git.sesse.net Git - vlc/blob - modules/codec/subtitles/subsdec.c

   1 /*****************************************************************************
   2  * subsdec.c : text subtitles decoder
   3  *****************************************************************************
   4  * Copyright (C) 2000-2006 the VideoLAN team
   5  * $Id$
   6  *
   7  * Authors: Gildas Bazin <gbazin@videolan.org>
   8  *          Samuel Hocevar <sam@zoy.org>
   9  *          Derk-Jan Hartman <hartman at videolan dot org>
  10  *          Bernie Purcell <bitmap@videolan.org>
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  25  *****************************************************************************/
  26
  27 /*****************************************************************************
  28  * Preamble
  29  *****************************************************************************/
  30
  31 #include "subsdec.h"
  32
  33 /*****************************************************************************
  34  * Local prototypes
  35  *****************************************************************************/
  36 static int  OpenDecoder   ( vlc_object_t * );
  37 static void CloseDecoder  ( vlc_object_t * );
  38
  39 static subpicture_t   *DecodeBlock   ( decoder_t *, block_t ** );
  40 static subpicture_t   *ParseText     ( decoder_t *, block_t * );
  41 static char           *StripTags      ( char * );
  42 static char           *CreateHtmlSubtitle ( char * );
  43
  44
  45 /*****************************************************************************
  46  * Module descriptor.
  47  *****************************************************************************/
  48 static const char *ppsz_encodings[] = { DEFAULT_NAME, "ASCII", "UTF-8", "",
  49     "ISO-8859-1", "CP1252", "MacRoman", "MacIceland","ISO-8859-15", "",
  50     "ISO-8859-2", "CP1250", "MacCentralEurope", "MacCroatian", "MacRomania", "",
  51     "ISO-8859-5", "CP1251", "MacCyrillic", "MacUkraine", "KOI8-R", "KOI8-U", "KOI8-RU", "",
  52     "ISO-8859-6", "CP1256", "MacArabic", "",
  53     "ISO-8859-7", "CP1253", "MacGreek", "",
  54     "ISO-8859-8", "CP1255", "MacHebrew", "",
  55     "ISO-8859-9", "CP1254", "MacTurkish", "",
  56     "ISO-8859-13", "CP1257", "",
  57     "ISO-2022-JP", "ISO-2022-JP-1", "ISO-2022-JP-2", "EUC-JP", "SHIFT_JIS", "",
  58     "ISO-2022-CN", "ISO-2022-CN-EXT", "EUC-CN", "EUC-TW", "BIG5", "BIG5-HKSCS", "",
  59     "ISO-2022-KR", "EUC-KR", "",
  60     "MacThai", "KOI8-T", "",
  61     "ISO-8859-3", "ISO-8859-4", "ISO-8859-10", "ISO-8859-14", "ISO-8859-16", "",
  62     "CP850", "CP862", "CP866", "CP874", "CP932", "CP949", "CP950", "CP1133", "CP1258", "",
  63     "Macintosh", "",
  64     "UTF-7", "UTF-16", "UTF-16BE", "UTF-16LE", "UTF-32", "UTF-32BE", "UTF-32LE",
  65     "C99", "JAVA", "UCS-2", "UCS-2BE", "UCS-2LE", "UCS-4", "UCS-4BE", "UCS-4LE", "",
  66     "HZ", "GBK", "GB18030", "JOHAB", "ARMSCII-8",
  67     "Georgian-Academy", "Georgian-PS", "TIS-620", "MuleLao-1", "VISCII", "TCVN",
  68     "HPROMAN8", "NEXTSTEP" };
