git.sesse.net Git - vlc/blob - plugins/spu_dec/spu_decoder.c

   1 /*****************************************************************************
   2  * spu_decoder.c : spu decoder thread
   3  *****************************************************************************
   4  * Copyright (C) 2000 VideoLAN
   5  * $Id: spu_decoder.c,v 1.1 2001/11/13 12:09:18 henri Exp $
   6  *
   7  * Authors: Samuel Hocevar <sam@zoy.org>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  22  *****************************************************************************/
  23
  24 #define MODULE_NAME spu_dec
  25 #include "modules_inner.h"
  26
  27 /*****************************************************************************
  28  * Preamble
  29  *****************************************************************************/
  30 #include "defs.h"
  31
  32 #ifdef HAVE_UNISTD_H
  33 #include <unistd.h>                                              /* getpid() */
  34 #endif
  35
  36 #ifdef WIN32                   /* getpid() for win32 is located in process.h */
  37 #include <process.h>
  38 #endif
  39
  40 #include <stdlib.h>                                      /* malloc(), free() */
  41 #include <string.h>                                    /* memcpy(), memset() */
  42
  43 #include "config.h"
  44 #include "common.h"
  45 #include "threads.h"
  46 #include "mtime.h"
  47 #include "intf_msg.h"
  48
  49 #include "video.h"
  50 #include "video_output.h"
  51
  52 #include "modules.h"
  53 #include "modules_export.h"
  54 #include "stream_control.h"
  55 #include "input_ext-dec.h"
  56
  57 #include "spu_decoder.h"
  58
  59 /*****************************************************************************
  60  * Local prototypes
  61  *****************************************************************************/
  62 static int spu_dec_Probe         ( probedata_t * );
  63 static int  spu_dec_Run          ( decoder_config_t * );
  64 static int  spu_dec_Init         ( spudec_thread_t * );
  65 static void spu_dec_ErrorThread  ( spudec_thread_t * );
  66 static void spu_dec_EndThread    ( spudec_thread_t * );
  67
  68 static int  SyncPacket           ( spudec_thread_t * );
  69 static void ParsePacket          ( spudec_thread_t * );
  70 static int  ParseControlSequences( spudec_thread_t *, subpicture_t * );
  71 static int  ParseRLE             ( spudec_thread_t *, subpicture_t *, u8 * );
  72
  73 /*****************************************************************************
  74  * Capabilities
  75  *****************************************************************************/
  76 void _M( spu_dec_getfunctions )( function_list_t * p_function_list )
  77 {
  78     p_function_list->pf_probe = spu_dec_Probe;
  79     p_function_list->functions.dec.pf_RunThread = spu_dec_Run;
  80 }
  81
  82 /*****************************************************************************
  83  * Build configuration tree.
  84  *****************************************************************************/
  85 MODULE_CONFIG_START
  86 ADD_WINDOW( "Configuration for SPU decoder module" )
  87     ADD_COMMENT( "Nothing to configure" )
  88 MODULE_CONFIG_STOP
  89
  90 MODULE_INIT_START
  91     p_module->i_capabilities = MODULE_CAPABILITY_DEC;
  92     p_module->psz_longname = "Subtitles decoder module";
  93 MODULE_INIT_STOP
  94
  95 MODULE_ACTIVATE_START
  96     _M( spu_dec_getfunctions )( &p_module->p_functions->dec );
  97 MODULE_ACTIVATE_STOP
  98
  99 MODULE_DEACTIVATE_START
 100 MODULE_DEACTIVATE_STOP
 101
 102 /*****************************************************************************
 103  * spu_dec_Probe: probe the decoder and return score
 104  *****************************************************************************
 105  * Tries to launch a decoder and return score so that the interface is able
 106  * to chose.
