modules/demux/mkv/Ebml_parser.cpp

   1
   2 /*****************************************************************************
   3  * mkv.cpp : matroska demuxer
   4  *****************************************************************************
   5  * Copyright (C) 2003-2004 the VideoLAN team
   6  * $Id$
   7  *
   8  * Authors: Laurent Aimar <fenrir@via.ecp.fr>
   9  *          Steve Lhomme <steve.lhomme@free.fr>
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  24  *****************************************************************************/
  25 #include "Ebml_parser.hpp"
  26
  27 /*****************************************************************************
  28  * Ebml Stream parser
  29  *****************************************************************************/
  30 EbmlParser::EbmlParser( EbmlStream *es, EbmlElement *el_start, demux_t *p_demux )
  31 {
  32     int i;
  33
  34     m_es = es;
  35     m_got = NULL;
  36     m_el[0] = el_start;
  37     mi_remain_size[0] = el_start->GetSize();
  38
  39     for( i = 1; i < 6; i++ )
  40     {
  41         m_el[i] = NULL;
  42     }
  43     mi_level = 1;
  44     mi_user_level = 1;
  45     mb_keep = false;
  46     mb_dummy = config_GetInt( p_demux, "mkv-use-dummy" );
  47 }
  48
  49 EbmlParser::~EbmlParser( void )
  50 {
  51     int i;
  52
  53     for( i = 1; i < mi_level; i++ )
  54     {
  55         if( !mb_keep )
  56         {
  57             delete m_el[i];
  58         }
  59         mb_keep = false;
  60     }
  61 }
  62
  63 EbmlElement* EbmlParser::UnGet( uint64 i_block_pos, uint64 i_cluster_pos )
  64 {
  65     if ( mi_user_level > mi_level )
  66     {
  67         while ( mi_user_level != mi_level )
  68         {
  69             delete m_el[mi_user_level];
  70             m_el[mi_user_level] = NULL;
  71             mi_user_level--;
  72         }
  73     }
  74     m_got = NULL;
  75     mb_keep = false;
  76     if ( m_el[1]->GetElementPosition() == i_cluster_pos )
  77     {
  78         m_es->I_O().setFilePointer( i_block_pos, seek_beginning );
  79         return (EbmlMaster*) m_el[1];
  80     }
  81     else
  82     {
  83         // seek to the previous Cluster
  84         m_es->I_O().setFilePointer( i_cluster_pos, seek_beginning );
  85         mi_level--;
  86         mi_user_level--;
  87         delete m_el[mi_level];
  88         m_el[mi_level] = NULL;
  89         return NULL;
  90     }
  91 }
  92
  93 void EbmlParser::Up( void )
  94 {
  95     if( mi_user_level == mi_level )
  96     {
  97         fprintf( stderr," arrrrrrrrrrrrrg Up cannot escape itself\n" );
  98     }
  99
 100     mi_user_level--;
 101 }
 102
 103 void EbmlParser::Down( void )
 104 {
 105     mi_user_level++;
 106     mi_level++;
 107 }
 108
 109 void EbmlParser::Keep( void )
 110 {
 111     mb_keep = true;
 112 }
 113
 114 int EbmlParser::GetLevel( void )
 115 {
 116     return mi_user_level;
 117 }
 118
 119 void EbmlParser::Reset( demux_t *p_demux )
 120 {
 121     while ( mi_level > 0)
 122     {
 123         delete m_el[mi_level];
 124         m_el[mi_level] = NULL;
 125         mi_level--;
 126     }
 127     mi_user_level = mi_level = 1;
 128     // a little faster and cleaner
 129     m_es->I_O().setFilePointer( static_cast<KaxSegment*>(m_el[0])->GetGlobalPosition(0) );
 130     mb_dummy = config_GetInt( p_demux, "mkv-use-dummy" );
 131 }
 132
 133
 134 /* This function workarounds a bug in KaxBlockVirtual implementation */
 135 class KaxBlockVirtualWorkaround : public KaxBlockVirtual
 136 {
 137 public:
 138     void Fix()
 139     {
 140         if( Data == DataBlock )
 141             SetBuffer( NULL, 0 );
 142     }
 143 };
 144
 145 EbmlElement *EbmlParser::Get( void )
 146 {
 147     int i_ulev = 0;
 148
 149     if( mi_user_level != mi_level )
 150     {
 151         return NULL;
 152     }
 153     if( m_got )
 154     {
 155         EbmlElement *ret = m_got;
 156         m_got = NULL;
 157
 158         return ret;
 159     }
 160
 161     if( m_el[mi_level] )
 162     {
 163         m_el[mi_level]->SkipData( *m_es, m_el[mi_level]->Generic().Context );
 164         if( !mb_keep )
 165         {
 166             if( MKV_IS_ID( m_el[mi_level], KaxBlockVirtual ) )
 167                 static_cast<KaxBlockVirtualWorkaround*>(m_el[mi_level])->Fix();
 168             delete m_el[mi_level];
 169         }
 170         mb_keep = false;
 171     }
 172
 173     m_el[mi_level] = m_es->FindNextElement( m_el[mi_level - 1]->Generic().Context, i_ulev, 0xFFFFFFFFL, mb_dummy != 0, 1 );
 174 //    mi_remain_size[mi_level] = m_el[mi_level]->GetSize();
 175     if( i_ulev > 0 )
 176     {
 177         while( i_ulev > 0 )
 178         {
 179             if( mi_level == 1 )
 180             {
 181                 mi_level = 0;
 182                 return NULL;
 183             }
 184
 185             delete m_el[mi_level - 1];
 186             m_got = m_el[mi_level -1] = m_el[mi_level];
 187             m_el[mi_level] = NULL;
 188
 189             mi_level--;
 190             i_ulev--;
 191         }
 192         return NULL;
 193     }
 194     else if( m_el[mi_level] == NULL )
 195     {
 196         fprintf( stderr," m_el[mi_level] == NULL\n" );
 197     }
 198
 199     return m_el[mi_level];
 200 }
 201
 202 bool EbmlParser::IsTopPresent( EbmlElement *el )
 203 {
 204     for( int i = 0; i < mi_level; i++ )
 205     {
 206         if( m_el[i] && m_el[i] == el )
 207             return true;
 208     }
 209     return false;
 210 }
 211
 212