKA_EYE_MODE_RIGHT = 0x1,
-  MATROSKA_EYE_MODE_LEFT  = 0x2,
-  MATROSKA_EYE_MODE_BOTH  = 0x3,
-} MatroskaEyeMode;
-
-typedef enum {
-  MATROSKA_ASPECT_RATIO_MODE_FREE  = 0x0,
-  MATROSKA_ASPECT_RATIO_MODE_KEEP  = 0x1,
-  MATROSKA_ASPECT_RATIO_MODE_FIXED = 0x2,
-} MatroskaAspectRatioMode;
-
-/*
- * These aren't in any way "matroska-form" things,
- * it's just something I use in the muxer/demuxer.
- */
-
-typedef enum {
-  MATROSKA_TRACK_ENABLED = (1<<0),
-  MATROSKA_TRACK_DEFAULT = (1<<1),
-  MATROSKA_TRACK_LACING  = (1<<2),
-  MATROSKA_TRACK_REAL_V  = (1<<4),
-  MATROSKA_TRACK_SHIFT   = (1<<16)
-} MatroskaTrackFlags;
-
-typedef enum {
-  MATROSKA_VIDEOTRACK_INTERLACED = (MATROSKA_TRACK_SHIFT<<0)
-} MatroskaVideoTrackFlags;
-
-/*
- * Matroska Codec IDs. Strings.
- */
-
-typedef struct CodecTags{
-    const char *str;
-    enum CodecID id;
-}CodecTags;
-
-#define MATROSKA_CODEC_ID_VIDEO_VFW_FOURCC   "V_MS/VFW/FOURCC"
-#define MATROSKA_CODEC_ID_AUDIO_ACM          "A_MS/ACM"
-
-static CodecTags codec_tags[]={
+CodecTags ff_mkv_codec_tags[]={
 //    {"V_MS/VFW/FOURCC"  , CODEC_ID_NONE},
     {"V_UNCOMPRESSED"   , CODEC_ID_RAWVIDEO},
     {"V_MPEG4/ISO/SP"   , CODEC_ID_MPEG4},
@@ -232,2613 +56,3 @@ static CodecTags codec_tags[]={
     {NULL               , CODEC_ID_NONE}
 /* TODO: AC3-9/10 (?), Real, Musepack, Quicktime */
 };
-
-/* max. depth in the EBML tree structure */
-#define EBML_MAX_DEPTH 16
-
-typedef struct Track {
-    MatroskaTrackType type;
-
-    /* Unique track number and track ID. stream_index is the index that
-     * the calling app uses for this track. */
-    uint32_t num,
-        uid,
-        stream_index;
-
-    char *name,
-        *language;
-
-    char *codec_id,
-        *codec_name;
-
-    unsigned char *codec_priv;
-    int codec_priv_size;
-
-    uint64_t default_duration;
-    MatroskaTrackFlags flags;
-} MatroskaTrack;
-
-typedef struct MatroskaVideoTrack {
-    MatroskaTrack track;
-
-    int pixel_width,
-        pixel_height,
-        display_width,
-        display_height;
-
-    uint32_t fourcc;
-
-    MatroskaAspectRatioMode ar_mode;
-    MatroskaEyeMode eye_mode;
-
-    //..
-} MatroskaVideoTrack;
-
-typedef struct MatroskaAudioTrack {
-    MatroskaTrack track;
-
-    int channels,
-        bitdepth,
-        internal_samplerate,
-        samplerate;
-    //..
-} MatroskaAudioTrack;
-
-typedef struct MatroskaSubtitleTrack {
-    MatroskaTrack track;
-
-    //..
-} MatroskaSubtitleTrack;
-
-#define MAX_TRACK_SIZE (FFMAX(FFMAX(sizeof(MatroskaVideoTrack), \
-                                    sizeof(MatroskaAudioTrack)), \
-                                    sizeof(MatroskaSubtitleTrack)))
-
-typedef struct MatroskaLevel {
-    uint64_t start, length;
-} MatroskaLevel;
-
-typedef struct MatroskaDemuxIndex {
-  uint64_t        pos;   /* of the corresponding *cluster*! */
-  uint16_t        track; /* reference to 'num' */
-  uint64_t        time;  /* in nanoseconds */
-} MatroskaDemuxIndex;
-
-typedef struct MatroskaDemuxContext {
-    AVFormatContext *ctx;
-
-    /* ebml stuff */
-    int num_levels;
-    MatroskaLevel levels[EBML_MAX_DEPTH];
-    int level_up;
-
-    /* matroska stuff */
-    char *writing_app,
-        *muxing_app;
-    int64_t created;
-
-    /* timescale in the file */
-    int64_t time_scale;
-
-    /* num_streams is the number of streams that av_new_stream() was called
-     * for ( = that are available to the calling program). */
-    int num_tracks, num_streams;
-    MatroskaTrack *tracks[MAX_STREAMS];
-
-    /* cache for ID peeking */
-    uint32_t peek_id;
-
-    /* byte position of the segment inside the stream */
-    offset_t segment_start;
-
-    /* The packet queue. */
-    AVPacket **packets;
-    int num_packets;
-
-    /* have we already parse metadata/cues/clusters? */
-    int metadata_parsed,
-        index_parsed,
-        done;
-
-    /* The index for seeking. */
-    int num_indexes;
-    MatroskaDemuxIndex *index;
-
-    /* What to skip before effectively reading a packet. */
-    int skip_to_keyframe;
-    AVStream *skip_to_stream;
-} MatroskaDemuxContext;
-
-/*
- * The first few functions handle EBML file parsing. The rest
- * is the document interpretation. Matroska really just is a
- * EBML file.
- */
-
-/*
- * Return: the amount of levels in the hierarchy that the
- * current element lies higher than the previous one.
- * The opposite isn't done - that's auto-done using master
- * element reading.
- */
-
-static int
-ebml_read_element_level_up (MatroskaDemuxContext *matroska)
-{
-    ByteIOContext *pb = &matroska->ctx->pb;
-    offset_t pos = url_ftell(pb);
-    int num = 0;
-
-    while (matroska->num_levels > 0) {
-        MatroskaLevel *level = &matroska->levels[matroska->num_levels - 1];
-
-        if (pos >= level->start + level->length) {
-            matroska->num_levels--;
-            num++;
-        } else {
-            break;
-        }
-    }
-
-    return num;
-}
-
-/*
- * Read: an "EBML number", which is defined as a variable-length
- * array of bytes. The first byte indicates the length by giving a
- * number of 0-bits followed by a one. The position of the first
- * "one" bit inside the first byte indicates the length of this
- * number.
- * Returns: num. of bytes read. < 0 on error.
- */
-
-static int
-ebml_read_num (MatroskaDemuxContext *matroska,
-               int                   max_size,
-               uint64_t             *number)
-{
-    ByteIOContext *pb = &matroska->ctx->pb;
-    int len_mask = 0x80, read = 1, n = 1;
-    int64_t total = 0;
-
-    /* the first byte tells us the length in bytes - get_byte() can normally
-     * return 0, but since that's not a valid first ebmlID byte, we can
-     * use it safely here to catch EOS. */
-    if (!(total = get_byte(pb))) {
-        /* we might encounter EOS here */
-        if (!url_feof(pb)) {
-            offset_t pos = url_ftell(pb);
-            av_log(matroska->ctx, AV_LOG_ERROR,
-                   "Read error at pos. %"PRIu64" (0x%"PRIx64")\n",
-                   pos, pos);
-        }
-        return AVERROR_IO; /* EOS or actual I/O error */
-    }
-
-    /* get the length of the EBML number */
-    while (read <= max_size && !(total & len_mask)) {
-        read++;
-        len_mask >>= 1;
-    }
-    if (read > max_size) {
-        offset_t pos = url_ftell(pb) - 1;
-        av_log(matroska->ctx, AV_LOG_ERROR,
-               "Invalid EBML number size tag 0x%02x at pos %"PRIu64" (0x%"PRIx64")\n",
-               (uint8_t) total, pos, pos);
-        return AVERROR_INVALIDDATA;
-    }
-
-    /* read out length */
-    total &= ~len_mask;
-    while (n++ < read)
-        total = (total << 8) | get_byte(pb);
-
-    *number = total;
-
-    return read;
-}
-
-/*
- * Read: the element content data ID.
- * Return: the number of bytes read or < 0 on error.
- */
-
-static int
-ebml_read_element_id (MatroskaDemuxContext *matroska,
-                      uint32_t             *id,
-                      int                  *level_up)
-{
-    int read;
-    uint64_t total;
-
-    /* if we re-call this, use our cached ID */
-    if (matroska->peek_id != 0) {
-        if (level_up)
-            *level_up = 0;
-        *id = matroska->peek_id;
-        return 0;
-    }
-
-    /* read out the "EBML number", include tag in ID */
-    if ((read = ebml_read_num(matroska, 4, &total)) < 0)
-        return read;
-    *id = matroska->peek_id  = total | (1 << (read * 7));
-
-    /* level tracking */
-    if (level_up)
-        *level_up = ebml_read_element_level_up(matroska);
-
-    return read;
-}
-
-/*
- * Read: element content length.
- * Return: the number of bytes read or < 0 on error.
- */
-
-static int
-ebml_read_element_length (MatroskaDemuxContext *matroska,
-                          uint64_t             *length)
-{
-    /* clear cache since we're now beyond that data point */
-    matroska->peek_id = 0;
-
-    /* read out the "EBML number", include tag in ID */
-    return ebml_read_num(matroska, 8, length);
-}
-
-/*
- * Return: the ID of the next element, or 0 on error.
- * Level_up contains the amount of levels that this
- * next element lies higher than the previous one.
- */
-
-static uint32_t
-ebml_peek_id (MatroskaDemuxContext *matroska,
-              int                  *level_up)
-{
-    uint32_t id;
-
-    assert(level_up != NULL);
-
-    if (ebml_read_element_id(matroska, &id, level_up) < 0)
-        return 0;
-
-    return id;
-}
-
-/*
- * Seek to a given offset.
- * 0 is success, -1 is failure.
- */
-
-static int
-ebml_read_seek (MatroskaDemuxContext *matroska,
-                offset_t              offset)
-{
-    ByteIOContext *pb = &matroska->ctx->pb;
-
-    /* clear ID cache, if any */
-    matroska->peek_id = 0;
-
-    return (url_fseek(pb, offset, SEEK_SET) == offset) ? 0 : -1;
-}
-
-/*
- * Skip the next element.
- * 0 is success, -1 is failure.
- */
-
-static int
-ebml_read_skip (MatroskaDemuxContext *matroska)
-{
-    ByteIOContext *pb = &matroska->ctx->pb;
-    uint32_t id;
-    uint64_t length;
-    int res;
-
-    if ((res = ebml_read_element_id(matroska, &id, NULL)) < 0 ||
-        (res = ebml_read_element_length(matroska, &length)) < 0)
-        return res;
-
-    url_fskip(pb, length);
-
-    return 0;
-}
-
-/*
- * Read the next element as an unsigned int.
- * 0 is success, < 0 is failure.
- */
-
-static int
-ebml_read_uint (MatroskaDemuxContext *matroska,
-                uint32_t             *id,
-                uint64_t             *num)
-{
-    ByteIOContext *pb = &matroska->ctx->pb;
-    int n = 0, size, res;
-    uint64_t rlength;
-
-    if ((res = ebml_read_element_id(matroska, id, NULL)) < 0 ||
-        (res = ebml_read_element_length(matroska, &rlength)) < 0)
-        return res;
-    size = rlength;
-    if (size < 1 || size > 8) {
-        offset_t pos = url_ftell(pb);
-        av_log(matroska->ctx, AV_LOG_ERROR,
-               "Invalid uint element size %d at position %"PRId64" (0x%"PRIx64")\n",
-                size, pos, pos);
-        return AVERROR_INVALIDDATA;
-    }
-
-    /* big-endian ordening; build up number */
-    *num = 0;
-    while (n++ < size)
-        *num = (*num << 8) | get_byte(pb);
-
-    return 0;
-}
-
-/*
- * Read the next element as a signed int.
- * 0 is success, < 0 is failure.
- */
-
-static int
-ebml_read_sint (MatroskaDemuxContext *matroska,
-                uint32_t             *id,
-                int64_t              *num)
-{
-    ByteIOContext *pb = &matroska->ctx->pb;
-    int size, n = 1, negative = 0, res;
-    uint64_t rlength;
-
-    if ((res = ebml_read_element_id(matroska, id, NULL)) < 0 ||
-        (res = ebml_read_element_length(matroska, &rlength)) < 0)
-        return res;
-    size = rlength;
-    if (size < 1 || size > 8) {
-        offset_t pos = url_ftell(pb);
-        av_log(matroska->ctx, AV_LOG_ERROR,
-               "Invalid sint element size %d at position %"PRId64" (0x%"PRIx64")\n",
-                size, pos, pos);
-        return AVERROR_INVALIDDATA;
-    }
-    if ((*num = get_byte(pb)) & 0x80) {
-        negative = 1;
-        *num &= ~0x80;
-    }
-    while (n++ < size)
-        *num = (*num << 8) | get_byte(pb);
-
-    /* make signed */
-    if (negative)
-        *num = *num - (1LL << ((8 * size) - 1));
-
-    return 0;
-}
-
-/*
- * Read the next element as a float.
- * 0 is success, < 0 is failure.
- */
-
-static int
-ebml_read_float (MatroskaDemuxContext *matroska,
-                 uint32_t             *id,
-                 double               *num)
-{
-    ByteIOContext *pb = &matroska->ctx->pb;
-    int size, res;
-    uint64_t rlength;
-
-    if ((res = ebml_read_element_id(matroska, id, NULL)) < 0 ||
-        (res = ebml_read_element_length(matroska, &rlength)) < 0)
-        return res;
-    size = rlength;
-
-    if (size == 4) {
-        *num= av_int2flt(get_be32(pb));
-    } else if(size==8){
-        *num= av_int2dbl(get_be64(pb));
-    } else{
-        offset_t pos = url_ftell(pb);
-        av_log(matroska->ctx, AV_LOG_ERROR,
-               "Invalid float element size %d at position %"PRIu64" (0x%"PRIx64")\n",
-               size, pos, pos);
-        return AVERROR_INVALIDDATA;
-    }
-
-    return 0;
-}
-
-/*
- * Read the next element as an ASCII string.
- * 0 is success, < 0 is failure.
- */
-
-static int
-ebml_read_ascii (MatroskaDemuxContext *matroska,
-                 uint32_t             *id,
-                 char                **str)
-{
-    ByteIOContext *pb = &matroska->ctx->pb;
-    int size, res;
-    uint64_t rlength;
-
-    if ((res = ebml_read_element_id(matroska, id, NULL)) < 0 ||
-        (res = ebml_read_element_length(matroska, &rlength)) < 0)
-        return res;
-    size = rlength;
-
-    /* ebml strings are usually not 0-terminated, so we allocate one
-     * byte more, read the string and NULL-terminate it ourselves. */
-    if (size < 0 || !(*str = av_malloc(size + 1))) {
-        av_log(matroska->ctx, AV_LOG_ERROR, "Memory allocation failed\n");
-        return AVERROR_NOMEM;
-    }
-    if (get_buffer(pb, (uint8_t *) *str, size) != size) {
-        offset_t pos = url_ftell(pb);
-        av_log(matroska->ctx, AV_LOG_ERROR,
-               "Read error at pos. %"PRIu64" (0x%"PRIx64")\n", pos, pos);
-        return AVERROR_IO;
-    }
-    (*str)[size] = '\0';
-
-    return 0;
-}
-
-/*
- * Read the next element as a UTF-8 string.
- * 0 is success, < 0 is failure.
- */
-
-static int
-ebml_read_utf8 (MatroskaDemuxContext *matroska,
-                uint32_t             *id,
-                char                **str)
-{
-  return ebml_read_ascii(matroska, id, str);
-}
-
-/*
- * Read the next element as a date (nanoseconds since 1/1/2000).
- * 0 is success, < 0 is failure.
- */
-
-static int
-ebml_read_date (MatroskaDemuxContext *matroska,
-                uint32_t             *id,
-                int64_t              *date)
-{
-  return ebml_read_sint(matroska, id, date);
-}
-
-/*
- * Read the next element, but only the header. The contents
- * are supposed to be sub-elements which can be read separately.
- * 0 is success, < 0 is failure.
- */
-
-static int
-ebml_read_master (MatroskaDemuxContext *matroska,
-                  uint32_t             *id)
-{
-    ByteIOContext *pb = &matroska->ctx->pb;
-    uint64_t length;
-    MatroskaLevel *level;
-    int res;
-
-    if ((res = ebml_read_element_id(matroska, id, NULL)) < 0 ||
-        (res = ebml_read_element_length(matroska, &length)) < 0)
-        return res;
-
-    /* protect... (Heaven forbids that the '>' is true) */
-    if (matroska->num_levels >= EBML_MAX_DEPTH) {
-        av_log(matroska->ctx, AV_LOG_ERROR,
-               "File moves beyond max. allowed depth (%d)\n", EBML_MAX_DEPTH);
-        return AVERROR_NOTSUPP;
-    }
-
-    /* remember level */
-    level = &matroska->levels[matroska->num_levels++];
-    level->start = url_ftell(pb);
-    level->length = length;
-
-    return 0;
-}
-
-/*
- * Read the next element as binary data.
- * 0 is success, < 0 is failure.
- */
-
-static int
-ebml_read_binary (MatroskaDemuxContext *matroska,
-                  uint32_t             *id,
-                  uint8_t             **binary,
-                  int                  *size)
-{
-    ByteIOContext *pb = &matroska->ctx->pb;
-    uint64_t rlength;
-    int res;
-
-    if ((res = ebml_read_element_id(matroska, id, NULL)) < 0 ||
-        (res = ebml_read_element_length(matroska, &rlength)) < 0)
-        return res;
-    *size = rlength;
-
-    if (!(*binary = av_malloc(*size))) {
-        av_log(matroska->ctx, AV_LOG_ERROR,
-               "Memory allocation error\n");
-        return AVERROR_NOMEM;
-    }
-
-    if (get_buffer(pb, *binary, *size) != *size) {
-        offset_t pos = url_ftell(pb);
-        av_log(matroska->ctx, AV_LOG_ERROR,
-               "Read error at pos. %"PRIu64" (0x%"PRIx64")\n", pos, pos);
-        return AVERROR_IO;
-    }
-
-    return 0;
-}
-
-/*
- * Read signed/unsigned "EBML" numbers.
- * Return: number of bytes processed, < 0 on error.
- * XXX: use ebml_read_num().
- */
-
-static int
-matroska_ebmlnum_uint (uint8_t  *data,
-                       uint32_t  size,
-                       uint64_t *num)
-{
-    int len_mask = 0x80, read = 1, n = 1, num_ffs = 0;
-    uint64_t total;
-
-    if (size <= 0)
-        return AVERROR_INVALIDDATA;
-
-    total = data[0];
-    while (read <= 8 && !(total & len_mask)) {
-        read++;
-        len_mask >>= 1;
-    }
-    if (read > 8)
-        return AVERROR_INVALIDDATA;
-
-    if ((total &= (len_mask - 1)) == len_mask - 1)
-        num_ffs++;
-    if (size < read)
-        return AVERROR_INVALIDDATA;
-    while (n < read) {
-        if (data[n] == 0xff)
-            num_ffs++;
-        total = (total << 8) | data[n];
-        n++;
-    }
-
-    if (read == num_ffs)
-        *num = (uint64_t)-1;
-    else
-        *num = total;
-
-    return read;
-}
-
-/*
- * Same as above, but signed.
- */
-
-static int
-matroska_ebmlnum_sint (uint8_t  *data,
-                       uint32_t  size,
-                       int64_t  *num)
-{
-    uint64_t unum;
-    int res;
-
-    /* read as unsigned number first */
-    if ((res = matroska_ebmlnum_uint(data, size, &unum)) < 0)
-        return res;
-
-    /* make signed (weird way) */
-    if (unum == (uint64_t)-1)
-        *num = INT64_MAX;
-    else
-        *num = unum - ((1LL << ((7 * res) - 1)) - 1);
-
-    return res;
-}
-
-/*
- * Read an EBML header.
- * 0 is success, < 0 is failure.
