modules/codec/cvdsub.c

   1 /*****************************************************************************
   2  * cvdsub.c : CVD Subtitle decoder
   3  *****************************************************************************
   4  * Copyright (C) 2003, 2004 VLC authors and VideoLAN
   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 it
  13  * under the terms of the GNU Lesser General Public License as published by
  14  * the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Lesser General Public License
  23  * along with this program; if not, write to the Free Software Foundation,
  24  * 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
  38 #include <vlc_bits.h>
  39
  40 #define DEBUG_CVDSUB 1
  41
  42 /*****************************************************************************
  43  * Module descriptor.
  44  *****************************************************************************/
  45 static int  DecoderOpen   ( vlc_object_t * );
  46 static int  PacketizerOpen( vlc_object_t * );
  47 static void DecoderClose  ( vlc_object_t * );
  48
  49 vlc_module_begin ()
  50     set_description( N_("CVD subtitle decoder") )
  51     set_capability( "spu decoder", 50 )
  52     set_callbacks( DecoderOpen, DecoderClose )
  53
  54     add_submodule ()
  55     set_description( N_("Chaoji VCD subtitle packetizer") )
  56     set_capability( "packetizer", 50 )
  57     set_callbacks( PacketizerOpen, DecoderClose )
  58 vlc_module_end ()
  59
  60 /*****************************************************************************
  61  * Local prototypes
  62  *****************************************************************************/
  63 static int Decode( decoder_t *, block_t * );
  64 static block_t *Packetize  ( decoder_t *, block_t ** );
  65 static block_t *Reassemble ( decoder_t *, block_t * );
  66 static void ParseMetaInfo  ( decoder_t *, block_t * );
  67 static void ParseHeader    ( decoder_t *, block_t * );
  68 static subpicture_t *DecodePacket( decoder_t *, block_t * );
  69 static void RenderImage( decoder_t *, block_t *, subpicture_region_t * );
  70
  71 #define SUBTITLE_BLOCK_EMPTY 0
  72 #define SUBTITLE_BLOCK_PARTIAL 1
  73 #define SUBTITLE_BLOCK_COMPLETE 2
  74
  75 struct decoder_sys_t
  76 {
  77   int      b_packetizer;
  78
  79   int      i_state;    /* data-gathering state for this subtitle */
  80
  81   block_t  *p_spu;   /* Bytes of the packet. */
  82
  83   size_t   i_spu_size;     /* goal for subtitle_data_pos while gathering,
  84                              size of used subtitle_data later */
  85
  86   uint16_t i_image_offset;      /* offset from subtitle_data to compressed
  87                                    image data */
  88   size_t i_image_length;           /* size of the compressed image data */
  89   size_t first_field_offset;       /* offset of even raster lines */
  90   size_t second_field_offset;      /* offset of odd raster lines */
  91   size_t metadata_offset;          /* offset to data describing the image */
  92   size_t metadata_length;          /* length of metadata */
  93
  94   mtime_t i_duration;   /* how long to display the image, 0 stands
  95                            for "until next subtitle" */
  96
  97   uint16_t i_x_start, i_y_start; /* position of top leftmost pixel of
  98                                     image when displayed */
  99   uint16_t i_width, i_height;    /* dimensions in pixels of image */
 100
 101   uint8_t p_palette[4][4];       /* Palette of colors used in subtitle */
 102   uint8_t p_palette_highlight[4][4];
 103 };
 104
 105 /*****************************************************************************
 106  * DecoderOpen: open/initialize the cvdsub decoder.
 107  *****************************************************************************/
 108 static int DecoderOpen( vlc_object_t *p_this )
 109 {
 110     decoder_t     *p_dec = (decoder_t*)p_this;
 111     decoder_sys_t *p_sys;
 112
 113     if( p_dec->fmt_in.i_codec != VLC_CODEC_CVD )
 114         return VLC_EGENERIC;
 115
 116     p_dec->p_sys = p_sys = malloc( sizeof( decoder_sys_t ) );
 117     if( !p_sys )
 118         return VLC_ENOMEM;
 119
 120     p_sys->b_packetizer  = false;
 121
 122     p_sys->i_state = SUBTITLE_BLOCK_EMPTY;
 123     p_sys->p_spu   = NULL;
 124
 125     p_dec->pf_decode     = Decode;
 126     p_dec->pf_packetize  = Packetize;
 127
 128     p_dec->fmt_out.i_codec = VLC_CODEC_YUVP;
 129
 130     return VLC_SUCCESS;
 131 }
 132
 133 /*****************************************************************************
 134  * PacketizerOpen: open/initialize the cvdsub packetizer.
