modules/codec/svcdsub.c

   1 /*****************************************************************************
   2  * svcdsub.c : Overlay Graphics Text (SVCD subtitles) decoder
   3  *****************************************************************************
   4  * Copyright (C) 2003, 2004 the VideoLAN team
   5  * $Id$
   6  *
   7  * Authors: Rocky Bernstein
   8  *          Gildas Bazin <gbazin@videolan.org>
   9  *          Julio Sanchez Fernandez (http://subhandler.sourceforge.net)
  10  *          Laurent Aimar <fenrir@via.ecp.fr>
  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 #ifdef HAVE_CONFIG_H
  31 # include "config.h"
  32 #endif
  33
  34 #include <vlc_common.h>
  35 #include <vlc_plugin.h>
  36 #include <vlc_codec.h>
  37 #include <vlc_bits.h>
  38
  39 /*****************************************************************************
  40  * Module descriptor.
  41  *****************************************************************************/
  42 static int  DecoderOpen   ( vlc_object_t * );
  43 static int  PacketizerOpen( vlc_object_t * );
  44 static void DecoderClose  ( vlc_object_t * );
  45
  46 vlc_module_begin ()
  47     set_description( N_("Philips OGT (SVCD subtitle) decoder") )
  48     set_shortname( N_("SVCD subtitles") )
  49     set_category( CAT_INPUT )
  50     set_subcategory( SUBCAT_INPUT_SCODEC )
  51     set_capability( "decoder", 50 )
  52     set_callbacks( DecoderOpen, DecoderClose )
  53
  54     add_obsolete_integer ( MODULE_STRING "-debug" )
  55
  56     add_submodule ()
  57     set_description( N_("Philips OGT (SVCD subtitle) packetizer") )
  58     set_capability( "packetizer", 50 )
  59     set_callbacks( PacketizerOpen, DecoderClose )
  60 vlc_module_end ()
  61
  62 /*****************************************************************************
  63  * Local prototypes
  64  *****************************************************************************/
  65 static subpicture_t *Decode( decoder_t *, block_t ** );
  66 static block_t *Packetize  ( decoder_t *, block_t ** );
  67 static block_t *Reassemble ( decoder_t *, block_t * );
  68 static void ParseHeader( decoder_t *, block_t * );
  69 static subpicture_t *DecodePacket( decoder_t *, block_t * );
  70 static void SVCDSubRenderImage( decoder_t *, block_t *, subpicture_region_t * );
  71
  72 #define GETINT16(p) ( (p[0] <<  8) +   p[1] )  ; p +=2;
  73
  74 #define GETINT32(p) ( (p[0] << 24) +  (p[1] << 16) +    \
  75                       (p[2] <<  8) +  (p[3]) ) ; p += 4;
  76
  77 typedef enum  {
  78   SUBTITLE_BLOCK_EMPTY    = 0,
  79   SUBTITLE_BLOCK_PARTIAL  = 1,
  80   SUBTITLE_BLOCK_COMPLETE = 2
  81 } packet_state_t;
  82
  83 #ifndef NDEBUG
  84 # define dbg_print( s, args...) \
  85      msg_Dbg(p_dec, "%s: "s, __func__ , ##args)
  86 #else
  87 # define dbg_print( s, args...)
  88 #endif
  89
  90 struct decoder_sys_t
  91 {
  92   packet_state_t i_state; /* data-gathering state for this subtitle */
  93
  94   block_t  *p_spu;        /* Bytes of the packet. */
  95
  96   uint16_t i_image;       /* image number in the subtitle stream */
  97   uint8_t  i_packet;      /* packet number for above image number */
  98
  99   size_t   i_spu_size;     /* goal for subtitle_data_pos while gathering,
 100                              size of used subtitle_data later */
 101
 102   uint16_t i_image_offset;      /* offset from subtitle_data to compressed
 103                                    image data */
 104   size_t i_image_length;           /* size of the compressed image data */
 105   size_t second_field_offset;      /* offset of odd raster lines */
 106   size_t metadata_offset;          /* offset to data describing the image */
 107   size_t metadata_length;          /* length of metadata */
 108
 109   mtime_t i_duration;   /* how long to display the image, 0 stands
 110                            for "until next subtitle" */
 111
 112   uint16_t i_x_start, i_y_start; /* position of top leftmost pixel of
 113                                     image when displayed */
 114   uint16_t i_width, i_height;    /* dimensions in pixels of image */
 115
 116   uint8_t p_palette[4][4];       /* Palette of colors used in subtitle */
 117 };
 118
 119 /*****************************************************************************
 120  * DecoderOpen: open/initialize the svcdsub decoder.