  69 /*
  70 SSA supports charset selection.
  71 The following known charsets are used:
  72
  73 0 = Ansi - Western European
  74 1 = default
  75 2 = symbol
  76 3 = invalid
  77 77 = Mac
  78 128 = Japanese (Shift JIS)
  79 129 = Hangul
  80 130 = Johab
  81 134 = GB2312 Simplified Chinese
  82 136 = Big5 Traditional Chinese
  83 161 = Greek
  84 162 = Turkish
  85 163 = Vietnamese
  86 177 = Hebrew
  87 178 = Arabic
  88 186 = Baltic
  89 204 = Russian (Cyrillic)
  90 222 = Thai
  91 238 = Eastern European
  92 254 = PC 437
  93 */
  94
  95 static int  pi_justification[] = { 0, 1, 2 };
  96 static const char *ppsz_justification_text[] = {N_("Center"),N_("Left"),N_("Right")};
  97
  98 #define ENCODING_TEXT N_("Subtitles text encoding")
  99 #define ENCODING_LONGTEXT N_("Set the encoding used in text subtitles")
 100 #define ALIGN_TEXT N_("Subtitles justification")
 101 #define ALIGN_LONGTEXT N_("Set the justification of subtitles")
 102 #define AUTODETECT_UTF8_TEXT N_("UTF-8 subtitles autodetection")
 103 #define AUTODETECT_UTF8_LONGTEXT N_("This enables automatic detection of " \
 104             "UTF-8 encoding within subtitles files.")
 105 #define FORMAT_TEXT N_("Formatted Subtitles")
 106 #define FORMAT_LONGTEXT N_("Some subtitle formats allow for text formatting. " \
 107  "VLC partly implements this, but you can choose to disable all formatting.")
 108
 109
 110 vlc_module_begin();
 111     set_shortname( _("Subtitles"));
 112     set_description( _("Text subtitles decoder") );
 113     set_capability( "decoder", 50 );
 114     set_callbacks( OpenDecoder, CloseDecoder );
 115     set_category( CAT_INPUT );
 116     set_subcategory( SUBCAT_INPUT_SCODEC );
 117
 118     add_integer( "subsdec-align", 0, NULL, ALIGN_TEXT, ALIGN_LONGTEXT,
 119                  VLC_FALSE );
 120         change_integer_list( pi_justification, ppsz_justification_text, 0 );
 121     add_string( "subsdec-encoding", DEFAULT_NAME, NULL,
 122                 ENCODING_TEXT, ENCODING_LONGTEXT, VLC_FALSE );
 123         change_string_list( ppsz_encodings, 0, 0 );
 124     add_bool( "subsdec-autodetect-utf8", VLC_TRUE, NULL,
 125               AUTODETECT_UTF8_TEXT, AUTODETECT_UTF8_LONGTEXT, VLC_FALSE );
 126     add_bool( "subsdec-formatted", VLC_TRUE, NULL, FORMAT_TEXT, FORMAT_LONGTEXT,
 127                  VLC_FALSE );
 128 vlc_module_end();
 129
 130 /*****************************************************************************
 131  * OpenDecoder: probe the decoder and return score
 132  *****************************************************************************
 133  * Tries to launch a decoder and return score so that the interface is able
 134  * to chose.
 135  *****************************************************************************/
 136 static int OpenDecoder( vlc_object_t *p_this )
 137 {
 138     decoder_t     *p_dec = (decoder_t*)p_this;
 139     decoder_sys_t *p_sys;
 140     vlc_value_t    val;
 141
 142     switch( p_dec->fmt_in.i_codec )
 143     {
 144         case VLC_FOURCC('s','u','b','t'):
 145         case VLC_FOURCC('s','s','a',' '):
 146         case VLC_FOURCC('t','1','4','0'):
 147             break;
 148         default:
 149             return VLC_EGENERIC;
 150     }
 151
 152     p_dec->pf_decode_sub = DecodeBlock;
 153
 154     /* Allocate the memory needed to store the decoder's structure */
 155     p_dec->p_sys = p_sys = malloc( sizeof( *p_sys ) );
 156     if( p_sys == NULL )
 157     {
 158         msg_Err( p_dec, "out of memory" );
 159         return VLC_ENOMEM;
 160     }
 161