 135  *****************************************************************************/
 136 static int PacketizerOpen( vlc_object_t *p_this )
 137 {
 138     decoder_t *p_dec = (decoder_t*)p_this;
 139
 140     if( DecoderOpen( p_this ) != VLC_SUCCESS ) return VLC_EGENERIC;
 141
 142     p_dec->fmt_out.i_codec = VLC_CODEC_CVD;
 143     p_dec->p_sys->b_packetizer = true;
 144
 145     return VLC_SUCCESS;
 146 }
 147
 148 /*****************************************************************************
 149  * DecoderClose: closes the cvdsub decoder/packetizer.
 150  *****************************************************************************/
 151 void DecoderClose( vlc_object_t *p_this )
 152 {
 153     decoder_t     *p_dec = (decoder_t*)p_this;
 154     decoder_sys_t *p_sys = p_dec->p_sys;
 155
 156     if( p_sys->p_spu ) block_ChainRelease( p_sys->p_spu );
 157     free( p_sys );
 158 }
 159
 160 /*****************************************************************************
 161  * Decode:
 162  *****************************************************************************/
 163 static int Decode( decoder_t *p_dec, block_t *p_block )
 164 {
 165     block_t *p_data;
 166
 167     if( p_block == NULL ) /* No Drain */
 168         return VLCDEC_SUCCESS;
 169
 170     if( p_block->i_flags & BLOCK_FLAG_CORRUPTED )
 171     {
 172         block_Release( p_block );
 173         return VLCDEC_SUCCESS;
 174     }
 175
 176     if( !(p_data = Reassemble( p_dec, p_block )) )
 177         return VLCDEC_SUCCESS;
 178
 179     /* Parse and decode */
 180     subpicture_t *p_spu = DecodePacket( p_dec, p_data );
 181     if( p_spu != NULL )
 182         decoder_QueueSub( p_dec, p_spu );
 183     return VLCDEC_SUCCESS;
 184 }
 185
 186 /*****************************************************************************
 187  * Packetize:
 188  *****************************************************************************/
 189 static block_t *Packetize( decoder_t *p_dec, block_t **pp_block )
 190 {
 191     block_t *p_block, *p_spu;
 192
 193     if( pp_block == NULL || *pp_block == NULL ) return NULL;
 194
 195     p_block = *pp_block;
 196     *pp_block = NULL;
 197
 198     if( !(p_spu = Reassemble( p_dec, p_block )) ) return NULL;
 199
 200     p_spu->i_dts = p_spu->i_pts;
 201     p_spu->i_length = 0;
 202
 203     return p_spu;
 204 }
 205
 206
 207 /*****************************************************************************
 208  Reassemble:
 209
 210  Data for single screen subtitle may come in several non-contiguous
 211  packets of a stream. This routine is called when the next packet in
 212  the stream comes in. The job of this routine is to parse the header,
 213  if this is the beginning, and combine the packets into one complete
 214  subtitle unit.