 107  *****************************************************************************/
 108 static int spu_dec_Probe( probedata_t *p_data )
 109 {
 110     if( p_data->i_type == DVD_SPU_ES )
 111         return( 50 );
 112     else
 113         return( 0 );
 114 }
 115
 116 /*****************************************************************************
 117  * spu_dec_Run: this function is called just after the thread is created
 118  *****************************************************************************/
 119 static int spu_dec_Run( decoder_config_t * p_config )
 120 {
 121     spudec_thread_t *     p_spudec;
 122
 123     intf_WarnMsg( 3, "spudec: thread launched. Initializing ..." );
 124
 125     /* Allocate the memory needed to store the thread's structure */
 126     p_spudec = (spudec_thread_t *)malloc( sizeof(spudec_thread_t) );
 127
 128     if ( p_spudec == NULL )
 129     {
 130         intf_ErrMsg( "spudec error: not enough memory "
 131                      "for spudec_CreateThread() to create the new thread" );
 132         return( -1 );
 133     }
 134
 135     /*
 136      * Initialize the thread properties
 137      */
 138     p_spudec->p_config = p_config;
 139
 140     p_spudec->p_fifo = p_config->p_decoder_fifo;
 141
 142     /*
 143      * Initialize thread and free configuration
 144      */
 145     p_spudec->p_fifo->b_error = spu_dec_Init( p_spudec );
 146
 147     /*
 148      * Main loop - it is not executed if an error occured during
 149      * initialization
 150      */
 151     while( (!p_spudec->p_fifo->b_die) && (!p_spudec->p_fifo->b_error) )
 152     {
 153         if( !SyncPacket( p_spudec ) )
 154         {
 155             ParsePacket( p_spudec );
 156         }
 157     }
 158
 159     /*
 160      * Error loop
 161      */
 162     if( p_spudec->p_fifo->b_error )
 163     {
 164         spu_dec_ErrorThread( p_spudec );
 165     }
 166
 167     /* End of thread */
 168     spu_dec_EndThread( p_spudec );
 169
 170     if( p_spudec->p_fifo->b_error )
 171     {
 172         return( -1 );
 173     }
 174
 175     return( 0 );
 176
 177 }
 178
 179 /* following functions are local */
 180
 181 /*****************************************************************************
 182  * spu_dec_Init: initialize spu decoder thread
 183  *****************************************************************************
 184  * This function is called from RunThread and performs the second step of the
 185  * initialization. It returns 0 on success. Note that the thread's flag are not
 186  * modified inside this function.
 187  *****************************************************************************/
 188 static int spu_dec_Init( spudec_thread_t *p_spudec )
 189 {
 190     /* Spawn a video output if there is none */
 191     vlc_mutex_lock( &p_vout_bank->lock );
 192
 193     if( p_vout_bank->i_count == 0 )
 194     {
 195         intf_WarnMsg( 1, "spudec: no vout present, spawning one" );
 196
 197         p_spudec->p_vout = vout_CreateThread( NULL, 0, 0 );
 198
 199         /* Everything failed */
 200         if( p_spudec->p_vout == NULL )
 201         {
 202             intf_Msg( "spudec: can't open vout, aborting" );
 203             vlc_mutex_unlock( &p_vout_bank->lock );
 204             free( p_spudec );
 205
 206             return( -1 );
 207         }
 208
 209         p_vout_bank->pp_vout[ p_vout_bank->i_count ] = p_spudec->p_vout;
 210         p_vout_bank->i_count++;
 211     }
 212     else
 213     {
 214         /* Take the first video output FIXME: take the best one */
 215         p_spudec->p_vout = p_vout_bank->pp_vout[ 0 ];
 216     }
 217
 218     vlc_mutex_unlock( &p_vout_bank->lock );
 219     p_spudec->p_config->pf_init_bit_stream(
 220             &p_spudec->bit_stream,
 221             p_spudec->p_config->p_decoder_fifo, NULL, NULL );
 222
 223     /* Mark thread as running and return */
 224     return( 0 );
 225 }
 226
 227 /*****************************************************************************
 228  * spu_dec_ErrorThread: spu_dec_Run() error loop
 229  *****************************************************************************
 230  * This function is called when an error occured during thread main's loop. The
 231  * thread can still receive feed, but must be ready to terminate as soon as
 232  * possible.