 121  *****************************************************************************/
 122 static int DecoderOpen( vlc_object_t *p_this )
 123 {
 124     decoder_t     *p_dec = (decoder_t*)p_this;
 125     decoder_sys_t *p_sys;
 126
 127     if( p_dec->fmt_in.i_codec != VLC_CODEC_OGT )
 128         return VLC_EGENERIC;
 129
 130     p_dec->p_sys = p_sys = calloc( 1, sizeof( decoder_sys_t ) );
 131     if( p_sys == NULL )
 132         return VLC_ENOMEM;
 133
 134
 135     p_sys->i_image = -1;
 136
 137     p_sys->i_state = SUBTITLE_BLOCK_EMPTY;
 138     p_sys->p_spu   = NULL;
 139
 140     es_format_Init( &p_dec->fmt_out, SPU_ES, VLC_CODEC_OGT );
 141
 142     p_dec->pf_decode_sub = Decode;
 143     p_dec->pf_packetize  = Packetize;
 144
 145     return VLC_SUCCESS;
 146 }
 147
 148 /*****************************************************************************
 149  * PacketizerOpen: open/initialize the svcdsub packetizer.
 150  *****************************************************************************/
 151 static int PacketizerOpen( vlc_object_t *p_this )
 152 {
 153     if( DecoderOpen( p_this ) != VLC_SUCCESS ) return VLC_EGENERIC;
 154
 155     return VLC_SUCCESS;
 156 }
 157
 158 /*****************************************************************************
 159  * DecoderClose: closes the svcdsub decoder/packetizer.
 160  *****************************************************************************/
 161 void DecoderClose( vlc_object_t *p_this )
 162 {
 163     decoder_t     *p_dec = (decoder_t*)p_this;
 164     decoder_sys_t *p_sys = p_dec->p_sys;
 165
 166     if( p_sys->p_spu ) block_ChainRelease( p_sys->p_spu );
 167     free( p_sys );
 168 }
 169
 170 /*****************************************************************************
 171  * Decode:
 172  *****************************************************************************/
 173 static subpicture_t *Decode( decoder_t *p_dec, block_t **pp_block )
 174 {
 175     block_t *p_block, *p_spu;
 176
 177     dbg_print( "" );
 178
 179     if( pp_block == NULL || *pp_block == NULL ) return NULL;
 180
 181     p_block = *pp_block;
 182     *pp_block = NULL;
 183
 184     if( !(p_spu = Reassemble( p_dec, p_block )) ) return NULL;
 185
 186     /* Parse and decode */
 187     return DecodePacket( p_dec, p_spu );
 188 }
 189
 190 /*****************************************************************************
 191  * Packetize:
 192  *****************************************************************************/
 193 static block_t *Packetize( decoder_t *p_dec, block_t **pp_block )
 194 {
 195     block_t *p_block, *p_spu;
 196
 197     if( pp_block == NULL || *pp_block == NULL ) return NULL;
 198
 199     p_block = *pp_block;
 200     *pp_block = NULL;
 201
 202     if( !(p_spu = Reassemble( p_dec, p_block )) ) return NULL;
 203
 204     p_spu->i_dts = p_spu->i_pts;
 205     p_spu->i_length = 0;
 206
 207     return p_spu;
 208 }
 209
 210 /*****************************************************************************
 211  Reassemble:
 212
 213  The data for single screen subtitle may come in one of many
 214  non-contiguous packets of a stream. This routine is called when the
 215  next packet in the stream comes in. The job of this routine is to
 216  parse the header, if this is the beginning, and combine the packets
 217  into one complete subtitle unit.
 218
 219  If everything is complete, we will return a block. Otherwise return
 220  NULL.
 221
 222
 223  The format of the beginning of the subtitle packet that is used here.
 224
 225    size    description
 226    -------------------------------------------
 227    byte    subtitle channel (0..7) in bits 0-3
 228    byte    subtitle packet number of this subtitle image 0-N,
 229            if the subtitle packet is complete, the top bit of the byte is 1.