 215
 216  If everything is complete, we will return a block. Otherwise return
 217  NULL.
 218
 219  *****************************************************************************/
 220 #define SPU_HEADER_LEN 1
 221
 222 static block_t *Reassemble( decoder_t *p_dec, block_t *p_block )
 223 {
 224     decoder_sys_t *p_sys = p_dec->p_sys;
 225
 226     if( p_block->i_buffer < SPU_HEADER_LEN )
 227     {
 228         msg_Dbg( p_dec, "invalid packet header (size %zu < %u)" ,
 229                  p_block->i_buffer, SPU_HEADER_LEN );
 230         block_Release( p_block );
 231         return NULL;
 232     }
 233
 234     /* From the scant data on the format, there is only only way known
 235      * to detect the first packet in a subtitle.  The first packet
 236      * seems to have a valid PTS while later packets for the same
 237      * image don't. */
 238     if( p_sys->i_state == SUBTITLE_BLOCK_EMPTY && p_block->i_pts <= VLC_TS_INVALID )
 239     {
 240         msg_Warn( p_dec, "first packet expected but no PTS present");
 241         return NULL;
 242     }
 243
 244     p_block->p_buffer += SPU_HEADER_LEN;
 245     p_block->i_buffer -= SPU_HEADER_LEN;
 246
 247     /* First packet in the subtitle block */
 248     if( p_sys->i_state == SUBTITLE_BLOCK_EMPTY ) ParseHeader( p_dec, p_block );
 249
 250     block_ChainAppend( &p_sys->p_spu, p_block );
 251     p_sys->p_spu = block_ChainGather( p_sys->p_spu );
 252
 253     if( p_sys->p_spu->i_buffer >= p_sys->i_spu_size )
 254     {
 255         block_t *p_spu = p_sys->p_spu;
 256
 257         if( p_spu->i_buffer != p_sys->i_spu_size )
 258         {
 259             msg_Warn( p_dec, "SPU packets size=%zu should be %zu",
 260                       p_spu->i_buffer, p_sys->i_spu_size );
 261         }
 262
 263         msg_Dbg( p_dec, "subtitle packet complete, size=%zuu", p_spu->i_buffer);
 264
 265         ParseMetaInfo( p_dec, p_spu );
 266
 267         p_sys->i_state = SUBTITLE_BLOCK_EMPTY;
 268         p_sys->p_spu = 0;
 269         return p_spu;
 270     }
 271     else
 272     {
 273         /* Not last block in subtitle, so wait for another. */
 274         p_sys->i_state = SUBTITLE_BLOCK_PARTIAL;
 275     }
 276
 277     return NULL;
 278 }
 279
 280 /*
 281   We do not have information on the subtitle format used on CVD's
 282   except the submux sample code and a couple of samples of dubious
 283   origin. Thus, this is the result of reading some code whose
 284   correctness is not known and some experimentation.
 285
 286   CVD subtitles are different in several ways from SVCD OGT subtitles.
 287   Image comes first and metadata is at the end.  So that the metadata
 288   can be found easily, the subtitle packet starts with two bytes
 289   (everything is big-endian again) that give the total size of the
 290   subtitle data and the offset to the metadata - i.e. size of the
 291   image data plus the four bytes at the beginning.
 292
 293   Image data comes interlaced is run-length encoded.  Each field is a
 294   four-bit nibble. Each nibble contains a two-bit repeat count and a
 295   two-bit color number so that up to three pixels can be described in
 296   four bits.  The function of a 0 repeat count is unknown; it might be
 297   used for RLE extension.  However when the full nibble is zero, the
 298   rest of the line is filled with the color value in the next nibble.
 299   It is unknown what happens if the color value is greater than three.
 300   The rest seems to use a 4-entries palette.  It is not impossible
 301   that the fill-line complete case above is not as described and the
 302   zero repeat count means fill line.  The sample code never produces
 303   this, so it may be untested.
 304 */
 305
 306 static void ParseHeader( decoder_t *p_dec, block_t *p_block )
 307 {
 308     decoder_sys_t *p_sys = p_dec->p_sys;
 309     uint8_t *p = p_block->p_buffer;
 310
 311     p_sys->i_spu_size = (p[0] << 8) + p[1] + 4; p += 2;
 312
 313     /* FIXME: check data sanity */
 314     p_sys->metadata_offset = (p[0] <<  8) +   p[1]; p +=2;
 315     p_sys->metadata_length = p_sys->i_spu_size - p_sys->metadata_offset;
 316
 317     p_sys->i_image_offset = 4;
 318     p_sys->i_image_length = p_sys->metadata_offset - p_sys->i_image_offset;
 319
 320 #ifdef DEBUG_CVDSUB
 321     msg_Dbg( p_dec, "total size: %zu  image size: %zu",
 322              p_sys->i_spu_size, p_sys->i_image_length );
 323 #endif
 324 }
 325
 326 /*
 327   We parse the metadata information here.
 328
 329   Although metadata information does not have to come in a fixed field
 330   order, every metadata field consists of a tag byte followed by
 331   parameters. In all cases known, the size including tag byte is
 332   exactly four bytes in length.