 233  *****************************************************************************/
 234 static void spu_dec_ErrorThread( spudec_thread_t *p_spudec )
 235 {
 236     /* We take the lock, because we are going to read/write the start/end
 237      * indexes of the decoder fifo */
 238     vlc_mutex_lock( &p_spudec->p_fifo->data_lock );
 239
 240     /* Wait until a `die' order is sent */
 241     while( !p_spudec->p_fifo->b_die )
 242     {
 243         /* Trash all received PES packets */
 244         while( !DECODER_FIFO_ISEMPTY(*p_spudec->p_fifo) )
 245         {
 246             p_spudec->p_fifo->pf_delete_pes( p_spudec->p_fifo->p_packets_mgt,
 247                     DECODER_FIFO_START(*p_spudec->p_fifo) );
 248             DECODER_FIFO_INCSTART( *p_spudec->p_fifo );
 249         }
 250
 251         /* Waiting for the input thread to put new PES packets in the fifo */
 252         vlc_cond_wait( &p_spudec->p_fifo->data_wait,
 253                        &p_spudec->p_fifo->data_lock );
 254     }
 255
 256     /* We can release the lock before leaving */
 257     vlc_mutex_unlock( &p_spudec->p_fifo->data_lock );
 258 }
 259
 260 /*****************************************************************************
 261  * spu_dec_EndThread: thread destruction
 262  *****************************************************************************
 263  * This function is called when the thread ends after a sucessful
 264  * initialization.
 265  *****************************************************************************/
 266 static void spu_dec_EndThread( spudec_thread_t *p_spudec )
 267 {
 268     free( p_spudec->p_config );
 269     free( p_spudec );
 270 }
 271
 272 /*****************************************************************************
 273  * SyncPacket: get in sync with the stream
 274  *****************************************************************************
 275  * This function makes a few sanity checks and returns 0 if it looks like we
 276  * are at the beginning of a subpicture packet.
 277  *****************************************************************************/
 278 static int SyncPacket( spudec_thread_t *p_spudec )
 279 {
 280     /* Re-align the buffer on an 8-bit boundary */
 281     RealignBits( &p_spudec->bit_stream );
 282
 283     /* The total SPU packet size, often bigger than a PS packet */
 284     p_spudec->i_spu_size = GetBits( &p_spudec->bit_stream, 16 );
 285
 286     /* The RLE stuff size (remove 4 because we just read 32 bits) */
 287     p_spudec->i_rle_size = ShowBits( &p_spudec->bit_stream, 16 ) - 4;
 288
 289     /* If the values we got are a bit strange, skip packet */
 290     if( !p_spudec->i_spu_size
 291          || ( p_spudec->i_rle_size >= p_spudec->i_spu_size ) )
 292     {
 293         return( 1 );
 294     }
 295
 296     RemoveBits( &p_spudec->bit_stream, 16 );
 297
 298     return( 0 );
 299 }
 300
 301 /*****************************************************************************
 302  * ParsePacket: parse an SPU packet and send it to the video output
 303  *****************************************************************************
 304  * This function parses the SPU packet and, if valid, sends it to the
 305  * video output.
