/*

  * Matroska file demuxer

  * Copyright (c) 2003-2008 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 file demuxer

  * @author Ronald Bultje <rbultje@ronald.bitfreak.net>
  * @author with a little help from Moritz Bunkus <moritz@bunkus.org>
  * @author totally reworked by Aurelien Jacobs <aurel@gnuage.org>
  * @see specs available on the Matroska project page: http://www.matroska.org/

  */
 

 #include <stdio.h>

 #include "avformat.h"

 #include "internal.h"

 #include "avio_internal.h"

 /* For ff_codec_get_id(). */

 #include "riff.h"

 #include "isom.h"

 #include "rmsipr.h"

 #include "matroska.h"

 #include "libavcodec/bytestream.h"

 #include "libavcodec/mpeg4audio.h"

 #include "libavutil/intfloat.h"

 #include "libavutil/intreadwrite.h"

 #include "libavutil/avstring.h"

 #include "libavutil/lzo.h"

 #include "libavutil/dict.h"

 #if CONFIG_ZLIB

 #include <zlib.h>
 #endif

 #if CONFIG_BZLIB

 #include <bzlib.h>
 #endif

 typedef enum {
     EBML_NONE,
     EBML_UINT,
     EBML_FLOAT,
     EBML_STR,
     EBML_UTF8,
     EBML_BIN,
     EBML_NEST,
     EBML_PASS,
     EBML_STOP,

     EBML_TYPE_COUNT

 } EbmlType;
 
 typedef const struct EbmlSyntax {
     uint32_t id;
     EbmlType type;
     int list_elem_size;
     int data_offset;
     union {
         uint64_t    u;
         double      f;
         const char *s;
         const struct EbmlSyntax *n;
     } def;
 } EbmlSyntax;
 
 typedef struct {
     int nb_elem;
     void *elem;
 } EbmlList;
 
 typedef struct {
     int      size;
     uint8_t *data;
     int64_t  pos;
 } EbmlBin;
 

 typedef struct {
     uint64_t version;
     uint64_t max_size;
     uint64_t id_length;
     char    *doctype;
     uint64_t doctype_version;
 } Ebml;
 

 typedef struct {
     uint64_t algo;
     EbmlBin  settings;
 } MatroskaTrackCompression;

 typedef struct {
     uint64_t scope;
     uint64_t type;
     MatroskaTrackCompression compression;
 } MatroskaTrackEncoding;

 typedef struct {
     double   frame_rate;
     uint64_t display_width;
     uint64_t display_height;
     uint64_t pixel_width;
     uint64_t pixel_height;

     EbmlBin color_space;

     uint64_t stereo_mode;

     uint64_t alpha_mode;

 } MatroskaTrackVideo;

 typedef struct {
     double   samplerate;
     double   out_samplerate;
     uint64_t bitdepth;
     uint64_t channels;
 
     /* real audio header (extracted from extradata) */
     int      coded_framesize;
     int      sub_packet_h;
     int      frame_size;
     int      sub_packet_size;
     int      sub_packet_cnt;
     int      pkt_cnt;

     uint64_t buf_timecode;

     uint8_t *buf;
 } MatroskaTrackAudio;

 typedef struct {

     uint64_t uid;
     uint64_t type;
 } MatroskaTrackPlane;
 
 typedef struct {
     EbmlList combine_planes;
 } MatroskaTrackOperation;
 
 typedef struct {

     uint64_t num;

     uint64_t uid;

     uint64_t type;

     char    *name;

     char    *codec_id;
     EbmlBin  codec_priv;
     char    *language;

     double time_scale;

     uint64_t default_duration;

     uint64_t flag_default;

     uint64_t flag_forced;

     MatroskaTrackVideo video;
     MatroskaTrackAudio audio;

     MatroskaTrackOperation operation;

     EbmlList encodings;

 
     AVStream *stream;

     int64_t end_timecode;

     int ms_compat;

     uint64_t max_block_additional_id;

 } MatroskaTrack;
 

 typedef struct {

     uint64_t uid;

     char *filename;
     char *mime;
     EbmlBin bin;

 
     AVStream *stream;

 } MatroskaAttachement;
 
 typedef struct {

     uint64_t start;
     uint64_t end;
     uint64_t uid;
     char    *title;

 
     AVChapter *chapter;

 } MatroskaChapter;
 
 typedef struct {

     uint64_t track;
     uint64_t pos;
 } MatroskaIndexPos;
 
 typedef struct {
     uint64_t time;
     EbmlList pos;
 } MatroskaIndex;
 

 typedef struct {

     char *name;
     char *string;

     char *lang;
     uint64_t def;

     EbmlList sub;
 } MatroskaTag;
 
 typedef struct {

     char    *type;
     uint64_t typevalue;
     uint64_t trackuid;
     uint64_t chapteruid;
     uint64_t attachuid;
 } MatroskaTagTarget;
 
 typedef struct {
     MatroskaTagTarget target;
     EbmlList tag;
 } MatroskaTags;
 
 typedef struct {

     uint64_t id;
     uint64_t pos;
 } MatroskaSeekhead;
 

 typedef struct {

     uint64_t start;
     uint64_t length;

 } MatroskaLevel;
 

 typedef struct {

     uint64_t timecode;
     EbmlList blocks;
 } MatroskaCluster;
 
 typedef struct {

     AVFormatContext *ctx;
 

     /* EBML stuff */

     int num_levels;
     MatroskaLevel levels[EBML_MAX_DEPTH];
     int level_up;

     uint32_t current_id;

     uint64_t time_scale;
     double   duration;
     char    *title;

     EbmlBin date_utc;

     EbmlList tracks;

     EbmlList attachments;

     EbmlList chapters;

     EbmlList index;

     EbmlList tags;

     EbmlList seekhead;

 
     /* byte position of the segment inside the stream */

     int64_t segment_start;

     /* the packet queue */

     AVPacket **packets;
     int num_packets;

     AVPacket *prev_pkt;

     int done;

 
     /* What to skip before effectively reading a packet. */
     int skip_to_keyframe;

     uint64_t skip_to_timecode;

 
     /* File has a CUES element, but we defer parsing until it is needed. */
     int cues_parsing_deferred;

 
     int current_cluster_num_blocks;
     int64_t current_cluster_pos;
     MatroskaCluster current_cluster;
 
     /* File has SSA subtitles which prevent incremental cluster parsing. */
     int contains_ssa;

 } MatroskaDemuxContext;
 

 typedef struct {
     uint64_t duration;
     int64_t  reference;

     uint64_t non_simple;

     EbmlBin  bin;

     uint64_t additional_id;
     EbmlBin  additional;

 } MatroskaBlock;
 

 static EbmlSyntax ebml_header[] = {
     { EBML_ID_EBMLREADVERSION,        EBML_UINT, 0, offsetof(Ebml,version), {.u=EBML_VERSION} },
     { EBML_ID_EBMLMAXSIZELENGTH,      EBML_UINT, 0, offsetof(Ebml,max_size), {.u=8} },
     { EBML_ID_EBMLMAXIDLENGTH,        EBML_UINT, 0, offsetof(Ebml,id_length), {.u=4} },
     { EBML_ID_DOCTYPE,                EBML_STR,  0, offsetof(Ebml,doctype), {.s="(none)"} },
     { EBML_ID_DOCTYPEREADVERSION,     EBML_UINT, 0, offsetof(Ebml,doctype_version), {.u=1} },
     { EBML_ID_EBMLVERSION,            EBML_NONE },
     { EBML_ID_DOCTYPEVERSION,         EBML_NONE },
     { 0 }
 };
 
 static EbmlSyntax ebml_syntax[] = {
     { EBML_ID_HEADER,                 EBML_NEST, 0, 0, {.n=ebml_header} },
     { 0 }
 };
 

 static EbmlSyntax matroska_info[] = {
     { MATROSKA_ID_TIMECODESCALE,      EBML_UINT,  0, offsetof(MatroskaDemuxContext,time_scale), {.u=1000000} },
     { MATROSKA_ID_DURATION,           EBML_FLOAT, 0, offsetof(MatroskaDemuxContext,duration) },
     { MATROSKA_ID_TITLE,              EBML_UTF8,  0, offsetof(MatroskaDemuxContext,title) },
     { MATROSKA_ID_WRITINGAPP,         EBML_NONE },
     { MATROSKA_ID_MUXINGAPP,          EBML_NONE },

     { MATROSKA_ID_DATEUTC,            EBML_BIN,  0, offsetof(MatroskaDemuxContext,date_utc) },

     { MATROSKA_ID_SEGMENTUID,         EBML_NONE },
     { 0 }
 };
 

 static EbmlSyntax matroska_track_video[] = {
     { MATROSKA_ID_VIDEOFRAMERATE,     EBML_FLOAT,0, offsetof(MatroskaTrackVideo,frame_rate) },
     { MATROSKA_ID_VIDEODISPLAYWIDTH,  EBML_UINT, 0, offsetof(MatroskaTrackVideo,display_width) },
     { MATROSKA_ID_VIDEODISPLAYHEIGHT, EBML_UINT, 0, offsetof(MatroskaTrackVideo,display_height) },
     { MATROSKA_ID_VIDEOPIXELWIDTH,    EBML_UINT, 0, offsetof(MatroskaTrackVideo,pixel_width) },
     { MATROSKA_ID_VIDEOPIXELHEIGHT,   EBML_UINT, 0, offsetof(MatroskaTrackVideo,pixel_height) },

     { MATROSKA_ID_VIDEOCOLORSPACE,    EBML_BIN,  0, offsetof(MatroskaTrackVideo,color_space) },

     { MATROSKA_ID_VIDEOSTEREOMODE,    EBML_UINT, 0, offsetof(MatroskaTrackVideo,stereo_mode) },

     { MATROSKA_ID_VIDEOALPHAMODE,     EBML_UINT, 0, offsetof(MatroskaTrackVideo,alpha_mode) },

     { MATROSKA_ID_VIDEOPIXELCROPB,    EBML_NONE },
     { MATROSKA_ID_VIDEOPIXELCROPT,    EBML_NONE },
     { MATROSKA_ID_VIDEOPIXELCROPL,    EBML_NONE },
     { MATROSKA_ID_VIDEOPIXELCROPR,    EBML_NONE },
     { MATROSKA_ID_VIDEODISPLAYUNIT,   EBML_NONE },

     { MATROSKA_ID_VIDEOFLAGINTERLACED,EBML_NONE },
     { MATROSKA_ID_VIDEOASPECTRATIO,   EBML_NONE },
     { 0 }
 };
 
 static EbmlSyntax matroska_track_audio[] = {
     { MATROSKA_ID_AUDIOSAMPLINGFREQ,  EBML_FLOAT,0, offsetof(MatroskaTrackAudio,samplerate), {.f=8000.0} },
     { MATROSKA_ID_AUDIOOUTSAMPLINGFREQ,EBML_FLOAT,0,offsetof(MatroskaTrackAudio,out_samplerate) },
     { MATROSKA_ID_AUDIOBITDEPTH,      EBML_UINT, 0, offsetof(MatroskaTrackAudio,bitdepth) },
     { MATROSKA_ID_AUDIOCHANNELS,      EBML_UINT, 0, offsetof(MatroskaTrackAudio,channels), {.u=1} },
     { 0 }
 };
 
 static EbmlSyntax matroska_track_encoding_compression[] = {
     { MATROSKA_ID_ENCODINGCOMPALGO,   EBML_UINT, 0, offsetof(MatroskaTrackCompression,algo), {.u=0} },
     { MATROSKA_ID_ENCODINGCOMPSETTINGS,EBML_BIN, 0, offsetof(MatroskaTrackCompression,settings) },
     { 0 }
 };
 
 static EbmlSyntax matroska_track_encoding[] = {
     { MATROSKA_ID_ENCODINGSCOPE,      EBML_UINT, 0, offsetof(MatroskaTrackEncoding,scope), {.u=1} },
     { MATROSKA_ID_ENCODINGTYPE,       EBML_UINT, 0, offsetof(MatroskaTrackEncoding,type), {.u=0} },
     { MATROSKA_ID_ENCODINGCOMPRESSION,EBML_NEST, 0, offsetof(MatroskaTrackEncoding,compression), {.n=matroska_track_encoding_compression} },

