git.sesse.net Git - vlc/blob - modules/codec/libmpeg2.c

   1 /*****************************************************************************
   2  * libmpeg2.c: mpeg2 video decoder module making use of libmpeg2.
   3  *****************************************************************************
   4  * Copyright (C) 1999-2001 VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Gildas Bazin <gbazin@netcourrier.com>
   8  *          Christophe Massiot <massiot@via.ecp.fr>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  23  *****************************************************************************/
  24
  25 /*****************************************************************************
  26  * Preamble
  27  *****************************************************************************/
  28 #include <vlc/vlc.h>
  29 #include <vlc/vout.h>
  30 #include <vlc/decoder.h>
  31
  32 #include <mpeg2dec/mpeg2.h>
  33
  34 #include "vout_synchro.h"
  35
  36 /* Aspect ratio (ISO/IEC 13818-2 section 6.3.3, table 6-3) */
  37 #define AR_SQUARE_PICTURE       1                           /* square pixels */
  38 #define AR_3_4_PICTURE          2                        /* 3:4 picture (TV) */
  39 #define AR_16_9_PICTURE         3              /* 16:9 picture (wide screen) */
  40 #define AR_221_1_PICTURE        4                  /* 2.21:1 picture (movie) */
  41
  42 /*****************************************************************************
  43  * decoder_sys_t : libmpeg2 decoder descriptor
  44  *****************************************************************************/
  45 struct decoder_sys_t
  46 {
  47     /*
  48      * libmpeg2 properties
  49      */
  50     mpeg2dec_t          *p_mpeg2dec;
  51     const mpeg2_info_t  *p_info;
  52     vlc_bool_t          b_skip;
  53
  54     /*
  55      * Input properties
  56      */
  57     mtime_t          i_pts;
  58     mtime_t          i_previous_pts;
  59     mtime_t          i_current_pts;
  60     int              i_current_rate;
  61     picture_t *      p_picture_to_destroy;
  62     vlc_bool_t       b_garbage_pic;
  63     vlc_bool_t       b_after_sequence_header; /* is it the next frame after
  64                                                * the sequence header ?    */
  65     vlc_bool_t       b_slice_i;             /* intra-slice refresh stream */
  66
  67     /*
  68      * Output properties
  69      */
  70     vout_synchro_t *p_synchro;
  71     int i_aspect;
  72
  73 };
  74
  75 /*****************************************************************************
  76  * Local prototypes
  77  *****************************************************************************/
  78 static int  OpenDecoder( vlc_object_t * );
  79 static void CloseDecoder( vlc_object_t * );
  80
  81 static picture_t *DecodeBlock( decoder_t *, block_t ** );
  82
  83 static picture_t *GetNewPicture( decoder_t *, uint8_t ** );
  84
  85 /*****************************************************************************
  86  * Module descriptor
  87  *****************************************************************************/
  88 vlc_module_begin();
  89     set_description( _("MPEG I/II video decoder (using libmpeg2)") );
  90     set_capability( "decoder", 150 );
  91     set_callbacks( OpenDecoder, CloseDecoder );
  92     add_shortcut( "libmpeg2" );
  93 vlc_module_end();
  94
  95 /*****************************************************************************
  96  * OpenDecoder: probe the decoder and return score
  97  *****************************************************************************/
  98 static int OpenDecoder( vlc_object_t *p_this )
  99 {
 100     decoder_t *p_dec = (decoder_t*)p_this;
 101     decoder_sys_t *p_sys;
 102     uint32_t i_accel = 0;
 103
 104     if( p_dec->fmt_in.i_codec != VLC_FOURCC('m','p','g','v') &&
 105         p_dec->fmt_in.i_codec != VLC_FOURCC('m','p','g','1') &&
 106         /* Pinnacle hardware-mpeg1 */
 107         p_dec->fmt_in.i_codec != VLC_FOURCC('P','I','M','1') &&
 108         /* ATI Video */
 109         p_dec->fmt_in.i_codec != VLC_FOURCC('V','C','R','2') &&
 110         p_dec->fmt_in.i_codec != VLC_FOURCC('m','p','g','2') )
 111     {
 112         return VLC_EGENERIC;
 113     }
 114
 115     /* Allocate the memory needed to store the decoder's structure */
 116     if( ( p_dec->p_sys = p_sys =
 117           (decoder_sys_t *)malloc(sizeof(decoder_sys_t)) ) == NULL )
 118     {
 119         msg_Err( p_dec, "out of memory" );
 120         return VLC_EGENERIC;
 121     }
 122
 123     /* Initialize the thread properties */
 124     memset( p_sys, 0, sizeof(decoder_sys_t) );
 125     p_sys->p_mpeg2dec = NULL;
 126     p_sys->p_synchro  = NULL;
 127     p_sys->p_info     = NULL;
 128     p_sys->i_pts      = mdate() + DEFAULT_PTS_DELAY;
 129     p_sys->i_current_pts  = 0;
 130     p_sys->i_previous_pts = 0;
 131     p_sys->p_picture_to_destroy = NULL;
 132     p_sys->b_garbage_pic = 0;
 133     p_sys->b_slice_i  = 0;
 134     p_sys->b_skip     = 0;
 135
 136 #if defined( __i386__ )