 306  *****************************************************************************/
 307 static void ParsePacket( spudec_thread_t *p_spudec )
 308 {
 309     subpicture_t * p_spu;
 310     u8           * p_src;
 311     unsigned int   i_offset;
 312
 313     intf_WarnMsg( 3, "spudec: trying to gather a 0x%.2x long subtitle",
 314                   p_spudec->i_spu_size );
 315
 316     /* We cannot display a subpicture with no date */
 317     if( DECODER_FIFO_START(*p_spudec->p_fifo)->i_pts == 0 )
 318     {
 319         intf_WarnMsg( 3, "spudec error: subtitle without a date" );
 320         return;
 321     }
 322
 323     /* Allocate the subpicture internal data. */
 324     p_spu = vout_CreateSubPicture( p_spudec->p_vout, DVD_SUBPICTURE,
 325                                    p_spudec->i_rle_size * 4 );
 326     /* Rationale for the "p_spudec->i_rle_size * 4": we are going to
 327      * expand the RLE stuff so that we won't need to read nibbles later
 328      * on. This will speed things up a lot. Plus, we'll only need to do
 329      * this stupid interlacing stuff once. */
 330
 331     if( p_spu == NULL )
 332     {
 333         return;
 334     }
 335
 336     /* Get display time now. If we do it later, we may miss the PTS. */
 337     p_spudec->i_pts = DECODER_FIFO_START(*p_spudec->p_fifo)->i_pts;
 338
 339     /* Allocate the temporary buffer we will parse */
 340     p_src = malloc( p_spudec->i_rle_size );
 341
 342     if( p_src == NULL )
 343     {
 344         intf_ErrMsg( "spudec error: could not allocate p_src" );
 345         vout_DestroySubPicture( p_spudec->p_vout, p_spu );
 346         return;
 347     }
 348
 349     /* Get RLE data */
 350     for( i_offset = 0;
 351          i_offset + SPU_CHUNK_SIZE < p_spudec->i_rle_size;
 352          i_offset += SPU_CHUNK_SIZE )
 353     {
 354         GetChunk( &p_spudec->bit_stream, p_src + i_offset, SPU_CHUNK_SIZE );
 355
 356         /* Abort subtitle parsing if we were requested to stop */
 357         if( p_spudec->p_fifo->b_die )
 358         {
 359             free( p_src );
 360             vout_DestroySubPicture( p_spudec->p_vout, p_spu );
 361             return;
 362         }
 363     }
 364
 365     GetChunk( &p_spudec->bit_stream, p_src + i_offset,
 366               p_spudec->i_rle_size - i_offset );
 367
 368 #if 0
 369     /* Dump the subtitle info */
 370     intf_WarnHexDump( 5, p_spu->p_data, p_spudec->i_rle_size );
 371 #endif
 372
 373     /* Getting the control part */
 374     if( ParseControlSequences( p_spudec, p_spu ) )
 375     {
 376         /* There was a parse error, delete the subpicture */
 377         free( p_src );
 378         vout_DestroySubPicture( p_spudec->p_vout, p_spu );
 379         return;
 380     }
 381
 382     /* At this point, no more GetBit() command is needed, so we have all
 383      * the data we need to tell whether the subtitle is valid. Thus we
 384      * try to display it and we ignore b_die. */
 385
 386     if( ParseRLE( p_spudec, p_spu, p_src ) )
 387     {
 388         /* There was a parse error, delete the subpicture */
 389         free( p_src );
 390         vout_DestroySubPicture( p_spudec->p_vout, p_spu );
 391         return;
 392     }
 393
 394     intf_WarnMsg( 3, "spudec: total size: 0x%x, RLE offsets: 0x%x 0x%x",
 395                   p_spudec->i_spu_size,
 396                   p_spu->type.spu.i_offset[0], p_spu->type.spu.i_offset[1] );
 397
 398     /* SPU is finished - we can ask the video output to display it */
 399     vout_DisplaySubPicture( p_spudec->p_vout, p_spu );
 400
 401     /* Clean up */
 402     free( p_src );
 403 }
 404
 405 /*****************************************************************************
 406  * ParseControlSequences: parse all SPU control sequences
 407  *****************************************************************************
 408  * This is the most important part in SPU decoding. We get dates, palette
 409  * information, coordinates, and so on. For more information on the
 410  * subtitles format, see http://sam.zoy.org/doc/dvd/subtitles/index.html