- */
-
-static int
-ebml_read_header (MatroskaDemuxContext *matroska,
-                  char                **doctype,
-                  int                  *version)
-{
-    uint32_t id;
-    int level_up, res = 0;
-
-    /* default init */
-    if (doctype)
-        *doctype = NULL;
-    if (version)
-        *version = 1;
-
-    if (!(id = ebml_peek_id(matroska, &level_up)) ||
-        level_up != 0 || id != EBML_ID_HEADER) {
-        av_log(matroska->ctx, AV_LOG_ERROR,
-               "This is not an EBML file (id=0x%x/0x%x)\n", id, EBML_ID_HEADER);
-        return AVERROR_INVALIDDATA;
-    }
-    if ((res = ebml_read_master(matroska, &id)) < 0)
-        return res;
-
-    while (res == 0) {
-        if (!(id = ebml_peek_id(matroska, &level_up)))
-            return AVERROR_IO;
-
-        /* end-of-header */
-        if (level_up)
-            break;
-
-        switch (id) {
-            /* is our read version uptodate? */
-            case EBML_ID_EBMLREADVERSION: {
-                uint64_t num;
-
-                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
-                    return res;
-                if (num > EBML_VERSION) {
-                    av_log(matroska->ctx, AV_LOG_ERROR,
-                           "EBML version %"PRIu64" (> %d) is not supported\n",
-                           num, EBML_VERSION);
-                    return AVERROR_INVALIDDATA;
-                }
-                break;
-            }
-
-            /* we only handle 8 byte lengths at max */
-            case EBML_ID_EBMLMAXSIZELENGTH: {
-                uint64_t num;
-
-                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
-                    return res;
-                if (num > sizeof(uint64_t)) {
-                    av_log(matroska->ctx, AV_LOG_ERROR,
-                           "Integers of size %"PRIu64" (> %zd) not supported\n",
-                           num, sizeof(uint64_t));
-                    return AVERROR_INVALIDDATA;
-                }
-                break;
-            }
-
-            /* we handle 4 byte IDs at max */
-            case EBML_ID_EBMLMAXIDLENGTH: {
-                uint64_t num;
-
-                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
-                    return res;
-                if (num > sizeof(uint32_t)) {
-                    av_log(matroska->ctx, AV_LOG_ERROR,
-                           "IDs of size %"PRIu64" (> %zu) not supported\n",
-                            num, sizeof(uint32_t));
-                    return AVERROR_INVALIDDATA;
-                }
-                break;
-            }
-
-            case EBML_ID_DOCTYPE: {
-                char *text;
-
-                if ((res = ebml_read_ascii(matroska, &id, &text)) < 0)
-                    return res;
-                if (doctype) {
-                    if (*doctype)
-                        av_free(*doctype);
-                    *doctype = text;
-                } else
-                    av_free(text);
-                break;
-            }
-
-            case EBML_ID_DOCTYPEREADVERSION: {
-                uint64_t num;
-
-                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
-                    return res;
-                if (version)
-                    *version = num;
-                break;
-            }
-
-            default:
-                av_log(matroska->ctx, AV_LOG_INFO,
-                       "Unknown data type 0x%x in EBML header", id);
-                /* pass-through */
-
-            case EBML_ID_VOID:
-            /* we ignore these two, as they don't tell us anything we
-             * care about */
-            case EBML_ID_EBMLVERSION:
-            case EBML_ID_DOCTYPEVERSION:
-                res = ebml_read_skip (matroska);
-                break;
-        }
-    }
-
-    return 0;
-}
-
-
-static int
-matroska_find_track_by_num (MatroskaDemuxContext *matroska,
-                            int                   num)
-{
-    int i;
-
-    for (i = 0; i < matroska->num_tracks; i++)
-        if (matroska->tracks[i]->num == num)
-            return i;
-
-    return -1;
-}
-
-
-/*
- * Put one packet in an application-supplied AVPacket struct.
- * Returns 0 on success or -1 on failure.
- */
-
-static int
-matroska_deliver_packet (MatroskaDemuxContext *matroska,
-                         AVPacket             *pkt)
-{
-    if (matroska->num_packets > 0) {
-        memcpy(pkt, matroska->packets[0], sizeof(AVPacket));
-        av_free(matroska->packets[0]);
-        if (matroska->num_packets > 1) {
-            memmove(&matroska->packets[0], &matroska->packets[1],
-                    (matroska->num_packets - 1) * sizeof(AVPacket *));
-            matroska->packets =
-                av_realloc(matroska->packets, (matroska->num_packets - 1) *
-                           sizeof(AVPacket *));
-        } else {
-            av_freep(&matroska->packets);
-        }
-        matroska->num_packets--;
-        return 0;
-    }
-
-    return -1;
-}
-
-/*
- * Put a packet into our internal queue. Will be delivered to the
- * user/application during the next get_packet() call.
- */
-
-static void
-matroska_queue_packet (MatroskaDemuxContext *matroska,
-                       AVPacket             *pkt)
-{
-    matroska->packets =
-        av_realloc(matroska->packets, (matroska->num_packets + 1) *
-                   sizeof(AVPacket *));
-    matroska->packets[matroska->num_packets] = pkt;
-    matroska->num_packets++;
-}
-
-
-/*
- * Autodetecting...
- */
-
-static int
-matroska_probe (AVProbeData *p)
-{
-    uint64_t total = 0;
-    int len_mask = 0x80, size = 1, n = 1;
-    uint8_t probe_data[] = { 'm', 'a', 't', 'r', 'o', 's', 'k', 'a' };
-
-    /* ebml header? */
-    if ((p->buf[0] << 24 | p->buf[1] << 16 |
-         p->buf[2] << 8 | p->buf[3]) != EBML_ID_HEADER)
-        return 0;
-
-    /* length of header */
-    total = p->buf[4];
-    while (size <= 8 && !(total & len_mask)) {
-        size++;
-        len_mask >>= 1;
-    }
-    if (size > 8)
-      return 0;
-    total &= (len_mask - 1);
-    while (n < size)
-        total = (total << 8) | p->buf[4 + n++];
-
-    /* does the probe data contain the whole header? */
-    if (p->buf_size < 4 + size + total)
-      return 0;
-
-    /* the header must contain the document type 'matroska'. For now,
-     * we don't parse the whole header but simply check for the
-     * availability of that array of characters inside the header.
-     * Not fully fool-proof, but good enough. */
-    for (n = 4 + size; n <= 4 + size + total - sizeof(probe_data); n++)
-        if (!memcmp (&p->buf[n], probe_data, sizeof(probe_data)))
-            return AVPROBE_SCORE_MAX;
-
-    return 0;
-}
-
-/*
- * From here on, it's all XML-style DTD stuff... Needs no comments.
- */
-
-static int
-matroska_parse_info (MatroskaDemuxContext *matroska)
-{
-    int res = 0;
-    uint32_t id;
-
-    av_log(matroska->ctx, AV_LOG_DEBUG, "Parsing info...\n");
-
-    while (res == 0) {
-        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
-            res = AVERROR_IO;
-            break;
-        } else if (matroska->level_up) {
-            matroska->level_up--;
-            break;
-        }
-
-        switch (id) {
-            /* cluster timecode */
-            case MATROSKA_ID_TIMECODESCALE: {
-                uint64_t num;
-                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
-                    break;
-                matroska->time_scale = num;
-                break;
-            }
-
-            case MATROSKA_ID_DURATION: {
-                double num;
-                if ((res = ebml_read_float(matroska, &id, &num)) < 0)
-                    break;
-                matroska->ctx->duration = num * matroska->time_scale * 1000 / AV_TIME_BASE;
-                break;
-            }
-
-            case MATROSKA_ID_TITLE: {
-                char *text;
-                if ((res = ebml_read_utf8(matroska, &id, &text)) < 0)
-                    break;
-                strncpy(matroska->ctx->title, text,
-                        sizeof(matroska->ctx->title)-1);
-                av_free(text);
-                break;
-            }
-
-            case MATROSKA_ID_WRITINGAPP: {
-                char *text;
-                if ((res = ebml_read_utf8(matroska, &id, &text)) < 0)
-                    break;
-                matroska->writing_app = text;
-                break;
-            }
-
-            case MATROSKA_ID_MUXINGAPP: {
-                char *text;
-                if ((res = ebml_read_utf8(matroska, &id, &text)) < 0)
-                    break;
-                matroska->muxing_app = text;
-                break;
-            }
-
-            case MATROSKA_ID_DATEUTC: {
-                int64_t time;
-                if ((res = ebml_read_date(matroska, &id, &time)) < 0)
-                    break;
-                matroska->created = time;
-                break;
-            }
-
-            default:
-                av_log(matroska->ctx, AV_LOG_INFO,
-                       "Unknown entry 0x%x in info header\n", id);
-                /* fall-through */
-
-            case EBML_ID_VOID:
-                res = ebml_read_skip(matroska);
-                break;
-        }
-
-        if (matroska->level_up) {
-            matroska->level_up--;
-            break;
-        }
-    }
-
-    return res;
-}
-
-static int
-matroska_add_stream (MatroskaDemuxContext *matroska)
-{
-    int res = 0;
-    uint32_t id;
-    MatroskaTrack *track;
-
-    av_log(matroska->ctx, AV_LOG_DEBUG, "parsing track, adding stream..,\n");
-
-    /* Allocate a generic track. As soon as we know its type we'll realloc. */
-    track = av_mallocz(MAX_TRACK_SIZE);
-    matroska->num_tracks++;
-
-    /* start with the master */
-    if ((res = ebml_read_master(matroska, &id)) < 0)
-        return res;
-
-    /* try reading the trackentry headers */
-    while (res == 0) {
-        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
-            res = AVERROR_IO;
-            break;
-        } else if (matroska->level_up > 0) {
-            matroska->level_up--;
-            break;
-        }
-
-        switch (id) {
-            /* track number (unique stream ID) */
-            case MATROSKA_ID_TRACKNUMBER: {
-                uint64_t num;
-                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
-                    break;
-                track->num = num;
-                break;
-            }
-
-            /* track UID (unique identifier) */
-            case MATROSKA_ID_TRACKUID: {
-                uint64_t num;
-                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
-                    break;
-                track->uid = num;
-                break;
-            }
-
-            /* track type (video, audio, combined, subtitle, etc.) */
-            case MATROSKA_ID_TRACKTYPE: {
-                uint64_t num;
-                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
-                    break;
-                if (track->type && track->type != num) {
-                    av_log(matroska->ctx, AV_LOG_INFO,
-                           "More than one tracktype in an entry - skip\n");
-                    break;
-                }
-                track->type = num;
-
-                switch (track->type) {
-                    case MATROSKA_TRACK_TYPE_VIDEO:
-                    case MATROSKA_TRACK_TYPE_AUDIO:
-                    case MATROSKA_TRACK_TYPE_SUBTITLE:
-                        break;
-                    case MATROSKA_TRACK_TYPE_COMPLEX:
-                    case MATROSKA_TRACK_TYPE_LOGO:
-                    case MATROSKA_TRACK_TYPE_CONTROL:
-                    default:
-                        av_log(matroska->ctx, AV_LOG_INFO,
-                               "Unknown or unsupported track type 0x%x\n",
-                               track->type);
-                        track->type = 0;
-                        break;
-                }
-                matroska->tracks[matroska->num_tracks - 1] = track;
-                break;
-            }
-
-            /* tracktype specific stuff for video */
-            case MATROSKA_ID_TRACKVIDEO: {
-                MatroskaVideoTrack *videotrack;
-                if (!track->type)
-                    track->type = MATROSKA_TRACK_TYPE_VIDEO;
-                if (track->type != MATROSKA_TRACK_TYPE_VIDEO) {
-                    av_log(matroska->ctx, AV_LOG_INFO,
-                           "video data in non-video track - ignoring\n");
-                    res = AVERROR_INVALIDDATA;
-                    break;
-                } else if ((res = ebml_read_master(matroska, &id)) < 0)
-                    break;
-                videotrack = (MatroskaVideoTrack *)track;
-
-                while (res == 0) {
-                    if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
-                        res = AVERROR_IO;
-                        break;
-                    } else if (matroska->level_up > 0) {
-                        matroska->level_up--;
-                        break;
-                    }
-
-                    switch (id) {
-                        /* fixme, this should be one-up, but I get it here */
-                        case MATROSKA_ID_TRACKDEFAULTDURATION: {
-                            uint64_t num;
-                            if ((res = ebml_read_uint (matroska, &id,
-                                                       &num)) < 0)
-                                break;
-                            track->default_duration = num/matroska->time_scale;
-                            break;
-                        }
-
-                        /* video framerate */
-                        case MATROSKA_ID_VIDEOFRAMERATE: {
-                            double num;
-                            if ((res = ebml_read_float(matroska, &id,
-                                                       &num)) < 0)
-                                break;
-                            track->default_duration = 1000000000/(matroska->time_scale*num);
-                            break;
-                        }
-
-                        /* width of the size to display the video at */
-                        case MATROSKA_ID_VIDEODISPLAYWIDTH: {
-                            uint64_t num;
-                            if ((res = ebml_read_uint(matroska, &id,
-                                                      &num)) < 0)
-                                break;
-                            videotrack->display_width = num;
-                            break;
-                        }
-
-                        /* height of the size to display the video at */
-                        case MATROSKA_ID_VIDEODISPLAYHEIGHT: {
-                            uint64_t num;
-                            if ((res = ebml_read_uint(matroska, &id,
-                                                      &num)) < 0)
-                                break;
-                            videotrack->display_height = num;
-                            break;
-                        }
-
-                        /* width of the video in the file */
-                        case MATROSKA_ID_VIDEOPIXELWIDTH: {
-                            uint64_t num;
-                            if ((res = ebml_read_uint(matroska, &id,
-                                                      &num)) < 0)
-                                break;
-                            videotrack->pixel_width = num;
-                            break;
-                        }
-
-                        /* height of the video in the file */
-                        case MATROSKA_ID_VIDEOPIXELHEIGHT: {
-                            uint64_t num;
-                            if ((res = ebml_read_uint(matroska, &id,
-                                                      &num)) < 0)
-                                break;
-                            videotrack->pixel_height = num;
-                            break;
-                        }
-
-                        /* whether the video is interlaced */
-                        case MATROSKA_ID_VIDEOFLAGINTERLACED: {
-                            uint64_t num;
-                            if ((res = ebml_read_uint(matroska, &id,
-                                                      &num)) < 0)
-                                break;
-                            if (num)
-                                track->flags |=
-                                    MATROSKA_VIDEOTRACK_INTERLACED;
-                            else
-                                track->flags &=
-                                    ~MATROSKA_VIDEOTRACK_INTERLACED;
-                            break;
-                        }
-
-                        /* stereo mode (whether the video has two streams,
-                         * where one is for the left eye and the other for
-                         * the right eye, which creates a 3D-like
-                         * effect) */
-                        case MATROSKA_ID_VIDEOSTEREOMODE: {
-                            uint64_t num;
-                            if ((res = ebml_read_uint(matroska, &id,
-                                                      &num)) < 0)
-                                break;
-                            if (num != MATROSKA_EYE_MODE_MONO &&
-                                num != MATROSKA_EYE_MODE_LEFT &&
-                                num != MATROSKA_EYE_MODE_RIGHT &&
-                                num != MATROSKA_EYE_MODE_BOTH) {
-                                av_log(matroska->ctx, AV_LOG_INFO,
-                                       "Ignoring unknown eye mode 0x%x\n",
-                                       (uint32_t) num);
-                                break;
-                            }
-                            videotrack->eye_mode = num;
-                            break;
-                        }
-
-                        /* aspect ratio behaviour */
-                        case MATROSKA_ID_VIDEOASPECTRATIO: {
-                            uint64_t num;
-                            if ((res = ebml_read_uint(matroska, &id,
-                                                      &num)) < 0)
-                                break;
-                            if (num != MATROSKA_ASPECT_RATIO_MODE_FREE &&
-                                num != MATROSKA_ASPECT_RATIO_MODE_KEEP &&
-                                num != MATROSKA_ASPECT_RATIO_MODE_FIXED) {
-                                av_log(matroska->ctx, AV_LOG_INFO,
-                                       "Ignoring unknown aspect ratio 0x%x\n",
-                                       (uint32_t) num);
-                                break;
-                            }
-                            videotrack->ar_mode = num;
-                            break;
-                        }
-
-                        /* colourspace (only matters for raw video)
-                         * fourcc */
-                        case MATROSKA_ID_VIDEOCOLOURSPACE: {
-                            uint64_t num;
-                            if ((res = ebml_read_uint(matroska, &id,
-                                                      &num)) < 0)
-                                break;
-                            videotrack->fourcc = num;
-                            break;
-                        }
-
-                        default:
-                            av_log(matroska->ctx, AV_LOG_INFO,
-                                   "Unknown video track header entry "
-                                   "0x%x - ignoring\n", id);
-                            /* pass-through */
-
-                        case EBML_ID_VOID:
-                            res = ebml_read_skip(matroska);
-                            break;
-                    }
-
-                    if (matroska->level_up) {
-                        matroska->level_up--;
-                        break;
-                    }
-                }
-                break;
-            }
-
-            /* tracktype specific stuff for audio */
-            case MATROSKA_ID_TRACKAUDIO: {
-                MatroskaAudioTrack *audiotrack;
-                if (!track->type)
-                    track->type = MATROSKA_TRACK_TYPE_AUDIO;
-                if (track->type != MATROSKA_TRACK_TYPE_AUDIO) {
-                    av_log(matroska->ctx, AV_LOG_INFO,
-                           "audio data in non-audio track - ignoring\n");
-                    res = AVERROR_INVALIDDATA;
-                    break;
-                } else if ((res = ebml_read_master(matroska, &id)) < 0)
-                    break;
-                audiotrack = (MatroskaAudioTrack *)track;
-                audiotrack->channels = 1;
-                audiotrack->samplerate = 8000;
-
-                while (res == 0) {
-                    if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
-                        res = AVERROR_IO;
-                        break;
-                    } else if (matroska->level_up > 0) {
-                        matroska->level_up--;
-                        break;
-                    }
-
-                    switch (id) {
-                        /* samplerate */
-                        case MATROSKA_ID_AUDIOSAMPLINGFREQ: {
-                            double num;
-                            if ((res = ebml_read_float(matroska, &id,
-                                                       &num)) < 0)
-                                break;
-                            audiotrack->internal_samplerate =
-                            audiotrack->samplerate = num;
-                            break;
-                        }
-
-                        case MATROSKA_ID_AUDIOOUTSAMPLINGFREQ: {
-                            double num;
-                            if ((res = ebml_read_float(matroska, &id,
-                                                       &num)) < 0)
-                                break;
-                            audiotrack->samplerate = num;
-                            break;
-                        }
-
-                            /* bitdepth */
-                        case MATROSKA_ID_AUDIOBITDEPTH: {
-                            uint64_t num;
-                            if ((res = ebml_read_uint(matroska, &id,
-                                                      &num)) < 0)
-                                break;
-                            audiotrack->bitdepth = num;
-                            break;
-                        }
-
-                            /* channels */
-                        case MATROSKA_ID_AUDIOCHANNELS: {
-                            uint64_t num;
-                            if ((res = ebml_read_uint(matroska, &id,
-                                                      &num)) < 0)
-                                break;
-                            audiotrack->channels = num;
-                            break;
-                        }
-
-                        default:
-                            av_log(matroska->ctx, AV_LOG_INFO,
-                                   "Unknown audio track header entry "
-                                   "0x%x - ignoring\n", id);
-                            /* pass-through */
-
-                        case EBML_ID_VOID:
-                            res = ebml_read_skip(matroska);
-                            break;
-                    }
-
-                    if (matroska->level_up) {
-                        matroska->level_up--;
-                        break;
-                    }
-                }
-                break;
-            }
-
-                /* codec identifier */
-            case MATROSKA_ID_CODECID: {
-                char *text;
-                if ((res = ebml_read_ascii(matroska, &id, &text)) < 0)
-                    break;
-                track->codec_id = text;
-                break;
-            }
-
-                /* codec private data */
-            case MATROSKA_ID_CODECPRIVATE: {
-                uint8_t *data;
-                int size;
-                if ((res = ebml_read_binary(matroska, &id, &data, &size) < 0))
-                    break;