 162     /* init of p_sys */
 163     memset( p_sys, 0, sizeof( *p_sys ) );
 164     p_sys->i_align = 0;
 165     p_sys->iconv_handle = (vlc_iconv_t)-1;
 166     p_sys->b_autodetect_utf8 = VLC_FALSE;
 167     p_sys->b_ass = VLC_FALSE;
 168     p_sys->i_original_height = -1;
 169     p_sys->i_original_width = -1;
 170     TAB_INIT( p_sys->i_ssa_styles, p_sys->pp_ssa_styles );
 171     TAB_INIT( p_sys->i_images, p_sys->pp_images );
 172
 173     char *psz_charset = NULL;
 174
 175     if( p_dec->fmt_in.i_codec == VLC_FOURCC('t','1','4','0') )
 176         psz_charset = strdup( "UTF-8" ); /* IUT T.140 is always using UTF-8 */
 177     else
 178     /* First try demux-specified encoding */
 179     if( p_dec->fmt_in.subs.psz_encoding && *p_dec->fmt_in.subs.psz_encoding )
 180     {
 181         psz_charset = strdup (p_dec->fmt_in.subs.psz_encoding);
 182         msg_Dbg (p_dec, "trying demuxer-specified character encoding: %s",
 183                  p_dec->fmt_in.subs.psz_encoding ?: "not specified");
 184     }
 185
 186     /* Second, try configured encoding */
 187     if (psz_charset == NULL)
 188     {
 189         psz_charset = var_CreateGetNonEmptyString (p_dec, "subsdec-encoding");
 190         if ((psz_charset != NULL) && !strcasecmp (psz_charset, DEFAULT_NAME))
 191         {
 192             free (psz_charset);
 193             psz_charset = NULL;
 194         }
 195
 196         msg_Dbg (p_dec, "trying configured character encoding: %s",
 197                  psz_charset ?: "not specified");
 198     }
 199
 200     /* Third, try "local" encoding with optional UTF-8 autodetection */
 201     if (psz_charset == NULL)
 202     {
 203         psz_charset = strdup (GetFallbackEncoding ());
 204         msg_Dbg (p_dec, "trying default character encoding: %s",
 205                  psz_charset ?: "not specified");
 206
 207         if (var_CreateGetBool (p_dec, "subsdec-autodetect-utf8"))
 208         {
 209             msg_Dbg (p_dec, "using automatic UTF-8 detection");
 210             p_sys->b_autodetect_utf8 = VLC_TRUE;
 211         }
 212     }
 213
 214     if (psz_charset == NULL)
 215     {
 216         psz_charset = strdup ("UTF-8");
 217         msg_Dbg (p_dec, "trying hard-coded character encoding: %s",
 218                  psz_charset ? psz_charset : "error");
 219     }
 220
 221     if (psz_charset == NULL)
 222     {
 223         free (p_sys);
 224         return VLC_ENOMEM;
 225     }
 226
 227     if (strcasecmp (psz_charset, "UTF-8") && strcasecmp (psz_charset, "utf8"))
 228     {
 229         p_sys->iconv_handle = vlc_iconv_open ("UTF-8", psz_charset);
 230         if (p_sys->iconv_handle == (vlc_iconv_t)(-1))
 231             msg_Err (p_dec, "cannot convert from %s: %s", psz_charset,
 232                      strerror (errno));
 233     }
 234     free (psz_charset);
 235
 236     var_Create( p_dec, "subsdec-align", VLC_VAR_INTEGER | VLC_VAR_DOINHERIT );
 237     var_Get( p_dec, "subsdec-align", &val );
 238     p_sys->i_align = val.i_int;
 239
 240     if( p_dec->fmt_in.i_codec == VLC_FOURCC('s','s','a',' ')
 241      && var_CreateGetBool( p_dec, "subsdec-formatted" ) )
 242     {
 243         if( p_dec->fmt_in.i_extra > 0 )
 244             ParseSSAHeader( p_dec );
 245     }
 246
 247     return VLC_SUCCESS;
 248 }
 249
 250 /****************************************************************************
 251  * DecodeBlock: the whole thing
 252  ****************************************************************************
 253  * This function must be fed with complete subtitles units.