     { MATROSKA_ID_ENCODINGORDER,      EBML_NONE },

     { 0 }
 };
 
 static EbmlSyntax matroska_track_encodings[] = {
     { MATROSKA_ID_TRACKCONTENTENCODING, EBML_NEST, sizeof(MatroskaTrackEncoding), offsetof(MatroskaTrack,encodings), {.n=matroska_track_encoding} },
     { 0 }
 };
 

 static EbmlSyntax matroska_track_plane[] = {
     { MATROSKA_ID_TRACKPLANEUID,  EBML_UINT, 0, offsetof(MatroskaTrackPlane,uid) },
     { MATROSKA_ID_TRACKPLANETYPE, EBML_UINT, 0, offsetof(MatroskaTrackPlane,type) },
     { 0 }
 };
 
 static EbmlSyntax matroska_track_combine_planes[] = {
     { MATROSKA_ID_TRACKPLANE, EBML_NEST, sizeof(MatroskaTrackPlane), offsetof(MatroskaTrackOperation,combine_planes), {.n=matroska_track_plane} },
     { 0 }
 };
 
 static EbmlSyntax matroska_track_operation[] = {
     { MATROSKA_ID_TRACKCOMBINEPLANES, EBML_NEST, 0, 0, {.n=matroska_track_combine_planes} },
     { 0 }
 };
 

 static EbmlSyntax matroska_track[] = {
     { MATROSKA_ID_TRACKNUMBER,          EBML_UINT, 0, offsetof(MatroskaTrack,num) },

     { MATROSKA_ID_TRACKNAME,            EBML_UTF8, 0, offsetof(MatroskaTrack,name) },

     { MATROSKA_ID_TRACKUID,             EBML_UINT, 0, offsetof(MatroskaTrack,uid) },

     { MATROSKA_ID_TRACKTYPE,            EBML_UINT, 0, offsetof(MatroskaTrack,type) },
     { MATROSKA_ID_CODECID,              EBML_STR,  0, offsetof(MatroskaTrack,codec_id) },
     { MATROSKA_ID_CODECPRIVATE,         EBML_BIN,  0, offsetof(MatroskaTrack,codec_priv) },
     { MATROSKA_ID_TRACKLANGUAGE,        EBML_UTF8, 0, offsetof(MatroskaTrack,language), {.s="eng"} },
     { MATROSKA_ID_TRACKDEFAULTDURATION, EBML_UINT, 0, offsetof(MatroskaTrack,default_duration) },
     { MATROSKA_ID_TRACKTIMECODESCALE,   EBML_FLOAT,0, offsetof(MatroskaTrack,time_scale), {.f=1.0} },
     { MATROSKA_ID_TRACKFLAGDEFAULT,     EBML_UINT, 0, offsetof(MatroskaTrack,flag_default), {.u=1} },

     { MATROSKA_ID_TRACKFLAGFORCED,      EBML_UINT, 0, offsetof(MatroskaTrack,flag_forced), {.u=0} },

     { MATROSKA_ID_TRACKVIDEO,           EBML_NEST, 0, offsetof(MatroskaTrack,video), {.n=matroska_track_video} },
     { MATROSKA_ID_TRACKAUDIO,           EBML_NEST, 0, offsetof(MatroskaTrack,audio), {.n=matroska_track_audio} },

     { MATROSKA_ID_TRACKOPERATION,       EBML_NEST, 0, offsetof(MatroskaTrack,operation), {.n=matroska_track_operation} },

     { MATROSKA_ID_TRACKCONTENTENCODINGS,EBML_NEST, 0, 0, {.n=matroska_track_encodings} },

     { MATROSKA_ID_TRACKMAXBLKADDID,     EBML_UINT, 0, offsetof(MatroskaTrack,max_block_additional_id) },

     { MATROSKA_ID_TRACKFLAGENABLED,     EBML_NONE },
     { MATROSKA_ID_TRACKFLAGLACING,      EBML_NONE },
     { MATROSKA_ID_CODECNAME,            EBML_NONE },
     { MATROSKA_ID_CODECDECODEALL,       EBML_NONE },
     { MATROSKA_ID_CODECINFOURL,         EBML_NONE },
     { MATROSKA_ID_CODECDOWNLOADURL,     EBML_NONE },
     { MATROSKA_ID_TRACKMINCACHE,        EBML_NONE },
     { MATROSKA_ID_TRACKMAXCACHE,        EBML_NONE },
     { 0 }
 };
 
 static EbmlSyntax matroska_tracks[] = {
     { MATROSKA_ID_TRACKENTRY,         EBML_NEST, sizeof(MatroskaTrack), offsetof(MatroskaDemuxContext,tracks), {.n=matroska_track} },
     { 0 }
 };
 

 static EbmlSyntax matroska_attachment[] = {

     { MATROSKA_ID_FILEUID,            EBML_UINT, 0, offsetof(MatroskaAttachement,uid) },

     { MATROSKA_ID_FILENAME,           EBML_UTF8, 0, offsetof(MatroskaAttachement,filename) },
     { MATROSKA_ID_FILEMIMETYPE,       EBML_STR,  0, offsetof(MatroskaAttachement,mime) },
     { MATROSKA_ID_FILEDATA,           EBML_BIN,  0, offsetof(MatroskaAttachement,bin) },

     { MATROSKA_ID_FILEDESC,           EBML_NONE },

     { 0 }
 };
 
 static EbmlSyntax matroska_attachments[] = {
     { MATROSKA_ID_ATTACHEDFILE,       EBML_NEST, sizeof(MatroskaAttachement), offsetof(MatroskaDemuxContext,attachments), {.n=matroska_attachment} },
     { 0 }
 };
 

 static EbmlSyntax matroska_chapter_display[] = {
     { MATROSKA_ID_CHAPSTRING,         EBML_UTF8, 0, offsetof(MatroskaChapter,title) },

     { MATROSKA_ID_CHAPLANG,           EBML_NONE },

     { 0 }
 };
 
 static EbmlSyntax matroska_chapter_entry[] = {
     { MATROSKA_ID_CHAPTERTIMESTART,   EBML_UINT, 0, offsetof(MatroskaChapter,start), {.u=AV_NOPTS_VALUE} },
     { MATROSKA_ID_CHAPTERTIMEEND,     EBML_UINT, 0, offsetof(MatroskaChapter,end), {.u=AV_NOPTS_VALUE} },
     { MATROSKA_ID_CHAPTERUID,         EBML_UINT, 0, offsetof(MatroskaChapter,uid) },
     { MATROSKA_ID_CHAPTERDISPLAY,     EBML_NEST, 0, 0, {.n=matroska_chapter_display} },
     { MATROSKA_ID_CHAPTERFLAGHIDDEN,  EBML_NONE },

     { MATROSKA_ID_CHAPTERFLAGENABLED, EBML_NONE },
     { MATROSKA_ID_CHAPTERPHYSEQUIV,   EBML_NONE },
     { MATROSKA_ID_CHAPTERATOM,        EBML_NONE },

     { 0 }
 };
 
 static EbmlSyntax matroska_chapter[] = {
     { MATROSKA_ID_CHAPTERATOM,        EBML_NEST, sizeof(MatroskaChapter), offsetof(MatroskaDemuxContext,chapters), {.n=matroska_chapter_entry} },
     { MATROSKA_ID_EDITIONUID,         EBML_NONE },
     { MATROSKA_ID_EDITIONFLAGHIDDEN,  EBML_NONE },
     { MATROSKA_ID_EDITIONFLAGDEFAULT, EBML_NONE },

     { MATROSKA_ID_EDITIONFLAGORDERED, EBML_NONE },

     { 0 }
 };
 
 static EbmlSyntax matroska_chapters[] = {
     { MATROSKA_ID_EDITIONENTRY,       EBML_NEST, 0, 0, {.n=matroska_chapter} },
     { 0 }
 };
 

 static EbmlSyntax matroska_index_pos[] = {
     { MATROSKA_ID_CUETRACK,           EBML_UINT, 0, offsetof(MatroskaIndexPos,track) },
     { MATROSKA_ID_CUECLUSTERPOSITION, EBML_UINT, 0, offsetof(MatroskaIndexPos,pos)   },

     { MATROSKA_ID_CUEBLOCKNUMBER,     EBML_NONE },

     { 0 }
 };
 
 static EbmlSyntax matroska_index_entry[] = {
     { MATROSKA_ID_CUETIME,            EBML_UINT, 0, offsetof(MatroskaIndex,time) },
     { MATROSKA_ID_CUETRACKPOSITION,   EBML_NEST, sizeof(MatroskaIndexPos), offsetof(MatroskaIndex,pos), {.n=matroska_index_pos} },
     { 0 }
 };
 
 static EbmlSyntax matroska_index[] = {
     { MATROSKA_ID_POINTENTRY,         EBML_NEST, sizeof(MatroskaIndex), offsetof(MatroskaDemuxContext,index), {.n=matroska_index_entry} },
     { 0 }
 };
 

 static EbmlSyntax matroska_simpletag[] = {
     { MATROSKA_ID_TAGNAME,            EBML_UTF8, 0, offsetof(MatroskaTag,name) },
     { MATROSKA_ID_TAGSTRING,          EBML_UTF8, 0, offsetof(MatroskaTag,string) },

     { MATROSKA_ID_TAGLANG,            EBML_STR,  0, offsetof(MatroskaTag,lang), {.s="und"} },
     { MATROSKA_ID_TAGDEFAULT,         EBML_UINT, 0, offsetof(MatroskaTag,def) },

     { MATROSKA_ID_TAGDEFAULT_BUG,     EBML_UINT, 0, offsetof(MatroskaTag,def) },

     { MATROSKA_ID_SIMPLETAG,          EBML_NEST, sizeof(MatroskaTag), offsetof(MatroskaTag,sub), {.n=matroska_simpletag} },
     { 0 }
 };
 

 static EbmlSyntax matroska_tagtargets[] = {
     { MATROSKA_ID_TAGTARGETS_TYPE,      EBML_STR,  0, offsetof(MatroskaTagTarget,type) },
     { MATROSKA_ID_TAGTARGETS_TYPEVALUE, EBML_UINT, 0, offsetof(MatroskaTagTarget,typevalue), {.u=50} },
     { MATROSKA_ID_TAGTARGETS_TRACKUID,  EBML_UINT, 0, offsetof(MatroskaTagTarget,trackuid) },
     { MATROSKA_ID_TAGTARGETS_CHAPTERUID,EBML_UINT, 0, offsetof(MatroskaTagTarget,chapteruid) },
     { MATROSKA_ID_TAGTARGETS_ATTACHUID, EBML_UINT, 0, offsetof(MatroskaTagTarget,attachuid) },
     { 0 }
 };
 

 static EbmlSyntax matroska_tag[] = {

     { MATROSKA_ID_SIMPLETAG,          EBML_NEST, sizeof(MatroskaTag), offsetof(MatroskaTags,tag), {.n=matroska_simpletag} },
     { MATROSKA_ID_TAGTARGETS,         EBML_NEST, 0, offsetof(MatroskaTags,target), {.n=matroska_tagtargets} },

     { 0 }
 };
 

 static EbmlSyntax matroska_tags[] = {

     { MATROSKA_ID_TAG,                EBML_NEST, sizeof(MatroskaTags), offsetof(MatroskaDemuxContext,tags), {.n=matroska_tag} },

     { 0 }
 };
 

 static EbmlSyntax matroska_seekhead_entry[] = {
     { MATROSKA_ID_SEEKID,             EBML_UINT, 0, offsetof(MatroskaSeekhead,id) },
     { MATROSKA_ID_SEEKPOSITION,       EBML_UINT, 0, offsetof(MatroskaSeekhead,pos), {.u=-1} },
     { 0 }
 };
 
 static EbmlSyntax matroska_seekhead[] = {
     { MATROSKA_ID_SEEKENTRY,          EBML_NEST, sizeof(MatroskaSeekhead), offsetof(MatroskaDemuxContext,seekhead), {.n=matroska_seekhead_entry} },
     { 0 }
 };
 

 static EbmlSyntax matroska_segment[] = {
     { MATROSKA_ID_INFO,           EBML_NEST, 0, 0, {.n=matroska_info       } },
     { MATROSKA_ID_TRACKS,         EBML_NEST, 0, 0, {.n=matroska_tracks     } },
     { MATROSKA_ID_ATTACHMENTS,    EBML_NEST, 0, 0, {.n=matroska_attachments} },
     { MATROSKA_ID_CHAPTERS,       EBML_NEST, 0, 0, {.n=matroska_chapters   } },
     { MATROSKA_ID_CUES,           EBML_NEST, 0, 0, {.n=matroska_index      } },
     { MATROSKA_ID_TAGS,           EBML_NEST, 0, 0, {.n=matroska_tags       } },
     { MATROSKA_ID_SEEKHEAD,       EBML_NEST, 0, 0, {.n=matroska_seekhead   } },