-                track->codec_priv = data;
-                track->codec_priv_size = size;
-                break;
-            }
-
-                /* name of the codec */
-            case MATROSKA_ID_CODECNAME: {
-                char *text;
-                if ((res = ebml_read_utf8(matroska, &id, &text)) < 0)
-                    break;
-                track->codec_name = text;
-                break;
-            }
-
-                /* name of this track */
-            case MATROSKA_ID_TRACKNAME: {
-                char *text;
-                if ((res = ebml_read_utf8(matroska, &id, &text)) < 0)
-                    break;
-                track->name = text;
-                break;
-            }
-
-                /* language (matters for audio/subtitles, mostly) */
-            case MATROSKA_ID_TRACKLANGUAGE: {
-                char *text;
-                if ((res = ebml_read_utf8(matroska, &id, &text)) < 0)
-                    break;
-                track->language = text;
-                break;
-            }
-
-                /* whether this is actually used */
-            case MATROSKA_ID_TRACKFLAGENABLED: {
-                uint64_t num;
-                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
-                    break;
-                if (num)
-                    track->flags |= MATROSKA_TRACK_ENABLED;
-                else
-                    track->flags &= ~MATROSKA_TRACK_ENABLED;
-                break;
-            }
-
-                /* whether it's the default for this track type */
-            case MATROSKA_ID_TRACKFLAGDEFAULT: {
-                uint64_t num;
-                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
-                    break;
-                if (num)
-                    track->flags |= MATROSKA_TRACK_DEFAULT;
-                else
-                    track->flags &= ~MATROSKA_TRACK_DEFAULT;
-                break;
-            }
-
-                /* lacing (like MPEG, where blocks don't end/start on frame
-                 * boundaries) */
-            case MATROSKA_ID_TRACKFLAGLACING: {
-                uint64_t num;
-                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
-                    break;
-                if (num)
-                    track->flags |= MATROSKA_TRACK_LACING;
-                else
-                    track->flags &= ~MATROSKA_TRACK_LACING;
-                break;
-            }
-
-                /* default length (in time) of one data block in this track */
-            case MATROSKA_ID_TRACKDEFAULTDURATION: {
-                uint64_t num;
-                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
-                    break;
-                track->default_duration = num / matroska->time_scale;
-                break;
-            }
-
-            default:
-                av_log(matroska->ctx, AV_LOG_INFO,
-                       "Unknown track header entry 0x%x - ignoring\n", id);
-                /* pass-through */
-
-            case EBML_ID_VOID:
-            /* we ignore these because they're nothing useful. */
-            case MATROSKA_ID_CODECINFOURL:
-            case MATROSKA_ID_CODECDOWNLOADURL:
-            case MATROSKA_ID_TRACKMINCACHE:
-            case MATROSKA_ID_TRACKMAXCACHE:
-                res = ebml_read_skip(matroska);
-                break;
-        }
-
-        if (matroska->level_up) {
-            matroska->level_up--;
-            break;
-        }
-    }
-
-    return res;
-}
-
-static int
-matroska_parse_tracks (MatroskaDemuxContext *matroska)
-{
-    int res = 0;
-    uint32_t id;
-
-    av_log(matroska->ctx, AV_LOG_DEBUG, "parsing tracks...\n");
-
-    while (res == 0) {
-        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
-            res = AVERROR_IO;
-            break;
-        } else if (matroska->level_up) {
-            matroska->level_up--;
-            break;
-        }
-
-        switch (id) {
-            /* one track within the "all-tracks" header */
-            case MATROSKA_ID_TRACKENTRY:
-                res = matroska_add_stream(matroska);
-                break;
-
-            default:
-                av_log(matroska->ctx, AV_LOG_INFO,
-                       "Unknown entry 0x%x in track header\n", id);
-                /* fall-through */
-
-            case EBML_ID_VOID:
-                res = ebml_read_skip(matroska);
-                break;
-        }
-
-        if (matroska->level_up) {
-            matroska->level_up--;
-            break;
-        }
-    }
-
-    return res;
-}
-
-static int
-matroska_parse_index (MatroskaDemuxContext *matroska)
-{
-    int res = 0;
-    uint32_t id;
-    MatroskaDemuxIndex idx;
-
-    av_log(matroska->ctx, AV_LOG_DEBUG, "parsing index...\n");
-
-    while (res == 0) {
-        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
-            res = AVERROR_IO;
-            break;
-        } else if (matroska->level_up) {
-            matroska->level_up--;
-            break;
-        }
-
-        switch (id) {
-            /* one single index entry ('point') */
-            case MATROSKA_ID_POINTENTRY:
-                if ((res = ebml_read_master(matroska, &id)) < 0)
-                    break;
-
-                /* in the end, we hope to fill one entry with a
-                 * timestamp, a file position and a tracknum */
-                idx.pos   = (uint64_t) -1;
-                idx.time  = (uint64_t) -1;
-                idx.track = (uint16_t) -1;
-
-                while (res == 0) {
-                    if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
-                        res = AVERROR_IO;
-                        break;
-                    } else if (matroska->level_up) {
-                        matroska->level_up--;
-                        break;
-                    }
-
-                    switch (id) {
-                        /* one single index entry ('point') */
-                        case MATROSKA_ID_CUETIME: {
-                            uint64_t time;
-                            if ((res = ebml_read_uint(matroska, &id,
-                                                      &time)) < 0)
-                                break;
-                            idx.time = time * matroska->time_scale;
-                            break;
-                        }
-
-                        /* position in the file + track to which it
-                         * belongs */
-                        case MATROSKA_ID_CUETRACKPOSITION:
-                            if ((res = ebml_read_master(matroska, &id)) < 0)
-                                break;
-
-                            while (res == 0) {
-                                if (!(id = ebml_peek_id (matroska,
-                                                    &matroska->level_up))) {
-                                    res = AVERROR_IO;
-                                    break;
-                                } else if (matroska->level_up) {
-                                    matroska->level_up--;
-                                    break;
-                                }
-
-                                switch (id) {
-                                    /* track number */
-                                    case MATROSKA_ID_CUETRACK: {
-                                        uint64_t num;
-                                        if ((res = ebml_read_uint(matroska,
-                                                          &id, &num)) < 0)
-                                            break;
-                                        idx.track = num;
-                                        break;
-                                    }
-
-                                        /* position in file */
-                                    case MATROSKA_ID_CUECLUSTERPOSITION: {
-                                        uint64_t num;
-                                        if ((res = ebml_read_uint(matroska,
-                                                          &id, &num)) < 0)
-                                            break;
-                                        idx.pos = num+matroska->segment_start;
-                                        break;
-                                    }
-
-                                    default:
-                                        av_log(matroska->ctx, AV_LOG_INFO,
-                                               "Unknown entry 0x%x in "
-                                               "CuesTrackPositions\n", id);
-                                        /* fall-through */
-
-                                    case EBML_ID_VOID:
-                                        res = ebml_read_skip(matroska);
-                                        break;
-                                }
-
-                                if (matroska->level_up) {
-                                    matroska->level_up--;
-                                    break;
-                                }
-                            }
-
-                            break;
-
-                        default:
-                            av_log(matroska->ctx, AV_LOG_INFO,
-                                   "Unknown entry 0x%x in cuespoint "
-                                   "index\n", id);
-                            /* fall-through */
-
-                        case EBML_ID_VOID:
-                            res = ebml_read_skip(matroska);
-                            break;
-                    }
-
-                    if (matroska->level_up) {
-                        matroska->level_up--;
-                        break;
-                    }
-                }
-
-                /* so let's see if we got what we wanted */
-                if (idx.pos   != (uint64_t) -1 &&
-                    idx.time  != (uint64_t) -1 &&
-                    idx.track != (uint16_t) -1) {
-                    if (matroska->num_indexes % 32 == 0) {
-                        /* re-allocate bigger index */
-                        matroska->index =
-                            av_realloc(matroska->index,
-                                       (matroska->num_indexes + 32) *
-                                       sizeof(MatroskaDemuxIndex));
-                    }
-                    matroska->index[matroska->num_indexes] = idx;
-                    matroska->num_indexes++;
-                }
-                break;
-
-            default:
-                av_log(matroska->ctx, AV_LOG_INFO,
-                       "Unknown entry 0x%x in cues header\n", id);
-                /* fall-through */
-
-            case EBML_ID_VOID:
-                res = ebml_read_skip(matroska);
-                break;
-        }
-
-        if (matroska->level_up) {
-            matroska->level_up--;
-            break;
-        }
-    }
-
-    return res;
-}
-
-static int
-matroska_parse_metadata (MatroskaDemuxContext *matroska)
-{
-    int res = 0;
-    uint32_t id;
-
-    while (res == 0) {
-        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
-            res = AVERROR_IO;
-            break;
-        } else if (matroska->level_up) {
-            matroska->level_up--;
-            break;
-        }
-
-        switch (id) {
-            /* Hm, this is unsupported... */
-            default:
-                av_log(matroska->ctx, AV_LOG_INFO,
-                       "Unknown entry 0x%x in metadata header\n", id);
-                /* fall-through */
-
-            case EBML_ID_VOID:
-                res = ebml_read_skip(matroska);
-                break;
-        }
-
-        if (matroska->level_up) {
-            matroska->level_up--;
-            break;
-        }
-    }
-
-    return res;
-}
-
-static int
-matroska_parse_seekhead (MatroskaDemuxContext *matroska)
-{
-    int res = 0;
-    uint32_t id;
-
-    av_log(matroska->ctx, AV_LOG_DEBUG, "parsing seekhead...\n");
-
-    while (res == 0) {
-        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
-            res = AVERROR_IO;
-            break;
-        } else if (matroska->level_up) {
-            matroska->level_up--;
-            break;
-        }
-
-        switch (id) {
-            case MATROSKA_ID_SEEKENTRY: {
-                uint32_t seek_id = 0, peek_id_cache = 0;
-                uint64_t seek_pos = (uint64_t) -1, t;
-
-                if ((res = ebml_read_master(matroska, &id)) < 0)
-                    break;
-
-                while (res == 0) {
-                    if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
-                        res = AVERROR_IO;
-                        break;
-                    } else if (matroska->level_up) {
-                        matroska->level_up--;
-                        break;
-                    }
-
-                    switch (id) {
-                        case MATROSKA_ID_SEEKID:
-                            res = ebml_read_uint(matroska, &id, &t);
-                            seek_id = t;
-                            break;
-
-                        case MATROSKA_ID_SEEKPOSITION:
-                            res = ebml_read_uint(matroska, &id, &seek_pos);
-                            break;
-
-                        default:
-                            av_log(matroska->ctx, AV_LOG_INFO,
-                                   "Unknown seekhead ID 0x%x\n", id);
-                            /* fall-through */
-
-                        case EBML_ID_VOID:
-                            res = ebml_read_skip(matroska);
-                            break;
-                    }
-
-                    if (matroska->level_up) {
-                        matroska->level_up--;
-                        break;
-                    }
-                }
-
-                if (!seek_id || seek_pos == (uint64_t) -1) {
-                    av_log(matroska->ctx, AV_LOG_INFO,
-                           "Incomplete seekhead entry (0x%x/%"PRIu64")\n",
-                           seek_id, seek_pos);
-                    break;
-                }
-
-                switch (seek_id) {
-                    case MATROSKA_ID_CUES:
-                    case MATROSKA_ID_TAGS: {
-                        uint32_t level_up = matroska->level_up;
-                        offset_t before_pos;
-                        uint64_t length;
-                        MatroskaLevel level;
-
-                        /* remember the peeked ID and the current position */
-                        peek_id_cache = matroska->peek_id;
-                        before_pos = url_ftell(&matroska->ctx->pb);
-
-                        /* seek */
-                        if ((res = ebml_read_seek(matroska, seek_pos +
-                                               matroska->segment_start)) < 0)
-                            return res;
-
-                        /* we don't want to lose our seekhead level, so we add
-                         * a dummy. This is a crude hack. */
-                        if (matroska->num_levels == EBML_MAX_DEPTH) {
-                            av_log(matroska->ctx, AV_LOG_INFO,
-                                   "Max EBML element depth (%d) reached, "
-                                   "cannot parse further.\n", EBML_MAX_DEPTH);
-                            return AVERROR_UNKNOWN;
-                        }
-
-                        level.start = 0;
-                        level.length = (uint64_t)-1;
-                        matroska->levels[matroska->num_levels] = level;
-                        matroska->num_levels++;
-
-                        /* check ID */
-                        if (!(id = ebml_peek_id (matroska,
-                                                 &matroska->level_up)))
-                            goto finish;
-                        if (id != seek_id) {
-                            av_log(matroska->ctx, AV_LOG_INFO,
-                                   "We looked for ID=0x%x but got "
-                                   "ID=0x%x (pos=%"PRIu64")",
-                                   seek_id, id, seek_pos +
-                                   matroska->segment_start);
-                            goto finish;
-                        }
-
-                        /* read master + parse */
-                        if ((res = ebml_read_master(matroska, &id)) < 0)
-                            goto finish;
-                        switch (id) {
-                            case MATROSKA_ID_CUES:
-                                if (!(res = matroska_parse_index(matroska)) ||
-                                    url_feof(&matroska->ctx->pb)) {
-                                    matroska->index_parsed = 1;
-                                    res = 0;
-                                }
-                                break;
-                            case MATROSKA_ID_TAGS:
-                                if (!(res = matroska_parse_metadata(matroska)) ||
-                                   url_feof(&matroska->ctx->pb)) {
-                                    matroska->metadata_parsed = 1;
-                                    res = 0;
-                                }
-                                break;
-                        }
-
-                    finish:
-                        /* remove dummy level */
-                        while (matroska->num_levels) {
-                            matroska->num_levels--;
-                            length =
-                                matroska->levels[matroska->num_levels].length;
-                            if (length == (uint64_t)-1)
-                                break;
-                        }
-
-                        /* seek back */
-                        if ((res = ebml_read_seek(matroska, before_pos)) < 0)
-                            return res;
-                        matroska->peek_id = peek_id_cache;
-                        matroska->level_up = level_up;
-                        break;
-                    }
-
-                    default:
-                        av_log(matroska->ctx, AV_LOG_INFO,
-                               "Ignoring seekhead entry for ID=0x%x\n",
-                               seek_id);
-                        break;
-                }
-
-                break;
-            }
-
-            default:
-                av_log(matroska->ctx, AV_LOG_INFO,
-                       "Unknown seekhead ID 0x%x\n", id);
-                /* fall-through */
-
-            case EBML_ID_VOID:
-                res = ebml_read_skip(matroska);
-                break;
-        }
-
-        if (matroska->level_up) {
-            matroska->level_up--;
-            break;
-        }
-    }
-
-    return res;
-}
-
-#define ARRAY_SIZE(x)  (sizeof(x)/sizeof(*x))
-
-static int
-matroska_aac_profile (char *codec_id)
-{
-    static const char *aac_profiles[] = {
-        "MAIN", "LC", "SSR"
-    };
-    int profile;
-
-    for (profile=0; profile<ARRAY_SIZE(aac_profiles); profile++)
-        if (strstr(codec_id, aac_profiles[profile]))
-            break;
-    return profile + 1;
-}
-
-static int
-matroska_aac_sri (int samplerate)
-{
-    static const int aac_sample_rates[] = {
-        96000, 88200, 64000, 48000, 44100, 32000,
-        24000, 22050, 16000, 12000, 11025,  8000,
-    };
-    int sri;
-
-    for (sri=0; sri<ARRAY_SIZE(aac_sample_rates); sri++)
-        if (aac_sample_rates[sri] == samplerate)
-            break;
-    return sri;
-}
-
-static int
-matroska_read_header (AVFormatContext    *s,
-                      AVFormatParameters *ap)
-{
-    MatroskaDemuxContext *matroska = s->priv_data;
-    char *doctype;
-    int version, last_level, res = 0;
-    uint32_t id;
-
-    matroska->ctx = s;
-
-    /* First read the EBML header. */
-    doctype = NULL;
-    if ((res = ebml_read_header(matroska, &doctype, &version)) < 0)
-        return res;
-    if ((doctype == NULL) || strcmp(doctype, "matroska")) {
-        av_log(matroska->ctx, AV_LOG_ERROR,
-               "Wrong EBML doctype ('%s' != 'matroska').\n",
-               doctype ? doctype : "(none)");
-        if (doctype)
-            av_free(doctype);
-        return AVERROR_NOFMT;
-    }
-    av_free(doctype);
-    if (version > 2) {
-        av_log(matroska->ctx, AV_LOG_ERROR,
-               "Matroska demuxer version 2 too old for file version %d\n",
-               version);
-        return AVERROR_NOFMT;
-    }
-
-    /* The next thing is a segment. */
-    while (1) {
-        if (!(id = ebml_peek_id(matroska, &last_level)))
-            return AVERROR_IO;
-        if (id == MATROSKA_ID_SEGMENT)
-            break;
-
-        /* oi! */
-        av_log(matroska->ctx, AV_LOG_INFO,
-               "Expected a Segment ID (0x%x), but received 0x%x!\n",
-               MATROSKA_ID_SEGMENT, id);
-        if ((res = ebml_read_skip(matroska)) < 0)
-            return res;
-    }
-
-    /* We now have a Matroska segment.
-     * Seeks are from the beginning of the segment,
-     * after the segment ID/length. */
-    if ((res = ebml_read_master(matroska, &id)) < 0)
-        return res;
-    matroska->segment_start = url_ftell(&s->pb);
-
-    matroska->time_scale = 1000000;
-    /* we've found our segment, start reading the different contents in here */
-    while (res == 0) {
-        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
-            res = AVERROR_IO;
-            break;
-        } else if (matroska->level_up) {
-            matroska->level_up--;
-            break;
-        }
-
-        switch (id) {
-            /* stream info */
-            case MATROSKA_ID_INFO: {
-                if ((res = ebml_read_master(matroska, &id)) < 0)
-                    break;
-                res = matroska_parse_info(matroska);
-                break;
-            }
-
-            /* track info headers */
-            case MATROSKA_ID_TRACKS: {
-                if ((res = ebml_read_master(matroska, &id)) < 0)
-                    break;
-                res = matroska_parse_tracks(matroska);
-                break;
-            }
-
-            /* stream index */
-            case MATROSKA_ID_CUES: {
-                if (!matroska->index_parsed) {
-                    if ((res = ebml_read_master(matroska, &id)) < 0)
-                        break;
-                    res = matroska_parse_index(matroska);
-                } else
-                    res = ebml_read_skip(matroska);
-                break;
-            }
-
-            /* metadata */
-            case MATROSKA_ID_TAGS: {
-                if (!matroska->metadata_parsed) {
-                    if ((res = ebml_read_master(matroska, &id)) < 0)
-                        break;
-                    res = matroska_parse_metadata(matroska);
-                } else
-                    res = ebml_read_skip(matroska);
-                break;
-            }
-
-            /* file index (if seekable, seek to Cues/Tags to parse it) */
-            case MATROSKA_ID_SEEKHEAD: {
-                if ((res = ebml_read_master(matroska, &id)) < 0)
-                    break;
-                res = matroska_parse_seekhead(matroska);
-                break;
-            }
-
-            case MATROSKA_ID_CLUSTER: {
-                /* Do not read the master - this will be done in the next
-                 * call to matroska_read_packet. */
-                res = 1;
-                break;
-            }
-
-            default:
-                av_log(matroska->ctx, AV_LOG_INFO,
-                       "Unknown matroska file header ID 0x%x\n", id);
-            /* fall-through */
-
-            case EBML_ID_VOID:
-                res = ebml_read_skip(matroska);
-                break;
-        }
-
-        if (matroska->level_up) {
-            matroska->level_up--;
-            break;
-        }
-    }
-
-    /* Have we found a cluster? */
-    if (ebml_peek_id(matroska, NULL) == MATROSKA_ID_CLUSTER) {
-        int i, j;
-        MatroskaTrack *track;
-        AVStream *st;
-
-        for (i = 0; i < matroska->num_tracks; i++) {
-            enum CodecID codec_id = CODEC_ID_NONE;
-            uint8_t *extradata = NULL;
-            int extradata_size = 0;
-            int extradata_offset = 0;
-            track = matroska->tracks[i];
-
-            /* libavformat does not really support subtitles.