 254  ****************************************************************************/
 255 static subpicture_t *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
 256 {
 257     subpicture_t *p_spu = NULL;
 258
 259     if( !pp_block || *pp_block == NULL ) return NULL;
 260
 261     p_spu = ParseText( p_dec, *pp_block );
 262
 263     block_Release( *pp_block );
 264     *pp_block = NULL;
 265
 266     return p_spu;
 267 }
 268
 269 /*****************************************************************************
 270  * CloseDecoder: clean up the decoder
 271  *****************************************************************************/
 272 static void CloseDecoder( vlc_object_t *p_this )
 273 {
 274     decoder_t *p_dec = (decoder_t *)p_this;
 275     decoder_sys_t *p_sys = p_dec->p_sys;
 276
 277     if( p_sys->iconv_handle != (vlc_iconv_t)-1 )
 278         vlc_iconv_close( p_sys->iconv_handle );
 279
 280     if( p_sys->pp_ssa_styles )
 281     {
 282         int i;
 283         for( i = 0; i < p_sys->i_ssa_styles; i++ )
 284         {
 285             if( !p_sys->pp_ssa_styles[i] )
 286                 continue;
 287
 288             if( p_sys->pp_ssa_styles[i]->psz_stylename )
 289                 free( p_sys->pp_ssa_styles[i]->psz_stylename );
 290             if( p_sys->pp_ssa_styles[i]->font_style.psz_fontname )
 291                 free( p_sys->pp_ssa_styles[i]->font_style.psz_fontname );
 292             if( p_sys->pp_ssa_styles[i] )
 293                 free( p_sys->pp_ssa_styles[i] );
 294         }
 295         TAB_CLEAN( p_sys->i_ssa_styles, p_sys->pp_ssa_styles );
 296     }
 297     if( p_sys->pp_images )
 298     {
 299         int i;
 300         for( i = 0; i < p_sys->i_images; i++ )
 301         {
 302             if( !p_sys->pp_images[i] )
 303                 continue;
 304
 305             if( p_sys->pp_images[i]->p_pic )
 306                 p_sys->pp_images[i]->p_pic->pf_release( p_sys->pp_images[i]->p_pic );
 307             if( p_sys->pp_images[i]->psz_filename )
 308                 free( p_sys->pp_images[i]->psz_filename );
 309
 310             free( p_sys->pp_images[i] );
 311         }
 312         TAB_CLEAN( p_sys->i_images, p_sys->pp_images );
 313     }
 314
 315     free( p_sys );
 316 }
 317
 318 /*****************************************************************************
 319  * ParseText: parse an text subtitle packet and send it to the video output
 320  *****************************************************************************/
 321 static subpicture_t *ParseText( decoder_t *p_dec, block_t *p_block )
 322 {
 323     decoder_sys_t *p_sys = p_dec->p_sys;
 324     subpicture_t *p_spu = NULL;
 325     char *psz_subtitle = NULL;
 326     video_format_t fmt;
 327
 328     /* We cannot display a subpicture with no date */
 329     if( p_block->i_pts == 0 )
 330     {
 331         msg_Warn( p_dec, "subtitle without a date" );
 332         return NULL;
 333     }
 334
 335     /* Check validity of packet data */
 336     /* An "empty" line containing only \0 can be used to force
 337        and ephemer picture from the screen */
 338     if( p_block->i_buffer < 1 )
 339     {
 340         msg_Warn( p_dec, "no subtitle data" );
 341         return NULL;
 342     }
 343
 344     /* Should be resiliant against bad subtitles */
 345     psz_subtitle = strndup( (const char *)p_block->p_buffer,
 346                             p_block->i_buffer );
 347     if( psz_subtitle == NULL )
 348         return NULL;
 349
 350     if( p_sys->iconv_handle == (vlc_iconv_t)-1 )
 351     {
 352         if (EnsureUTF8( psz_subtitle ) == NULL)
 353         {
 354             msg_Err( p_dec, _("failed to convert subtitle encoding.\n"
 355                      "Try manually setting a character-encoding "
 356                      "before you open the file.") );
 357         }
 358     }
 359     else
 360     {
 361
 362         if( p_sys->b_autodetect_utf8 )
 363         {
 364             if( IsUTF8( psz_subtitle ) == NULL )
 365             {