 411  *****************************************************************************/
 412 static int ParseControlSequences( spudec_thread_t *p_spudec,
 413                                   subpicture_t * p_spu )
 414 {
 415     /* Our current index in the SPU packet */
 416     int i_index = p_spudec->i_rle_size + 4;
 417
 418     /* The next start-of-control-sequence index and the previous one */
 419     int i_next_seq, i_cur_seq;
 420
 421     /* Command time and date */
 422     u8  i_command;
 423     int i_date;
 424
 425     /* XXX: temporary variables */
 426     boolean_t b_force_display = 0;
 427
 428     /* Initialize the structure */
 429     p_spu->i_start = p_spu->i_stop = 0;
 430     p_spu->b_ephemer = 0;
 431
 432     do
 433     {
 434         /* Get the control sequence date */
 435         i_date = GetBits( &p_spudec->bit_stream, 16 );
 436
 437         /* Next offset */
 438         i_cur_seq = i_index;
 439         i_next_seq = GetBits( &p_spudec->bit_stream, 16 );
 440
 441         /* Skip what we just read */
 442         i_index += 4;
 443
 444         do
 445         {
 446             i_command = GetBits( &p_spudec->bit_stream, 8 );
 447             i_index++;
 448
 449             switch( i_command )
 450             {
 451                 case SPU_CMD_FORCE_DISPLAY:
 452
 453                     /* 00 (force displaying) */
 454                     p_spu->i_start = p_spudec->i_pts + ( i_date * 11000 );
 455                     b_force_display = 1;
 456
 457                     break;
 458
 459                 /* Convert the dates in seconds to PTS values */
 460                 case SPU_CMD_START_DISPLAY:
 461
 462                     /* 01 (start displaying) */
 463                     p_spu->i_start = p_spudec->i_pts + ( i_date * 11000 );
 464
 465                     break;
 466
 467                 case SPU_CMD_STOP_DISPLAY:
 468
 469                     /* 02 (stop displaying) */
 470                     p_spu->i_stop = p_spudec->i_pts + ( i_date * 11000 );
 471
 472                     break;
 473
 474                 case SPU_CMD_SET_PALETTE:
 475
 476                     /* 03xxxx (palette) - trashed */
 477                     RemoveBits( &p_spudec->bit_stream, 16 );
 478                     i_index += 2;
 479
 480                     break;
 481
 482                 case SPU_CMD_SET_ALPHACHANNEL:
 483
 484                     /* 04xxxx (alpha channel) - trashed */
 485                     RemoveBits( &p_spudec->bit_stream, 16 );
 486                     i_index += 2;
 487
 488                     break;
 489
 490                 case SPU_CMD_SET_COORDINATES:
 491
 492                     /* 05xxxyyyxxxyyy (coordinates) */
 493                     p_spu->i_x = GetBits( &p_spudec->bit_stream, 12 );
 494                     p_spu->i_width = GetBits( &p_spudec->bit_stream, 12 )
 495                                       - p_spu->i_x + 1;
 496
 497                     p_spu->i_y = GetBits( &p_spudec->bit_stream, 12 );
 498                     p_spu->i_height = GetBits( &p_spudec->bit_stream, 12 )
 499                                        - p_spu->i_y + 1;
 500
 501                     i_index += 6;
 502
 503                     break;
 504
 505                 case SPU_CMD_SET_OFFSETS:
 506
 507                     /* 06xxxxyyyy (byte offsets) */
 508                     p_spu->type.spu.i_offset[0] =
 509                         GetBits( &p_spudec->bit_stream, 16 ) - 4;
 510
 511                     p_spu->type.spu.i_offset[1] =
 512                         GetBits( &p_spudec->bit_stream, 16 ) - 4;
 513
 514                     i_index += 4;
 515
 516                     break;
 517
 518                 case SPU_CMD_END:
 519
 520                     /* ff (end) */
 521                     break;
 522
 523                 default:
 524
 525                     /* xx (unknown command) */
 526                     intf_ErrMsg( "spudec error: unknown command 0x%.2x",
 527                                  i_command );
 528                     return( 1 );
 529             }
 530
 531             /* We need to check for quit commands here */
 532             if( p_spudec->p_fifo->b_die )