-             * Also apply some sanity checks. */
-            if ((track->type == MATROSKA_TRACK_TYPE_SUBTITLE) ||
-                (track->codec_id == NULL))
-                continue;
-
-            for(j=0; codec_tags[j].str; j++){
-                if(!strncmp(codec_tags[j].str, track->codec_id,
-                            strlen(codec_tags[j].str))){
-                    codec_id= codec_tags[j].id;
-                    break;
-                }
-            }
-
-            /* Set the FourCC from the CodecID. */
-            /* This is the MS compatibility mode which stores a
-             * BITMAPINFOHEADER in the CodecPrivate. */
-            if (!strcmp(track->codec_id,
-                        MATROSKA_CODEC_ID_VIDEO_VFW_FOURCC) &&
-                (track->codec_priv_size >= 40) &&
-                (track->codec_priv != NULL)) {
-                unsigned char *p;
-
-                /* Offset of biCompression. Stored in LE. */
-                p = (unsigned char *)track->codec_priv + 16;
-                ((MatroskaVideoTrack *)track)->fourcc = (p[3] << 24) |
-                                 (p[2] << 16) | (p[1] << 8) | p[0];
-                codec_id = codec_get_id(codec_bmp_tags, ((MatroskaVideoTrack *)track)->fourcc);
-
-            }
-
-            /* This is the MS compatibility mode which stores a
-             * WAVEFORMATEX in the CodecPrivate. */
-            else if (!strcmp(track->codec_id,
-                             MATROSKA_CODEC_ID_AUDIO_ACM) &&
-                (track->codec_priv_size >= 18) &&
-                (track->codec_priv != NULL)) {
-                unsigned char *p;
-                uint16_t tag;
-
-                /* Offset of wFormatTag. Stored in LE. */
-                p = (unsigned char *)track->codec_priv;
-                tag = (p[1] << 8) | p[0];
-                codec_id = codec_get_id(codec_wav_tags, tag);
-
-            }
-
-            else if (codec_id == CODEC_ID_AAC && !track->codec_priv_size) {
-                MatroskaAudioTrack *audiotrack = (MatroskaAudioTrack *) track;
-                int profile = matroska_aac_profile(track->codec_id);
-                int sri = matroska_aac_sri(audiotrack->internal_samplerate);
-                extradata = av_malloc(5);
-                if (extradata == NULL)
-                    return AVERROR_NOMEM;
-                extradata[0] = (profile << 3) | ((sri&0x0E) >> 1);
-                extradata[1] = ((sri&0x01) << 7) | (audiotrack->channels<<3);
-                if (strstr(track->codec_id, "SBR")) {
-                    sri = matroska_aac_sri(audiotrack->samplerate);
-                    extradata[2] = 0x56;
-                    extradata[3] = 0xE5;
-                    extradata[4] = 0x80 | (sri<<3);
-                    extradata_size = 5;
-                } else {
-                    extradata_size = 2;
-                }
-                track->default_duration = 1024*1000 / audiotrack->internal_samplerate;
-            }
-
-            else if (codec_id == CODEC_ID_TTA) {
-                MatroskaAudioTrack *audiotrack = (MatroskaAudioTrack *) track;
-                ByteIOContext b;
-                extradata_size = 30;
-                extradata = av_mallocz(extradata_size);
-                if (extradata == NULL)
-                    return AVERROR_NOMEM;
-                init_put_byte(&b, extradata, extradata_size, 1,
-                              NULL, NULL, NULL, NULL);
-                put_buffer(&b, (uint8_t *) "TTA1", 4);
-                put_le16(&b, 1);
-                put_le16(&b, audiotrack->channels);
-                put_le16(&b, audiotrack->bitdepth);
-                put_le32(&b, audiotrack->samplerate);
-                put_le32(&b, matroska->ctx->duration * audiotrack->samplerate);
-            }
-
-            else if (codec_id == CODEC_ID_RV10 || codec_id == CODEC_ID_RV20 ||
-                     codec_id == CODEC_ID_RV30 || codec_id == CODEC_ID_RV40) {
-                extradata_offset = 26;
-                track->codec_priv_size -= extradata_offset;
-                track->flags |= MATROSKA_TRACK_REAL_V;
-            }
-
-            if (codec_id == CODEC_ID_NONE) {
-                av_log(matroska->ctx, AV_LOG_INFO,
-                       "Unknown/unsupported CodecID %s.\n",
-                       track->codec_id);
-            }
-
-            track->stream_index = matroska->num_streams;
-
-            matroska->num_streams++;
-            st = av_new_stream(s, track->stream_index);
-            if (st == NULL)
-                return AVERROR_NOMEM;
-            av_set_pts_info(st, 64, matroska->time_scale, 1000*1000*1000); /* 64 bit pts in ns */
-
-            st->codec->codec_id = codec_id;
-            st->start_time = 0;
-
-            if (track->default_duration)
-                av_reduce(&st->codec->time_base.num, &st->codec->time_base.den,
-                          track->default_duration, 1000, 30000);
-
-            if(extradata){
-                st->codec->extradata = extradata;
-                st->codec->extradata_size = extradata_size;
-            } else if(track->codec_priv && track->codec_priv_size > 0){
-                st->codec->extradata = av_malloc(track->codec_priv_size);
-                if(st->codec->extradata == NULL)
-                    return AVERROR_NOMEM;
-                st->codec->extradata_size = track->codec_priv_size;
-                memcpy(st->codec->extradata,track->codec_priv+extradata_offset,
-                       track->codec_priv_size);
-            }
-
-            if (track->type == MATROSKA_TRACK_TYPE_VIDEO) {
-                MatroskaVideoTrack *videotrack = (MatroskaVideoTrack *)track;
-
-                st->codec->codec_type = CODEC_TYPE_VIDEO;
-                st->codec->codec_tag = videotrack->fourcc;
-                st->codec->width = videotrack->pixel_width;
-                st->codec->height = videotrack->pixel_height;
-                if (videotrack->display_width == 0)
-                    videotrack->display_width= videotrack->pixel_width;
-                if (videotrack->display_height == 0)
-                    videotrack->display_height= videotrack->pixel_height;
-                av_reduce(&st->codec->sample_aspect_ratio.num,
-                          &st->codec->sample_aspect_ratio.den,
-                          st->codec->height * videotrack->display_width,
-                          st->codec-> width * videotrack->display_height,
-                          255);
-                st->need_parsing = AVSTREAM_PARSE_HEADERS;
-            } else if (track->type == MATROSKA_TRACK_TYPE_AUDIO) {
-                MatroskaAudioTrack *audiotrack = (MatroskaAudioTrack *)track;
-
-                st->codec->codec_type = CODEC_TYPE_AUDIO;
-                st->codec->sample_rate = audiotrack->samplerate;
-                st->codec->channels = audiotrack->channels;
-            } else if (track->type == MATROSKA_TRACK_TYPE_SUBTITLE) {
-                st->codec->codec_type = CODEC_TYPE_SUBTITLE;
-            }
-
-            /* What do we do with private data? E.g. for Vorbis. */
-        }
-        res = 0;
-    }
-
-    if (matroska->index_parsed) {
-        int i, track, stream;
-        for (i=0; i<matroska->num_indexes; i++) {
-            MatroskaDemuxIndex *idx = &matroska->index[i];
-            track = matroska_find_track_by_num(matroska, idx->track);
-            stream = matroska->tracks[track]->stream_index;
-            av_add_index_entry(matroska->ctx->streams[stream],
-                               idx->pos, idx->time/matroska->time_scale,
-                               0, 0, AVINDEX_KEYFRAME);
-        }
-    }
-
-    return res;
-}
-
-static inline int
-rv_offset(uint8_t *data, int slice, int slices)
-{
-    return AV_RL32(data+8*slice+4) + 8*slices;
-}
-
-static int
-matroska_parse_block(MatroskaDemuxContext *matroska, uint8_t *data, int size,
-                     int64_t pos, uint64_t cluster_time, uint64_t duration,
-                     int is_keyframe, int is_bframe)
-{
-    int res = 0;
-    int track;
-    AVStream *st;
-    AVPacket *pkt;
-    uint8_t *origdata = data;
-    int16_t block_time;
-    uint32_t *lace_size = NULL;
-    int n, flags, laces = 0;
-    uint64_t num;
-
-    /* first byte(s): tracknum */
-    if ((n = matroska_ebmlnum_uint(data, size, &num)) < 0) {
-        av_log(matroska->ctx, AV_LOG_ERROR, "EBML block data error\n");
-        av_free(origdata);
-        return res;
-    }
-    data += n;
-    size -= n;
-
-    /* fetch track from num */
-    track = matroska_find_track_by_num(matroska, num);
-    if (size <= 3 || track < 0 || track >= matroska->num_tracks) {
-        av_log(matroska->ctx, AV_LOG_INFO,
-               "Invalid stream %d or size %u\n", track, size);
-        av_free(origdata);
-        return res;
-    }
-    st = matroska->ctx->streams[matroska->tracks[track]->stream_index];
-    if (st->discard >= AVDISCARD_ALL) {
-        av_free(origdata);
-        return res;
-    }
-    if (duration == AV_NOPTS_VALUE)
-        duration = matroska->tracks[track]->default_duration;
-
-    /* block_time (relative to cluster time) */
-    block_time = (data[0] << 8) | data[1];
-    data += 2;
-    size -= 2;
-    flags = *data;
-    data += 1;
-    size -= 1;
-    if (is_keyframe == -1)
-        is_keyframe = flags & 1 ? PKT_FLAG_KEY : 0;
-
-    if (matroska->skip_to_keyframe) {
-        if (!is_keyframe || st != matroska->skip_to_stream)
-            return res;
-        matroska->skip_to_keyframe = 0;
-    }
-
-    switch ((flags & 0x06) >> 1) {
-        case 0x0: /* no lacing */
-            laces = 1;
-            lace_size = av_mallocz(sizeof(int));
-            lace_size[0] = size;
-            break;
-
-        case 0x1: /* xiph lacing */
-        case 0x2: /* fixed-size lacing */
-        case 0x3: /* EBML lacing */
-            if (size == 0) {
-                res = -1;
-                break;
-            }
-            laces = (*data) + 1;
-            data += 1;
-            size -= 1;
-            lace_size = av_mallocz(laces * sizeof(int));
-
-            switch ((flags & 0x06) >> 1) {
-                case 0x1: /* xiph lacing */ {
-                    uint8_t temp;
-                    uint32_t total = 0;
-                    for (n = 0; res == 0 && n < laces - 1; n++) {
-                        while (1) {
-                            if (size == 0) {
-                                res = -1;
-                                break;
-                            }
-                            temp = *data;
-                            lace_size[n] += temp;
-                            data += 1;
-                            size -= 1;
-                            if (temp != 0xff)
-                                break;
-                        }
-                        total += lace_size[n];
-                    }
-                    lace_size[n] = size - total;
-                    break;
-                }
-
-                case 0x2: /* fixed-size lacing */
-                    for (n = 0; n < laces; n++)
-                        lace_size[n] = size / laces;
-                    break;
-
-                case 0x3: /* EBML lacing */ {
-                    uint32_t total;
-                    n = matroska_ebmlnum_uint(data, size, &num);
-                    if (n < 0) {
-                        av_log(matroska->ctx, AV_LOG_INFO,
-                               "EBML block data error\n");
-                        break;
-                    }
-                    data += n;
-                    size -= n;
-                    total = lace_size[0] = num;
-                    for (n = 1; res == 0 && n < laces - 1; n++) {
-                        int64_t snum;
-                        int r;
-                        r = matroska_ebmlnum_sint (data, size, &snum);
-                        if (r < 0) {
-                            av_log(matroska->ctx, AV_LOG_INFO,
-                                   "EBML block data error\n");
-                            break;
-                        }
-                        data += r;
-                        size -= r;
-                        lace_size[n] = lace_size[n - 1] + snum;
-                        total += lace_size[n];
-                    }
-                    lace_size[n] = size - total;
-                    break;
-                }
-            }
-            break;
-    }
-
-    if (res == 0) {
-        int real_v = matroska->tracks[track]->flags & MATROSKA_TRACK_REAL_V;
-        uint64_t timecode = AV_NOPTS_VALUE;
-
-        if (cluster_time != (uint64_t)-1 && cluster_time + block_time >= 0)
-            timecode = cluster_time + block_time;
-
-        for (n = 0; n < laces; n++) {
-            int slice, slices = 1;
-
-            if (real_v) {
-                slices = *data++ + 1;
-                lace_size[n]--;
-            }
-
-            for (slice=0; slice<slices; slice++) {
-                int slice_size, slice_offset = 0;
-                if (real_v)
-                    slice_offset = rv_offset(data, slice, slices);
-                if (slice+1 == slices)
-                    slice_size = lace_size[n] - slice_offset;
-                else
-                    slice_size = rv_offset(data, slice+1, slices) - slice_offset;
-                pkt = av_mallocz(sizeof(AVPacket));
-                /* XXX: prevent data copy... */
-                if (av_new_packet(pkt, slice_size) < 0) {
-                    res = AVERROR_NOMEM;
-                    n = laces-1;
-                    break;
-                }
-                memcpy (pkt->data, data+slice_offset, slice_size);
-
-                if (n == 0)
-                    pkt->flags = is_keyframe;
-                pkt->stream_index = matroska->tracks[track]->stream_index;
-
-                pkt->pts = timecode;
-                pkt->pos = pos;
-                pkt->duration = duration;
-
-                matroska_queue_packet(matroska, pkt);
-
-                if (timecode != AV_NOPTS_VALUE)
-                    timecode = duration ? timecode + duration : AV_NOPTS_VALUE;
-            }
-            data += lace_size[n];
-        }
-    }
-
-    av_free(lace_size);
-    av_free(origdata);
-    return res;
-}
-
-static int
-matroska_parse_blockgroup (MatroskaDemuxContext *matroska,
-                           uint64_t              cluster_time)
-{
-    int res = 0;
-    uint32_t id;
-    int is_bframe = 0;
-    int is_keyframe = PKT_FLAG_KEY, last_num_packets = matroska->num_packets;
-    uint64_t duration = AV_NOPTS_VALUE;
-    uint8_t *data;
-    int size = 0;
-    int64_t pos = 0;
-
-    av_log(matroska->ctx, AV_LOG_DEBUG, "parsing blockgroup...\n");
-
-    while (res == 0) {
-        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
-            res = AVERROR_IO;
-            break;
-        } else if (matroska->level_up) {
-            matroska->level_up--;
-            break;
-        }
-
-        switch (id) {
-            /* one block inside the group. Note, block parsing is one
-             * of the harder things, so this code is a bit complicated.
-             * See http://www.matroska.org/ for documentation. */
-            case MATROSKA_ID_BLOCK: {
-                pos = url_ftell(&matroska->ctx->pb);
-                res = ebml_read_binary(matroska, &id, &data, &size);
-                break;
-            }
-
-            case MATROSKA_ID_BLOCKDURATION: {
-                if ((res = ebml_read_uint(matroska, &id, &duration)) < 0)
-                    break;
-                duration /= matroska->time_scale;
-                break;
-            }
-
-            case MATROSKA_ID_BLOCKREFERENCE: {
-                int64_t num;
-                /* We've found a reference, so not even the first frame in
-                 * the lace is a key frame. */
-                is_keyframe = 0;
-                if (last_num_packets != matroska->num_packets)
-                    matroska->packets[last_num_packets]->flags = 0;
-                if ((res = ebml_read_sint(matroska, &id, &num)) < 0)
-                    break;
-                if (num > 0)
-                    is_bframe = 1;
-                break;
-            }
-
-            default:
-                av_log(matroska->ctx, AV_LOG_INFO,
-                       "Unknown entry 0x%x in blockgroup data\n", id);
-                /* fall-through */
-
-            case EBML_ID_VOID:
-                res = ebml_read_skip(matroska);
-                break;
-        }
-
-        if (matroska->level_up) {
-            matroska->level_up--;
-            break;
-        }
-    }
-
-    if (res)
-        return res;
-
-    if (size > 0)
-        res = matroska_parse_block(matroska, data, size, pos, cluster_time,
-                                   duration, is_keyframe, is_bframe);
-
-    return res;
-}
-
-static int
-matroska_parse_cluster (MatroskaDemuxContext *matroska)
-{
-    int res = 0;
-    uint32_t id;
-    uint64_t cluster_time = 0;
-    uint8_t *data;
-    int64_t pos;
-    int size;
-
-    av_log(matroska->ctx, AV_LOG_DEBUG,
-           "parsing cluster at %"PRId64"\n", url_ftell(&matroska->ctx->pb));
-
-    while (res == 0) {
-        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
-            res = AVERROR_IO;
-            break;
-        } else if (matroska->level_up) {
-            matroska->level_up--;
-            break;
-        }
-
-        switch (id) {
-            /* cluster timecode */
-            case MATROSKA_ID_CLUSTERTIMECODE: {
-                uint64_t num;
-                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
-                    break;
-                cluster_time = num;
-                break;
-            }
-
-                /* a group of blocks inside a cluster */
-            case MATROSKA_ID_BLOCKGROUP:
-                if ((res = ebml_read_master(matroska, &id)) < 0)
-                    break;
-                res = matroska_parse_blockgroup(matroska, cluster_time);
-                break;
-
-            case MATROSKA_ID_SIMPLEBLOCK:
-                pos = url_ftell(&matroska->ctx->pb);
-                res = ebml_read_binary(matroska, &id, &data, &size);
-                if (res == 0)
-                    res = matroska_parse_block(matroska, data, size, pos,
-                                               cluster_time, AV_NOPTS_VALUE,
-                                               -1, 0);
-                break;
-
-            default:
-                av_log(matroska->ctx, AV_LOG_INFO,
-                       "Unknown entry 0x%x in cluster data\n", id);
-                /* fall-through */
-
-            case EBML_ID_VOID:
-                res = ebml_read_skip(matroska);
-                break;
-        }
-
-        if (matroska->level_up) {
-            matroska->level_up--;
-            break;
-        }
-    }
-
-    return res;
-}
-
-static int
-matroska_read_packet (AVFormatContext *s,
-                      AVPacket        *pkt)
-{
-    MatroskaDemuxContext *matroska = s->priv_data;
-    int res = 0;
-    uint32_t id;
-
-    /* Read stream until we have a packet queued. */
-    while (matroska_deliver_packet(matroska, pkt)) {
-
-        /* Have we already reached the end? */
-        if (matroska->done)
-            return AVERROR_IO;
-
-        while (res == 0) {
-            if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
-                return AVERROR_IO;
-            } else if (matroska->level_up) {
-                matroska->level_up--;
-                break;
-            }
-
-            switch (id) {
-                case MATROSKA_ID_CLUSTER:
-                    if ((res = ebml_read_master(matroska, &id)) < 0)
-                        break;
-                    if ((res = matroska_parse_cluster(matroska)) == 0)
-                        res = 1; /* Parsed one cluster, let's get out. */
-                    break;
-
-                default:
-                case EBML_ID_VOID:
-                    res = ebml_read_skip(matroska);
-                    break;
-            }
-
-            if (matroska->level_up) {
-                matroska->level_up--;
-                break;
-            }
-        }
-
-        if (res == -1)
-            matroska->done = 1;
-    }
-
-    return 0;
-}
-
-static int
-matroska_read_seek (AVFormatContext *s, int stream_index, int64_t timestamp,
-                    int flags)
-{
-    MatroskaDemuxContext *matroska = s->priv_data;
-    AVStream *st = s->streams[stream_index];
-    int index;
-
-    /* find index entry */
-    index = av_index_search_timestamp(st, timestamp, flags);
-    if (index < 0)
-        return 0;
-
-    /* do the seek */
-    url_fseek(&s->pb, st->index_entries[index].pos, SEEK_SET);
-    matroska->skip_to_keyframe = !(flags & AVSEEK_FLAG_ANY);
-    matroska->skip_to_stream = st;
-    matroska->num_packets = 0;
-    matroska->peek_id = 0;
-    return 0;
-}
-
-static int
-matroska_read_close (AVFormatContext *s)
-{
-    MatroskaDemuxContext *matroska = s->priv_data;
-    int n = 0;
-
-    av_free(matroska->writing_app);
-    av_free(matroska->muxing_app);
-    av_free(matroska->index);
-
-    if (matroska->packets != NULL) {
-        for (n = 0; n < matroska->num_packets; n++) {
-            av_free_packet(matroska->packets[n]);
-            av_free(matroska->packets[n]);
-        }
-        av_free(matroska->packets);
-    }
-
-    for (n = 0; n < matroska->num_tracks; n++) {
-        MatroskaTrack *track = matroska->tracks[n];
-        av_free(track->codec_id);
-        av_free(track->codec_name);
-        av_free(track->codec_priv);
-        av_free(track->name);
-        av_free(track->language);
-
-        av_free(track);
-    }
-
-    return 0;
-}
-
-AVInputFormat matroska_demuxer = {
-    "matroska",
-    "Matroska file format",
-    sizeof(MatroskaDemuxContext),
-    matroska_probe,
-    matroska_read_header,
-    matroska_read_packet,
-    matroska_read_close,
-    matroska_read_seek,
-};
diff --git a/libavformat/matroska.h b/libavformat/matroska.h
new file mode 100644
index 0000000000..98b2165fda
--- /dev/null
+++ b/libavformat/matroska.h
@@ -0,0 +1,196 @@
+/*
+ * Matroska constants
+ * Copyright (c) 2003-2004 The ffmpeg Project
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef MATROSKA_H
+#define MATROSKA_H
+
+#include "avcodec.h"
+
+/* EBML version supported */
+#define EBML_VERSION 1
+
+/* top-level master-IDs */
+#define EBML_ID_HEADER             0x1A45DFA3
+
+/* IDs in the HEADER master */
+#define EBML_ID_EBMLVERSION        0x4286
+#define EBML_ID_EBMLREADVERSION    0x42F7
+#define EBML_ID_EBMLMAXIDLENGTH    0x42F2
+#define EBML_ID_EBMLMAXSIZELENGTH  0x42F3
+#define EBML_ID_DOCTYPE            0x4282
+#define EBML_ID_DOCTYPEVERSION     0x4287
+#define EBML_ID_DOCTYPEREADVERSION 0x4285
+
+/* general EBML types */
+#define EBML_ID_VOID               0xEC
+
+/*
+ * Matroska element IDs. max. 32-bit.