 230    uint16  subtitle image number
 231
 232  *****************************************************************************/
 233 #define SPU_HEADER_LEN 5
 234
 235 static block_t *Reassemble( decoder_t *p_dec, block_t *p_block )
 236 {
 237     decoder_sys_t *p_sys = p_dec->p_sys;
 238     uint8_t *p_buffer;
 239     uint16_t i_expected_image;
 240     uint8_t  i_packet, i_expected_packet;
 241
 242     if( p_block->i_flags & (BLOCK_FLAG_DISCONTINUITY|BLOCK_FLAG_CORRUPTED) )
 243     {
 244         block_Release( p_block );
 245         return NULL;
 246     }
 247
 248     if( p_block->i_buffer < SPU_HEADER_LEN )
 249     {
 250         msg_Dbg( p_dec, "invalid packet header (size %zu < %u)" ,
 251                  p_block->i_buffer, SPU_HEADER_LEN );
 252         block_Release( p_block );
 253         return NULL;
 254     }
 255
 256     p_buffer = p_block->p_buffer;
 257
 258     if( p_sys->i_state == SUBTITLE_BLOCK_EMPTY )
 259     {
 260         i_expected_image  = p_sys->i_image + 1;
 261         i_expected_packet = 0;
 262     }
 263     else
 264     {
 265         i_expected_image  = p_sys->i_image;
 266         i_expected_packet = p_sys->i_packet + 1;
 267     }
 268
 269     /* The dummy ES that the menu selection uses has an 0x70 at
 270        the head which we need to strip off. */
 271     p_buffer += 2;
 272
 273     if( *p_buffer & 0x80 )
 274     {
 275         p_sys->i_state = SUBTITLE_BLOCK_COMPLETE;
 276         i_packet       = *p_buffer++ & 0x7F;
 277     }
 278     else
 279     {
 280         p_sys->i_state = SUBTITLE_BLOCK_PARTIAL;
 281         i_packet       = *p_buffer++;
 282     }
 283
 284     p_sys->i_image = GETINT16(p_buffer);
 285
 286     if( p_sys->i_image != i_expected_image )
 287     {
 288         msg_Warn( p_dec, "expected subtitle image %u but found %u",
 289                   i_expected_image, p_sys->i_image );
 290     }
 291
 292     if( i_packet != i_expected_packet )
 293     {
 294         msg_Warn( p_dec, "expected subtitle image packet %u but found %u",
 295                   i_expected_packet, i_packet );
 296     }
 297
 298     p_block->p_buffer += SPU_HEADER_LEN;
 299     p_block->i_buffer -= SPU_HEADER_LEN;
 300
 301     p_sys->i_packet = i_packet;
 302     /* First packet in the subtitle block */
 303     if( !p_sys->i_packet ) ParseHeader( p_dec, p_block );
 304
 305     block_ChainAppend( &p_sys->p_spu, p_block );
 306
 307     if( p_sys->i_state == SUBTITLE_BLOCK_COMPLETE )
 308     {
 309         block_t *p_spu = block_ChainGather( p_sys->p_spu );
 310
 311         if( p_spu->i_buffer != p_sys->i_spu_size )
 312         {
 313             msg_Warn( p_dec, "subtitle packets size=%zu should be %zu",
 314                       p_spu->i_buffer, p_sys->i_spu_size );
 315         }
 316
 317         dbg_print( "subtitle packet complete, size=%zu", p_spu->i_buffer );
 318
 319         p_sys->i_state = SUBTITLE_BLOCK_EMPTY;
 320         p_sys->p_spu = 0;
 321         return p_spu;
 322     }
 323
 324     return NULL;
 325 }
 326
 327 /******************************************************************************
 328   The format is roughly as follows (everything is big-endian):
 329
 330    size     description
 331    -------------------------------------------
 332    byte     subtitle channel (0..7) in bits 0-3
 333    byte     subtitle packet number of this subtitle image 0-N,
 334             if the subtitle packet is complete, the top bit of the byte is 1.