 366                 msg_Dbg( p_dec, "invalid UTF-8 sequence: "
 367                          "disabling UTF-8 subtitles autodetection" );
 368                 p_sys->b_autodetect_utf8 = VLC_FALSE;
 369             }
 370         }
 371
 372         if( !p_sys->b_autodetect_utf8 )
 373         {
 374             size_t inbytes_left = strlen( psz_subtitle );
 375             size_t outbytes_left = 6 * inbytes_left;
 376             char *psz_new_subtitle = malloc( outbytes_left + 1 );
 377             char *psz_convert_buffer_out = psz_new_subtitle;
 378             const char *psz_convert_buffer_in = psz_subtitle;
 379
 380             size_t ret = vlc_iconv( p_sys->iconv_handle,
 381                                     &psz_convert_buffer_in, &inbytes_left,
 382                                     &psz_convert_buffer_out, &outbytes_left );
 383
 384             *psz_convert_buffer_out++ = '\0';
 385             free( psz_subtitle );
 386
 387             if( ( ret == (size_t)(-1) ) || inbytes_left )
 388             {
 389                 free( psz_new_subtitle );
 390                 msg_Err( p_dec, _("failed to convert subtitle encoding.\n"
 391                         "Try manually setting a character-encoding "
 392                                 "before you open the file.") );
 393                 return NULL;
 394             }
 395
 396             psz_subtitle = realloc( psz_new_subtitle,
 397                                     psz_convert_buffer_out - psz_new_subtitle );
 398         }
 399     }
 400
 401     /* Create the subpicture unit */
 402     p_spu = p_dec->pf_spu_buffer_new( p_dec );
 403     if( !p_spu )
 404     {
 405         msg_Warn( p_dec, "can't get spu buffer" );
 406         if( psz_subtitle ) free( psz_subtitle );
 407         return NULL;
 408     }
 409
 410     p_spu->b_pausable = VLC_TRUE;
 411
 412     /* Create a new subpicture region */
 413     memset( &fmt, 0, sizeof(video_format_t) );
 414     fmt.i_chroma = VLC_FOURCC('T','E','X','T');
 415     fmt.i_aspect = 0;
 416     fmt.i_width = fmt.i_height = 0;
 417     fmt.i_x_offset = fmt.i_y_offset = 0;
 418     p_spu->p_region = p_spu->pf_create_region( VLC_OBJECT(p_dec), &fmt );
 419     if( !p_spu->p_region )
 420     {
 421         msg_Err( p_dec, "cannot allocate SPU region" );
 422         if( psz_subtitle ) free( psz_subtitle );
 423         p_dec->pf_spu_buffer_del( p_dec, p_spu );
 424         return NULL;
 425     }
 426
 427     /* Decode and format the subpicture unit */
 428     if( p_dec->fmt_in.i_codec != VLC_FOURCC('s','s','a',' ') )
 429     {
 430         /* Normal text subs, easy markup */
 431         p_spu->p_region->i_align = SUBPICTURE_ALIGN_BOTTOM | p_sys->i_align;
 432         p_spu->i_x = p_sys->i_align ? 20 : 0;
 433         p_spu->i_y = 10;
 434
 435         /* Remove formatting from string */
 436
 437         p_spu->p_region->psz_text = StripTags( psz_subtitle );
 438         if( var_CreateGetBool( p_dec, "subsdec-formatted" ) )
 439         {
 440             p_spu->p_region->psz_html = CreateHtmlSubtitle( psz_subtitle );
 441         }
 442
 443         p_spu->i_start = p_block->i_pts;
 444         p_spu->i_stop = p_block->i_pts + p_block->i_length;
 445         p_spu->b_ephemer = (p_block->i_length == 0);
 446         p_spu->b_absolute = VLC_FALSE;
 447     }
 448     else
 449     {
 450         /* Decode SSA/USF strings */
 451         if( p_dec->fmt_in.i_codec == VLC_FOURCC('s','s','a',' ') )
 452             ParseSSAString( p_dec, psz_subtitle, p_spu );
 453
 454         p_spu->i_start = p_block->i_pts;
 455         p_spu->i_stop = p_block->i_pts + p_block->i_length;
 456         p_spu->b_ephemer = (p_block->i_length == 0);
 457         p_spu->b_absolute = VLC_FALSE;
 458         p_spu->i_original_picture_width = p_sys->i_original_width;
 459         p_spu->i_original_picture_height = p_sys->i_original_height;
 460     }
 461     if( psz_subtitle ) free( psz_subtitle );
 462
 463     return p_spu;
 464 }
 465
 466 char* GotoNextLine( char *psz_text )