+ */
+
+/* toplevel segment */
+#define MATROSKA_ID_SEGMENT    0x18538067
+
+/* matroska top-level master IDs */
+#define MATROSKA_ID_INFO       0x1549A966
+#define MATROSKA_ID_TRACKS     0x1654AE6B
+#define MATROSKA_ID_CUES       0x1C53BB6B
+#define MATROSKA_ID_TAGS       0x1254C367
+#define MATROSKA_ID_SEEKHEAD   0x114D9B74
+#define MATROSKA_ID_CLUSTER    0x1F43B675
+
+/* IDs in the info master */
+#define MATROSKA_ID_TIMECODESCALE 0x2AD7B1
+#define MATROSKA_ID_DURATION   0x4489
+#define MATROSKA_ID_TITLE      0x7BA9
+#define MATROSKA_ID_WRITINGAPP 0x5741
+#define MATROSKA_ID_MUXINGAPP  0x4D80
+#define MATROSKA_ID_DATEUTC    0x4461
+
+/* ID in the tracks master */
+#define MATROSKA_ID_TRACKENTRY 0xAE
+
+/* IDs in the trackentry master */
+#define MATROSKA_ID_TRACKNUMBER 0xD7
+#define MATROSKA_ID_TRACKUID   0x73C5
+#define MATROSKA_ID_TRACKTYPE  0x83
+#define MATROSKA_ID_TRACKAUDIO 0xE1
+#define MATROSKA_ID_TRACKVIDEO 0xE0
+#define MATROSKA_ID_CODECID    0x86
+#define MATROSKA_ID_CODECPRIVATE 0x63A2
+#define MATROSKA_ID_CODECNAME  0x258688
+#define MATROSKA_ID_CODECINFOURL 0x3B4040
+#define MATROSKA_ID_CODECDOWNLOADURL 0x26B240
+#define MATROSKA_ID_TRACKNAME  0x536E
+#define MATROSKA_ID_TRACKLANGUAGE 0x22B59C
+#define MATROSKA_ID_TRACKFLAGENABLED 0xB9
+#define MATROSKA_ID_TRACKFLAGDEFAULT 0x88
+#define MATROSKA_ID_TRACKFLAGLACING 0x9C
+#define MATROSKA_ID_TRACKMINCACHE 0x6DE7
+#define MATROSKA_ID_TRACKMAXCACHE 0x6DF8
+#define MATROSKA_ID_TRACKDEFAULTDURATION 0x23E383
+
+/* IDs in the trackvideo master */
+#define MATROSKA_ID_VIDEOFRAMERATE 0x2383E3
+#define MATROSKA_ID_VIDEODISPLAYWIDTH 0x54B0
+#define MATROSKA_ID_VIDEODISPLAYHEIGHT 0x54BA
+#define MATROSKA_ID_VIDEOPIXELWIDTH 0xB0
+#define MATROSKA_ID_VIDEOPIXELHEIGHT 0xBA
+#define MATROSKA_ID_VIDEOFLAGINTERLACED 0x9A
+#define MATROSKA_ID_VIDEOSTEREOMODE 0x53B9
+#define MATROSKA_ID_VIDEOASPECTRATIO 0x54B3
+#define MATROSKA_ID_VIDEOCOLOURSPACE 0x2EB524
+
+/* IDs in the trackaudio master */
+#define MATROSKA_ID_AUDIOSAMPLINGFREQ 0xB5
+#define MATROSKA_ID_AUDIOOUTSAMPLINGFREQ 0x78B5
+
+#define MATROSKA_ID_AUDIOBITDEPTH 0x6264
+#define MATROSKA_ID_AUDIOCHANNELS 0x9F
+
+/* ID in the cues master */
+#define MATROSKA_ID_POINTENTRY 0xBB
+
+/* IDs in the pointentry master */
+#define MATROSKA_ID_CUETIME    0xB3
+#define MATROSKA_ID_CUETRACKPOSITION 0xB7
+
+/* IDs in the cuetrackposition master */
+#define MATROSKA_ID_CUETRACK   0xF7
+#define MATROSKA_ID_CUECLUSTERPOSITION 0xF1
+
+/* IDs in the tags master */
+/* TODO */
+
+/* IDs in the seekhead master */
+#define MATROSKA_ID_SEEKENTRY  0x4DBB
+
+/* IDs in the seekpoint master */
+#define MATROSKA_ID_SEEKID     0x53AB
+#define MATROSKA_ID_SEEKPOSITION 0x53AC
+
+/* IDs in the cluster master */
+#define MATROSKA_ID_CLUSTERTIMECODE 0xE7
+#define MATROSKA_ID_BLOCKGROUP 0xA0
+#define MATROSKA_ID_SIMPLEBLOCK 0xA3
+
+/* IDs in the blockgroup master */
+#define MATROSKA_ID_BLOCK      0xA1
+#define MATROSKA_ID_BLOCKDURATION 0x9B
+#define MATROSKA_ID_BLOCKREFERENCE 0xFB
+
+typedef enum {
+  MATROSKA_TRACK_TYPE_VIDEO    = 0x1,
+  MATROSKA_TRACK_TYPE_AUDIO    = 0x2,
+  MATROSKA_TRACK_TYPE_COMPLEX  = 0x3,
+  MATROSKA_TRACK_TYPE_LOGO     = 0x10,
+  MATROSKA_TRACK_TYPE_SUBTITLE = 0x11,
+  MATROSKA_TRACK_TYPE_CONTROL  = 0x20,
+} MatroskaTrackType;
+
+typedef enum {
+  MATROSKA_EYE_MODE_MONO  = 0x0,
+  MATROSKA_EYE_MODE_RIGHT = 0x1,
+  MATROSKA_EYE_MODE_LEFT  = 0x2,
+  MATROSKA_EYE_MODE_BOTH  = 0x3,
+} MatroskaEyeMode;
+
+typedef enum {
+  MATROSKA_ASPECT_RATIO_MODE_FREE  = 0x0,
+  MATROSKA_ASPECT_RATIO_MODE_KEEP  = 0x1,
+  MATROSKA_ASPECT_RATIO_MODE_FIXED = 0x2,
+} MatroskaAspectRatioMode;
+
+/*
+ * These aren't in any way "matroska-form" things,
+ * it's just something I use in the muxer/demuxer.
+ */
+
+typedef enum {
+  MATROSKA_TRACK_ENABLED = (1<<0),
+  MATROSKA_TRACK_DEFAULT = (1<<1),
+  MATROSKA_TRACK_LACING  = (1<<2),
+  MATROSKA_TRACK_REAL_V  = (1<<4),
+  MATROSKA_TRACK_SHIFT   = (1<<16)
+} MatroskaTrackFlags;
+
+typedef enum {
+  MATROSKA_VIDEOTRACK_INTERLACED = (MATROSKA_TRACK_SHIFT<<0)
+} MatroskaVideoTrackFlags;
+
+/*
+ * Matroska Codec IDs. Strings.
+ */
+
+typedef struct CodecTags{
+    const char *str;
+    enum CodecID id;
+}CodecTags;
+
+#define MATROSKA_CODEC_ID_VIDEO_VFW_FOURCC   "V_MS/VFW/FOURCC"
+#define MATROSKA_CODEC_ID_AUDIO_ACM          "A_MS/ACM"
+
+/* max. depth in the EBML tree structure */
+#define EBML_MAX_DEPTH 16
+
+extern CodecTags ff_mkv_codec_tags[];
+
+#endif /* MATROSKA_H */
diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
new file mode 100644
index 0000000000..a74944bb38
--- /dev/null
+++ b/libavformat/matroskadec.c
@@ -0,0 +1,2642 @@
+/*
+ * Matroska file demuxer (no muxer yet)
+ * Copyright (c) 2003-2004 The ffmpeg Project
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file matroska.c
+ * Matroska file demuxer
+ * by Ronald Bultje <rbultje@ronald.bitfreak.net>
+ * with a little help from Moritz Bunkus <moritz@bunkus.org>
+ * Specs available on the matroska project page:
+ * http://www.matroska.org/.
+ */
+
+#include "avformat.h"
+/* For codec_get_id(). */
+#include "riff.h"
+#include "intfloat_readwrite.h"
+#include "matroska.h"
+
+typedef struct Track {
+    MatroskaTrackType type;
+
+    /* Unique track number and track ID. stream_index is the index that
+     * the calling app uses for this track. */
+    uint32_t num,
+        uid,
+        stream_index;
+
+    char *name,
+        *language;
+
+    char *codec_id,
+        *codec_name;
+
+    unsigned char *codec_priv;
+    int codec_priv_size;
+
+    uint64_t default_duration;
+    MatroskaTrackFlags flags;
+} MatroskaTrack;
+
+typedef struct MatroskaVideoTrack {
+    MatroskaTrack track;
+
+    int pixel_width,
+        pixel_height,
+        display_width,
+        display_height;
+
+    uint32_t fourcc;
+
+    MatroskaAspectRatioMode ar_mode;
+    MatroskaEyeMode eye_mode;
+
+    //..
+} MatroskaVideoTrack;
+
+typedef struct MatroskaAudioTrack {
+    MatroskaTrack track;
+
+    int channels,
+        bitdepth,
+        internal_samplerate,
+        samplerate;
+    //..
+} MatroskaAudioTrack;
+
+typedef struct MatroskaSubtitleTrack {
+    MatroskaTrack track;
+
+    //..
+} MatroskaSubtitleTrack;
+
+#define MAX_TRACK_SIZE (FFMAX(FFMAX(sizeof(MatroskaVideoTrack), \
+                                    sizeof(MatroskaAudioTrack)), \
+                                    sizeof(MatroskaSubtitleTrack)))
+
+typedef struct MatroskaLevel {
+    uint64_t start, length;
+} MatroskaLevel;
+
+typedef struct MatroskaDemuxIndex {
+  uint64_t        pos;   /* of the corresponding *cluster*! */
+  uint16_t        track; /* reference to 'num' */
+  uint64_t        time;  /* in nanoseconds */
+} MatroskaDemuxIndex;
+
+typedef struct MatroskaDemuxContext {
+    AVFormatContext *ctx;
+
+    /* ebml stuff */
+    int num_levels;
+    MatroskaLevel levels[EBML_MAX_DEPTH];
+    int level_up;
+
+    /* matroska stuff */
+    char *writing_app,
+        *muxing_app;
+    int64_t created;
+
+    /* timescale in the file */
+    int64_t time_scale;
+
+    /* num_streams is the number of streams that av_new_stream() was called
+     * for ( = that are available to the calling program). */
+    int num_tracks, num_streams;
+    MatroskaTrack *tracks[MAX_STREAMS];
+
+    /* cache for ID peeking */
+    uint32_t peek_id;
+
+    /* byte position of the segment inside the stream */
+    offset_t segment_start;
+
+    /* The packet queue. */
+    AVPacket **packets;
+    int num_packets;
+
+    /* have we already parse metadata/cues/clusters? */
+    int metadata_parsed,
+        index_parsed,
+        done;
+
+    /* The index for seeking. */
+    int num_indexes;
+    MatroskaDemuxIndex *index;
+
+    /* What to skip before effectively reading a packet. */
+    int skip_to_keyframe;
+    AVStream *skip_to_stream;
+} MatroskaDemuxContext;
+
+/*
+ * The first few functions handle EBML file parsing. The rest
+ * is the document interpretation. Matroska really just is a
+ * EBML file.
+ */
+
+/*
+ * Return: the amount of levels in the hierarchy that the
+ * current element lies higher than the previous one.
+ * The opposite isn't done - that's auto-done using master
+ * element reading.
+ */
+
+static int
+ebml_read_element_level_up (MatroskaDemuxContext *matroska)
+{
+    ByteIOContext *pb = &matroska->ctx->pb;
+    offset_t pos = url_ftell(pb);
+    int num = 0;
+
+    while (matroska->num_levels > 0) {
+        MatroskaLevel *level = &matroska->levels[matroska->num_levels - 1];
+
+        if (pos >= level->start + level->length) {
+            matroska->num_levels--;
+            num++;
+        } else {
+            break;
+        }
+    }
+
+    return num;
+}
+
+/*
+ * Read: an "EBML number", which is defined as a variable-length
+ * array of bytes. The first byte indicates the length by giving a
+ * number of 0-bits followed by a one. The position of the first
+ * "one" bit inside the first byte indicates the length of this
+ * number.
+ * Returns: num. of bytes read. < 0 on error.
+ */
+
+static int
+ebml_read_num (MatroskaDemuxContext *matroska,
+               int                   max_size,
+               uint64_t             *number)
+{
+    ByteIOContext *pb = &matroska->ctx->pb;
+    int len_mask = 0x80, read = 1, n = 1;
+    int64_t total = 0;
+
+    /* the first byte tells us the length in bytes - get_byte() can normally
+     * return 0, but since that's not a valid first ebmlID byte, we can
+     * use it safely here to catch EOS. */
+    if (!(total = get_byte(pb))) {
+        /* we might encounter EOS here */
+        if (!url_feof(pb)) {
+            offset_t pos = url_ftell(pb);
+            av_log(matroska->ctx, AV_LOG_ERROR,
+                   "Read error at pos. %"PRIu64" (0x%"PRIx64")\n",
+                   pos, pos);
+        }
+        return AVERROR_IO; /* EOS or actual I/O error */
+    }
+
+    /* get the length of the EBML number */
+    while (read <= max_size && !(total & len_mask)) {
+        read++;
+        len_mask >>= 1;
+    }
+    if (read > max_size) {
+        offset_t pos = url_ftell(pb) - 1;
+        av_log(matroska->ctx, AV_LOG_ERROR,
+               "Invalid EBML number size tag 0x%02x at pos %"PRIu64" (0x%"PRIx64")\n",
+               (uint8_t) total, pos, pos);
+        return AVERROR_INVALIDDATA;
+    }
+
+    /* read out length */
+    total &= ~len_mask;
+    while (n++ < read)
+        total = (total << 8) | get_byte(pb);
+
+    *number = total;
+
+    return read;
+}
+
+/*
+ * Read: the element content data ID.
+ * Return: the number of bytes read or < 0 on error.
+ */
+
+static int
+ebml_read_element_id (MatroskaDemuxContext *matroska,
+                      uint32_t             *id,
+                      int                  *level_up)
+{
+    int read;
+    uint64_t total;
+
+    /* if we re-call this, use our cached ID */
+    if (matroska->peek_id != 0) {
+        if (level_up)
+            *level_up = 0;
+        *id = matroska->peek_id;
+        return 0;
+    }
+
+    /* read out the "EBML number", include tag in ID */
+    if ((read = ebml_read_num(matroska, 4, &total)) < 0)
+        return read;
+    *id = matroska->peek_id  = total | (1 << (read * 7));
+
+    /* level tracking */
+    if (level_up)
+        *level_up = ebml_read_element_level_up(matroska);
+
+    return read;
+}
+
+/*
+ * Read: element content length.
+ * Return: the number of bytes read or < 0 on error.
+ */
+
+static int
+ebml_read_element_length (MatroskaDemuxContext *matroska,
+                          uint64_t             *length)
+{
+    /* clear cache since we're now beyond that data point */
+    matroska->peek_id = 0;
+
+    /* read out the "EBML number", include tag in ID */
+    return ebml_read_num(matroska, 8, length);
+}
+
+/*
+ * Return: the ID of the next element, or 0 on error.
+ * Level_up contains the amount of levels that this
+ * next element lies higher than the previous one.
+ */
+
+static uint32_t
+ebml_peek_id (MatroskaDemuxContext *matroska,
+              int                  *level_up)
+{
+    uint32_t id;
+
+    assert(level_up != NULL);
+
+    if (ebml_read_element_id(matroska, &id, level_up) < 0)
+        return 0;
+
+    return id;
+}
+
+/*
+ * Seek to a given offset.
+ * 0 is success, -1 is failure.
+ */
+
+static int
+ebml_read_seek (MatroskaDemuxContext *matroska,
+                offset_t              offset)
+{
+    ByteIOContext *pb = &matroska->ctx->pb;
+
+    /* clear ID cache, if any */
+    matroska->peek_id = 0;
+
+    return (url_fseek(pb, offset, SEEK_SET) == offset) ? 0 : -1;
+}
+
+/*
+ * Skip the next element.
+ * 0 is success, -1 is failure.
+ */
+
+static int
+ebml_read_skip (MatroskaDemuxContext *matroska)
+{
+    ByteIOContext *pb = &matroska->ctx->pb;
+    uint32_t id;
+    uint64_t length;
+    int res;
+
+    if ((res = ebml_read_element_id(matroska, &id, NULL)) < 0 ||
+        (res = ebml_read_element_length(matroska, &length)) < 0)
+        return res;
+
+    url_fskip(pb, length);
+
+    return 0;
+}
+
+/*
+ * Read the next element as an unsigned int.
+ * 0 is success, < 0 is failure.
+ */
+
+static int
+ebml_read_uint (MatroskaDemuxContext *matroska,
+                uint32_t             *id,
+                uint64_t             *num)
+{
+    ByteIOContext *pb = &matroska->ctx->pb;
+    int n = 0, size, res;
+    uint64_t rlength;
+
+    if ((res = ebml_read_element_id(matroska, id, NULL)) < 0 ||
+        (res = ebml_read_element_length(matroska, &rlength)) < 0)
+        return res;
+    size = rlength;
+    if (size < 1 || size > 8) {
+        offset_t pos = url_ftell(pb);
+        av_log(matroska->ctx, AV_LOG_ERROR,
+               "Invalid uint element size %d at position %"PRId64" (0x%"PRIx64")\n",
+                size, pos, pos);
+        return AVERROR_INVALIDDATA;
+    }
+
+    /* big-endian ordening; build up number */
+    *num = 0;
+    while (n++ < size)
+        *num = (*num << 8) | get_byte(pb);
+
+    return 0;
+}
+
+/*
+ * Read the next element as a signed int.
+ * 0 is success, < 0 is failure.
+ */
+
+static int
+ebml_read_sint (MatroskaDemuxContext *matroska,
+                uint32_t             *id,
+                int64_t              *num)
+{
+    ByteIOContext *pb = &matroska->ctx->pb;
+    int size, n = 1, negative = 0, res;
+    uint64_t rlength;
+
+    if ((res = ebml_read_element_id(matroska, id, NULL)) < 0 ||
+        (res = ebml_read_element_length(matroska, &rlength)) < 0)
+        return res;
+    size = rlength;
+    if (size < 1 || size > 8) {
+        offset_t pos = url_ftell(pb);
+        av_log(matroska->ctx, AV_LOG_ERROR,
+               "Invalid sint element size %d at position %"PRId64" (0x%"PRIx64")\n",
+                size, pos, pos);
+        return AVERROR_INVALIDDATA;
+    }
+    if ((*num = get_byte(pb)) & 0x80) {
+        negative = 1;
+        *num &= ~0x80;
+    }
+    while (n++ < size)
+        *num = (*num << 8) | get_byte(pb);
+
+    /* make signed */
+    if (negative)
+        *num = *num - (1LL << ((8 * size) - 1));
+
+    return 0;
+}
+
+/*
+ * Read the next element as a float.
+ * 0 is success, < 0 is failure.
+ */
+
+static int
+ebml_read_float (MatroskaDemuxContext *matroska,
+                 uint32_t             *id,
+                 double               *num)
+{
+    ByteIOContext *pb = &matroska->ctx->pb;
+    int size, res;
+    uint64_t rlength;
+
+    if ((res = ebml_read_element_id(matroska, id, NULL)) < 0 ||
+        (res = ebml_read_element_length(matroska, &rlength)) < 0)
+        return res;
+    size = rlength;
+
+    if (size == 4) {
+        *num= av_int2flt(get_be32(pb));
+    } else if(size==8){
+        *num= av_int2dbl(get_be64(pb));
+    } else{
+        offset_t pos = url_ftell(pb);
+        av_log(matroska->ctx, AV_LOG_ERROR,
+               "Invalid float element size %d at position %"PRIu64" (0x%"PRIx64")\n",
+               size, pos, pos);
+        return AVERROR_INVALIDDATA;
+    }
+
+    return 0;
+}
+
+/*
+ * Read the next element as an ASCII string.
+ * 0 is success, < 0 is failure.
+ */
+
+static int
+ebml_read_ascii (MatroskaDemuxContext *matroska,
+                 uint32_t             *id,
+                 char                **str)
+{
+    ByteIOContext *pb = &matroska->ctx->pb;
+    int size, res;
+    uint64_t rlength;
+
+    if ((res = ebml_read_element_id(matroska, id, NULL)) < 0 ||
+        (res = ebml_read_element_length(matroska, &rlength)) < 0)
+        return res;
+    size = rlength;
+
+    /* ebml strings are usually not 0-terminated, so we allocate one
+     * byte more, read the string and NULL-terminate it ourselves. */
+    if (size < 0 || !(*str = av_malloc(size + 1))) {
+        av_log(matroska->ctx, AV_LOG_ERROR, "Memory allocation failed\n");
+        return AVERROR_NOMEM;
+    }
+    if (get_buffer(pb, (uint8_t *) *str, size) != size) {
+        offset_t pos = url_ftell(pb);
+        av_log(matroska->ctx, AV_LOG_ERROR,
+               "Read error at pos. %"PRIu64" (0x%"PRIx64")\n", pos, pos);
+        return AVERROR_IO;
+    }
+    (*str)[size] = '\0';
+
+    return 0;
+}
+
+/*
+ * Read the next element as a UTF-8 string.
+ * 0 is success, < 0 is failure.
+ */
+
+static int
+ebml_read_utf8 (MatroskaDemuxContext *matroska,
+                uint32_t             *id,
+                char                **str)
+{
+  return ebml_read_ascii(matroska, id, str);
+}
+
+/*
+ * Read the next element as a date (nanoseconds since 1/1/2000).
+ * 0 is success, < 0 is failure.
+ */
+
+static int
+ebml_read_date (MatroskaDemuxContext *matroska,
+                uint32_t             *id,
+                int64_t              *date)
+{
+  return ebml_read_sint(matroska, id, date);
+}
+
+/*
+ * Read the next element, but only the header. The contents
+ * are supposed to be sub-elements which can be read separately.
+ * 0 is success, < 0 is failure.
+ */
+
+static int
+ebml_read_master (MatroskaDemuxContext *matroska,
+                  uint32_t             *id)
+{
+    ByteIOContext *pb = &matroska->ctx->pb;
+    uint64_t length;
+    MatroskaLevel *level;
+    int res;
+
+    if ((res = ebml_read_element_id(matroska, id, NULL)) < 0 ||
+        (res = ebml_read_element_length(matroska, &length)) < 0)
+        return res;
+
+    /* protect... (Heaven forbids that the '>' is true) */
+    if (matroska->num_levels >= EBML_MAX_DEPTH) {
+        av_log(matroska->ctx, AV_LOG_ERROR,
+               "File moves beyond max. allowed depth (%d)\n", EBML_MAX_DEPTH);
+        return AVERROR_NOTSUPP;
+    }
+
+    /* remember level */
+    level = &matroska->levels[matroska->num_levels++];
+    level->start = url_ftell(pb);
+    level->length = length;
+
+    return 0;
+}
+
+/*
+ * Read the next element as binary data.
+ * 0 is success, < 0 is failure.