 533             {
 534                 return( 1 );
 535             }
 536
 537         } while( i_command != SPU_CMD_END );
 538
 539     } while( i_index == i_next_seq );
 540
 541     /* Check that the next sequence index matches the current one */
 542     if( i_next_seq != i_cur_seq )
 543     {
 544         intf_ErrMsg( "spudec error: index mismatch (0x%.4x != 0x%.4x)",
 545                      i_next_seq, i_cur_seq );
 546         return( 1 );
 547     }
 548
 549     if( i_index > p_spudec->i_spu_size )
 550     {
 551         intf_ErrMsg( "spudec error: uh-oh, we went too far (0x%.4x > 0x%.4x)",
 552                      i_index, p_spudec->i_spu_size );
 553         return( 1 );
 554     }
 555
 556     if( !p_spu->i_start )
 557     {
 558         intf_ErrMsg( "spudec error: no `start display' command" );
 559     }
 560
 561     if( !p_spu->i_stop )
 562     {
 563         /* This subtitle will live for 5 seconds or until the next subtitle */
 564         p_spu->i_stop = p_spu->i_start + 500 * 11000;
 565         p_spu->b_ephemer = 1;
 566     }
 567
 568     /* Get rid of padding bytes */
 569     switch( p_spudec->i_spu_size - i_index )
 570     {
 571         /* Zero or one padding byte, quite usual */
 572         case 1:
 573             RemoveBits( &p_spudec->bit_stream, 8 );
 574             i_index++;
 575         case 0:
 576             break;
 577
 578         /* More than one padding byte - this is very strange, but
 579          * we can deal with it */
 580         default:
 581             intf_WarnMsg( 2, "spudec warning: %i padding bytes, we usually "
 582                              "get 0 or 1 of them",
 583                           p_spudec->i_spu_size - i_index );
 584
 585             while( i_index < p_spudec->i_spu_size )
 586             {
 587                 RemoveBits( &p_spudec->bit_stream, 8 );
 588                 i_index++;
 589             }
 590
 591             break;
 592     }
 593
 594     if( b_force_display )
 595     {
 596         intf_ErrMsg( "spudec: \"force display\" command" );
 597         intf_ErrMsg( "spudec: send mail to <sam@zoy.org> if you "
 598                      "want to help debugging this" );
 599     }
 600
 601     /* Successfully parsed ! */
 602     return( 0 );
 603 }
 604
 605 /*****************************************************************************
 606  * ParseRLE: parse the RLE part of the subtitle
 607  *****************************************************************************
 608  * This part parses the subtitle graphical data and stores it in a more
 609  * convenient structure for later decoding. For more information on the
 610  * subtitles format, see http://sam.zoy.org/doc/dvd/subtitles/index.html
 611  *****************************************************************************/
 612 static int ParseRLE( spudec_thread_t *p_spudec,
 613                      subpicture_t * p_spu, u8 * p_src )
 614 {
 615     unsigned int i_code;
 616
 617     unsigned int i_width = p_spu->i_width;
 618     unsigned int i_height = p_spu->i_height;
 619     unsigned int i_x, i_y;
 620
 621     u16 *p_dest = (u16 *)p_spu->p_data;
 622
 623     /* The subtitles are interlaced, we need two offsets */
 624     unsigned int  i_id = 0;                   /* Start on the even SPU layer */
 625     unsigned int  pi_table[ 2 ];
 626     unsigned int *pi_offset;
 627
 628     boolean_t b_empty_top = 1,
 629               b_empty_bottom = 0;
 630     unsigned int i_skipped_top = 0,
 631                  i_skipped_bottom = 0;
 632
 633     pi_table[ 0 ] = p_spu->type.spu.i_offset[ 0 ] << 1;
 634     pi_table[ 1 ] = p_spu->type.spu.i_offset[ 1 ] << 1;
 635
 636     for( i_y = 0 ; i_y < i_height ; i_y++ )
 637     {
 638         pi_offset = pi_table + i_id;
 639
 640         for( i_x = 0 ; i_x < i_width ; i_x += i_code >> 2 )
 641         {
 642             i_code = AddNibble( 0, p_src, pi_offset );
 643
 644             if( i_code < 0x04 )
 645             {
 646                 i_code = AddNibble( i_code, p_src, pi_offset );
 647
 648                 if( i_code < 0x10 )
 649                 {