 467 {
 468     char *p_newline = psz_text;
 469
 470     while( p_newline[0] != '\0' )
 471     {
 472         if( p_newline[0] == '\n' || p_newline[0] == '\r' )
 473         {
 474             p_newline++;
 475             while( p_newline[0] == '\n' || p_newline[0] == '\r' )
 476                 p_newline++;
 477             break;
 478         }
 479         else p_newline++;
 480     }
 481     return p_newline;
 482 }
 483
 484 /* Function now handles tags with attribute values, and tries
 485  * to deal with &' commands too. It no longer modifies the string
 486  * in place, so that the original text can be reused
 487  */
 488 static char *StripTags( char *psz_subtitle )
 489 {
 490     char *psz_text_start;
 491     char *psz_text;
 492
 493     psz_text = psz_text_start = malloc( strlen( psz_subtitle ) + 1 );
 494     if( !psz_text_start )
 495         return NULL;
 496
 497     while( *psz_subtitle )
 498     {
 499         if( *psz_subtitle == '<' )
 500         {
 501             if( strncasecmp( psz_subtitle, "<br/>", 5 ) == 0 )
 502                 *psz_text++ = '\n';
 503
 504             psz_subtitle += strcspn( psz_subtitle, ">" );
 505         }
 506         else if( *psz_subtitle == '&' )
 507         {
 508             if( !strncasecmp( psz_subtitle, "&lt;", 4 ))
 509             {
 510                 *psz_text++ = '<';
 511                 psz_subtitle += strcspn( psz_subtitle, ";" );
 512             }
 513             else if( !strncasecmp( psz_subtitle, "&gt;", 4 ))
 514             {
 515                 *psz_text++ = '>';
 516                 psz_subtitle += strcspn( psz_subtitle, ";" );
 517             }
 518             else if( !strncasecmp( psz_subtitle, "&amp;", 5 ))
 519             {
 520                 *psz_text++ = '&';
 521                 psz_subtitle += strcspn( psz_subtitle, ";" );
 522             }
 523             else if( !strncasecmp( psz_subtitle, "&quot;", 6 ))
 524             {
 525                 *psz_text++ = '\"';
 526                 psz_subtitle += strcspn( psz_subtitle, ";" );
 527             }
 528             else
 529             {
 530                 /* Assume it is just a normal ampersand */
 531                 *psz_text++ = '&';
 532             }
 533         }
 534         else
 535         {
 536             *psz_text++ = *psz_subtitle;
 537         }
 538
 539         psz_subtitle++;
 540     }
 541     *psz_text = '\0';
 542     psz_text_start = realloc( psz_text_start, strlen( psz_text_start ) + 1 );
 543
 544     return psz_text_start;
 545 }
 546
 547 /* Try to respect any style tags present in the subtitle string. The main
 548  * problem here is a lack of adequate specs for the subtitle formats.
 549  * SSA/ASS and USF are both detail spec'ed -- but they are handled elsewhere.
 550  * SAMI has a detailed spec, but extensive rework is needed in the demux
 551  * code to prevent all this style information being excised, as it presently
 552  * does.
 553  * That leaves the others - none of which were (I guess) originally intended
 554  * to be carrying style information. Over time people have used them that way.
 555  * In the absence of specifications from which to work, the tags supported
 556  * have been restricted to the simple set permitted by the USF DTD, ie. :
 557  *  Basic: <br>, <i>, <b>, <u>
 558  *  Extended: <font>
 559  *    Attributes: face
 560  *                family
 561  *                size
 562  *                color
 563  *                outline-color
 564  *                shadow-color
 565  *                outline-level
 566  *                shadow-level
 567  *                back-color
 568  *                alpha
 569  * There is also the further restriction that the subtitle be well-formed
 570  * as an XML entity, ie. the HTML sentence:
 571  *        <b><i>Bold and Italics</b></i>
 572  * doesn't qualify because the tags aren't nested one inside the other.
 573  * <text> tags are automatically added to the output to ensure
 574  * well-formedness.