+ */
+
+static int
+ebml_read_binary (MatroskaDemuxContext *matroska,
+                  uint32_t             *id,
+                  uint8_t             **binary,
+                  int                  *size)
+{
+    ByteIOContext *pb = &matroska->ctx->pb;
+    uint64_t rlength;
+    int res;
+
+    if ((res = ebml_read_element_id(matroska, id, NULL)) < 0 ||
+        (res = ebml_read_element_length(matroska, &rlength)) < 0)
+        return res;
+    *size = rlength;
+
+    if (!(*binary = av_malloc(*size))) {
+        av_log(matroska->ctx, AV_LOG_ERROR,
+               "Memory allocation error\n");
+        return AVERROR_NOMEM;
+    }
+
+    if (get_buffer(pb, *binary, *size) != *size) {
+        offset_t pos = url_ftell(pb);
+        av_log(matroska->ctx, AV_LOG_ERROR,
+               "Read error at pos. %"PRIu64" (0x%"PRIx64")\n", pos, pos);
+        return AVERROR_IO;
+    }
+
+    return 0;
+}
+
+/*
+ * Read signed/unsigned "EBML" numbers.
+ * Return: number of bytes processed, < 0 on error.
+ * XXX: use ebml_read_num().
+ */
+
+static int
+matroska_ebmlnum_uint (uint8_t  *data,
+                       uint32_t  size,
+                       uint64_t *num)
+{
+    int len_mask = 0x80, read = 1, n = 1, num_ffs = 0;
+    uint64_t total;
+
+    if (size <= 0)
+        return AVERROR_INVALIDDATA;
+
+    total = data[0];
+    while (read <= 8 && !(total & len_mask)) {
+        read++;
+        len_mask >>= 1;
+    }
+    if (read > 8)
+        return AVERROR_INVALIDDATA;
+
+    if ((total &= (len_mask - 1)) == len_mask - 1)
+        num_ffs++;
+    if (size < read)
+        return AVERROR_INVALIDDATA;
+    while (n < read) {
+        if (data[n] == 0xff)
+            num_ffs++;
+        total = (total << 8) | data[n];
+        n++;
+    }
+
+    if (read == num_ffs)
+        *num = (uint64_t)-1;
+    else
+        *num = total;
+
+    return read;
+}
+
+/*
+ * Same as above, but signed.
+ */
+
+static int
+matroska_ebmlnum_sint (uint8_t  *data,
+                       uint32_t  size,
+                       int64_t  *num)
+{
+    uint64_t unum;
+    int res;
+
+    /* read as unsigned number first */
+    if ((res = matroska_ebmlnum_uint(data, size, &unum)) < 0)
+        return res;
+
+    /* make signed (weird way) */
+    if (unum == (uint64_t)-1)
+        *num = INT64_MAX;
+    else
+        *num = unum - ((1LL << ((7 * res) - 1)) - 1);
+
+    return res;
+}
+
+/*
+ * Read an EBML header.
+ * 0 is success, < 0 is failure.
+ */
+
+static int
+ebml_read_header (MatroskaDemuxContext *matroska,
+                  char                **doctype,
+                  int                  *version)
+{
+    uint32_t id;
+    int level_up, res = 0;
+
+    /* default init */
+    if (doctype)
+        *doctype = NULL;
+    if (version)
+        *version = 1;
+
+    if (!(id = ebml_peek_id(matroska, &level_up)) ||
+        level_up != 0 || id != EBML_ID_HEADER) {
+        av_log(matroska->ctx, AV_LOG_ERROR,
+               "This is not an EBML file (id=0x%x/0x%x)\n", id, EBML_ID_HEADER);
+        return AVERROR_INVALIDDATA;
+    }
+    if ((res = ebml_read_master(matroska, &id)) < 0)
+        return res;
+
+    while (res == 0) {
+        if (!(id = ebml_peek_id(matroska, &level_up)))
+            return AVERROR_IO;
+
+        /* end-of-header */
+        if (level_up)
+            break;
+
+        switch (id) {
+            /* is our read version uptodate? */
+            case EBML_ID_EBMLREADVERSION: {
+                uint64_t num;
+
+                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
+                    return res;
+                if (num > EBML_VERSION) {
+                    av_log(matroska->ctx, AV_LOG_ERROR,
+                           "EBML version %"PRIu64" (> %d) is not supported\n",
+                           num, EBML_VERSION);
+                    return AVERROR_INVALIDDATA;
+                }
+                break;
+            }
+
+            /* we only handle 8 byte lengths at max */
+            case EBML_ID_EBMLMAXSIZELENGTH: {
+                uint64_t num;
+
+                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
+                    return res;
+                if (num > sizeof(uint64_t)) {
+                    av_log(matroska->ctx, AV_LOG_ERROR,
+                           "Integers of size %"PRIu64" (> %zd) not supported\n",
+                           num, sizeof(uint64_t));
+                    return AVERROR_INVALIDDATA;
+                }
+                break;
+            }
+
+            /* we handle 4 byte IDs at max */
+            case EBML_ID_EBMLMAXIDLENGTH: {
+                uint64_t num;
+
+                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
+                    return res;
+                if (num > sizeof(uint32_t)) {
+                    av_log(matroska->ctx, AV_LOG_ERROR,
+                           "IDs of size %"PRIu64" (> %zu) not supported\n",
+                            num, sizeof(uint32_t));
+                    return AVERROR_INVALIDDATA;
+                }
+                break;
+            }
+
+            case EBML_ID_DOCTYPE: {
+                char *text;
+
+                if ((res = ebml_read_ascii(matroska, &id, &text)) < 0)
+                    return res;
+                if (doctype) {
+                    if (*doctype)
+                        av_free(*doctype);
+                    *doctype = text;
+                } else
+                    av_free(text);
+                break;
+            }
+
+            case EBML_ID_DOCTYPEREADVERSION: {
+                uint64_t num;
+
+                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
+                    return res;
+                if (version)
+                    *version = num;
+                break;
+            }
+
+            default:
+                av_log(matroska->ctx, AV_LOG_INFO,
+                       "Unknown data type 0x%x in EBML header", id);
+                /* pass-through */
+
+            case EBML_ID_VOID:
+            /* we ignore these two, as they don't tell us anything we
+             * care about */
+            case EBML_ID_EBMLVERSION:
+            case EBML_ID_DOCTYPEVERSION:
+                res = ebml_read_skip (matroska);
+                break;
+        }
+    }
+
+    return 0;
+}
+
+
+static int
+matroska_find_track_by_num (MatroskaDemuxContext *matroska,
+                            int                   num)
+{
+    int i;
+
+    for (i = 0; i < matroska->num_tracks; i++)
+        if (matroska->tracks[i]->num == num)
+            return i;
+
+    return -1;
+}
+
+
+/*
+ * Put one packet in an application-supplied AVPacket struct.
+ * Returns 0 on success or -1 on failure.
+ */
+
+static int
+matroska_deliver_packet (MatroskaDemuxContext *matroska,
+                         AVPacket             *pkt)
+{
+    if (matroska->num_packets > 0) {
+        memcpy(pkt, matroska->packets[0], sizeof(AVPacket));
+        av_free(matroska->packets[0]);
+        if (matroska->num_packets > 1) {
+            memmove(&matroska->packets[0], &matroska->packets[1],
+                    (matroska->num_packets - 1) * sizeof(AVPacket *));
+            matroska->packets =
+                av_realloc(matroska->packets, (matroska->num_packets - 1) *
+                           sizeof(AVPacket *));
+        } else {
+            av_freep(&matroska->packets);
+        }
+        matroska->num_packets--;
+        return 0;
+    }
+
+    return -1;
+}
+
+/*
+ * Put a packet into our internal queue. Will be delivered to the
+ * user/application during the next get_packet() call.
+ */
+
+static void
+matroska_queue_packet (MatroskaDemuxContext *matroska,
+                       AVPacket             *pkt)
+{
+    matroska->packets =
+        av_realloc(matroska->packets, (matroska->num_packets + 1) *
+                   sizeof(AVPacket *));
+    matroska->packets[matroska->num_packets] = pkt;
+    matroska->num_packets++;
+}
+
+
+/*
+ * Autodetecting...
+ */
+
+static int
+matroska_probe (AVProbeData *p)
+{
+    uint64_t total = 0;
+    int len_mask = 0x80, size = 1, n = 1;
+    uint8_t probe_data[] = { 'm', 'a', 't', 'r', 'o', 's', 'k', 'a' };
+
+    /* ebml header? */
+    if ((p->buf[0] << 24 | p->buf[1] << 16 |
+         p->buf[2] << 8 | p->buf[3]) != EBML_ID_HEADER)
+        return 0;
+
+    /* length of header */
+    total = p->buf[4];
+    while (size <= 8 && !(total & len_mask)) {
+        size++;
+        len_mask >>= 1;
+    }
+    if (size > 8)
+      return 0;
+    total &= (len_mask - 1);
+    while (n < size)
+        total = (total << 8) | p->buf[4 + n++];
+
+    /* does the probe data contain the whole header? */
+    if (p->buf_size < 4 + size + total)
+      return 0;
+
+    /* the header must contain the document type 'matroska'. For now,
+     * we don't parse the whole header but simply check for the
+     * availability of that array of characters inside the header.
+     * Not fully fool-proof, but good enough. */
+    for (n = 4 + size; n <= 4 + size + total - sizeof(probe_data); n++)
+        if (!memcmp (&p->buf[n], probe_data, sizeof(probe_data)))
+            return AVPROBE_SCORE_MAX;
+
+    return 0;
+}
+
+/*
+ * From here on, it's all XML-style DTD stuff... Needs no comments.
+ */
+
+static int
+matroska_parse_info (MatroskaDemuxContext *matroska)
+{
+    int res = 0;
+    uint32_t id;
+
+    av_log(matroska->ctx, AV_LOG_DEBUG, "Parsing info...\n");
+
+    while (res == 0) {
+        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
+            res = AVERROR_IO;
+            break;
+        } else if (matroska->level_up) {
+            matroska->level_up--;
+            break;
+        }
+
+        switch (id) {
+            /* cluster timecode */
+            case MATROSKA_ID_TIMECODESCALE: {
+                uint64_t num;
+                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
+                    break;
+                matroska->time_scale = num;
+                break;
+            }
+
+            case MATROSKA_ID_DURATION: {
+                double num;
+                if ((res = ebml_read_float(matroska, &id, &num)) < 0)
+                    break;
+                matroska->ctx->duration = num * matroska->time_scale * 1000 / AV_TIME_BASE;
+                break;
+            }
+
+            case MATROSKA_ID_TITLE: {
+                char *text;
+                if ((res = ebml_read_utf8(matroska, &id, &text)) < 0)
+                    break;
+                strncpy(matroska->ctx->title, text,
+                        sizeof(matroska->ctx->title)-1);
+                av_free(text);
+                break;
+            }
+
+            case MATROSKA_ID_WRITINGAPP: {
+                char *text;
+                if ((res = ebml_read_utf8(matroska, &id, &text)) < 0)
+                    break;
+                matroska->writing_app = text;
+                break;
+            }
+
+            case MATROSKA_ID_MUXINGAPP: {
+                char *text;
+                if ((res = ebml_read_utf8(matroska, &id, &text)) < 0)
+                    break;
+                matroska->muxing_app = text;
+                break;
+            }
+
+            case MATROSKA_ID_DATEUTC: {
+                int64_t time;
+                if ((res = ebml_read_date(matroska, &id, &time)) < 0)
+                    break;
+                matroska->created = time;
+                break;
+            }
+
+            default:
+                av_log(matroska->ctx, AV_LOG_INFO,
+                       "Unknown entry 0x%x in info header\n", id);
+                /* fall-through */
+
+            case EBML_ID_VOID:
+                res = ebml_read_skip(matroska);
+                break;
+        }
+
+        if (matroska->level_up) {
+            matroska->level_up--;
+            break;
+        }
+    }
+
+    return res;
+}
+
+static int
+matroska_add_stream (MatroskaDemuxContext *matroska)
+{
+    int res = 0;
+    uint32_t id;
+    MatroskaTrack *track;
+
+    av_log(matroska->ctx, AV_LOG_DEBUG, "parsing track, adding stream..,\n");
+
+    /* Allocate a generic track. As soon as we know its type we'll realloc. */
+    track = av_mallocz(MAX_TRACK_SIZE);
+    matroska->num_tracks++;
+
+    /* start with the master */
+    if ((res = ebml_read_master(matroska, &id)) < 0)
+        return res;
+
+    /* try reading the trackentry headers */
+    while (res == 0) {
+        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
+            res = AVERROR_IO;
+            break;
+        } else if (matroska->level_up > 0) {
+            matroska->level_up--;
+            break;
+        }
+
+        switch (id) {
+            /* track number (unique stream ID) */
+            case MATROSKA_ID_TRACKNUMBER: {
+                uint64_t num;
+                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
+                    break;
+                track->num = num;
+                break;
+            }
+
+            /* track UID (unique identifier) */
+            case MATROSKA_ID_TRACKUID: {
+                uint64_t num;
+                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
+                    break;
+                track->uid = num;
+                break;
+            }
+
+            /* track type (video, audio, combined, subtitle, etc.) */
+            case MATROSKA_ID_TRACKTYPE: {
+                uint64_t num;
+                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
+                    break;
+                if (track->type && track->type != num) {
+                    av_log(matroska->ctx, AV_LOG_INFO,
+                           "More than one tracktype in an entry - skip\n");
+                    break;
+                }
+                track->type = num;
+
+                switch (track->type) {
+                    case MATROSKA_TRACK_TYPE_VIDEO:
+                    case MATROSKA_TRACK_TYPE_AUDIO:
+                    case MATROSKA_TRACK_TYPE_SUBTITLE:
+                        break;
+                    case MATROSKA_TRACK_TYPE_COMPLEX:
+                    case MATROSKA_TRACK_TYPE_LOGO:
+                    case MATROSKA_TRACK_TYPE_CONTROL:
+                    default:
+                        av_log(matroska->ctx, AV_LOG_INFO,
+                               "Unknown or unsupported track type 0x%x\n",
+                               track->type);
+                        track->type = 0;
+                        break;
+                }
+                matroska->tracks[matroska->num_tracks - 1] = track;
+                break;
+            }
+
+            /* tracktype specific stuff for video */
+            case MATROSKA_ID_TRACKVIDEO: {
+                MatroskaVideoTrack *videotrack;
+                if (!track->type)
+                    track->type = MATROSKA_TRACK_TYPE_VIDEO;
+                if (track->type != MATROSKA_TRACK_TYPE_VIDEO) {
+                    av_log(matroska->ctx, AV_LOG_INFO,
+                           "video data in non-video track - ignoring\n");
+                    res = AVERROR_INVALIDDATA;
+                    break;
+                } else if ((res = ebml_read_master(matroska, &id)) < 0)
+                    break;
+                videotrack = (MatroskaVideoTrack *)track;
+
+                while (res == 0) {
+                    if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
+                        res = AVERROR_IO;
+                        break;
+                    } else if (matroska->level_up > 0) {
+                        matroska->level_up--;
+                        break;
+                    }
+
+                    switch (id) {
+                        /* fixme, this should be one-up, but I get it here */
+                        case MATROSKA_ID_TRACKDEFAULTDURATION: {
+                            uint64_t num;
+                            if ((res = ebml_read_uint (matroska, &id,
+                                                       &num)) < 0)
+                                break;
+                            track->default_duration = num/matroska->time_scale;
+                            break;
+                        }
+
+                        /* video framerate */
+                        case MATROSKA_ID_VIDEOFRAMERATE: {
+                            double num;
+                            if ((res = ebml_read_float(matroska, &id,
+                                                       &num)) < 0)
+                                break;
+                            track->default_duration = 1000000000/(matroska->time_scale*num);
+                            break;
+                        }
+
+                        /* width of the size to display the video at */
+                        case MATROSKA_ID_VIDEODISPLAYWIDTH: {
+                            uint64_t num;
+                            if ((res = ebml_read_uint(matroska, &id,
+                                                      &num)) < 0)
+                                break;
+                            videotrack->display_width = num;
+                            break;
+                        }
+
+                        /* height of the size to display the video at */
+                        case MATROSKA_ID_VIDEODISPLAYHEIGHT: {
+                            uint64_t num;
+                            if ((res = ebml_read_uint(matroska, &id,
+                                                      &num)) < 0)
+                                break;
+                            videotrack->display_height = num;
+                            break;
+                        }
+
+                        /* width of the video in the file */
+                        case MATROSKA_ID_VIDEOPIXELWIDTH: {
+                            uint64_t num;
+                            if ((res = ebml_read_uint(matroska, &id,
+                                                      &num)) < 0)
+                                break;
+                            videotrack->pixel_width = num;
+                            break;
+                        }
+
+                        /* height of the video in the file */
+                        case MATROSKA_ID_VIDEOPIXELHEIGHT: {
+                            uint64_t num;
+                            if ((res = ebml_read_uint(matroska, &id,
+                                                      &num)) < 0)
+                                break;
+                            videotrack->pixel_height = num;
+                            break;
+                        }
+
+                        /* whether the video is interlaced */
+                        case MATROSKA_ID_VIDEOFLAGINTERLACED: {
+                            uint64_t num;
+                            if ((res = ebml_read_uint(matroska, &id,
+                                                      &num)) < 0)
+                                break;
+                            if (num)
+                                track->flags |=
+                                    MATROSKA_VIDEOTRACK_INTERLACED;
+                            else
+                                track->flags &=
+                                    ~MATROSKA_VIDEOTRACK_INTERLACED;
+                            break;
+                        }
+
+                        /* stereo mode (whether the video has two streams,
+                         * where one is for the left eye and the other for
+                         * the right eye, which creates a 3D-like
+                         * effect) */
+                        case MATROSKA_ID_VIDEOSTEREOMODE: {
+                            uint64_t num;
+                            if ((res = ebml_read_uint(matroska, &id,
+                                                      &num)) < 0)
+                                break;
+                            if (num != MATROSKA_EYE_MODE_MONO &&
+                                num != MATROSKA_EYE_MODE_LEFT &&
+                                num != MATROSKA_EYE_MODE_RIGHT &&
+                                num != MATROSKA_EYE_MODE_BOTH) {
+                                av_log(matroska->ctx, AV_LOG_INFO,
+                                       "Ignoring unknown eye mode 0x%x\n",
+                                       (uint32_t) num);
+                                break;
+                            }
+                            videotrack->eye_mode = num;
+                            break;
+                        }
+
+                        /* aspect ratio behaviour */
+                        case MATROSKA_ID_VIDEOASPECTRATIO: {
+                            uint64_t num;
+                            if ((res = ebml_read_uint(matroska, &id,
+                                                      &num)) < 0)
+                                break;
+                            if (num != MATROSKA_ASPECT_RATIO_MODE_FREE &&
+                                num != MATROSKA_ASPECT_RATIO_MODE_KEEP &&
+                                num != MATROSKA_ASPECT_RATIO_MODE_FIXED) {
+                                av_log(matroska->ctx, AV_LOG_INFO,
+                                       "Ignoring unknown aspect ratio 0x%x\n",
+                                       (uint32_t) num);
+                                break;
+                            }
+                            videotrack->ar_mode = num;
+                            break;
+                        }
+
+                        /* colourspace (only matters for raw video)
+                         * fourcc */
+                        case MATROSKA_ID_VIDEOCOLOURSPACE: {
+                            uint64_t num;
+                            if ((res = ebml_read_uint(matroska, &id,
+                                                      &num)) < 0)
+                                break;
+                            videotrack->fourcc = num;
+                            break;
+                        }
+
+                        default:
+                            av_log(matroska->ctx, AV_LOG_INFO,
+                                   "Unknown video track header entry "
+                                   "0x%x - ignoring\n", id);
+                            /* pass-through */
+
+                        case EBML_ID_VOID:
+                            res = ebml_read_skip(matroska);
+                            break;
+                    }
+
+                    if (matroska->level_up) {
+                        matroska->level_up--;
+                        break;
+                    }
+                }
+                break;
+            }
+
+            /* tracktype specific stuff for audio */
+            case MATROSKA_ID_TRACKAUDIO: {
+                MatroskaAudioTrack *audiotrack;
+                if (!track->type)
+                    track->type = MATROSKA_TRACK_TYPE_AUDIO;
+                if (track->type != MATROSKA_TRACK_TYPE_AUDIO) {
+                    av_log(matroska->ctx, AV_LOG_INFO,
+                           "audio data in non-audio track - ignoring\n");
+                    res = AVERROR_INVALIDDATA;
+                    break;
+                } else if ((res = ebml_read_master(matroska, &id)) < 0)
+                    break;
+                audiotrack = (MatroskaAudioTrack *)track;
+                audiotrack->channels = 1;
+                audiotrack->samplerate = 8000;
+
+                while (res == 0) {
+                    if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
+                        res = AVERROR_IO;
+                        break;
+                    } else if (matroska->level_up > 0) {
+                        matroska->level_up--;
+                        break;
+                    }
+
+                    switch (id) {
+                        /* samplerate */
+                        case MATROSKA_ID_AUDIOSAMPLINGFREQ: {
+                            double num;
+                            if ((res = ebml_read_float(matroska, &id,
+                                                       &num)) < 0)
+                                break;
+                            audiotrack->internal_samplerate =
+                            audiotrack->samplerate = num;
+                            break;
+                        }
+
+                        case MATROSKA_ID_AUDIOOUTSAMPLINGFREQ: {
+                            double num;
+                            if ((res = ebml_read_float(matroska, &id,
+                                                       &num)) < 0)
+                                break;
+                            audiotrack->samplerate = num;
+                            break;
+                        }
+
+                            /* bitdepth */
+                        case MATROSKA_ID_AUDIOBITDEPTH: {
+                            uint64_t num;
+                            if ((res = ebml_read_uint(matroska, &id,
+                                                      &num)) < 0)
+                                break;
+                            audiotrack->bitdepth = num;
+                            break;
+                        }
+
+                            /* channels */
+                        case MATROSKA_ID_AUDIOCHANNELS: {
+                            uint64_t num;
+                            if ((res = ebml_read_uint(matroska, &id,
+                                                      &num)) < 0)
+                                break;
+                            audiotrack->channels = num;
+                            break;