     { MATROSKA_ID_CLUSTER,        EBML_STOP },

     { 0 }
 };
 
 static EbmlSyntax matroska_segments[] = {
     { MATROSKA_ID_SEGMENT,        EBML_NEST, 0, 0, {.n=matroska_segment    } },
     { 0 }
 };
 

 static EbmlSyntax matroska_blockmore[] = {
     { MATROSKA_ID_BLOCKADDID,      EBML_UINT, 0, offsetof(MatroskaBlock,additional_id) },
     { MATROSKA_ID_BLOCKADDITIONAL, EBML_BIN,  0, offsetof(MatroskaBlock,additional) },
     { 0 }
 };
 
 static EbmlSyntax matroska_blockadditions[] = {
     { MATROSKA_ID_BLOCKMORE, EBML_NEST, 0, 0, {.n=matroska_blockmore} },
     { 0 }
 };
 

 static EbmlSyntax matroska_blockgroup[] = {
     { MATROSKA_ID_BLOCK,          EBML_BIN,  0, offsetof(MatroskaBlock,bin) },

     { MATROSKA_ID_BLOCKADDITIONS, EBML_NEST, 0, 0, {.n=matroska_blockadditions} },

     { MATROSKA_ID_SIMPLEBLOCK,    EBML_BIN,  0, offsetof(MatroskaBlock,bin) },

     { MATROSKA_ID_BLOCKDURATION,  EBML_UINT, 0, offsetof(MatroskaBlock,duration) },

     { MATROSKA_ID_BLOCKREFERENCE, EBML_UINT, 0, offsetof(MatroskaBlock,reference) },

     { 1,                          EBML_UINT, 0, offsetof(MatroskaBlock,non_simple), {.u=1} },

     { 0 }
 };
 
 static EbmlSyntax matroska_cluster[] = {
     { MATROSKA_ID_CLUSTERTIMECODE,EBML_UINT,0, offsetof(MatroskaCluster,timecode) },
     { MATROSKA_ID_BLOCKGROUP,     EBML_NEST, sizeof(MatroskaBlock), offsetof(MatroskaCluster,blocks), {.n=matroska_blockgroup} },
     { MATROSKA_ID_SIMPLEBLOCK,    EBML_PASS, sizeof(MatroskaBlock), offsetof(MatroskaCluster,blocks), {.n=matroska_blockgroup} },

     { MATROSKA_ID_CLUSTERPOSITION,EBML_NONE },
     { MATROSKA_ID_CLUSTERPREVSIZE,EBML_NONE },

     { 0 }
 };
 
 static EbmlSyntax matroska_clusters[] = {
     { MATROSKA_ID_CLUSTER,        EBML_NEST, 0, 0, {.n=matroska_cluster} },

     { MATROSKA_ID_INFO,           EBML_NONE },
     { MATROSKA_ID_CUES,           EBML_NONE },
     { MATROSKA_ID_TAGS,           EBML_NONE },
     { MATROSKA_ID_SEEKHEAD,       EBML_NONE },

     { 0 }
 };
 

 static EbmlSyntax matroska_cluster_incremental_parsing[] = {
     { MATROSKA_ID_CLUSTERTIMECODE,EBML_UINT,0, offsetof(MatroskaCluster,timecode) },
     { MATROSKA_ID_BLOCKGROUP,     EBML_NEST, sizeof(MatroskaBlock), offsetof(MatroskaCluster,blocks), {.n=matroska_blockgroup} },
     { MATROSKA_ID_SIMPLEBLOCK,    EBML_PASS, sizeof(MatroskaBlock), offsetof(MatroskaCluster,blocks), {.n=matroska_blockgroup} },
     { MATROSKA_ID_CLUSTERPOSITION,EBML_NONE },
     { MATROSKA_ID_CLUSTERPREVSIZE,EBML_NONE },
     { MATROSKA_ID_INFO,           EBML_NONE },
     { MATROSKA_ID_CUES,           EBML_NONE },
     { MATROSKA_ID_TAGS,           EBML_NONE },
     { MATROSKA_ID_SEEKHEAD,       EBML_NONE },
     { MATROSKA_ID_CLUSTER,        EBML_STOP },
     { 0 }
 };
 
 static EbmlSyntax matroska_cluster_incremental[] = {
     { MATROSKA_ID_CLUSTERTIMECODE,EBML_UINT,0, offsetof(MatroskaCluster,timecode) },
     { MATROSKA_ID_BLOCKGROUP,     EBML_STOP },
     { MATROSKA_ID_SIMPLEBLOCK,    EBML_STOP },
     { MATROSKA_ID_CLUSTERPOSITION,EBML_NONE },
     { MATROSKA_ID_CLUSTERPREVSIZE,EBML_NONE },
     { 0 }
 };
 
 static EbmlSyntax matroska_clusters_incremental[] = {
     { MATROSKA_ID_CLUSTER,        EBML_NEST, 0, 0, {.n=matroska_cluster_incremental} },
     { MATROSKA_ID_INFO,           EBML_NONE },
     { MATROSKA_ID_CUES,           EBML_NONE },
     { MATROSKA_ID_TAGS,           EBML_NONE },
     { MATROSKA_ID_SEEKHEAD,       EBML_NONE },
     { 0 }
 };
 

 static const char *const matroska_doctypes[] = { "matroska", "webm" };

 static int matroska_resync(MatroskaDemuxContext *matroska, int64_t last_pos)
 {
     AVIOContext *pb = matroska->ctx->pb;
     uint32_t id;
     matroska->current_id = 0;
     matroska->num_levels = 0;
 
     // seek to next position to resync from
     if (avio_seek(pb, last_pos + 1, SEEK_SET) < 0 || avio_tell(pb) <= last_pos)
         goto eof;
 
     id = avio_rb32(pb);
 
     // try to find a toplevel element
     while (!url_feof(pb)) {
         if (id == MATROSKA_ID_INFO || id == MATROSKA_ID_TRACKS ||
             id == MATROSKA_ID_CUES || id == MATROSKA_ID_TAGS ||
             id == MATROSKA_ID_SEEKHEAD || id == MATROSKA_ID_ATTACHMENTS ||
             id == MATROSKA_ID_CLUSTER || id == MATROSKA_ID_CHAPTERS)
         {
             matroska->current_id = id;
             return 0;
         }
         id = (id << 8) | avio_r8(pb);
     }
 eof:
     matroska->done = 1;
     return AVERROR_EOF;
 }
 

 /*

  * Return: Whether we reached the end of a level in the hierarchy or not.

  */

 static int ebml_level_end(MatroskaDemuxContext *matroska)

 {

     AVIOContext *pb = matroska->ctx->pb;

     int64_t pos = avio_tell(pb);

     if (matroska->num_levels > 0) {

         MatroskaLevel *level = &matroska->levels[matroska->num_levels - 1];

         if (pos - level->start >= level->length || matroska->current_id) {

             matroska->num_levels--;

             return 1;

         }
     }

     return 0;

 }
 
 /*
  * 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: number of bytes read, < 0 on error

  */

 static int ebml_read_num(MatroskaDemuxContext *matroska, AVIOContext *pb,

                          int max_size, uint64_t *number)

 {

     int read = 1, n = 1;
     uint64_t total = 0;

     /* The first byte tells us the length in bytes - avio_r8() 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 = avio_r8(pb))) {

         /* we might encounter EOS here */
         if (!url_feof(pb)) {

             int64_t pos = avio_tell(pb);

             av_log(matroska->ctx, AV_LOG_ERROR,
                    "Read error at pos. %"PRIu64" (0x%"PRIx64")\n",
                    pos, pos);

             return pb->error ? pb->error : AVERROR(EIO);

         }

         return AVERROR_EOF;

     }
 
     /* get the length of the EBML number */

     read = 8 - ff_log2_tab[total];

     if (read > max_size) {

         int64_t pos = avio_tell(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 ^= 1 << ff_log2_tab[total];

     while (n++ < read)

         total = (total << 8) | avio_r8(pb);

 
     *number = total;
 
     return read;
 }
 

 /**
  * Read a EBML length value.
  * This needs special handling for the "unknown length" case which has multiple
  * encodings.
  */

 static int ebml_read_length(MatroskaDemuxContext *matroska, AVIOContext *pb,

                             uint64_t *number)
 {
     int res = ebml_read_num(matroska, pb, 8, number);
     if (res > 0 && *number + 1 == 1ULL << (7 * res))
         *number = 0xffffffffffffffULL;
     return res;
 }
 

 /*
  * Read the next element as an unsigned int.
  * 0 is success, < 0 is failure.
  */

 static int ebml_read_uint(AVIOContext *pb, int size, uint64_t *num)

 {

     int n = 0;

     if (size > 8)

         return AVERROR_INVALIDDATA;
 

     /* big-endian ordering; build up number */

     *num = 0;
     while (n++ < size)

         *num = (*num << 8) | avio_r8(pb);

 
     return 0;
 }
 
 /*
  * Read the next element as a float.
  * 0 is success, < 0 is failure.
  */

 static int ebml_read_float(AVIOContext *pb, int size, double *num)

 {

     if (size == 0) {
         *num = 0;
     } else if (size == 4) {

         *num = av_int2float(avio_rb32(pb));
     } else if (size == 8){
         *num = av_int2double(avio_rb64(pb));

     } else

         return AVERROR_INVALIDDATA;
 
     return 0;
 }
 
 /*
  * Read the next element as an ASCII string.
  * 0 is success, < 0 is failure.
  */

 static int ebml_read_ascii(AVIOContext *pb, int size, char **str)

 {

     char *res;
 

     /* EBML strings are usually not 0-terminated, so we allocate one

      * byte more, read the string and NULL-terminate it ourselves. */

     if (!(res = av_malloc(size + 1)))

         return AVERROR(ENOMEM);

     if (avio_read(pb, (uint8_t *) res, size) != size) {
         av_free(res);

         return AVERROR(EIO);

     }

     (res)[size] = '\0';
     av_free(*str);
     *str = res;

 
     return 0;
 }
 
 /*

  * Read the next element as binary data.
  * 0 is success, < 0 is failure.
  */

 static int ebml_read_binary(AVIOContext *pb, int length, EbmlBin *bin)

 {

     av_fast_padded_malloc(&bin->data, &bin->size, length);
     if (!bin->data)

         return AVERROR(ENOMEM);
 
     bin->size = length;

     bin->pos  = avio_tell(pb);

     if (avio_read(pb, bin->data, length) != length) {

         av_freep(&bin->data);

         bin->size = 0;

         return AVERROR(EIO);

     }

 
     return 0;
 }
 
 /*

  * 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, uint64_t length)

 {

     AVIOContext *pb = matroska->ctx->pb;

     MatroskaLevel *level;
 
     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(ENOSYS);

     }
 
     level = &matroska->levels[matroska->num_levels++];

     level->start = avio_tell(pb);

     level->length = length;
 
     return 0;
 }
 
 /*
  * Read signed/unsigned "EBML" numbers.