 333 */
 334
 335 #define ExtractXY(x, y) x = ((p[1]&0x0f)<<6) + (p[2]>>2); \
 336                         y = ((p[2]&0x03)<<8) + p[3];
 337
 338 static void ParseMetaInfo( decoder_t *p_dec, block_t *p_spu  )
 339 {
 340     /* Last packet in subtitle block. */
 341
 342     decoder_sys_t *p_sys = p_dec->p_sys;
 343     uint8_t       *p     = p_spu->p_buffer + p_sys->metadata_offset;
 344     uint8_t       *p_end = p + p_sys->metadata_length;
 345
 346     for( ; p < p_end; p += 4 )
 347     {
 348         switch( p[0] )
 349         {
 350         case 0x04: /* subtitle duration in 1/90000ths of a second */
 351             p_sys->i_duration = (p[1]<<16) + (p[2]<<8) + p[3];
 352
 353 #ifdef DEBUG_CVDSUB
 354             msg_Dbg( p_dec, "subtitle display duration %lu secs",
 355                      (long unsigned int)(p_sys->i_duration / 90000) );
 356 #endif
 357             p_sys->i_duration *= 100 / 9;
 358             break;
 359
 360         case 0x0c: /* unknown */
 361 #ifdef DEBUG_CVDSUB
 362             msg_Dbg( p_dec, "subtitle command unknown 0x%0x 0x%0x 0x%0x 0x%0x",
 363                      (int)p[0], (int)p[1], (int)p[2], (int)p[3] );
 364 #endif
 365             break;
 366
 367         case 0x17: /* coordinates of subtitle upper left x, y position */
 368             ExtractXY(p_sys->i_x_start, p_sys->i_y_start);
 369
 370 #ifdef DEBUG_CVDSUB
 371             msg_Dbg( p_dec, "start position (%d,%d)",
 372                      p_sys->i_x_start, p_sys->i_y_start );
 373 #endif
 374             break;
 375
 376         case 0x1f: /* coordinates of subtitle bottom right x, y position */
 377         {
 378             int lastx;
 379             int lasty;
 380             ExtractXY(lastx, lasty);
 381             p_sys->i_width  = lastx - p_sys->i_x_start + 1;
 382             p_sys->i_height = lasty - p_sys->i_y_start + 1;
 383
 384 #ifdef DEBUG_CVDSUB
 385             msg_Dbg( p_dec, "end position (%d,%d), w x h: %dx%d",
 386                      lastx, lasty, p_sys->i_width, p_sys->i_height );
 387 #endif
 388             break;
 389         }
 390
 391         case 0x24:
 392         case 0x25:
 393         case 0x26:
 394         case 0x27:
 395         {
 396             uint8_t v = p[0] - 0x24;
 397
 398 #ifdef DEBUG_CVDSUB
 399             /* Primary Palette */
 400             msg_Dbg( p_dec, "primary palette %d (y,u,v): (0x%0x,0x%0x,0x%0x)",
 401                      (int)v, (int)p[1], (int)p[2], (int)p[3] );
 402 #endif
 403
 404             p_sys->p_palette[v][0] = p[1]; /* Y */
 405             p_sys->p_palette[v][1] = p[3]; /* Cr / V */
 406             p_sys->p_palette[v][2] = p[2]; /* Cb / U */
 407             break;
 408         }
 409
 410         case 0x2c:
 411         case 0x2d:
 412         case 0x2e:
 413         case 0x2f:
 414         {
 415             uint8_t v = p[0] - 0x2c;
 416
 417 #ifdef DEBUG_CVDSUB
 418             msg_Dbg( p_dec,"highlight palette %d (y,u,v): (0x%0x,0x%0x,0x%0x)",
 419                      (int)v, (int)p[1], (int)p[2], (int)p[3] );
 420 #endif
 421
 422             /* Highlight Palette */
 423             p_sys->p_palette_highlight[v][0] = p[1]; /* Y */