 335    u_int16  subtitle image number
 336    u_int16  length in bytes of the rest
 337    byte     option flags, unknown meaning except bit 3 (0x08) indicates
 338             presence of the duration field
 339    byte     unknown
 340    u_int32  duration in 1/90000ths of a second (optional), start time
 341             is as indicated by the PTS in the PES header
 342    u_int32  xpos
 343    u_int32  ypos
 344    u_int32  width (must be even)
 345    u_int32  height (must be even)
 346    byte[16] palette, 4 palette entries, each contains values for
 347             Y, U, V and transparency, 0 standing for transparent
 348    byte     command,
 349             cmd>>6==1 indicates shift
 350             (cmd>>4)&3 is direction from, (0=top,1=left,2=right,3=bottom)
 351    u_int32  shift duration in 1/90000ths of a second
 352    u_int16  offset of odd-numbered scanlines - subtitle images are
 353             given in interlace order
 354    byte[]   limited RLE image data in interlace order (0,2,4... 1,3,5) with
 355             2-bits per palette number
 356 ******************************************************************************/
 357 static void ParseHeader( decoder_t *p_dec, block_t *p_block )
 358 {
 359     decoder_sys_t *p_sys = p_dec->p_sys;
 360     uint8_t *p = p_block->p_buffer;
 361     uint8_t i_options, i_options2, i_cmd, i_cmd_arg;
 362     int i;
 363
 364     p_sys->i_spu_size = GETINT16(p);
 365     i_options  = *p++;
 366     i_options2 = *p++;
 367
 368     if( i_options & 0x08 ) { p_sys->i_duration = GETINT32(p); }
 369     else p_sys->i_duration = 0; /* Ephemer subtitle */
 370     p_sys->i_duration *= 100 / 9;
 371
 372     p_sys->i_x_start = GETINT16(p);
 373     p_sys->i_y_start = GETINT16(p);
 374     p_sys->i_width   = GETINT16(p);
 375     p_sys->i_height  = GETINT16(p);
 376
 377     for( i = 0; i < 4; i++ )
 378     {
 379         p_sys->p_palette[i][0] = *p++; /* Y */
 380         p_sys->p_palette[i][2] = *p++; /* Cr / V */
 381         p_sys->p_palette[i][1] = *p++; /* Cb / U */
 382         p_sys->p_palette[i][3] = *p++; /* T */
 383     }
 384
 385     i_cmd = *p++;
 386     /* We do not really know this, FIXME */
 387     if( i_cmd ) {i_cmd_arg = GETINT32(p);}
 388
 389     /* Actually, this is measured against a different origin, so we have to
 390      * adjust it */
 391     p_sys->second_field_offset = GETINT16(p);
 392     p_sys->i_image_offset  = p - p_block->p_buffer;
 393     p_sys->i_image_length  = p_sys->i_spu_size - p_sys->i_image_offset;
 394     p_sys->metadata_length = p_sys->i_image_offset;
 395
 396 #ifndef NDEBUG
 397     msg_Dbg( p_dec, "x-start: %d, y-start: %d, width: %d, height %d, "
 398              "spu size: %zu, duration: %"PRIu64" (d:%zu p:%"PRIu16")",
 399              p_sys->i_x_start, p_sys->i_y_start,
 400              p_sys->i_width, p_sys->i_height,
 401              p_sys->i_spu_size, p_sys->i_duration,
 402              p_sys->i_image_length, p_sys->i_image_offset);
 403
 404     for( i = 0; i < 4; i++ )
 405     {
 406         msg_Dbg( p_dec, "palette[%d]= T: %2x, Y: %2x, u: %2x, v: %2x", i,
 407                  p_sys->p_palette[i][3], p_sys->p_palette[i][0],
 408                  p_sys->p_palette[i][1], p_sys->p_palette[i][2] );
 409     }
 410 #endif
 411 }
 412
 413 /*****************************************************************************
 414  * DecodePacket: parse and decode an subtitle packet
 415  *****************************************************************************
 416  * This function parses and decodes an SPU packet and, if valid, returns a
 417  * subpicture.
 418  *****************************************************************************/
 419 static subpicture_t *DecodePacket( decoder_t *p_dec, block_t *p_data )
 420 {
 421     decoder_sys_t *p_sys = p_dec->p_sys;
 422     subpicture_t  *p_spu;
 423     subpicture_region_t *p_region;
 424     video_format_t fmt;
 425     video_palette_t palette;
 426     int i;
 427
 428     /* Allocate the subpicture internal data. */
 429     p_spu = decoder_NewSubpicture( p_dec, NULL );
 430     if( !p_spu ) return NULL;
 431
 432     p_spu->i_start = p_data->i_pts;
 433     p_spu->i_stop  = p_data->i_pts + p_sys->i_duration;
 434     p_spu->b_ephemer = true;
 435
 436     /* Create new subtitle region */
 437     memset( &fmt, 0, sizeof(video_format_t) );
 438     fmt.i_chroma = VLC_CODEC_YUVP;
 439
 440     /**
 441        The video on which the subtitle sits, is scaled, probably
 442        4:3. However subtitle bitmaps assume an 1:1 aspect ratio.