 650                     i_code = AddNibble( i_code, p_src, pi_offset );
 651
 652                     if( i_code < 0x040 )
 653                     {
 654                         i_code = AddNibble( i_code, p_src, pi_offset );
 655
 656                         if( i_code < 0x0100 )
 657                         {
 658                             /* If the 14 first bits are set to 0, then it's a
 659                              * new line. We emulate it. */
 660                             if( i_code < 0x0004 )
 661                             {
 662                                 i_code |= ( i_width - i_x ) << 2;
 663                             }
 664                             else
 665                             {
 666                                 /* We have a boo boo ! */
 667                                 intf_ErrMsg( "spudec error: unknown RLE code "
 668                                              "0x%.4x", i_code );
 669                                 return( 1 );
 670                             }
 671                         }
 672                     }
 673                 }
 674             }
 675
 676             if( ( (i_code >> 2) + i_x + i_y * i_width ) > i_height * i_width )
 677             {
 678                 intf_ErrMsg( "spudec error: out of bounds, %i at (%i,%i) is "
 679                              "out of %ix%i",
 680                              i_code >> 2, i_x, i_y, i_width, i_height );
 681                 return( 1 );
 682             }
 683
 684             if( i_code == (i_width << 2) ) /* FIXME: we assume 0 is transp */
 685             {
 686                 if( b_empty_top )
 687                 {
 688                     /* This is a blank top line, we skip it */
 689                     i_skipped_top++;
 690                 }
 691                 else
 692                 {
 693                     /* We can't be sure the current lines will be skipped,
 694                      * so we store the code just in case. */
 695                     *p_dest++ = i_code;
 696
 697                     b_empty_bottom = 1;
 698                     i_skipped_bottom++;
 699                 }
 700             }
 701             else
 702             {
 703                 /* We got a valid code, store it */
 704                 *p_dest++ = i_code;
 705
 706                 /* Valid code means no blank line */
 707                 b_empty_top = 0;
 708                 b_empty_bottom = 0;
 709                 i_skipped_bottom = 0;
 710             }
 711         }
 712
 713         /* Check that we didn't go too far */
 714         if( i_x > i_width )
 715         {
 716             intf_ErrMsg( "spudec error: i_x overflowed, %i > %i",
 717                          i_x, i_width );
 718             return( 1 );
 719         }
 720
 721         /* Byte-align the stream */
 722         if( *pi_offset & 0x1 )
 723         {
 724             (*pi_offset)++;
 725         }
 726
 727         /* Swap fields */
 728         i_id = ~i_id & 0x1;
 729     }
 730
 731     /* We shouldn't get any padding bytes */
 732     if( i_y < i_height )
 733     {
 734         intf_ErrMsg( "spudec: padding bytes found in RLE sequence" );
 735         intf_ErrMsg( "spudec: send mail to <sam@zoy.org> if you "
 736                      "want to help debugging this" );
 737
 738         /* Skip them just in case */
 739         while( i_y < i_height )
 740         {
 741             *p_dest++ = i_width << 2;
 742             i_y++;
 743         }
 744
 745         return( 1 );
 746     }
 747
 748     intf_WarnMsg( 3, "spudec: valid subtitle, size: %ix%i, position: %i,%i",
 749                   p_spu->i_width, p_spu->i_height, p_spu->i_x, p_spu->i_y );
 750
 751     /* Crop if necessary */
 752     if( i_skipped_top || i_skipped_bottom )
 753     {
 754         p_spu->i_y += i_skipped_top;
 755         p_spu->i_height -= i_skipped_top + i_skipped_bottom;
 756
 757         intf_WarnMsg( 3, "spudec: cropped to: %ix%i, position: %i,%i",
 758                       p_spu->i_width, p_spu->i_height, p_spu->i_x, p_spu->i_y );
 759     }
 760
 761     return( 0 );
 762 }
 763