+                        }
+
+                        default:
+                            av_log(matroska->ctx, AV_LOG_INFO,
+                                   "Unknown audio track header entry "
+                                   "0x%x - ignoring\n", id);
+                            /* pass-through */
+
+                        case EBML_ID_VOID:
+                            res = ebml_read_skip(matroska);
+                            break;
+                    }
+
+                    if (matroska->level_up) {
+                        matroska->level_up--;
+                        break;
+                    }
+                }
+                break;
+            }
+
+                /* codec identifier */
+            case MATROSKA_ID_CODECID: {
+                char *text;
+                if ((res = ebml_read_ascii(matroska, &id, &text)) < 0)
+                    break;
+                track->codec_id = text;
+                break;
+            }
+
+                /* codec private data */
+            case MATROSKA_ID_CODECPRIVATE: {
+                uint8_t *data;
+                int size;
+                if ((res = ebml_read_binary(matroska, &id, &data, &size) < 0))
+                    break;
+                track->codec_priv = data;
+                track->codec_priv_size = size;
+                break;
+            }
+
+                /* name of the codec */
+            case MATROSKA_ID_CODECNAME: {
+                char *text;
+                if ((res = ebml_read_utf8(matroska, &id, &text)) < 0)
+                    break;
+                track->codec_name = text;
+                break;
+            }
+
+                /* name of this track */
+            case MATROSKA_ID_TRACKNAME: {
+                char *text;
+                if ((res = ebml_read_utf8(matroska, &id, &text)) < 0)
+                    break;
+                track->name = text;
+                break;
+            }
+
+                /* language (matters for audio/subtitles, mostly) */
+            case MATROSKA_ID_TRACKLANGUAGE: {
+                char *text;
+                if ((res = ebml_read_utf8(matroska, &id, &text)) < 0)
+                    break;
+                track->language = text;
+                break;
+            }
+
+                /* whether this is actually used */
+            case MATROSKA_ID_TRACKFLAGENABLED: {
+                uint64_t num;
+                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
+                    break;
+                if (num)
+                    track->flags |= MATROSKA_TRACK_ENABLED;
+                else
+                    track->flags &= ~MATROSKA_TRACK_ENABLED;
+                break;
+            }
+
+                /* whether it's the default for this track type */
+            case MATROSKA_ID_TRACKFLAGDEFAULT: {
+                uint64_t num;
+                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
+                    break;
+                if (num)
+                    track->flags |= MATROSKA_TRACK_DEFAULT;
+                else
+                    track->flags &= ~MATROSKA_TRACK_DEFAULT;
+                break;
+            }
+
+                /* lacing (like MPEG, where blocks don't end/start on frame
+                 * boundaries) */
+            case MATROSKA_ID_TRACKFLAGLACING: {
+                uint64_t num;
+                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
+                    break;
+                if (num)
+                    track->flags |= MATROSKA_TRACK_LACING;
+                else
+                    track->flags &= ~MATROSKA_TRACK_LACING;
+                break;
+            }
+
+                /* default length (in time) of one data block in this track */
+            case MATROSKA_ID_TRACKDEFAULTDURATION: {
+                uint64_t num;
+                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
+                    break;
+                track->default_duration = num / matroska->time_scale;
+                break;
+            }
+
+            default:
+                av_log(matroska->ctx, AV_LOG_INFO,
+                       "Unknown track header entry 0x%x - ignoring\n", id);
+                /* pass-through */
+
+            case EBML_ID_VOID:
+            /* we ignore these because they're nothing useful. */
+            case MATROSKA_ID_CODECINFOURL:
+            case MATROSKA_ID_CODECDOWNLOADURL:
+            case MATROSKA_ID_TRACKMINCACHE:
+            case MATROSKA_ID_TRACKMAXCACHE:
+                res = ebml_read_skip(matroska);
+                break;
+        }
+
+        if (matroska->level_up) {
+            matroska->level_up--;
+            break;
+        }
+    }
+
+    return res;
+}
+
+static int
+matroska_parse_tracks (MatroskaDemuxContext *matroska)
+{
+    int res = 0;
+    uint32_t id;
+
+    av_log(matroska->ctx, AV_LOG_DEBUG, "parsing tracks...\n");
+
+    while (res == 0) {
+        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
+            res = AVERROR_IO;
+            break;
+        } else if (matroska->level_up) {
+            matroska->level_up--;
+            break;
+        }
+
+        switch (id) {
+            /* one track within the "all-tracks" header */
+            case MATROSKA_ID_TRACKENTRY:
+                res = matroska_add_stream(matroska);
+                break;
+
+            default:
+                av_log(matroska->ctx, AV_LOG_INFO,
+                       "Unknown entry 0x%x in track header\n", id);
+                /* fall-through */
+
+            case EBML_ID_VOID:
+                res = ebml_read_skip(matroska);
+                break;
+        }
+
+        if (matroska->level_up) {
+            matroska->level_up--;
+            break;
+        }
+    }
+
+    return res;
+}
+
+static int
+matroska_parse_index (MatroskaDemuxContext *matroska)
+{
+    int res = 0;
+    uint32_t id;
+    MatroskaDemuxIndex idx;
+
+    av_log(matroska->ctx, AV_LOG_DEBUG, "parsing index...\n");
+
+    while (res == 0) {
+        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
+            res = AVERROR_IO;
+            break;
+        } else if (matroska->level_up) {
+            matroska->level_up--;
+            break;
+        }
+
+        switch (id) {
+            /* one single index entry ('point') */
+            case MATROSKA_ID_POINTENTRY:
+                if ((res = ebml_read_master(matroska, &id)) < 0)
+                    break;
+
+                /* in the end, we hope to fill one entry with a
+                 * timestamp, a file position and a tracknum */
+                idx.pos   = (uint64_t) -1;
+                idx.time  = (uint64_t) -1;
+                idx.track = (uint16_t) -1;
+
+                while (res == 0) {
+                    if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
+                        res = AVERROR_IO;
+                        break;
+                    } else if (matroska->level_up) {
+                        matroska->level_up--;
+                        break;
+                    }
+
+                    switch (id) {
+                        /* one single index entry ('point') */
+                        case MATROSKA_ID_CUETIME: {
+                            uint64_t time;
+                            if ((res = ebml_read_uint(matroska, &id,
+                                                      &time)) < 0)
+                                break;
+                            idx.time = time * matroska->time_scale;
+                            break;
+                        }
+
+                        /* position in the file + track to which it
+                         * belongs */
+                        case MATROSKA_ID_CUETRACKPOSITION:
+                            if ((res = ebml_read_master(matroska, &id)) < 0)
+                                break;
+
+                            while (res == 0) {
+                                if (!(id = ebml_peek_id (matroska,
+                                                    &matroska->level_up))) {
+                                    res = AVERROR_IO;
+                                    break;
+                                } else if (matroska->level_up) {
+                                    matroska->level_up--;
+                                    break;
+                                }
+
+                                switch (id) {
+                                    /* track number */
+                                    case MATROSKA_ID_CUETRACK: {
+                                        uint64_t num;
+                                        if ((res = ebml_read_uint(matroska,
+                                                          &id, &num)) < 0)
+                                            break;
+                                        idx.track = num;
+                                        break;
+                                    }
+
+                                        /* position in file */
+                                    case MATROSKA_ID_CUECLUSTERPOSITION: {
+                                        uint64_t num;
+                                        if ((res = ebml_read_uint(matroska,
+                                                          &id, &num)) < 0)
+                                            break;
+                                        idx.pos = num+matroska->segment_start;
+                                        break;
+                                    }
+
+                                    default:
+                                        av_log(matroska->ctx, AV_LOG_INFO,
+                                               "Unknown entry 0x%x in "
+                                               "CuesTrackPositions\n", id);
+                                        /* fall-through */
+
+                                    case EBML_ID_VOID:
+                                        res = ebml_read_skip(matroska);
+                                        break;
+                                }
+
+                                if (matroska->level_up) {
+                                    matroska->level_up--;
+                                    break;
+                                }
+                            }
+
+                            break;
+
+                        default:
+                            av_log(matroska->ctx, AV_LOG_INFO,
+                                   "Unknown entry 0x%x in cuespoint "
+                                   "index\n", id);
+                            /* fall-through */
+
+                        case EBML_ID_VOID:
+                            res = ebml_read_skip(matroska);
+                            break;
+                    }
+
+                    if (matroska->level_up) {
+                        matroska->level_up--;
+                        break;
+                    }
+                }
+
+                /* so let's see if we got what we wanted */
+                if (idx.pos   != (uint64_t) -1 &&
+                    idx.time  != (uint64_t) -1 &&
+                    idx.track != (uint16_t) -1) {
+                    if (matroska->num_indexes % 32 == 0) {
+                        /* re-allocate bigger index */
+                        matroska->index =
+                            av_realloc(matroska->index,
+                                       (matroska->num_indexes + 32) *
+                                       sizeof(MatroskaDemuxIndex));
+                    }
+                    matroska->index[matroska->num_indexes] = idx;
+                    matroska->num_indexes++;
+                }
+                break;
+
+            default:
+                av_log(matroska->ctx, AV_LOG_INFO,
+                       "Unknown entry 0x%x in cues header\n", id);
+                /* fall-through */
+
+            case EBML_ID_VOID:
+                res = ebml_read_skip(matroska);
+                break;
+        }
+
+        if (matroska->level_up) {
+            matroska->level_up--;
+            break;
+        }
+    }
+
+    return res;
+}
+
+static int
+matroska_parse_metadata (MatroskaDemuxContext *matroska)
+{
+    int res = 0;
+    uint32_t id;
+
+    while (res == 0) {
+        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
+            res = AVERROR_IO;
+            break;
+        } else if (matroska->level_up) {
+            matroska->level_up--;
+            break;
+        }
+
+        switch (id) {
+            /* Hm, this is unsupported... */
+            default:
+                av_log(matroska->ctx, AV_LOG_INFO,
+                       "Unknown entry 0x%x in metadata header\n", id);
+                /* fall-through */
+
+            case EBML_ID_VOID:
+                res = ebml_read_skip(matroska);
+                break;
+        }
+
+        if (matroska->level_up) {
+            matroska->level_up--;
+            break;
+        }
+    }
+
+    return res;
+}
+
+static int
+matroska_parse_seekhead (MatroskaDemuxContext *matroska)
+{
+    int res = 0;
+    uint32_t id;
+
+    av_log(matroska->ctx, AV_LOG_DEBUG, "parsing seekhead...\n");
+
+    while (res == 0) {
+        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
+            res = AVERROR_IO;
+            break;
+        } else if (matroska->level_up) {
+            matroska->level_up--;
+            break;
+        }
+
+        switch (id) {
+            case MATROSKA_ID_SEEKENTRY: {
+                uint32_t seek_id = 0, peek_id_cache = 0;
+                uint64_t seek_pos = (uint64_t) -1, t;
+
+                if ((res = ebml_read_master(matroska, &id)) < 0)
+                    break;
+
+                while (res == 0) {
+                    if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
+                        res = AVERROR_IO;
+                        break;
+                    } else if (matroska->level_up) {
+                        matroska->level_up--;
+                        break;
+                    }
+
+                    switch (id) {
+                        case MATROSKA_ID_SEEKID:
+                            res = ebml_read_uint(matroska, &id, &t);
+                            seek_id = t;
+                            break;
+
+                        case MATROSKA_ID_SEEKPOSITION:
+                            res = ebml_read_uint(matroska, &id, &seek_pos);
+                            break;
+
+                        default:
+                            av_log(matroska->ctx, AV_LOG_INFO,
+                                   "Unknown seekhead ID 0x%x\n", id);
+                            /* fall-through */
+
+                        case EBML_ID_VOID:
+                            res = ebml_read_skip(matroska);
+                            break;
+                    }
+
+                    if (matroska->level_up) {
+                        matroska->level_up--;
+                        break;
+                    }
+                }
+
+                if (!seek_id || seek_pos == (uint64_t) -1) {
+                    av_log(matroska->ctx, AV_LOG_INFO,
+                           "Incomplete seekhead entry (0x%x/%"PRIu64")\n",
+                           seek_id, seek_pos);
+                    break;
+                }
+
+                switch (seek_id) {
+                    case MATROSKA_ID_CUES:
+                    case MATROSKA_ID_TAGS: {
+                        uint32_t level_up = matroska->level_up;
+                        offset_t before_pos;
+                        uint64_t length;
+                        MatroskaLevel level;
+
+                        /* remember the peeked ID and the current position */
+                        peek_id_cache = matroska->peek_id;
+                        before_pos = url_ftell(&matroska->ctx->pb);
+
+                        /* seek */
+                        if ((res = ebml_read_seek(matroska, seek_pos +
+                                               matroska->segment_start)) < 0)
+                            return res;
+
+                        /* we don't want to lose our seekhead level, so we add
+                         * a dummy. This is a crude hack. */
+                        if (matroska->num_levels == EBML_MAX_DEPTH) {
+                            av_log(matroska->ctx, AV_LOG_INFO,
+                                   "Max EBML element depth (%d) reached, "
+                                   "cannot parse further.\n", EBML_MAX_DEPTH);
+                            return AVERROR_UNKNOWN;
+                        }
+
+                        level.start = 0;
+                        level.length = (uint64_t)-1;
+                        matroska->levels[matroska->num_levels] = level;
+                        matroska->num_levels++;
+
+                        /* check ID */
+                        if (!(id = ebml_peek_id (matroska,
+                                                 &matroska->level_up)))
+                            goto finish;
+                        if (id != seek_id) {
+                            av_log(matroska->ctx, AV_LOG_INFO,
+                                   "We looked for ID=0x%x but got "
+                                   "ID=0x%x (pos=%"PRIu64")",
+                                   seek_id, id, seek_pos +
+                                   matroska->segment_start);
+                            goto finish;
+                        }
+
+                        /* read master + parse */
+                        if ((res = ebml_read_master(matroska, &id)) < 0)
+                            goto finish;
+                        switch (id) {
+                            case MATROSKA_ID_CUES:
+                                if (!(res = matroska_parse_index(matroska)) ||
+                                    url_feof(&matroska->ctx->pb)) {
+                                    matroska->index_parsed = 1;
+                                    res = 0;
+                                }
+                                break;
+                            case MATROSKA_ID_TAGS:
+                                if (!(res = matroska_parse_metadata(matroska)) ||
+                                   url_feof(&matroska->ctx->pb)) {
+                                    matroska->metadata_parsed = 1;
+                                    res = 0;
+                                }
+                                break;
+                        }
+
+                    finish:
+                        /* remove dummy level */
+                        while (matroska->num_levels) {
+                            matroska->num_levels--;
+                            length =
+                                matroska->levels[matroska->num_levels].length;
+                            if (length == (uint64_t)-1)
+                                break;
+                        }
+
+                        /* seek back */
+                        if ((res = ebml_read_seek(matroska, before_pos)) < 0)
+                            return res;
+                        matroska->peek_id = peek_id_cache;
+                        matroska->level_up = level_up;
+                        break;
+                    }
+
+                    default:
+                        av_log(matroska->ctx, AV_LOG_INFO,
+                               "Ignoring seekhead entry for ID=0x%x\n",
+                               seek_id);
+                        break;
+                }
+
+                break;
+            }
+
+            default:
+                av_log(matroska->ctx, AV_LOG_INFO,
+                       "Unknown seekhead ID 0x%x\n", id);
+                /* fall-through */
+
+            case EBML_ID_VOID:
+                res = ebml_read_skip(matroska);
+                break;
+        }
+
+        if (matroska->level_up) {
+            matroska->level_up--;
+            break;
+        }
+    }
+
+    return res;
+}
+
+#define ARRAY_SIZE(x)  (sizeof(x)/sizeof(*x))
+
+static int
+matroska_aac_profile (char *codec_id)
+{
+    static const char *aac_profiles[] = {
+        "MAIN", "LC", "SSR"
+    };
+    int profile;
+
+    for (profile=0; profile<ARRAY_SIZE(aac_profiles); profile++)
+        if (strstr(codec_id, aac_profiles[profile]))
+            break;
+    return profile + 1;
+}
+
+static int
+matroska_aac_sri (int samplerate)
+{
+    static const int aac_sample_rates[] = {
+        96000, 88200, 64000, 48000, 44100, 32000,
+        24000, 22050, 16000, 12000, 11025,  8000,
+    };
+    int sri;
+
+    for (sri=0; sri<ARRAY_SIZE(aac_sample_rates); sri++)
+        if (aac_sample_rates[sri] == samplerate)
+            break;
+    return sri;
+}
+
+static int
+matroska_read_header (AVFormatContext    *s,
+                      AVFormatParameters *ap)
+{
+    MatroskaDemuxContext *matroska = s->priv_data;
+    char *doctype;
+    int version, last_level, res = 0;
+    uint32_t id;
+
+    matroska->ctx = s;
+
+    /* First read the EBML header. */
+    doctype = NULL;
+    if ((res = ebml_read_header(matroska, &doctype, &version)) < 0)
+        return res;
+    if ((doctype == NULL) || strcmp(doctype, "matroska")) {
+        av_log(matroska->ctx, AV_LOG_ERROR,
+               "Wrong EBML doctype ('%s' != 'matroska').\n",
+               doctype ? doctype : "(none)");
+        if (doctype)
+            av_free(doctype);
+        return AVERROR_NOFMT;
+    }
+    av_free(doctype);
+    if (version > 2) {
+        av_log(matroska->ctx, AV_LOG_ERROR,
+               "Matroska demuxer version 2 too old for file version %d\n",
+               version);
+        return AVERROR_NOFMT;
+    }
+
+    /* The next thing is a segment. */
+    while (1) {
+        if (!(id = ebml_peek_id(matroska, &last_level)))
+            return AVERROR_IO;
+        if (id == MATROSKA_ID_SEGMENT)
+            break;
+
+        /* oi! */
+        av_log(matroska->ctx, AV_LOG_INFO,
+               "Expected a Segment ID (0x%x), but received 0x%x!\n",
+               MATROSKA_ID_SEGMENT, id);
+        if ((res = ebml_read_skip(matroska)) < 0)
+            return res;
+    }
+
+    /* We now have a Matroska segment.
+     * Seeks are from the beginning of the segment,
+     * after the segment ID/length. */
+    if ((res = ebml_read_master(matroska, &id)) < 0)
+        return res;
+    matroska->segment_start = url_ftell(&s->pb);
+
+    matroska->time_scale = 1000000;
+    /* we've found our segment, start reading the different contents in here */
+    while (res == 0) {
+        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
+            res = AVERROR_IO;
+            break;
+        } else if (matroska->level_up) {
+            matroska->level_up--;
+            break;
+        }
+
+        switch (id) {
+            /* stream info */
+            case MATROSKA_ID_INFO: {
+                if ((res = ebml_read_master(matroska, &id)) < 0)
+                    break;
+                res = matroska_parse_info(matroska);
+                break;
+            }
+
+            /* track info headers */
+            case MATROSKA_ID_TRACKS: {
+                if ((res = ebml_read_master(matroska, &id)) < 0)
+                    break;
+                res = matroska_parse_tracks(matroska);
+                break;
+            }
+
+            /* stream index */
+            case MATROSKA_ID_CUES: {
+                if (!matroska->index_parsed) {
+                    if ((res = ebml_read_master(matroska, &id)) < 0)
+                        break;
+                    res = matroska_parse_index(matroska);
+                } else
+                    res = ebml_read_skip(matroska);
+                break;
+            }
+
+            /* metadata */
+            case MATROSKA_ID_TAGS: {
+                if (!matroska->metadata_parsed) {
+                    if ((res = ebml_read_master(matroska, &id)) < 0)
+                        break;
+                    res = matroska_parse_metadata(matroska);
+                } else
+                    res = ebml_read_skip(matroska);
+                break;
+            }
+
+            /* file index (if seekable, seek to Cues/Tags to parse it) */
+            case MATROSKA_ID_SEEKHEAD: {
+                if ((res = ebml_read_master(matroska, &id)) < 0)
+                    break;
+                res = matroska_parse_seekhead(matroska);
+                break;
+            }
+
+            case MATROSKA_ID_CLUSTER: {
+                /* Do not read the master - this will be done in the next
+                 * call to matroska_read_packet. */
+                res = 1;
+                break;
+            }
+
+            default:
+                av_log(matroska->ctx, AV_LOG_INFO,
+                       "Unknown matroska file header ID 0x%x\n", id);
+            /* fall-through */
+
+            case EBML_ID_VOID:
+                res = ebml_read_skip(matroska);
+                break;
+        }
+
+        if (matroska->level_up) {
+            matroska->level_up--;
+            break;
+        }
+    }
+
+    /* Have we found a cluster? */
+    if (ebml_peek_id(matroska, NULL) == MATROSKA_ID_CLUSTER) {
+        int i, j;
+        MatroskaTrack *track;
+        AVStream *st;
+
+        for (i = 0; i < matroska->num_tracks; i++) {
+            enum CodecID codec_id = CODEC_ID_NONE;
+            uint8_t *extradata = NULL;
+            int extradata_size = 0;
+            int extradata_offset = 0;
+            track = matroska->tracks[i];
+
+            /* libavformat does not really support subtitles.