  * Return: number of bytes processed, < 0 on error

  */

 static int matroska_ebmlnum_uint(MatroskaDemuxContext *matroska,
                                  uint8_t *data, uint32_t size, uint64_t *num)

 {

     AVIOContext pb;

     ffio_init_context(&pb, data, size, 0, NULL, NULL, NULL, NULL);

     return ebml_read_num(matroska, &pb, FFMIN(size, 8), num);

 }
 
 /*
  * Same as above, but signed.
  */

 static int matroska_ebmlnum_sint(MatroskaDemuxContext *matroska,
                                  uint8_t *data, uint32_t size, int64_t *num)

 {
     uint64_t unum;
     int res;
 
     /* read as unsigned number first */

     if ((res = matroska_ebmlnum_uint(matroska, data, size, &unum)) < 0)

         return res;
 
     /* make signed (weird way) */

     *num = unum - ((1LL << (7*res - 1)) - 1);

 
     return res;
 }
 

 static int ebml_parse_elem(MatroskaDemuxContext *matroska,
                            EbmlSyntax *syntax, void *data);

 static int ebml_parse_id(MatroskaDemuxContext *matroska, EbmlSyntax *syntax,
                          uint32_t id, void *data)

 {
     int i;

     for (i=0; syntax[i].id; i++)
         if (id == syntax[i].id)
             break;

     if (!syntax[i].id && id == MATROSKA_ID_CLUSTER &&
         matroska->num_levels > 0 &&

         matroska->levels[matroska->num_levels-1].length == 0xffffffffffffff)

         return 0;  // we reached the end of an unknown size cluster

     if (!syntax[i].id && id != EBML_ID_VOID && id != EBML_ID_CRC32) {

         av_log(matroska->ctx, AV_LOG_INFO, "Unknown entry 0x%X\n", id);

         if (matroska->ctx->error_recognition & AV_EF_EXPLODE)
             return AVERROR_INVALIDDATA;
     }

     return ebml_parse_elem(matroska, &syntax[i], data);

 }
 

 static int ebml_parse(MatroskaDemuxContext *matroska, EbmlSyntax *syntax,
                       void *data)

 {

     if (!matroska->current_id) {

         uint64_t id;
         int res = ebml_read_num(matroska, matroska->ctx->pb, 4, &id);
         if (res < 0)
             return res;
         matroska->current_id = id | 1 << 7*res;

     }
     return ebml_parse_id(matroska, syntax, matroska->current_id, data);

 }
 

 static int ebml_parse_nest(MatroskaDemuxContext *matroska, EbmlSyntax *syntax,
                            void *data)

 {

     int i, res = 0;

     for (i=0; syntax[i].id; i++)
         switch (syntax[i].type) {
         case EBML_UINT:
             *(uint64_t *)((char *)data+syntax[i].data_offset) = syntax[i].def.u;
             break;
         case EBML_FLOAT:
             *(double   *)((char *)data+syntax[i].data_offset) = syntax[i].def.f;
             break;
         case EBML_STR:
         case EBML_UTF8:
             *(char    **)((char *)data+syntax[i].data_offset) = av_strdup(syntax[i].def.s);
             break;

         }

     while (!res && !ebml_level_end(matroska))
         res = ebml_parse(matroska, syntax, data);

     return res;

 }
 

 static int ebml_parse_elem(MatroskaDemuxContext *matroska,
                            EbmlSyntax *syntax, void *data)
 {

     static const uint64_t max_lengths[EBML_TYPE_COUNT] = {
         [EBML_UINT]  = 8,
         [EBML_FLOAT] = 8,
         // max. 16 MB for strings
         [EBML_STR]   = 0x1000000,
         [EBML_UTF8]  = 0x1000000,
         // max. 256 MB for binary data
         [EBML_BIN]   = 0x10000000,
         // no limits for anything else
     };

     AVIOContext *pb = matroska->ctx->pb;

     uint32_t id = syntax->id;

     uint64_t length;

     int res;

     void *newelem;

 
     data = (char *)data + syntax->data_offset;
     if (syntax->list_elem_size) {
         EbmlList *list = data;

         newelem = av_realloc(list->elem, (list->nb_elem+1)*syntax->list_elem_size);
         if (!newelem)
             return AVERROR(ENOMEM);
         list->elem = newelem;

         data = (char*)list->elem + list->nb_elem*syntax->list_elem_size;
         memset(data, 0, syntax->list_elem_size);
         list->nb_elem++;
     }
 

     if (syntax->type != EBML_PASS && syntax->type != EBML_STOP) {
         matroska->current_id = 0;

         if ((res = ebml_read_length(matroska, pb, &length)) < 0)

             return res;

         if (max_lengths[syntax->type] && length > max_lengths[syntax->type]) {
             av_log(matroska->ctx, AV_LOG_ERROR,
                    "Invalid length 0x%"PRIx64" > 0x%"PRIx64" for syntax element %i\n",
                    length, max_lengths[syntax->type], syntax->type);
             return AVERROR_INVALIDDATA;
         }

     }

     switch (syntax->type) {

     case EBML_UINT:  res = ebml_read_uint  (pb, length, data);  break;
     case EBML_FLOAT: res = ebml_read_float (pb, length, data);  break;

     case EBML_STR:

     case EBML_UTF8:  res = ebml_read_ascii (pb, length, data);  break;

     case EBML_BIN:   res = ebml_read_binary(pb, length, data);  break;

     case EBML_NEST:  if ((res=ebml_read_master(matroska, length)) < 0)

                          return res;
                      if (id == MATROSKA_ID_SEGMENT)

                          matroska->segment_start = avio_tell(matroska->ctx->pb);

                      return ebml_parse_nest(matroska, syntax->def.n, data);

     case EBML_PASS:  return ebml_parse_id(matroska, syntax->def.n, id, data);

     case EBML_STOP:  return 1;

     default:
         if(ffio_limit(pb, length) != length)
             return AVERROR(EIO);
         return avio_skip(pb,length)<0 ? AVERROR(EIO) : 0;

     }

     if (res == AVERROR_INVALIDDATA)
         av_log(matroska->ctx, AV_LOG_ERROR, "Invalid element\n");
     else if (res == AVERROR(EIO))
         av_log(matroska->ctx, AV_LOG_ERROR, "Read error\n");
     return res;

 }
 
 static void ebml_free(EbmlSyntax *syntax, void *data)
 {
     int i, j;
     for (i=0; syntax[i].id; i++) {
         void *data_off = (char *)data + syntax[i].data_offset;
         switch (syntax[i].type) {
         case EBML_STR:
         case EBML_UTF8:  av_freep(data_off);                      break;
         case EBML_BIN:   av_freep(&((EbmlBin *)data_off)->data);  break;
         case EBML_NEST:
             if (syntax[i].list_elem_size) {
                 EbmlList *list = data_off;
                 char *ptr = list->elem;
                 for (j=0; j<list->nb_elem; j++, ptr+=syntax[i].list_elem_size)
                     ebml_free(syntax[i].def.n, ptr);
                 av_free(list->elem);
             } else
                 ebml_free(syntax[i].def.n, data_off);
         default:  break;
         }
     }
 }
 

 
 /*
  * Autodetecting...
  */
 static int matroska_probe(AVProbeData *p)
 {
     uint64_t total = 0;

     int len_mask = 0x80, size = 1, n = 1, i;

     /* EBML header? */

     if (AV_RB32(p->buf) != 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 should contain a known document type. 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 (i = 0; i < FF_ARRAY_ELEMS(matroska_doctypes); i++) {
         int probelen = strlen(matroska_doctypes[i]);

         if (total < probelen)
             continue;

         for (n = 4+size; n <= 4+size+total-probelen; n++)
             if (!memcmp(p->buf+n, matroska_doctypes[i], probelen))
                 return AVPROBE_SCORE_MAX;
     }

     // probably valid EBML header but no recognized doctype
     return AVPROBE_SCORE_MAX/2;

 }
 
 static MatroskaTrack *matroska_find_track_by_num(MatroskaDemuxContext *matroska,
                                                  int num)
 {
     MatroskaTrack *tracks = matroska->tracks.elem;
     int i;
 
     for (i=0; i < matroska->tracks.nb_elem; i++)
         if (tracks[i].num == num)
             return &tracks[i];
 
     av_log(matroska->ctx, AV_LOG_ERROR, "Invalid track number %d\n", num);
     return NULL;
 }
 

 static int matroska_decode_buffer(uint8_t** buf, int* buf_size,
                                   MatroskaTrack *track)

 {

     MatroskaTrackEncoding *encodings = track->encodings.elem;

     uint8_t* data = *buf;
     int isize = *buf_size;
     uint8_t* pkt_data = NULL;

     uint8_t av_unused *newpktdata;

     int pkt_size = isize;
     int result = 0;
     int olen;
 

     if (pkt_size >= 10000000U)

         return AVERROR_INVALIDDATA;

     switch (encodings[0].compression.algo) {

     case MATROSKA_TRACK_ENCODING_COMP_HEADERSTRIP: {
         int header_size = encodings[0].compression.settings.size;
         uint8_t *header = encodings[0].compression.settings.data;
 

         if (header_size && !header) {

             av_log(NULL, AV_LOG_ERROR, "Compression size but no data in headerstrip\n");

             return -1;
         }

         if (!header_size)
             return 0;
 
         pkt_size = isize + header_size;
         pkt_data = av_malloc(pkt_size);
         if (!pkt_data)
             return AVERROR(ENOMEM);
 
         memcpy(pkt_data, header, header_size);
         memcpy(pkt_data + header_size, data, isize);
         break;
     }

 #if CONFIG_LZO

     case MATROSKA_TRACK_ENCODING_COMP_LZO:
         do {
             olen = pkt_size *= 3;

             newpktdata = av_realloc(pkt_data, pkt_size + AV_LZO_OUTPUT_PADDING);
             if (!newpktdata) {

                 result = AVERROR(ENOMEM);

                 goto failed;
             }
             pkt_data = newpktdata;

             result = av_lzo1x_decode(pkt_data, &olen, data, &isize);
         } while (result==AV_LZO_OUTPUT_FULL && pkt_size<10000000);

         if (result) {
             result = AVERROR_INVALIDDATA;

             goto failed;

         }

         pkt_size -= olen;
         break;

 #endif

 #if CONFIG_ZLIB

     case MATROSKA_TRACK_ENCODING_COMP_ZLIB: {
         z_stream zstream = {0};
         if (inflateInit(&zstream) != Z_OK)
             return -1;
         zstream.next_in = data;
         zstream.avail_in = isize;
         do {
             pkt_size *= 3;

             newpktdata = av_realloc(pkt_data, pkt_size);
             if (!newpktdata) {
                 inflateEnd(&zstream);
                 goto failed;
             }
             pkt_data = newpktdata;

             zstream.avail_out = pkt_size - zstream.total_out;
             zstream.next_out = pkt_data + zstream.total_out;

             if (pkt_data) {
                 result = inflate(&zstream, Z_NO_FLUSH);
             } else
                 result = Z_MEM_ERROR;

         } while (result==Z_OK && pkt_size<10000000);
         pkt_size = zstream.total_out;
         inflateEnd(&zstream);

         if (result != Z_STREAM_END) {
             if (result == Z_MEM_ERROR)
                 result = AVERROR(ENOMEM);
             else
                 result = AVERROR_INVALIDDATA;

             goto failed;

         }

         break;
     }
 #endif

 #if CONFIG_BZLIB

     case MATROSKA_TRACK_ENCODING_COMP_BZLIB: {
         bz_stream bzstream = {0};
         if (BZ2_bzDecompressInit(&bzstream, 0, 0) != BZ_OK)
             return -1;
         bzstream.next_in = data;
         bzstream.avail_in = isize;
         do {
             pkt_size *= 3;

             newpktdata = av_realloc(pkt_data, pkt_size);
             if (!newpktdata) {
                 BZ2_bzDecompressEnd(&bzstream);
                 goto failed;
             }
             pkt_data = newpktdata;

             bzstream.avail_out = pkt_size - bzstream.total_out_lo32;
             bzstream.next_out = pkt_data + bzstream.total_out_lo32;

             if (pkt_data) {
                 result = BZ2_bzDecompress(&bzstream);
             } else
                 result = BZ_MEM_ERROR;

         } while (result==BZ_OK && pkt_size<10000000);
         pkt_size = bzstream.total_out_lo32;
         BZ2_bzDecompressEnd(&bzstream);

         if (result != BZ_STREAM_END) {
             if (result == BZ_MEM_ERROR)
                 result = AVERROR(ENOMEM);
             else
                 result = AVERROR_INVALIDDATA;

             goto failed;

         }

         break;
     }
 #endif

     default:

         return AVERROR_INVALIDDATA;

     }
 
     *buf = pkt_data;
     *buf_size = pkt_size;
     return 0;
  failed:
     av_free(pkt_data);

     return result;

 }
 

 static void matroska_fix_ass_packet(MatroskaDemuxContext *matroska,

                                     AVPacket *pkt, uint64_t display_duration)

 {
     char *line, *layer, *ptr = pkt->data, *end = ptr+pkt->size;
     for (; *ptr!=',' && ptr<end-1; ptr++);
     if (*ptr == ',')

         ptr++;
     layer = ptr;

     for (; *ptr!=',' && ptr<end-1; ptr++);
     if (*ptr == ',') {

         int64_t end_pts = pkt->pts + display_duration;

         int sc = matroska->time_scale * pkt->pts / 10000000;
         int ec = matroska->time_scale * end_pts  / 10000000;
         int sh, sm, ss, eh, em, es, len;
         sh = sc/360000;  sc -= 360000*sh;
         sm = sc/  6000;  sc -=   6000*sm;
         ss = sc/   100;  sc -=    100*ss;
         eh = ec/360000;  ec -= 360000*eh;
         em = ec/  6000;  ec -=   6000*em;
         es = ec/   100;  ec -=    100*es;
         *ptr++ = '\0';
         len = 50 + end-ptr + FF_INPUT_BUFFER_PADDING_SIZE;
         if (!(line = av_malloc(len)))
             return;

         snprintf(line,len,"Dialogue: %s,%d:%02d:%02d.%02d,%d:%02d:%02d.%02d,%s\r\n",

                  layer, sh, sm, ss, sc, eh, em, es, ec, ptr);
         av_free(pkt->data);
         pkt->data = line;
         pkt->size = strlen(line);
     }
 }
 

 static int matroska_merge_packets(AVPacket *out, AVPacket *in)