 424             p_sys->p_palette_highlight[v][1] = p[3]; /* Cr / V */
 425             p_sys->p_palette_highlight[v][2] = p[2]; /* Cb / U */
 426             break;
 427         }
 428
 429         case 0x37:
 430             /* transparency for primary palette */
 431             p_sys->p_palette[0][3] = (p[3] & 0x0f) << 4;
 432             p_sys->p_palette[1][3] = (p[3] >> 4) << 4;
 433             p_sys->p_palette[2][3] = (p[2] & 0x0f) << 4;
 434             p_sys->p_palette[3][3] = (p[2] >> 4) << 4;
 435
 436 #ifdef DEBUG_CVDSUB
 437             msg_Dbg( p_dec, "transparency for primary palette 0..3: "
 438                      "0x%0x 0x%0x 0x%0x 0x%0x",
 439                      (int)p_sys->p_palette[0][3], (int)p_sys->p_palette[1][3],
 440                      (int)p_sys->p_palette[2][3], (int)p_sys->p_palette[3][3]);
 441 #endif
 442             break;
 443
 444         case 0x3f:
 445             /* transparency for highlight palette */
 446             p_sys->p_palette_highlight[0][3] = (p[2] & 0x0f) << 4;
 447             p_sys->p_palette_highlight[1][3] = (p[2] >> 4) << 4;
 448             p_sys->p_palette_highlight[2][3] = (p[1] & 0x0f) << 4;
 449             p_sys->p_palette_highlight[3][3] = (p[1] >> 4) << 4;
 450
 451 #ifdef DEBUG_CVDSUB
 452             msg_Dbg( p_dec, "transparency for highlight palette 0..3: "
 453                      "0x%0x 0x%0x 0x%0x 0x%0x",
 454                      (int)p_sys->p_palette_highlight[0][3],
 455                      (int)p_sys->p_palette_highlight[1][3],
 456                      (int)p_sys->p_palette_highlight[2][3],
 457                      (int)p_sys->p_palette_highlight[3][3] );
 458 #endif
 459             break;
 460
 461         case 0x47:
 462             /* offset to start of even rows of interlaced image, we correct
 463              * to make it relative to i_image_offset (usually 4) */
 464             p_sys->first_field_offset =
 465                 (p[2] << 8) + p[3] - p_sys->i_image_offset;
 466 #ifdef DEBUG_CVDSUB
 467             msg_Dbg( p_dec, "1st_field_offset %zu",
 468                      p_sys->first_field_offset );
 469 #endif
 470             break;
 471
 472         case 0x4f:
 473             /* offset to start of odd rows of interlaced image, we correct
 474              * to make it relative to i_image_offset (usually 4) */
 475             p_sys->second_field_offset =
 476                 (p[2] << 8) + p[3] - p_sys->i_image_offset;
 477 #ifdef DEBUG_CVDSUB
 478             msg_Dbg( p_dec, "2nd_field_offset %zu",
 479                      p_sys->second_field_offset);
 480 #endif
 481             break;
 482
 483         default:
 484 #ifdef DEBUG_CVDSUB
 485             msg_Warn( p_dec, "unknown sequence in control header "
 486                       "0x%0x 0x%0x 0x%0x 0x%0x", p[0], p[1], p[2], p[3]);
 487 #endif
 488         }
 489     }
 490 }
 491
 492 /*****************************************************************************
 493  * DecodePacket: parse and decode an SPU packet
 494  *****************************************************************************
 495  * This function parses and decodes an SPU packet and, if valid, returns a
 496  * subpicture.