 443
 444        FIXME: We should get the video aspect ratio from somewhere.
 445        Two candidates are the video and the other possibility would be
 446        the access module.
 447     */
 448     fmt.i_sar_num = p_sys->i_height;
 449     fmt.i_sar_den = p_sys->i_width;
 450
 451     fmt.i_width = fmt.i_visible_width = p_sys->i_width;
 452     fmt.i_height = fmt.i_visible_height = p_sys->i_height;
 453     fmt.i_x_offset = fmt.i_y_offset = 0;
 454     fmt.p_palette = &palette;
 455     fmt.p_palette->i_entries = 4;
 456     for( i = 0; i < fmt.p_palette->i_entries; i++ )
 457     {
 458         fmt.p_palette->palette[i][0] = p_sys->p_palette[i][0];
 459         fmt.p_palette->palette[i][1] = p_sys->p_palette[i][1];
 460         fmt.p_palette->palette[i][2] = p_sys->p_palette[i][2];
 461         fmt.p_palette->palette[i][3] = p_sys->p_palette[i][3];
 462     }
 463
 464     p_region = subpicture_region_New( &fmt );
 465     if( !p_region )
 466     {
 467         msg_Err( p_dec, "cannot allocate SVCD subtitle region" );
 468         decoder_DeleteSubpicture( p_dec, p_spu );
 469         return NULL;
 470     }
 471
 472     p_spu->p_region = p_region;
 473     p_region->i_x = p_sys->i_x_start;
 474     p_region->i_y = p_sys->i_y_start;
 475
 476     SVCDSubRenderImage( p_dec, p_data, p_region );
 477
 478     return p_spu;
 479 }
 480
 481 /*****************************************************************************
 482  * SVCDSubRenderImage: reorders bytes of image data in subpicture region.
 483  *****************************************************************************
 484
 485  The image is encoded using two bits per pixel that select a palette
 486  entry except that value 0 starts a limited run-length encoding for
 487  color 0.  When 0 is seen, the next two bits encode one less than the
 488  number of pixels, so we can encode run lengths from 1 to 4. These get
 489  filled with the color in palette entry 0.
 490
 491  The encoding of each line is padded to a whole number of bytes.  The
 492  first field is padded to an even byte length and the complete subtitle
 493  is padded to a 4-byte multiple that always include one zero byte at
 494  the end.
 495
 496  However we'll transform this so that that the RLE is expanded and
 497  interlacing will also be removed.
 498  *****************************************************************************/
 499 static void SVCDSubRenderImage( decoder_t *p_dec, block_t *p_data,
 500                 subpicture_region_t *p_region )
 501 {
 502     decoder_sys_t *p_sys = p_dec->p_sys;
 503     uint8_t *p_dest = p_region->p_picture->Y_PIXELS;
 504     int i_field;            /* The subtitles are interlaced */
 505     int i_row, i_column;    /* scanline row/column number */
 506     uint8_t i_color, i_count;
 507     bs_t bs;
 508
 509     bs_init( &bs, p_data->p_buffer + p_sys->i_image_offset,
 510              p_data->i_buffer - p_sys->i_image_offset );
 511
 512     for( i_field = 0; i_field < 2; i_field++ )
 513     {
 514         for( i_row = i_field; i_row < p_sys->i_height; i_row += 2 )
 515         {
 516             for( i_column = 0; i_column < p_sys->i_width; i_column++ )
 517             {
 518                 i_color = bs_read( &bs, 2 );
 519                 if( i_color == 0 && (i_count = bs_read( &bs, 2 )) )
 520                 {
 521                     i_count = __MIN( i_count, p_sys->i_width - i_column );
 522                     memset( &p_dest[i_row * p_region->p_picture->Y_PITCH +
 523                                     i_column], 0, i_count + 1 );
 524                     i_column += i_count;
 525                     continue;
 526                 }
 527
 528                 p_dest[i_row * p_region->p_picture->Y_PITCH + i_column] = i_color;
 529             }
 530
 531             bs_align( &bs );
 532         }
 533
 534         /* odd field */
 535         bs_init( &bs, p_data->p_buffer + p_sys->i_image_offset +
 536                  p_sys->second_field_offset,
 537                  p_data->i_buffer - p_sys->i_image_offset -
 538                  p_sys->second_field_offset );
 539     }
 540 }