 {

     int ret = av_grow_packet(out, in->size);
     if (ret < 0)
         return ret;

     memcpy(out->data + out->size - in->size, in->data, in->size);

 
     av_free_packet(in);

     av_free(in);

     return 0;

 }
 

 static void matroska_convert_tag(AVFormatContext *s, EbmlList *list,

                                  AVDictionary **metadata, char *prefix)

 {
     MatroskaTag *tags = list->elem;

     char key[1024];
     int i;

 
     for (i=0; i < list->nb_elem; i++) {

         const char *lang= (tags[i].lang && strcmp(tags[i].lang, "und")) ? tags[i].lang : NULL;

 
         if (!tags[i].name) {
             av_log(s, AV_LOG_WARNING, "Skipping invalid tag with no TagName.\n");
             continue;
         }

         if (prefix)  snprintf(key, sizeof(key), "%s/%s", prefix, tags[i].name);
         else         av_strlcpy(key, tags[i].name, sizeof(key));

         if (tags[i].def || !lang) {

         av_dict_set(metadata, key, tags[i].string, 0);

         if (tags[i].sub.nb_elem)

             matroska_convert_tag(s, &tags[i].sub, metadata, key);

         }
         if (lang) {
             av_strlcat(key, "-", sizeof(key));
             av_strlcat(key, lang, sizeof(key));

             av_dict_set(metadata, key, tags[i].string, 0);

             if (tags[i].sub.nb_elem)
                 matroska_convert_tag(s, &tags[i].sub, metadata, key);
         }

     }

     ff_metadata_conv(metadata, NULL, ff_mkv_metadata_conv);

 }
 
 static void matroska_convert_tags(AVFormatContext *s)
 {
     MatroskaDemuxContext *matroska = s->priv_data;
     MatroskaTags *tags = matroska->tags.elem;
     int i, j;
 
     for (i=0; i < matroska->tags.nb_elem; i++) {
         if (tags[i].target.attachuid) {
             MatroskaAttachement *attachment = matroska->attachments.elem;
             for (j=0; j<matroska->attachments.nb_elem; j++)

                 if (attachment[j].uid == tags[i].target.attachuid
                     && attachment[j].stream)

                     matroska_convert_tag(s, &tags[i].tag,
                                          &attachment[j].stream->metadata, NULL);
         } else if (tags[i].target.chapteruid) {
             MatroskaChapter *chapter = matroska->chapters.elem;
             for (j=0; j<matroska->chapters.nb_elem; j++)

                 if (chapter[j].uid == tags[i].target.chapteruid
                     && chapter[j].chapter)

                     matroska_convert_tag(s, &tags[i].tag,
                                          &chapter[j].chapter->metadata, NULL);
         } else if (tags[i].target.trackuid) {
             MatroskaTrack *track = matroska->tracks.elem;
             for (j=0; j<matroska->tracks.nb_elem; j++)

                 if (track[j].uid == tags[i].target.trackuid && track[j].stream)

                     matroska_convert_tag(s, &tags[i].tag,
                                          &track[j].stream->metadata, NULL);
         } else {

             matroska_convert_tag(s, &tags[i].tag, &s->metadata,
                                  tags[i].target.type);

         }

     }
 }
 

 static int matroska_parse_seekhead_entry(MatroskaDemuxContext *matroska, int idx)

 {
     EbmlList *seekhead_list = &matroska->seekhead;
     MatroskaSeekhead *seekhead = seekhead_list->elem;
     uint32_t level_up = matroska->level_up;

     int64_t before_pos = avio_tell(matroska->ctx->pb);

     uint32_t saved_id = matroska->current_id;

     MatroskaLevel level;

     int64_t offset;
     int ret = 0;

     if (idx >= seekhead_list->nb_elem
             || seekhead[idx].id == MATROSKA_ID_SEEKHEAD
             || seekhead[idx].id == MATROSKA_ID_CLUSTER)
         return 0;

     /* seek */

     offset = seekhead[idx].pos + matroska->segment_start;
     if (avio_seek(matroska->ctx->pb, offset, SEEK_SET) == offset) {

         /* 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);

             ret = AVERROR_INVALIDDATA;
         } else {

             level.start = 0;
             level.length = (uint64_t)-1;
             matroska->levels[matroska->num_levels] = level;
             matroska->num_levels++;
             matroska->current_id = 0;
 

             ret = ebml_parse(matroska, matroska_segment, matroska);

 
             /* remove dummy level */
             while (matroska->num_levels) {
                 uint64_t length = matroska->levels[--matroska->num_levels].length;
                 if (length == (uint64_t)-1)
                     break;
             }

         }

     }

     /* seek back */

     avio_seek(matroska->ctx->pb, before_pos, SEEK_SET);

     matroska->level_up = level_up;

     matroska->current_id = saved_id;

 
     return ret;
 }
 
 static void matroska_execute_seekhead(MatroskaDemuxContext *matroska)
 {
     EbmlList *seekhead_list = &matroska->seekhead;
     int64_t before_pos = avio_tell(matroska->ctx->pb);

     int i;

     // we should not do any seeking in the streaming case

     if (!matroska->ctx->pb->seekable ||

         (matroska->ctx->flags & AVFMT_FLAG_IGNIDX))
         return;
 

     for (i = 0; i < seekhead_list->nb_elem; i++) {

         MatroskaSeekhead *seekhead = seekhead_list->elem;

         if (seekhead[i].pos <= before_pos)

             continue;

         // defer cues parsing until we actually need cue data.
         if (seekhead[i].id == MATROSKA_ID_CUES) {
             matroska->cues_parsing_deferred = 1;

             continue;

         }

         if (matroska_parse_seekhead_entry(matroska, i) < 0) {
             // mark index as broken
             matroska->cues_parsing_deferred = -1;

             break;

         }

     }
 }

 static void matroska_add_index_entries(MatroskaDemuxContext *matroska) {

     EbmlList *index_list;
     MatroskaIndex *index;
     int index_scale = 1;
     int i, j;

     index_list = &matroska->index;
     index = index_list->elem;
     if (index_list->nb_elem
         && index[0].time > 1E14/matroska->time_scale) {
         av_log(matroska->ctx, AV_LOG_WARNING, "Working around broken index.\n");
         index_scale = matroska->time_scale;
     }
     for (i = 0; i < index_list->nb_elem; i++) {
         EbmlList *pos_list = &index[i].pos;
         MatroskaIndexPos *pos = pos_list->elem;
         for (j = 0; j < pos_list->nb_elem; j++) {
             MatroskaTrack *track = matroska_find_track_by_num(matroska, pos[j].track);
             if (track && track->stream)
                 av_add_index_entry(track->stream,
                                    pos[j].pos + matroska->segment_start,
                                    index[i].time/index_scale, 0, 0,
                                    AVINDEX_KEYFRAME);

         }

     }

 }
 

 static void matroska_parse_cues(MatroskaDemuxContext *matroska) {
     EbmlList *seekhead_list = &matroska->seekhead;
     MatroskaSeekhead *seekhead = seekhead_list->elem;
     int i;
 
     for (i = 0; i < seekhead_list->nb_elem; i++)
         if (seekhead[i].id == MATROSKA_ID_CUES)
             break;
     assert(i <= seekhead_list->nb_elem);
 

     if (matroska_parse_seekhead_entry(matroska, i) < 0)
        matroska->cues_parsing_deferred = -1;

     matroska_add_index_entries(matroska);
 }
 

 static int matroska_aac_profile(char *codec_id)

 {

     static const char * const aac_profiles[] = { "MAIN", "LC", "SSR" };

     int profile;
 

     for (profile=0; profile<FF_ARRAY_ELEMS(aac_profiles); profile++)

         if (strstr(codec_id, aac_profiles[profile]))
             break;
     return profile + 1;
 }
 

 static int matroska_aac_sri(int samplerate)

 {
     int sri;
 

     for (sri=0; sri<FF_ARRAY_ELEMS(avpriv_mpeg4audio_sample_rates); sri++)
         if (avpriv_mpeg4audio_sample_rates[sri] == samplerate)

             break;
     return sri;
 }
 

 static void matroska_metadata_creation_time(AVDictionary **metadata, int64_t date_utc)
 {
     char buffer[32];
     /* Convert to seconds and adjust by number of seconds between 2001-01-01 and Epoch */
     time_t creation_time = date_utc / 1000000000 + 978307200;
     struct tm *ptm = gmtime(&creation_time);
     if (!ptm) return;
     strftime(buffer, sizeof(buffer), "%Y-%m-%d %H:%M:%S", ptm);
     av_dict_set(metadata, "creation_time", buffer, 0);
 }
 

 static int matroska_read_header(AVFormatContext *s)

 {
     MatroskaDemuxContext *matroska = s->priv_data;

     EbmlList *attachements_list = &matroska->attachments;
     MatroskaAttachement *attachements;
     EbmlList *chapters_list = &matroska->chapters;
     MatroskaChapter *chapters;

     MatroskaTrack *tracks;

     uint64_t max_start = 0;

     int64_t pos;

     Ebml ebml = { 0 };

     AVStream *st;

     int i, j, k, res;

 
     matroska->ctx = s;
 
     /* First read the EBML header. */

     if (ebml_parse(matroska, ebml_syntax, &ebml)

         || ebml.version > EBML_VERSION       || ebml.max_size > sizeof(uint64_t)

         || ebml.id_length > sizeof(uint32_t) || ebml.doctype_version > 3 || !ebml.doctype) {

         av_log(matroska->ctx, AV_LOG_ERROR,

                "EBML header using unsupported features\n"
                "(EBML version %"PRIu64", doctype %s, doc version %"PRIu64")\n",
                ebml.version, ebml.doctype, ebml.doctype_version);

         ebml_free(ebml_syntax, &ebml);
         return AVERROR_PATCHWELCOME;

     } else if (ebml.doctype_version == 3) {
         av_log(matroska->ctx, AV_LOG_WARNING,
                "EBML header using unsupported features\n"
                "(EBML version %"PRIu64", doctype %s, doc version %"PRIu64")\n",
                ebml.version, ebml.doctype, ebml.doctype_version);

     }
     for (i = 0; i < FF_ARRAY_ELEMS(matroska_doctypes); i++)
         if (!strcmp(ebml.doctype, matroska_doctypes[i]))
             break;
     if (i >= FF_ARRAY_ELEMS(matroska_doctypes)) {

         av_log(s, AV_LOG_WARNING, "Unknown EBML doctype '%s'\n", ebml.doctype);

         if (matroska->ctx->error_recognition & AV_EF_EXPLODE) {
             ebml_free(ebml_syntax, &ebml);
             return AVERROR_INVALIDDATA;
         }

     }

     ebml_free(ebml_syntax, &ebml);

 
     /* The next thing is a segment. */

     pos = avio_tell(matroska->ctx->pb);
     res = ebml_parse(matroska, matroska_segments, matroska);
     // try resyncing until we find a EBML_STOP type element.
     while (res != 1) {
         res = matroska_resync(matroska, pos);
         if (res < 0)
             return res;
         pos = avio_tell(matroska->ctx->pb);
         res = ebml_parse(matroska, matroska_segment, matroska);
     }

     matroska_execute_seekhead(matroska);

     if (!matroska->time_scale)
         matroska->time_scale = 1000000;

     if (matroska->duration)
         matroska->ctx->duration = matroska->duration * matroska->time_scale
                                   * 1000 / AV_TIME_BASE;

     av_dict_set(&s->metadata, "title", matroska->title, 0);

     if (matroska->date_utc.size == 8)
         matroska_metadata_creation_time(&s->metadata, AV_RB64(matroska->date_utc.data));
 

     tracks = matroska->tracks.elem;
     for (i=0; i < matroska->tracks.nb_elem; i++) {
         MatroskaTrack *track = &tracks[i];

         enum AVCodecID codec_id = AV_CODEC_ID_NONE;

         EbmlList *encodings_list = &track->encodings;

         MatroskaTrackEncoding *encodings = encodings_list->elem;

         uint8_t *extradata = NULL;
         int extradata_size = 0;
         int extradata_offset = 0;

         uint32_t fourcc = 0;

         AVIOContext b;