 497  *****************************************************************************/
 498 static subpicture_t *DecodePacket( decoder_t *p_dec, block_t *p_data )
 499 {
 500     decoder_sys_t *p_sys = p_dec->p_sys;
 501     subpicture_t  *p_spu;
 502     subpicture_region_t *p_region;
 503     video_format_t fmt;
 504     video_palette_t palette;
 505     int i;
 506
 507     /* Allocate the subpicture internal data. */
 508     p_spu = decoder_NewSubpicture( p_dec, NULL );
 509     if( !p_spu ) return NULL;
 510
 511     p_spu->i_start = p_data->i_pts;
 512     p_spu->i_stop  = p_data->i_pts + p_sys->i_duration;
 513     p_spu->b_ephemer = true;
 514
 515     /* Create new SPU region */
 516     video_format_Init( &fmt, VLC_CODEC_YUVP );
 517     fmt.i_sar_num = 1;
 518     fmt.i_sar_den = 1;
 519     fmt.i_width = fmt.i_visible_width = p_sys->i_width;
 520     fmt.i_height = fmt.i_visible_height = p_sys->i_height;
 521     fmt.i_x_offset = fmt.i_y_offset = 0;
 522     fmt.p_palette = &palette;
 523     fmt.p_palette->i_entries = 4;
 524     for( i = 0; i < fmt.p_palette->i_entries; i++ )
 525     {
 526         fmt.p_palette->palette[i][0] = p_sys->p_palette[i][0];
 527         fmt.p_palette->palette[i][1] = p_sys->p_palette[i][1];
 528         fmt.p_palette->palette[i][2] = p_sys->p_palette[i][2];
 529         fmt.p_palette->palette[i][3] = p_sys->p_palette[i][3];
 530     }
 531
 532     p_region = subpicture_region_New( &fmt );
 533     video_format_Clean( &fmt );
 534     if( !p_region )
 535     {
 536         msg_Err( p_dec, "cannot allocate SPU region" );
 537         subpicture_Delete( p_spu );
 538         return NULL;
 539     }
 540
 541     p_spu->p_region = p_region;
 542     p_region->i_x = p_sys->i_x_start;
 543     p_region->i_x = p_region->i_x * 3 / 4; /* FIXME: use aspect ratio for x? */
 544     p_region->i_y = p_sys->i_y_start;
 545
 546     RenderImage( p_dec, p_data, p_region );
 547
 548     return p_spu;
 549 }
 550
 551 /*****************************************************************************
 552  * ParseImage: parse and render the image part of the subtitle
 553  *****************************************************************************
 554  This part parses the subtitle graphical data and renders it.
 555
 556  Image data comes interlaced and is run-length encoded (RLE). Each
 557  field is a four-bit nibbles that is further subdivided in a two-bit
 558  repeat count and a two-bit color number - up to three pixels can be
 559  described in four bits.  What a 0 repeat count means is unknown.  It
 560  might be used for RLE extension.  There is a special case of a 0
 561  repeat count though.  When the full nibble is zero, the rest of the
 562  line is filled with the color value in the next nibble.  It is
 563  unknown what happens if the color value is greater than three.  The
 564  rest seems to use a 4-entries palette.  It is not impossible that the
 565  fill-line complete case above is not as described and the zero repeat
 566  count means fill line.  The sample code never produces this, so it
 567  may be untested.
 568
 569  However we'll transform this so that that the RLE is expanded and
 570  interlacing will also be removed. On output each pixel entry will by
 571  a 4-bit alpha (filling 8 bits), and 8-bit y, u, and v entry.
 572
 573  *****************************************************************************/
 574 static void RenderImage( decoder_t *p_dec, block_t *p_data,
 575                          subpicture_region_t *p_region )
 576 {
 577     decoder_sys_t *p_sys = p_dec->p_sys;
 578     uint8_t *p_dest = p_region->p_picture->Y_PIXELS;
 579     int i_field;            /* The subtitles are interlaced */
 580     int i_row, i_column;    /* scanline row/column number */
 581     uint8_t i_color, i_count;
 582     bs_t bs;
 583
 584     bs_init( &bs, p_data->p_buffer + p_sys->i_image_offset,
 585              p_data->i_buffer - p_sys->i_image_offset );
 586
 587     for( i_field = 0; i_field < 2; i_field++ )
 588     {
 589         for( i_row = i_field; i_row < p_sys->i_height; i_row += 2 )
 590         {
 591             for( i_column = 0; i_column < p_sys->i_width; i_column++ )
 592             {
 593                 uint8_t i_val = bs_read( &bs, 4 );
 594
 595                 if( i_val == 0 )
 596                 {
 597                     /* Fill the rest of the line with next color */
 598                     i_color = bs_read( &bs, 4 );
 599
 600                     memset( &p_dest[i_row * p_region->p_picture->Y_PITCH +
 601                                     i_column], i_color,
 602                             p_sys->i_width - i_column );
 603                     i_column = p_sys->i_width;
 604                     continue;
 605                 }
 606                 else
 607                 {
 608                     /* Normal case: get color and repeat count */
 609                     i_count = (i_val >> 2);
 610                     i_color = i_val & 0x3;
 611
 612                     i_count = __MIN( i_count, p_sys->i_width - i_column );
 613
 614                     memset( &p_dest[i_row * p_region->p_picture->Y_PITCH +
 615                                     i_column], i_color, i_count );
 616                     i_column += i_count - 1;
 617                     continue;
 618                 }
 619             }
 620
 621             bs_align( &bs );
 622         }
 623     }
 624 }