+             * Also apply some sanity checks. */
+            if ((track->type == MATROSKA_TRACK_TYPE_SUBTITLE) ||
+                (track->codec_id == NULL))
+                continue;
+
+            for(j=0; ff_mkv_codec_tags[j].str; j++){
+                if(!strncmp(ff_mkv_codec_tags[j].str, track->codec_id,
+                            strlen(ff_mkv_codec_tags[j].str))){
+                    codec_id= ff_mkv_codec_tags[j].id;
+                    break;
+                }
+            }
+
+            /* Set the FourCC from the CodecID. */
+            /* This is the MS compatibility mode which stores a
+             * BITMAPINFOHEADER in the CodecPrivate. */
+            if (!strcmp(track->codec_id,
+                        MATROSKA_CODEC_ID_VIDEO_VFW_FOURCC) &&
+                (track->codec_priv_size >= 40) &&
+                (track->codec_priv != NULL)) {
+                unsigned char *p;
+
+                /* Offset of biCompression. Stored in LE. */
+                p = (unsigned char *)track->codec_priv + 16;
+                ((MatroskaVideoTrack *)track)->fourcc = (p[3] << 24) |
+                                 (p[2] << 16) | (p[1] << 8) | p[0];
+                codec_id = codec_get_id(codec_bmp_tags, ((MatroskaVideoTrack *)track)->fourcc);
+
+            }
+
+            /* This is the MS compatibility mode which stores a
+             * WAVEFORMATEX in the CodecPrivate. */
+            else if (!strcmp(track->codec_id,
+                             MATROSKA_CODEC_ID_AUDIO_ACM) &&
+                (track->codec_priv_size >= 18) &&
+                (track->codec_priv != NULL)) {
+                unsigned char *p;
+                uint16_t tag;
+
+                /* Offset of wFormatTag. Stored in LE. */
+                p = (unsigned char *)track->codec_priv;
+                tag = (p[1] << 8) | p[0];
+                codec_id = codec_get_id(codec_wav_tags, tag);
+
+            }
+
+            else if (codec_id == CODEC_ID_AAC && !track->codec_priv_size) {
+                MatroskaAudioTrack *audiotrack = (MatroskaAudioTrack *) track;
+                int profile = matroska_aac_profile(track->codec_id);
+                int sri = matroska_aac_sri(audiotrack->internal_samplerate);
+                extradata = av_malloc(5);
+                if (extradata == NULL)
+                    return AVERROR_NOMEM;
+                extradata[0] = (profile << 3) | ((sri&0x0E) >> 1);
+                extradata[1] = ((sri&0x01) << 7) | (audiotrack->channels<<3);
+                if (strstr(track->codec_id, "SBR")) {
+                    sri = matroska_aac_sri(audiotrack->samplerate);
+                    extradata[2] = 0x56;
+                    extradata[3] = 0xE5;
+                    extradata[4] = 0x80 | (sri<<3);
+                    extradata_size = 5;
+                } else {
+                    extradata_size = 2;
+                }
+                track->default_duration = 1024*1000 / audiotrack->internal_samplerate;
+            }
+
+            else if (codec_id == CODEC_ID_TTA) {
+                MatroskaAudioTrack *audiotrack = (MatroskaAudioTrack *) track;
+                ByteIOContext b;
+                extradata_size = 30;
+                extradata = av_mallocz(extradata_size);
+                if (extradata == NULL)
+                    return AVERROR_NOMEM;
+                init_put_byte(&b, extradata, extradata_size, 1,
+                              NULL, NULL, NULL, NULL);
+                put_buffer(&b, (uint8_t *) "TTA1", 4);
+                put_le16(&b, 1);
+                put_le16(&b, audiotrack->channels);
+                put_le16(&b, audiotrack->bitdepth);
+                put_le32(&b, audiotrack->samplerate);
+                put_le32(&b, matroska->ctx->duration * audiotrack->samplerate);
+            }
+
+            else if (codec_id == CODEC_ID_RV10 || codec_id == CODEC_ID_RV20 ||
+                     codec_id == CODEC_ID_RV30 || codec_id == CODEC_ID_RV40) {
+                extradata_offset = 26;
+                track->codec_priv_size -= extradata_offset;
+                track->flags |= MATROSKA_TRACK_REAL_V;
+            }
+
+            if (codec_id == CODEC_ID_NONE) {
+                av_log(matroska->ctx, AV_LOG_INFO,
+                       "Unknown/unsupported CodecID %s.\n",
+                       track->codec_id);
+            }
+
+            track->stream_index = matroska->num_streams;
+
+            matroska->num_streams++;
+            st = av_new_stream(s, track->stream_index);
+            if (st == NULL)
+                return AVERROR_NOMEM;
+            av_set_pts_info(st, 64, matroska->time_scale, 1000*1000*1000); /* 64 bit pts in ns */
+
+            st->codec->codec_id = codec_id;
+            st->start_time = 0;
+
+            if (track->default_duration)
+                av_reduce(&st->codec->time_base.num, &st->codec->time_base.den,
+                          track->default_duration, 1000, 30000);
+
+            if(extradata){
+                st->codec->extradata = extradata;
+                st->codec->extradata_size = extradata_size;
+            } else if(track->codec_priv && track->codec_priv_size > 0){
+                st->codec->extradata = av_malloc(track->codec_priv_size);
+                if(st->codec->extradata == NULL)
+                    return AVERROR_NOMEM;
+                st->codec->extradata_size = track->codec_priv_size;
+                memcpy(st->codec->extradata,track->codec_priv+extradata_offset,
+                       track->codec_priv_size);
+            }
+
+            if (track->type == MATROSKA_TRACK_TYPE_VIDEO) {
+                MatroskaVideoTrack *videotrack = (MatroskaVideoTrack *)track;
+
+                st->codec->codec_type = CODEC_TYPE_VIDEO;
+                st->codec->codec_tag = videotrack->fourcc;
+                st->codec->width = videotrack->pixel_width;
+                st->codec->height = videotrack->pixel_height;
+                if (videotrack->display_width == 0)
+                    videotrack->display_width= videotrack->pixel_width;
+                if (videotrack->display_height == 0)
+                    videotrack->display_height= videotrack->pixel_height;
+                av_reduce(&st->codec->sample_aspect_ratio.num,
+                          &st->codec->sample_aspect_ratio.den,
+                          st->codec->height * videotrack->display_width,
+                          st->codec-> width * videotrack->display_height,
+                          255);
+                st->need_parsing = AVSTREAM_PARSE_HEADERS;
+            } else if (track->type == MATROSKA_TRACK_TYPE_AUDIO) {
+                MatroskaAudioTrack *audiotrack = (MatroskaAudioTrack *)track;
+
+                st->codec->codec_type = CODEC_TYPE_AUDIO;
+                st->codec->sample_rate = audiotrack->samplerate;
+                st->codec->channels = audiotrack->channels;
+            } else if (track->type == MATROSKA_TRACK_TYPE_SUBTITLE) {
+                st->codec->codec_type = CODEC_TYPE_SUBTITLE;
+            }
+
+            /* What do we do with private data? E.g. for Vorbis. */
+        }
+        res = 0;
+    }
+
+    if (matroska->index_parsed) {
+        int i, track, stream;
+        for (i=0; i<matroska->num_indexes; i++) {
+            MatroskaDemuxIndex *idx = &matroska->index[i];
+            track = matroska_find_track_by_num(matroska, idx->track);
+            stream = matroska->tracks[track]->stream_index;
+            av_add_index_entry(matroska->ctx->streams[stream],
+                               idx->pos, idx->time/matroska->time_scale,
+                               0, 0, AVINDEX_KEYFRAME);
+        }
+    }
+
+    return res;
+}
+
+static inline int
+rv_offset(uint8_t *data, int slice, int slices)
+{
+    return AV_RL32(data+8*slice+4) + 8*slices;
+}
+
+static int
+matroska_parse_block(MatroskaDemuxContext *matroska, uint8_t *data, int size,
+                     int64_t pos, uint64_t cluster_time, uint64_t duration,
+                     int is_keyframe, int is_bframe)
+{
+    int res = 0;
+    int track;
+    AVStream *st;
+    AVPacket *pkt;
+    uint8_t *origdata = data;
+    int16_t block_time;
+    uint32_t *lace_size = NULL;
+    int n, flags, laces = 0;
+    uint64_t num;
+
+    /* first byte(s): tracknum */
+    if ((n = matroska_ebmlnum_uint(data, size, &num)) < 0) {
+        av_log(matroska->ctx, AV_LOG_ERROR, "EBML block data error\n");
+        av_free(origdata);
+        return res;
+    }
+    data += n;
+    size -= n;
+
+    /* fetch track from num */
+    track = matroska_find_track_by_num(matroska, num);
+    if (size <= 3 || track < 0 || track >= matroska->num_tracks) {
+        av_log(matroska->ctx, AV_LOG_INFO,
+               "Invalid stream %d or size %u\n", track, size);
+        av_free(origdata);
+        return res;
+    }
+    st = matroska->ctx->streams[matroska->tracks[track]->stream_index];
+    if (st->discard >= AVDISCARD_ALL) {
+        av_free(origdata);
+        return res;
+    }
+    if (duration == AV_NOPTS_VALUE)
+        duration = matroska->tracks[track]->default_duration;
+
+    /* block_time (relative to cluster time) */
+    block_time = (data[0] << 8) | data[1];
+    data += 2;
+    size -= 2;
+    flags = *data;
+    data += 1;
+    size -= 1;
+    if (is_keyframe == -1)
+        is_keyframe = flags & 1 ? PKT_FLAG_KEY : 0;
+
+    if (matroska->skip_to_keyframe) {
+        if (!is_keyframe || st != matroska->skip_to_stream)
+            return res;
+        matroska->skip_to_keyframe = 0;
+    }
+
+    switch ((flags & 0x06) >> 1) {
+        case 0x0: /* no lacing */
+            laces = 1;
+            lace_size = av_mallocz(sizeof(int));
+            lace_size[0] = size;
+            break;
+
+        case 0x1: /* xiph lacing */
+        case 0x2: /* fixed-size lacing */
+        case 0x3: /* EBML lacing */
+            if (size == 0) {
+                res = -1;
+                break;
+            }
+            laces = (*data) + 1;
+            data += 1;
+            size -= 1;
+            lace_size = av_mallocz(laces * sizeof(int));
+
+            switch ((flags & 0x06) >> 1) {
+                case 0x1: /* xiph lacing */ {
+                    uint8_t temp;
+                    uint32_t total = 0;
+                    for (n = 0; res == 0 && n < laces - 1; n++) {
+                        while (1) {
+                            if (size == 0) {
+                                res = -1;
+                                break;
+                            }
+                            temp = *data;
+                            lace_size[n] += temp;
+                            data += 1;
+                            size -= 1;
+                            if (temp != 0xff)
+                                break;
+                        }
+                        total += lace_size[n];
+                    }
+                    lace_size[n] = size - total;
+                    break;
+                }
+
+                case 0x2: /* fixed-size lacing */
+                    for (n = 0; n < laces; n++)
+                        lace_size[n] = size / laces;
+                    break;
+
+                case 0x3: /* EBML lacing */ {
+                    uint32_t total;
+                    n = matroska_ebmlnum_uint(data, size, &num);
+                    if (n < 0) {
+                        av_log(matroska->ctx, AV_LOG_INFO,
+                               "EBML block data error\n");
+                        break;
+                    }
+                    data += n;
+                    size -= n;
+                    total = lace_size[0] = num;
+                    for (n = 1; res == 0 && n < laces - 1; n++) {
+                        int64_t snum;
+                        int r;
+                        r = matroska_ebmlnum_sint (data, size, &snum);
+                        if (r < 0) {
+                            av_log(matroska->ctx, AV_LOG_INFO,
+                                   "EBML block data error\n");
+                            break;
+                        }
+                        data += r;
+                        size -= r;
+                        lace_size[n] = lace_size[n - 1] + snum;
+                        total += lace_size[n];
+                    }
+                    lace_size[n] = size - total;
+                    break;
+                }
+            }
+            break;
+    }
+
+    if (res == 0) {
+        int real_v = matroska->tracks[track]->flags & MATROSKA_TRACK_REAL_V;
+        uint64_t timecode = AV_NOPTS_VALUE;
+
+        if (cluster_time != (uint64_t)-1 && cluster_time + block_time >= 0)
+            timecode = cluster_time + block_time;
+
+        for (n = 0; n < laces; n++) {
+            int slice, slices = 1;
+
+            if (real_v) {
+                slices = *data++ + 1;
+                lace_size[n]--;
+            }
+
+            for (slice=0; slice<slices; slice++) {
+                int slice_size, slice_offset = 0;
+                if (real_v)
+                    slice_offset = rv_offset(data, slice, slices);
+                if (slice+1 == slices)
+                    slice_size = lace_size[n] - slice_offset;
+                else
+                    slice_size = rv_offset(data, slice+1, slices) - slice_offset;
+                pkt = av_mallocz(sizeof(AVPacket));
+                /* XXX: prevent data copy... */
+                if (av_new_packet(pkt, slice_size) < 0) {
+                    res = AVERROR_NOMEM;
+                    n = laces-1;
+                    break;
+                }
+                memcpy (pkt->data, data+slice_offset, slice_size);
+
+                if (n == 0)
+                    pkt->flags = is_keyframe;
+                pkt->stream_index = matroska->tracks[track]->stream_index;
+
+                pkt->pts = timecode;
+                pkt->pos = pos;
+                pkt->duration = duration;
+
+                matroska_queue_packet(matroska, pkt);
+
+                if (timecode != AV_NOPTS_VALUE)
+                    timecode = duration ? timecode + duration : AV_NOPTS_VALUE;
+            }
+            data += lace_size[n];
+        }
+    }
+
+    av_free(lace_size);
+    av_free(origdata);
+    return res;
+}
+
+static int
+matroska_parse_blockgroup (MatroskaDemuxContext *matroska,
+                           uint64_t              cluster_time)
+{
+    int res = 0;
+    uint32_t id;
+    int is_bframe = 0;
+    int is_keyframe = PKT_FLAG_KEY, last_num_packets = matroska->num_packets;
+    uint64_t duration = AV_NOPTS_VALUE;
+    uint8_t *data;
+    int size = 0;
+    int64_t pos = 0;
+
+    av_log(matroska->ctx, AV_LOG_DEBUG, "parsing blockgroup...\n");
+
+    while (res == 0) {
+        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
+            res = AVERROR_IO;
+            break;
+        } else if (matroska->level_up) {
+            matroska->level_up--;
+            break;
+        }
+
+        switch (id) {
+            /* one block inside the group. Note, block parsing is one
+             * of the harder things, so this code is a bit complicated.
+             * See http://www.matroska.org/ for documentation. */
+            case MATROSKA_ID_BLOCK: {
+                pos = url_ftell(&matroska->ctx->pb);
+                res = ebml_read_binary(matroska, &id, &data, &size);
+                break;
+            }
+
+            case MATROSKA_ID_BLOCKDURATION: {
+                if ((res = ebml_read_uint(matroska, &id, &duration)) < 0)
+                    break;
+                duration /= matroska->time_scale;
+                break;
+            }
+
+            case MATROSKA_ID_BLOCKREFERENCE: {
+                int64_t num;
+                /* We've found a reference, so not even the first frame in
+                 * the lace is a key frame. */
+                is_keyframe = 0;
+                if (last_num_packets != matroska->num_packets)
+                    matroska->packets[last_num_packets]->flags = 0;
+                if ((res = ebml_read_sint(matroska, &id, &num)) < 0)
+                    break;
+                if (num > 0)
+                    is_bframe = 1;
+                break;
+            }
+
+            default:
+                av_log(matroska->ctx, AV_LOG_INFO,
+                       "Unknown entry 0x%x in blockgroup data\n", id);
+                /* fall-through */
+
+            case EBML_ID_VOID:
+                res = ebml_read_skip(matroska);
+                break;
+        }
+
+        if (matroska->level_up) {
+            matroska->level_up--;
+            break;
+        }
+    }
+
+    if (res)
+        return res;
+
+    if (size > 0)
+        res = matroska_parse_block(matroska, data, size, pos, cluster_time,
+                                   duration, is_keyframe, is_bframe);
+
+    return res;
+}
+
+static int
+matroska_parse_cluster (MatroskaDemuxContext *matroska)
+{
+    int res = 0;
+    uint32_t id;
+    uint64_t cluster_time = 0;
+    uint8_t *data;
+    int64_t pos;
+    int size;
+
+    av_log(matroska->ctx, AV_LOG_DEBUG,
+           "parsing cluster at %"PRId64"\n", url_ftell(&matroska->ctx->pb));
+
+    while (res == 0) {
+        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
+            res = AVERROR_IO;
+            break;
+        } else if (matroska->level_up) {
+            matroska->level_up--;
+            break;
+        }
+
+        switch (id) {
+            /* cluster timecode */
+            case MATROSKA_ID_CLUSTERTIMECODE: {
+                uint64_t num;
+                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
+                    break;
+                cluster_time = num;
+                break;
+            }
+
+                /* a group of blocks inside a cluster */
+            case MATROSKA_ID_BLOCKGROUP:
+                if ((res = ebml_read_master(matroska, &id)) < 0)
+                    break;
+                res = matroska_parse_blockgroup(matroska, cluster_time);
+                break;
+
+            case MATROSKA_ID_SIMPLEBLOCK:
+                pos = url_ftell(&matroska->ctx->pb);
+                res = ebml_read_binary(matroska, &id, &data, &size);
+                if (res == 0)
+                    res = matroska_parse_block(matroska, data, size, pos,
+                                               cluster_time, AV_NOPTS_VALUE,
+                                               -1, 0);
+                break;
+
+            default:
+                av_log(matroska->ctx, AV_LOG_INFO,
+                       "Unknown entry 0x%x in cluster data\n", id);
+                /* fall-through */
+
+            case EBML_ID_VOID:
+                res = ebml_read_skip(matroska);
+                break;
+        }
+
+        if (matroska->level_up) {
+            matroska->level_up--;
+            break;
+        }
+    }
+
+    return res;
+}
+
+static int
+matroska_read_packet (AVFormatContext *s,
+                      AVPacket        *pkt)
+{
+    MatroskaDemuxContext *matroska = s->priv_data;
+    int res = 0;
+    uint32_t id;
+
+    /* Read stream until we have a packet queued. */
+    while (matroska_deliver_packet(matroska, pkt)) {
+
+        /* Have we already reached the end? */
+        if (matroska->done)
+            return AVERROR_IO;
+
+        while (res == 0) {
+            if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
+                return AVERROR_IO;
+            } else if (matroska->level_up) {
+                matroska->level_up--;
+                break;
+            }
+
+            switch (id) {
+                case MATROSKA_ID_CLUSTER:
+                    if ((res = ebml_read_master(matroska, &id)) < 0)
+                        break;
+                    if ((res = matroska_parse_cluster(matroska)) == 0)
+                        res = 1; /* Parsed one cluster, let's get out. */
+                    break;
+
+                default:
+                case EBML_ID_VOID:
+                    res = ebml_read_skip(matroska);
+                    break;
+            }
+
+            if (matroska->level_up) {
+                matroska->level_up--;
+                break;
+            }
+        }
+
+        if (res == -1)
+            matroska->done = 1;
+    }
+
+    return 0;
+}
+
+static int
+matroska_read_seek (AVFormatContext *s, int stream_index, int64_t timestamp,
+                    int flags)
+{
+    MatroskaDemuxContext *matroska = s->priv_data;
+    AVStream *st = s->streams[stream_index];
+    int index;
+
+    /* find index entry */
+    index = av_index_search_timestamp(st, timestamp, flags);
+    if (index < 0)
+        return 0;
+
+    /* do the seek */
+    url_fseek(&s->pb, st->index_entries[index].pos, SEEK_SET);
+    matroska->skip_to_keyframe = !(flags & AVSEEK_FLAG_ANY);
+    matroska->skip_to_stream = st;
+    matroska->num_packets = 0;
+    matroska->peek_id = 0;
+    return 0;
+}
+
+static int
+matroska_read_close (AVFormatContext *s)
+{
+    MatroskaDemuxContext *matroska = s->priv_data;
+    int n = 0;
+
+    av_free(matroska->writing_app);
+    av_free(matroska->muxing_app);
+    av_free(matroska->index);
+
+    if (matroska->packets != NULL) {
+        for (n = 0; n < matroska->num_packets; n++) {
+            av_free_packet(matroska->packets[n]);
+            av_free(matroska->packets[n]);
+        }
+        av_free(matroska->packets);
+    }
+
+    for (n = 0; n < matroska->num_tracks; n++) {
+        MatroskaTrack *track = matroska->tracks[n];
+        av_free(track->codec_id);
+        av_free(track->codec_name);
+        av_free(track->codec_priv);
+        av_free(track->name);
+        av_free(track->language);
+
+        av_free(track);
+    }
+
+    return 0;
+}
+
+AVInputFormat matroska_demuxer = {
+    "matroska",
+    "Matroska file format",
+    sizeof(MatroskaDemuxContext),
+    matroska_probe,
+    matroska_read_header,
+    matroska_read_packet,
+    matroska_read_close,
+    matroska_read_seek,
+};