 575  * If the text doesn't qualify for any reason, a NULL string is
 576  * returned, and the rendering engine will fall back to the
 577  * plain text version of the subtitle.
 578  */
 579 static char *CreateHtmlSubtitle( char *psz_subtitle )
 580 {
 581     char    psz_tagStack[ 100 ];
 582     size_t  i_buf_size     = strlen( psz_subtitle ) + 100;
 583     char   *psz_html_start = malloc( i_buf_size );
 584
 585     psz_tagStack[ 0 ] = '\0';
 586
 587     if( psz_html_start != NULL )
 588     {
 589         char *psz_html = psz_html_start;
 590
 591         strcpy( psz_html, "<text>" );
 592         psz_html += 6;
 593
 594         while( *psz_subtitle )
 595         {
 596             if( *psz_subtitle == '\n' )
 597             {
 598                 strcpy( psz_html, "<br/>" );
 599                 psz_html += 5;
 600                 psz_subtitle++;
 601             }
 602             else if( *psz_subtitle == '<' )
 603             {
 604                 if( !strncasecmp( psz_subtitle, "<br/>", 5 ))
 605                 {
 606                     strcpy( psz_html, "<br/>" );
 607                     psz_html += 5;
 608                     psz_subtitle += 5;
 609                 }
 610                 else if( !strncasecmp( psz_subtitle, "<b>", 3 ) )
 611                 {
 612                     strcpy( psz_html, "<b>" );
 613                     strcat( psz_tagStack, "b" );
 614                     psz_html += 3;
 615                     psz_subtitle += 3;
 616                 }
 617                 else if( !strncasecmp( psz_subtitle, "<i>", 3 ) )
 618                 {
 619                     strcpy( psz_html, "<i>" );
 620                     strcat( psz_tagStack, "i" );
 621                     psz_html += 3;
 622                     psz_subtitle += 3;
 623                 }
 624                 else if( !strncasecmp( psz_subtitle, "<u>", 3 ) )
 625                 {
 626                     strcpy( psz_html, "<u>" );
 627                     strcat( psz_tagStack, "u" );
 628                     psz_html += 3;
 629                     psz_subtitle += 3;
 630                 }
 631                 else if( !strncasecmp( psz_subtitle, "<font ", 6 ))
 632                 {
 633                     const char *psz_attribs[] = { "face=\"", "family=\"", "size=\"",
 634                             "color=\"", "outline-color=\"", "shadow-color=\"",
 635                             "outline-level=\"", "shadow-level=\"", "back-color=\"",
 636                             "alpha=\"", NULL };
 637
 638                     strcpy( psz_html, "<font " );
 639                     strcat( psz_tagStack, "f" );
 640                     psz_html += 6;
 641                     psz_subtitle += 6;
 642
 643                     while( *psz_subtitle != '>' )
 644                     {
 645                         int  k;
 646
 647                         for( k=0; psz_attribs[ k ]; k++ )
 648                         {
 649                             int i_len = strlen( psz_attribs[ k ] );
 650
 651                             if( !strncasecmp( psz_subtitle, psz_attribs[ k ], i_len ))
 652                             {
 653                                 i_len += strcspn( psz_subtitle + i_len, "\"" ) + 1;
 654
 655                                 strncpy( psz_html, psz_subtitle, i_len );
 656                                 psz_html += i_len;
 657                                 psz_subtitle += i_len;
 658                                 break;
 659                             }
 660                         }
 661                         if( psz_attribs[ k ] == NULL )
 662                         {
 663                             /* Jump over unrecognised tag */
 664                             int i_len = strcspn( psz_subtitle, "\"" ) + 1;
 665
 666                             i_len += strcspn( psz_subtitle + i_len, "\"" ) + 1;
 667                             psz_subtitle += i_len;
 668                         }
 669                         while (*psz_subtitle == ' ')
 670                             *psz_html++ = *psz_subtitle++;
 671                     }
 672                     *psz_html++ = *psz_subtitle++;
 673                 }
 674                 else if( !strncmp( psz_subtitle, "</", 2 ))
 675                 {
 676                     vlc_bool_t  b_match     = VLC_FALSE;
 677                     int         i_len       = strlen( psz_tagStack ) - 1;
 678                     char       *psz_lastTag = NULL;
 679
 680                     if( i_len >= 0 )
 681                     {