 
         /* Apply some sanity checks. */

         if (track->type != MATROSKA_TRACK_TYPE_VIDEO &&
             track->type != MATROSKA_TRACK_TYPE_AUDIO &&
             track->type != MATROSKA_TRACK_TYPE_SUBTITLE) {
             av_log(matroska->ctx, AV_LOG_INFO,
                    "Unknown or unsupported track type %"PRIu64"\n",
                    track->type);
             continue;
         }

         if (track->codec_id == NULL)
             continue;
 

         if (track->type == MATROSKA_TRACK_TYPE_VIDEO) {

             if (!track->default_duration && track->video.frame_rate > 0)

                 track->default_duration = 1000000000/track->video.frame_rate;
             if (!track->video.display_width)
                 track->video.display_width = track->video.pixel_width;
             if (!track->video.display_height)
                 track->video.display_height = track->video.pixel_height;

             if (track->video.color_space.size == 4)
                 fourcc = AV_RL32(track->video.color_space.data);

         } else if (track->type == MATROSKA_TRACK_TYPE_AUDIO) {
             if (!track->audio.out_samplerate)
                 track->audio.out_samplerate = track->audio.samplerate;
         }
         if (encodings_list->nb_elem > 1) {
             av_log(matroska->ctx, AV_LOG_ERROR,

                    "Multiple combined encodings not supported");

         } else if (encodings_list->nb_elem == 1) {
             if (encodings[0].type ||

                 (

 #if CONFIG_ZLIB

                  encodings[0].compression.algo != MATROSKA_TRACK_ENCODING_COMP_ZLIB &&
 #endif

 #if CONFIG_BZLIB

                  encodings[0].compression.algo != MATROSKA_TRACK_ENCODING_COMP_BZLIB &&
 #endif

 #if CONFIG_LZO
                  encodings[0].compression.algo != MATROSKA_TRACK_ENCODING_COMP_LZO &&
 #endif
                  encodings[0].compression.algo != MATROSKA_TRACK_ENCODING_COMP_HEADERSTRIP)) {

                 encodings[0].scope = 0;
                 av_log(matroska->ctx, AV_LOG_ERROR,
                        "Unsupported encoding type");
             } else if (track->codec_priv.size && encodings[0].scope&2) {
                 uint8_t *codec_priv = track->codec_priv.data;

                 int ret = matroska_decode_buffer(&track->codec_priv.data,
                                                  &track->codec_priv.size,
                                                  track);
                 if (ret < 0) {

                     track->codec_priv.data = NULL;
                     track->codec_priv.size = 0;
                     av_log(matroska->ctx, AV_LOG_ERROR,
                            "Failed to decode codec private data\n");
                 }

                 if (codec_priv != track->codec_priv.data)
                     av_free(codec_priv);
             }
         }
 

         for(j=0; ff_mkv_codec_tags[j].id != AV_CODEC_ID_NONE; 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;

             }

         }

         st = track->stream = avformat_new_stream(s, NULL);

         if (st == NULL)
             return AVERROR(ENOMEM);
 

         if (!strcmp(track->codec_id, "V_MS/VFW/FOURCC")

             && track->codec_priv.size >= 40
             && track->codec_priv.data != NULL) {

             track->ms_compat = 1;

             fourcc = AV_RL32(track->codec_priv.data + 16);
             codec_id = ff_codec_get_id(ff_codec_bmp_tags, fourcc);

             extradata_offset = 40;

         } else if (!strcmp(track->codec_id, "A_MS/ACM")

                    && track->codec_priv.size >= 14

                    && track->codec_priv.data != NULL) {

             int ret;

             ffio_init_context(&b, track->codec_priv.data, track->codec_priv.size,

                               0, NULL, NULL, NULL, NULL);

             ret = ff_get_wav_header(&b, st->codec, track->codec_priv.size);
             if (ret < 0)
                 return ret;

             codec_id = st->codec->codec_id;

             extradata_offset = FFMIN(track->codec_priv.size, 18);

         } else if (!strcmp(track->codec_id, "V_QUICKTIME")
                    && (track->codec_priv.size >= 86)
                    && (track->codec_priv.data != NULL)) {

             fourcc = AV_RL32(track->codec_priv.data);

             codec_id = ff_codec_get_id(ff_codec_movvideo_tags, fourcc);

         } else if (codec_id == AV_CODEC_ID_ALAC && track->codec_priv.size && track->codec_priv.size < INT_MAX-12) {

             /* Only ALAC's magic cookie is stored in Matroska's track headers.
                Create the "atom size", "tag", and "tag version" fields the
                decoder expects manually. */
             extradata_size = 12 + track->codec_priv.size;

             extradata = av_mallocz(extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);

             if (extradata == NULL)
                 return AVERROR(ENOMEM);
             AV_WB32(extradata, extradata_size);
             memcpy(&extradata[4], "alac", 4);
             AV_WB32(&extradata[8], 0);
             memcpy(&extradata[12], track->codec_priv.data, track->codec_priv.size);

         } else if (codec_id == AV_CODEC_ID_PCM_S16BE) {

             switch (track->audio.bitdepth) {

             case  8:  codec_id = AV_CODEC_ID_PCM_U8;     break;
             case 24:  codec_id = AV_CODEC_ID_PCM_S24BE;  break;
             case 32:  codec_id = AV_CODEC_ID_PCM_S32BE;  break;

             }

         } else if (codec_id == AV_CODEC_ID_PCM_S16LE) {

             switch (track->audio.bitdepth) {

             case  8:  codec_id = AV_CODEC_ID_PCM_U8;     break;
             case 24:  codec_id = AV_CODEC_ID_PCM_S24LE;  break;
             case 32:  codec_id = AV_CODEC_ID_PCM_S32LE;  break;

             }

         } else if (codec_id==AV_CODEC_ID_PCM_F32LE && track->audio.bitdepth==64) {
             codec_id = AV_CODEC_ID_PCM_F64LE;
         } else if (codec_id == AV_CODEC_ID_AAC && !track->codec_priv.size) {

             int profile = matroska_aac_profile(track->codec_id);
             int sri = matroska_aac_sri(track->audio.samplerate);

             extradata = av_mallocz(5 + FF_INPUT_BUFFER_PADDING_SIZE);

             if (extradata == NULL)
                 return AVERROR(ENOMEM);
             extradata[0] = (profile << 3) | ((sri&0x0E) >> 1);
             extradata[1] = ((sri&0x01) << 7) | (track->audio.channels<<3);
             if (strstr(track->codec_id, "SBR")) {
                 sri = matroska_aac_sri(track->audio.out_samplerate);
                 extradata[2] = 0x56;
                 extradata[3] = 0xE5;
                 extradata[4] = 0x80 | (sri<<3);
                 extradata_size = 5;

             } else

                 extradata_size = 2;

         } else if (codec_id == AV_CODEC_ID_TTA) {

             extradata_size = 30;

             extradata = av_mallocz(extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);

             if (extradata == NULL)
                 return AVERROR(ENOMEM);

             ffio_init_context(&b, extradata, extradata_size, 1,

                           NULL, NULL, NULL, NULL);

             avio_write(&b, "TTA1", 4);
             avio_wl16(&b, 1);
             avio_wl16(&b, track->audio.channels);
             avio_wl16(&b, track->audio.bitdepth);

             if (track->audio.out_samplerate < 0 || track->audio.out_samplerate > INT_MAX)
                 return AVERROR_INVALIDDATA;

             avio_wl32(&b, track->audio.out_samplerate);

             avio_wl32(&b, av_rescale((matroska->duration * matroska->time_scale), track->audio.out_samplerate, AV_TIME_BASE * 1000));

         } else if (codec_id == AV_CODEC_ID_RV10 || codec_id == AV_CODEC_ID_RV20 ||
                    codec_id == AV_CODEC_ID_RV30 || codec_id == AV_CODEC_ID_RV40) {

             extradata_offset = 26;

         } else if (codec_id == AV_CODEC_ID_RA_144) {

             track->audio.out_samplerate = 8000;
             track->audio.channels = 1;

         } else if ((codec_id == AV_CODEC_ID_RA_288 || codec_id == AV_CODEC_ID_COOK ||
                     codec_id == AV_CODEC_ID_ATRAC3 || codec_id == AV_CODEC_ID_SIPR)

                     && track->codec_priv.data) {

             int flavor;

             ffio_init_context(&b, track->codec_priv.data,track->codec_priv.size,

                           0, NULL, NULL, NULL, NULL);

             avio_skip(&b, 22);

             flavor                       = avio_rb16(&b);
             track->audio.coded_framesize = avio_rb32(&b);

             avio_skip(&b, 12);

             track->audio.sub_packet_h    = avio_rb16(&b);
             track->audio.frame_size      = avio_rb16(&b);
             track->audio.sub_packet_size = avio_rb16(&b);

             track->audio.buf = av_malloc(track->audio.frame_size * track->audio.sub_packet_h);

             if (codec_id == AV_CODEC_ID_RA_288) {

                 st->codec->block_align = track->audio.coded_framesize;
                 track->codec_priv.size = 0;
             } else {

                 if (codec_id == AV_CODEC_ID_SIPR && flavor < 4) {

                     const int sipr_bit_rate[4] = { 6504, 8496, 5000, 16000 };
                     track->audio.sub_packet_size = ff_sipr_subpk_size[flavor];
                     st->codec->bit_rate = sipr_bit_rate[flavor];
                 }

                 st->codec->block_align = track->audio.sub_packet_size;
                 extradata_offset = 78;

             }

         }

         track->codec_priv.size -= extradata_offset;

         if (codec_id == AV_CODEC_ID_NONE)

             av_log(matroska->ctx, AV_LOG_INFO,

                    "Unknown/unsupported AVCodecID %s.\n", track->codec_id);

         if (track->time_scale < 0.01)
             track->time_scale = 1.0;

         avpriv_set_pts_info(st, 64, matroska->time_scale*track->time_scale, 1000*1000*1000); /* 64 bit pts in ns */

         st->codec->codec_id = codec_id;
         st->start_time = 0;
         if (strcmp(track->language, "und"))

             av_dict_set(&st->metadata, "language", track->language, 0);
         av_dict_set(&st->metadata, "title", track->name, 0);

         if (track->flag_default)
             st->disposition |= AV_DISPOSITION_DEFAULT;

         if (track->flag_forced)
             st->disposition |= AV_DISPOSITION_FORCED;

         if (!st->codec->extradata) {

             if(extradata){
                 st->codec->extradata = extradata;
                 st->codec->extradata_size = extradata_size;
             } else if(track->codec_priv.data && track->codec_priv.size > 0){
                 st->codec->extradata = av_mallocz(track->codec_priv.size +
                                                   FF_INPUT_BUFFER_PADDING_SIZE);
                 if(st->codec->extradata == NULL)
                     return AVERROR(ENOMEM);
                 st->codec->extradata_size = track->codec_priv.size;
                 memcpy(st->codec->extradata,
                        track->codec_priv.data + extradata_offset,
                        track->codec_priv.size);
             }

         }

 
         if (track->type == MATROSKA_TRACK_TYPE_VIDEO) {

             MatroskaTrackPlane *planes = track->operation.combine_planes.elem;
 

             st->codec->codec_type = AVMEDIA_TYPE_VIDEO;

             st->codec->codec_tag  = fourcc;

             st->codec->width  = track->video.pixel_width;
             st->codec->height = track->video.pixel_height;

             av_reduce(&st->sample_aspect_ratio.num,
                       &st->sample_aspect_ratio.den,

                       st->codec->height * track->video.display_width,
                       st->codec-> width * track->video.display_height,
                       255);
             st->need_parsing = AVSTREAM_PARSE_HEADERS;

             if (track->default_duration) {

                 av_reduce(&st->avg_frame_rate.num, &st->avg_frame_rate.den,

                           1000000000, track->default_duration, 30000);

 #if FF_API_R_FRAME_RATE
                 st->r_frame_rate = st->avg_frame_rate;
 #endif

             }

             /* export stereo mode flag as metadata tag */
             if (track->video.stereo_mode && track->video.stereo_mode < MATROSKA_VIDEO_STEREO_MODE_COUNT)

                 av_dict_set(&st->metadata, "stereo_mode", ff_matroska_video_stereo_mode[track->video.stereo_mode], 0);

             /* export alpha mode flag as metadata tag  */
             if (track->video.alpha_mode)
                 av_dict_set(&st->metadata, "alpha_mode", "1", 0);
 

             /* if we have virtual track, mark the real tracks */
             for (j=0; j < track->operation.combine_planes.nb_elem; j++) {
                 char buf[32];

                 if (planes[j].type >= MATROSKA_VIDEO_STEREO_PLANE_COUNT)

                     continue;
                 snprintf(buf, sizeof(buf), "%s_%d",

                          ff_matroska_video_stereo_plane[planes[j].type], i);

                 for (k=0; k < matroska->tracks.nb_elem; k++)
                     if (planes[j].uid == tracks[k].uid) {

                         av_dict_set(&s->streams[k]->metadata,
                                     "stereo_mode", buf, 0);

                         break;
                     }
             }

         } else if (track->type == MATROSKA_TRACK_TYPE_AUDIO) {

             st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

             st->codec->sample_rate = track->audio.out_samplerate;
             st->codec->channels = track->audio.channels;

             st->codec->bits_per_coded_sample = track->audio.bitdepth;

             if (st->codec->codec_id != AV_CODEC_ID_AAC)

             st->need_parsing = AVSTREAM_PARSE_HEADERS;

         } else if (track->type == MATROSKA_TRACK_TYPE_SUBTITLE) {

             st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;

             if (st->codec->codec_id == AV_CODEC_ID_SSA)

                 matroska->contains_ssa = 1;

         }

     }
 

     attachements = attachements_list->elem;
     for (j=0; j<attachements_list->nb_elem; j++) {
         if (!(attachements[j].filename && attachements[j].mime &&
               attachements[j].bin.data && attachements[j].bin.size > 0)) {
             av_log(matroska->ctx, AV_LOG_ERROR, "incomplete attachment\n");
         } else {

             AVStream *st = avformat_new_stream(s, NULL);

             if (st == NULL)
                 break;

             av_dict_set(&st->metadata, "filename",attachements[j].filename, 0);

             av_dict_set(&st->metadata, "mimetype", attachements[j].mime, 0);

             st->codec->codec_id = AV_CODEC_ID_NONE;

             st->codec->codec_type = AVMEDIA_TYPE_ATTACHMENT;

             st->codec->extradata  = av_malloc(attachements[j].bin.size + FF_INPUT_BUFFER_PADDING_SIZE);

             if(st->codec->extradata == NULL)
                 break;
             st->codec->extradata_size = attachements[j].bin.size;
             memcpy(st->codec->extradata, attachements[j].bin.data, attachements[j].bin.size);
 

             for (i=0; ff_mkv_mime_tags[i].id != AV_CODEC_ID_NONE; i++) {

                 if (!strncmp(ff_mkv_mime_tags[i].str, attachements[j].mime,
                              strlen(ff_mkv_mime_tags[i].str))) {
                     st->codec->codec_id = ff_mkv_mime_tags[i].id;
                     break;
                 }
             }

             attachements[j].stream = st;

         }
     }
 
     chapters = chapters_list->elem;
     for (i=0; i<chapters_list->nb_elem; i++)

         if (chapters[i].start != AV_NOPTS_VALUE && chapters[i].uid
             && (max_start==0 || chapters[i].start > max_start)) {

             chapters[i].chapter =

             avpriv_new_chapter(s, chapters[i].uid, (AVRational){1, 1000000000},

                            chapters[i].start, chapters[i].end,
                            chapters[i].title);

             av_dict_set(&chapters[i].chapter->metadata,

                              "title", chapters[i].title, 0);

             max_start = chapters[i].start;
         }

     matroska_add_index_entries(matroska);
 

     matroska_convert_tags(s);
 

     return 0;

 }
 

 /*
  * 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) {

             void *newpackets;

             memmove(&matroska->packets[0], &matroska->packets[1],
                     (matroska->num_packets - 1) * sizeof(AVPacket *));

             newpackets = av_realloc(matroska->packets,
                             (matroska->num_packets - 1) * sizeof(AVPacket *));
             if (newpackets)
                 matroska->packets = newpackets;

         } else {
             av_freep(&matroska->packets);

             matroska->prev_pkt = NULL;

         }
         matroska->num_packets--;
         return 0;
     }
 
     return -1;
 }
 
 /*
  * Free all packets in our internal queue.
  */
 static void matroska_clear_queue(MatroskaDemuxContext *matroska)
 {

     matroska->prev_pkt = NULL;

     if (matroska->packets) {
         int n;
         for (n = 0; n < matroska->num_packets; n++) {
             av_free_packet(matroska->packets[n]);
             av_free(matroska->packets[n]);
         }

         av_freep(&matroska->packets);

         matroska->num_packets = 0;
     }
 }
 

 static int matroska_parse_laces(MatroskaDemuxContext *matroska, uint8_t **buf,

                                 int* buf_size, int type,

                                 uint32_t **lace_buf, int *laces)
 {

     int res = 0, n, size = *buf_size;

     uint8_t *data = *buf;
     uint32_t *lace_size;
 
     if (!type) {
         *laces = 1;
         *lace_buf = av_mallocz(sizeof(int));
         if (!*lace_buf)
             return AVERROR(ENOMEM);
 
         *lace_buf[0] = size;
         return 0;
     }
 

     av_assert0(size > 0);

     *laces = *data + 1;
     data += 1;
     size -= 1;
     lace_size = av_mallocz(*laces * sizeof(int));
     if (!lace_size)
         return AVERROR(ENOMEM);
 
     switch (type) {
     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 = AVERROR_EOF;
                     break;
                 }
                 temp = *data;
                 lace_size[n] += temp;
                 data += 1;
                 size -= 1;
                 if (temp != 0xff)
                     break;
             }
             total += lace_size[n];
         }
         if (size <= total) {
             res = AVERROR_INVALIDDATA;
             break;
         }
 
         lace_size[n] = size - total;
         break;
     }
 
     case 0x2: /* fixed-size lacing */

         if (size % (*laces)) {

             res = AVERROR_INVALIDDATA;
             break;
         }
         for (n = 0; n < *laces; n++)
             lace_size[n] = size / *laces;
         break;
 
     case 0x3: /* EBML lacing */ {
         uint64_t num;
         uint32_t total;
         n = matroska_ebmlnum_uint(matroska, data, size, &num);
         if (n < 0) {
             av_log(matroska->ctx, AV_LOG_INFO,
                    "EBML block data error\n");
             res = 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(matroska, data, size, &snum);
             if (r < 0) {
                 av_log(matroska->ctx, AV_LOG_INFO,
                        "EBML block data error\n");
                 res = r;
                 break;
             }
             data += r;
             size -= r;
             lace_size[n] = lace_size[n - 1] + snum;
             total += lace_size[n];
         }
         if (size <= total) {
             res = AVERROR_INVALIDDATA;
             break;
         }
         lace_size[*laces - 1] = size - total;
         break;
     }
     }
 
     *buf      = data;
     *lace_buf = lace_size;

     *buf_size = size;

 
     return res;
 }
 

 static int matroska_parse_rm_audio(MatroskaDemuxContext *matroska,
                                    MatroskaTrack *track,
                                    AVStream *st,
                                    uint8_t *data, int size,

                                    uint64_t timecode,

                                    int64_t pos)
 {
     int a = st->codec->block_align;
     int sps = track->audio.sub_packet_size;
     int cfs = track->audio.coded_framesize;
     int h = track->audio.sub_packet_h;
     int y = track->audio.sub_packet_cnt;
     int w = track->audio.frame_size;
     int x;
 
     if (!track->audio.pkt_cnt) {
         if (track->audio.sub_packet_cnt == 0)
             track->audio.buf_timecode = timecode;
         if (st->codec->codec_id == AV_CODEC_ID_RA_288) {
             if (size < cfs * h / 2) {
                 av_log(matroska->ctx, AV_LOG_ERROR,
                        "Corrupt int4 RM-style audio packet size\n");
                 return AVERROR_INVALIDDATA;
             }
             for (x=0; x<h/2; x++)
                 memcpy(track->audio.buf+x*2*w+y*cfs,
                        data+x*cfs, cfs);
         } else if (st->codec->codec_id == AV_CODEC_ID_SIPR) {
             if (size < w) {
                 av_log(matroska->ctx, AV_LOG_ERROR,
                        "Corrupt sipr RM-style audio packet size\n");
                 return AVERROR_INVALIDDATA;
             }
             memcpy(track->audio.buf + y*w, data, w);
         } else {

             if (size < sps * w / sps || h<=0) {

                 av_log(matroska->ctx, AV_LOG_ERROR,
                        "Corrupt generic RM-style audio packet size\n");
                 return AVERROR_INVALIDDATA;
             }
             for (x=0; x<w/sps; x++)
                 memcpy(track->audio.buf+sps*(h*x+((h+1)/2)*(y&1)+(y>>1)), data+x*sps, sps);
         }
 
         if (++track->audio.sub_packet_cnt >= h) {
             if (st->codec->codec_id == AV_CODEC_ID_SIPR)
                 ff_rm_reorder_sipr_data(track->audio.buf, h, w);
             track->audio.sub_packet_cnt = 0;
             track->audio.pkt_cnt = h*w / a;
         }
     }
 
     while (track->audio.pkt_cnt) {

         AVPacket *pkt = NULL;
         if (!(pkt = av_mallocz(sizeof(AVPacket))) || av_new_packet(pkt, a) < 0){
             av_free(pkt);
             return AVERROR(ENOMEM);
         }

         memcpy(pkt->data, track->audio.buf
                + a * (h*w / a - track->audio.pkt_cnt--), a);
         pkt->pts = track->audio.buf_timecode;
         track->audio.buf_timecode = AV_NOPTS_VALUE;
         pkt->pos = pos;
         pkt->stream_index = st->index;
         dynarray_add(&matroska->packets,&matroska->num_packets,pkt);
     }
 
     return 0;
 }
 static int matroska_parse_frame(MatroskaDemuxContext *matroska,
                                 MatroskaTrack *track,
                                 AVStream *st,
                                 uint8_t *data, int pkt_size,

                                 uint64_t timecode, uint64_t lace_duration,

                                 int64_t pos, int is_keyframe,
                                 uint8_t *additional, uint64_t additional_id, int additional_size)

 {
     MatroskaTrackEncoding *encodings = track->encodings.elem;
     uint8_t *pkt_data = data;
     int offset = 0, res;
     AVPacket *pkt;
 
     if (encodings && encodings->scope & 1) {
         res = matroska_decode_buffer(&pkt_data, &pkt_size, track);
         if (res < 0)
             return res;
     }
 
     if (st->codec->codec_id == AV_CODEC_ID_PRORES)
         offset = 8;
 
     pkt = av_mallocz(sizeof(AVPacket));
     /* XXX: prevent data copy... */
     if (av_new_packet(pkt, pkt_size + offset) < 0) {
         av_free(pkt);
         return AVERROR(ENOMEM);
     }
 
     if (st->codec->codec_id == AV_CODEC_ID_PRORES) {
         uint8_t *buf = pkt->data;
         bytestream_put_be32(&buf, pkt_size);
         bytestream_put_be32(&buf, MKBETAG('i', 'c', 'p', 'f'));
     }
 
     memcpy(pkt->data + offset, pkt_data, pkt_size);
 
     if (pkt_data != data)
         av_free(pkt_data);
 
     pkt->flags = is_keyframe;
     pkt->stream_index = st->index;
 

     if (additional_size > 0) {
         uint8_t *side_data = av_packet_new_side_data(pkt,
                                                      AV_PKT_DATA_MATROSKA_BLOCKADDITIONAL,

                                                      additional_size + 8);

         if(side_data == NULL) {
             return AVERROR(ENOMEM);
         }

         AV_WB64(side_data, additional_id);

         memcpy(side_data + 8, additional, additional_size);
     }
 

     if (track->ms_compat)
         pkt->dts = timecode;
     else
         pkt->pts = timecode;
     pkt->pos = pos;

     if (st->codec->codec_id == AV_CODEC_ID_SUBRIP) {
         /*
          * For backward compatibility.
          * Historically, we have put subtitle duration
          * in convergence_duration, on the off chance
          * that the time_scale is less than 1us, which
          * could result in a 32bit overflow on the
          * normal duration field.
          */
         pkt->convergence_duration = lace_duration;
     }
 
     if (track->type != MATROSKA_TRACK_TYPE_SUBTITLE ||
         lace_duration <= INT_MAX) {
         /*
          * For non subtitle tracks, just store the duration
          * as normal.
          *
          * If it's a subtitle track and duration value does
          * not overflow a uint32, then also store it normally.
          */
         pkt->duration = lace_duration;
     }

 
     if (st->codec->codec_id == AV_CODEC_ID_SSA)

         matroska_fix_ass_packet(matroska, pkt, lace_duration);

 
     if (matroska->prev_pkt &&
         timecode != AV_NOPTS_VALUE &&
         matroska->prev_pkt->pts == timecode &&
         matroska->prev_pkt->stream_index == st->index &&
         st->codec->codec_id == AV_CODEC_ID_SSA)
         matroska_merge_packets(matroska->prev_pkt, pkt);
     else {
         dynarray_add(&matroska->packets,&matroska->num_packets,pkt);
         matroska->prev_pkt = pkt;
     }
 
     return 0;
 }
 

 static int matroska_parse_block(MatroskaDemuxContext *matroska, uint8_t *data,
                                 int size, int64_t pos, uint64_t cluster_time,