 682                         psz_lastTag = psz_tagStack + i_len;
 683                         i_len = 0;
 684
 685                         switch( *psz_lastTag )
 686                         {
 687                             case 'b':
 688                                 b_match = !strncasecmp( psz_subtitle, "</b>", 4 );
 689                                 i_len   = 4;
 690                                 break;
 691                             case 'i':
 692                                 b_match = !strncasecmp( psz_subtitle, "</i>", 4 );
 693                                 i_len   = 4;
 694                                 break;
 695                             case 'u':
 696                                 b_match = !strncasecmp( psz_subtitle, "</u>", 4 );
 697                                 i_len   = 4;
 698                                 break;
 699                             case 'f':
 700                                 b_match = !strncasecmp( psz_subtitle, "</font>", 7 );
 701                                 i_len   = 7;
 702                                 break;
 703                         }
 704                     }
 705                     if( ! b_match )
 706                     {
 707                         /* Not well formed -- kill everything */
 708                         free( psz_html_start );
 709                         psz_html_start = NULL;
 710                         break;
 711                     }
 712                     *psz_lastTag = '\0';
 713                     strncpy( psz_html, psz_subtitle, i_len );
 714                     psz_html += i_len;
 715                     psz_subtitle += i_len;
 716                 }
 717                 else
 718                 {
 719                     psz_subtitle += strcspn( psz_subtitle, ">" );
 720                 }
 721             }
 722             else if( *psz_subtitle == '&' )
 723             {
 724                 if( !strncasecmp( psz_subtitle, "&lt;", 4 ))
 725                 {
 726                     strcpy( psz_html, "&lt;" );
 727                     psz_html += 4;
 728                     psz_subtitle += 4;
 729                 }
 730                 else if( !strncasecmp( psz_subtitle, "&gt;", 4 ))
 731                 {
 732                     strcpy( psz_html, "&gt;" );
 733                     psz_html += 4;
 734                     psz_subtitle += 4;
 735                 }
 736                 else if( !strncasecmp( psz_subtitle, "&amp;", 5 ))
 737                 {
 738                     strcpy( psz_html, "&amp;" );
 739                     psz_html += 5;
 740                     psz_subtitle += 5;
 741                 }
 742                 else
 743                 {
 744                     strcpy( psz_html, "&amp;" );
 745                     psz_html += 5;
 746                     psz_subtitle++;
 747                 }
 748             }
 749             else
 750             {
 751                 *psz_html = *psz_subtitle;
 752                 if( psz_html > psz_html_start )
 753                 {
 754                     /* Check for double whitespace */
 755                     if((( *psz_html == ' ' ) ||
 756                         ( *psz_html == '\t' )) &&
 757                        (( *(psz_html-1) == ' ' ) ||
 758                         ( *(psz_html-1) == '\t' )))
 759                     {
 760                         strcpy( psz_html, NO_BREAKING_SPACE );
 761                         psz_html += strlen( NO_BREAKING_SPACE ) - 1;
 762                     }
 763                 }
 764                 psz_html++;
 765                 psz_subtitle++;
 766             }
 767
 768             if( ( size_t )( psz_html - psz_html_start ) > i_buf_size - 10 )
 769             {
 770                 int i_len = psz_html - psz_html_start;
 771
 772                 i_buf_size += 100;
 773                 psz_html_start = realloc( psz_html_start, i_buf_size );
 774                 psz_html = psz_html_start + i_len;
 775                 *psz_html = '\0';
 776             }
 777         }
 778         strcpy( psz_html, "</text>" );
 779         psz_html += 7;
 780
 781         if( psz_tagStack[ 0 ] != '\0' )
 782         {
 783             /* Not well formed -- kill everything */
 784             free( psz_html_start );
 785             psz_html_start = NULL;
 786         }
 787         else if( psz_html_start )
 788         {
 789             /* Shrink the memory requirements */
 790             psz_html_start = realloc( psz_html_start,  psz_html - psz_html_start + 1 );
 791         }
 792     }
 793     return psz_html_start;
 794 }