                                 uint64_t block_duration, int is_keyframe,

                                 uint8_t *additional, uint64_t additional_id, int additional_size,

                                 int64_t cluster_pos)

 {

     uint64_t timecode = AV_NOPTS_VALUE;

     MatroskaTrack *track;

     int res = 0;

     AVStream *st;
     int16_t block_time;
     uint32_t *lace_size = NULL;
     int n, flags, laces = 0;
     uint64_t num;

     int trust_default_duration = 1;

     if ((n = matroska_ebmlnum_uint(matroska, data, size, &num)) < 0) {

         av_log(matroska->ctx, AV_LOG_ERROR, "EBML block data error\n");

         return n;

     }
     data += n;
     size -= n;
 
     track = matroska_find_track_by_num(matroska, num);

     if (!track || !track->stream) {

         av_log(matroska->ctx, AV_LOG_INFO,

                "Invalid stream %"PRIu64" or size %u\n", num, size);

         return AVERROR_INVALIDDATA;

     } else if (size <= 3)
         return 0;

     st = track->stream;

     if (st->discard >= AVDISCARD_ALL)

         return res;

     av_assert1(block_duration != AV_NOPTS_VALUE);

     block_time = AV_RB16(data);

     data += 2;

     flags = *data++;
     size -= 3;

     if (is_keyframe == -1)

         is_keyframe = flags & 0x80 ? AV_PKT_FLAG_KEY : 0;

     if (cluster_time != (uint64_t)-1
         && (block_time >= 0 || cluster_time >= -block_time)) {
         timecode = cluster_time + block_time;

         if (track->type == MATROSKA_TRACK_TYPE_SUBTITLE
             && timecode < track->end_timecode)
             is_keyframe = 0;  /* overlapping subtitles are not key frame */

         if (is_keyframe)

             av_add_index_entry(st, cluster_pos, timecode, 0,0,AVINDEX_KEYFRAME);
     }
 

     if (matroska->skip_to_keyframe && track->type != MATROSKA_TRACK_TYPE_SUBTITLE) {

         if (timecode < matroska->skip_to_timecode)

             return res;

         if (!st->skip_to_keyframe) {
             av_log(matroska->ctx, AV_LOG_ERROR, "File is broken, keyframes not correctly marked!\n");
             matroska->skip_to_keyframe = 0;
         }
         if (is_keyframe)
             matroska->skip_to_keyframe = 0;

     }
 

     res = matroska_parse_laces(matroska, &data, &size, (flags & 0x06) >> 1,

                                &lace_size, &laces);

     if (res)
         goto end;

     if (track->audio.samplerate == 8000) {
         // If this is needed for more codecs, then add them here
         if (st->codec->codec_id == AV_CODEC_ID_AC3) {
             if(track->audio.samplerate != st->codec->sample_rate || !st->codec->frame_size)
                 trust_default_duration = 0;
         }
     }
 
     if (!block_duration && trust_default_duration)

         block_duration = track->default_duration * laces / matroska->time_scale;

     if (cluster_time != (uint64_t)-1 && (block_time >= 0 || cluster_time >= -block_time))

         track->end_timecode =
             FFMAX(track->end_timecode, timecode + block_duration);

     for (n = 0; n < laces; n++) {

         int64_t lace_duration = block_duration*(n+1) / laces - block_duration*n / laces;

         if (lace_size[n] > size) {
             av_log(matroska->ctx, AV_LOG_ERROR, "Invalid packet size\n");
             break;
         }

         if ((st->codec->codec_id == AV_CODEC_ID_RA_288 ||
              st->codec->codec_id == AV_CODEC_ID_COOK ||
              st->codec->codec_id == AV_CODEC_ID_SIPR ||
              st->codec->codec_id == AV_CODEC_ID_ATRAC3) &&
              st->codec->block_align && track->audio.sub_packet_size) {

             res = matroska_parse_rm_audio(matroska, track, st, data, size,

                                           timecode, pos);

             if (res)
                 goto end;

         } else {
             res = matroska_parse_frame(matroska, track, st, data, lace_size[n],

                                       timecode, lace_duration,

                                       pos, !n? is_keyframe : 0,
                                       additional, additional_id, additional_size);

             if (res)
                 goto end;

         }

 
         if (timecode != AV_NOPTS_VALUE)

             timecode = lace_duration ? timecode + lace_duration : AV_NOPTS_VALUE;

         data += lace_size[n];
         size -= lace_size[n];

     }
 

 end:

     av_free(lace_size);

     return res;

 }
 

 static int matroska_parse_cluster_incremental(MatroskaDemuxContext *matroska)
 {
     EbmlList *blocks_list;
     MatroskaBlock *blocks;
     int i, res;
     res = ebml_parse(matroska,
                      matroska_cluster_incremental_parsing,
                      &matroska->current_cluster);
     if (res == 1) {
         /* New Cluster */
         if (matroska->current_cluster_pos)
             ebml_level_end(matroska);
         ebml_free(matroska_cluster, &matroska->current_cluster);
         memset(&matroska->current_cluster, 0, sizeof(MatroskaCluster));
         matroska->current_cluster_num_blocks = 0;
         matroska->current_cluster_pos = avio_tell(matroska->ctx->pb);
         matroska->prev_pkt = NULL;
         /* sizeof the ID which was already read */
         if (matroska->current_id)
             matroska->current_cluster_pos -= 4;
         res = ebml_parse(matroska,
                          matroska_clusters_incremental,
                          &matroska->current_cluster);
         /* Try parsing the block again. */
         if (res == 1)
             res = ebml_parse(matroska,
                              matroska_cluster_incremental_parsing,
                              &matroska->current_cluster);
     }
 
     if (!res &&
         matroska->current_cluster_num_blocks <
             matroska->current_cluster.blocks.nb_elem) {
         blocks_list = &matroska->current_cluster.blocks;
         blocks = blocks_list->elem;
 
         matroska->current_cluster_num_blocks = blocks_list->nb_elem;
         i = blocks_list->nb_elem - 1;
         if (blocks[i].bin.size > 0 && blocks[i].bin.data) {
             int is_keyframe = blocks[i].non_simple ? !blocks[i].reference : -1;

             uint8_t* additional = blocks[i].additional.size > 0 ?
                                     blocks[i].additional.data : NULL;

             if (!blocks[i].non_simple)

                 blocks[i].duration = 0;

             res = matroska_parse_block(matroska,
                                        blocks[i].bin.data, blocks[i].bin.size,
                                        blocks[i].bin.pos,
                                        matroska->current_cluster.timecode,
                                        blocks[i].duration, is_keyframe,

                                        additional, blocks[i].additional_id,
                                        blocks[i].additional.size,

                                        matroska->current_cluster_pos);
         }
     }
 
     return res;
 }
 

 static int matroska_parse_cluster(MatroskaDemuxContext *matroska)

 {

     MatroskaCluster cluster = { 0 };
     EbmlList *blocks_list;
     MatroskaBlock *blocks;

     int i, res;

     int64_t pos;
     if (!matroska->contains_ssa)
         return matroska_parse_cluster_incremental(matroska);
     pos = avio_tell(matroska->ctx->pb);

     matroska->prev_pkt = NULL;

     if (matroska->current_id)

         pos -= 4;  /* sizeof the ID which was already read */

     res = ebml_parse(matroska, matroska_clusters, &cluster);

     blocks_list = &cluster.blocks;
     blocks = blocks_list->elem;

     for (i=0; i<blocks_list->nb_elem; i++)

         if (blocks[i].bin.size > 0 && blocks[i].bin.data) {

             int is_keyframe = blocks[i].non_simple ? !blocks[i].reference : -1;

             res=matroska_parse_block(matroska,
                                      blocks[i].bin.data, blocks[i].bin.size,
                                      blocks[i].bin.pos,  cluster.timecode,

                                      blocks[i].duration, is_keyframe, NULL, 0, 0,

                                      pos);

         }

     ebml_free(matroska_cluster, &cluster);

     return res;
 }
 

 static int matroska_read_packet(AVFormatContext *s, AVPacket *pkt)

 {
     MatroskaDemuxContext *matroska = s->priv_data;
 

     while (matroska_deliver_packet(matroska, pkt)) {

         int64_t pos = avio_tell(matroska->ctx->pb);

         if (matroska->done)

             return AVERROR_EOF;

         if (matroska_parse_cluster(matroska) < 0)
             matroska_resync(matroska, pos);

     }
 

     return 0;

 }
 

 static int matroska_read_seek(AVFormatContext *s, int stream_index,
                               int64_t timestamp, int flags)

 {
     MatroskaDemuxContext *matroska = s->priv_data;

     MatroskaTrack *tracks = matroska->tracks.elem;

     AVStream *st = s->streams[stream_index];

     int i, index, index_sub, index_min;

     /* Parse the CUES now since we need the index data to seek. */

     if (matroska->cues_parsing_deferred > 0) {

         matroska->cues_parsing_deferred = 0;

         matroska_parse_cues(matroska);

     }
 

     if (!st->nb_index_entries)

         goto err;

     timestamp = FFMAX(timestamp, st->index_entries[0].timestamp);

     if ((index = av_index_search_timestamp(st, timestamp, flags)) < 0) {

         avio_seek(s->pb, st->index_entries[st->nb_index_entries-1].pos, SEEK_SET);

         matroska->current_id = 0;

         while ((index = av_index_search_timestamp(st, timestamp, flags)) < 0) {
             matroska_clear_queue(matroska);
             if (matroska_parse_cluster(matroska) < 0)
                 break;
         }

     }

     matroska_clear_queue(matroska);

     if (index < 0 || (matroska->cues_parsing_deferred < 0 && index == st->nb_index_entries - 1))
         goto err;

     index_min = index;
     for (i=0; i < matroska->tracks.nb_elem; i++) {

         tracks[i].audio.pkt_cnt = 0;
         tracks[i].audio.sub_packet_cnt = 0;
         tracks[i].audio.buf_timecode = AV_NOPTS_VALUE;

         tracks[i].end_timecode = 0;
         if (tracks[i].type == MATROSKA_TRACK_TYPE_SUBTITLE

             && tracks[i].stream->discard != AVDISCARD_ALL) {

             index_sub = av_index_search_timestamp(tracks[i].stream, st->index_entries[index].timestamp, AVSEEK_FLAG_BACKWARD);

             while(index_sub >= 0
                   && index_min >= 0
                   && tracks[i].stream->index_entries[index_sub].pos < st->index_entries[index_min].pos
                   && st->index_entries[index].timestamp - tracks[i].stream->index_entries[index_sub].timestamp < 30000000000/matroska->time_scale)
                 index_min--;

         }
     }
 

     avio_seek(s->pb, st->index_entries[index_min].pos, SEEK_SET);

     matroska->current_id = 0;

     if (flags & AVSEEK_FLAG_ANY) {
         st->skip_to_keyframe = 0;
         matroska->skip_to_timecode = timestamp;
     } else {
         st->skip_to_keyframe = 1;
         matroska->skip_to_timecode = st->index_entries[index].timestamp;
     }
     matroska->skip_to_keyframe = 1;

     matroska->done = 0;

     matroska->num_levels = 0;

     ff_update_cur_dts(s, st, st->index_entries[index].timestamp);

     return 0;

 err:
     // slightly hackish but allows proper fallback to
     // the generic seeking code.
     matroska_clear_queue(matroska);
     matroska->current_id = 0;

     st->skip_to_keyframe =

     matroska->skip_to_keyframe = 0;
     matroska->done = 0;
     matroska->num_levels = 0;
     return -1;

 }
 

 static int matroska_read_close(AVFormatContext *s)

 {
     MatroskaDemuxContext *matroska = s->priv_data;

     MatroskaTrack *tracks = matroska->tracks.elem;

     int n;

     matroska_clear_queue(matroska);

     for (n=0; n < matroska->tracks.nb_elem; n++)
         if (tracks[n].type == MATROSKA_TRACK_TYPE_AUDIO)
             av_free(tracks[n].audio.buf);

     ebml_free(matroska_cluster, &matroska->current_cluster);

     ebml_free(matroska_segment, matroska);

 
     return 0;
 }
 

 AVInputFormat ff_matroska_demuxer = {

     .name           = "matroska,webm",

     .long_name      = NULL_IF_CONFIG_SMALL("Matroska / WebM"),

     .priv_data_size = sizeof(MatroskaDemuxContext),
     .read_probe     = matroska_probe,
     .read_header    = matroska_read_header,
     .read_packet    = matroska_read_packet,
     .read_close     = matroska_read_close,
     .read_seek      = matroska_read_seek,

 };