 137     if( p_dec->p_libvlc->i_cpu & CPU_CAPABILITY_MMX )
 138     {
 139         i_accel |= MPEG2_ACCEL_X86_MMX;
 140     }
 141
 142     if( p_dec->p_libvlc->i_cpu & CPU_CAPABILITY_3DNOW )
 143     {
 144         i_accel |= MPEG2_ACCEL_X86_3DNOW;
 145     }
 146
 147     if( p_dec->p_libvlc->i_cpu & CPU_CAPABILITY_MMXEXT )
 148     {
 149         i_accel |= MPEG2_ACCEL_X86_MMXEXT;
 150     }
 151
 152 #elif defined( __powerpc__ ) || defined( SYS_DARWIN )
 153     if( p_dec->p_libvlc->i_cpu & CPU_CAPABILITY_ALTIVEC )
 154     {
 155         i_accel |= MPEG2_ACCEL_PPC_ALTIVEC;
 156     }
 157
 158 #else
 159     /* If we do not know this CPU, trust libmpeg2's feature detection */
 160     i_accel = MPEG2_ACCEL_DETECT;
 161
 162 #endif
 163
 164     /* Set CPU acceleration features */
 165     mpeg2_accel( i_accel );
 166
 167     /* Initialize decoder */
 168     p_sys->p_mpeg2dec = mpeg2_init();
 169     if( p_sys->p_mpeg2dec == NULL)
 170     {
 171         msg_Err( p_dec, "mpeg2_init() failed" );
 172         free( p_sys );
 173         return VLC_EGENERIC;
 174     }
 175
 176     p_sys->p_info = mpeg2_info( p_sys->p_mpeg2dec );
 177
 178     p_dec->pf_decode_video = DecodeBlock;
 179
 180     return VLC_SUCCESS;
 181 }
 182
 183 /*****************************************************************************
 184  * RunDecoder: the libmpeg2 decoder
 185  *****************************************************************************/
 186 static picture_t *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
 187 {
 188     decoder_sys_t   *p_sys = p_dec->p_sys;
 189     mpeg2_state_t   state;
 190     picture_t       *p_pic;
 191
 192     block_t *p_block;
 193
 194     if( !pp_block || !*pp_block ) return NULL;
 195
 196     p_block = *pp_block;
 197
 198     while( 1 )
 199     {
 200         state = mpeg2_parse( p_sys->p_mpeg2dec );
 201
 202         switch( state )
 203         {
 204         case STATE_BUFFER:
 205             if( !p_block->i_buffer )
 206             {
 207                 block_Release( p_block );
 208                 return NULL;
 209             }
 210
 211             if( (p_block->i_flags&BLOCK_FLAG_DISCONTINUITY) &&
 212                 p_sys->p_synchro &&
 213                 p_sys->p_info->sequence &&
 214                 p_sys->p_info->sequence->width != (unsigned)-1 )
 215             {
 216                 vout_SynchroReset( p_sys->p_synchro );
 217                 if( p_sys->p_info->current_fbuf != NULL
 218                     && p_sys->p_info->current_fbuf->id != NULL )
 219                 {
 220                     p_sys->b_garbage_pic = 1;
 221                     p_pic = p_sys->p_info->current_fbuf->id;
 222                 }
 223                 else
 224                 {
 225                     uint8_t *buf[3];
 226                     buf[0] = buf[1] = buf[2] = NULL;
 227                     if( (p_pic = GetNewPicture( p_dec, buf )) == NULL )
 228                         break;
 229                     mpeg2_set_buf( p_sys->p_mpeg2dec, buf, p_pic );
 230                 }
 231                 p_sys->p_picture_to_destroy = p_pic;
 232
 233                 if ( p_sys->b_slice_i )
 234                 {
 235                     vout_SynchroNewPicture( p_sys->p_synchro,
 236                         I_CODING_TYPE, 2, 0, 0, p_sys->i_current_rate );
 237                     vout_SynchroDecode( p_sys->p_synchro );
 238                     vout_SynchroEnd( p_sys->p_synchro, I_CODING_TYPE, 0 );
 239                 }
 240             }
 241
 242             if( p_block->i_pts )
 243             {
 244 #ifdef PIC_FLAG_PTS
 245                 mpeg2_pts( p_sys->p_mpeg2dec, (uint32_t)p_block->i_pts );
 246
 247 #else /* New interface */
 248                 mpeg2_tag_picture( p_sys->p_mpeg2dec,
 249                                    (uint32_t)p_block->i_pts, 0/*dts*/ );
 250 #endif
 251                 p_sys->i_previous_pts = p_sys->i_current_pts;
 252                 p_sys->i_current_pts = p_block->i_pts;
 253             }
 254
 255             p_sys->i_current_rate = p_block->i_rate;
 256
 257             mpeg2_buffer( p_sys->p_mpeg2dec, p_block->p_buffer,
 258                           p_block->p_buffer + p_block->i_buffer );
 259
 260             p_block->i_buffer = 0;
 261             break;
 262
 263         case STATE_SEQUENCE:
 264         {
 265             /* Initialize video output */
 266             uint8_t *buf[3];
 267             buf[0] = buf[1] = buf[2] = NULL;
 268
 269             /* Check whether the input gave a particular aspect ratio */
 270             if( p_dec->fmt_in.video.i_aspect )
 271             {
 272                 p_sys->i_aspect = p_dec->fmt_in.video.i_aspect;
 273                 if( p_sys->i_aspect <= AR_221_1_PICTURE )
 274                 switch( p_sys->i_aspect )
 275                 {
 276                 case AR_3_4_PICTURE:
 277                     p_sys->i_aspect = VOUT_ASPECT_FACTOR * 4 / 3;
 278                     break;
 279                 case AR_16_9_PICTURE:
 280                     p_sys->i_aspect = VOUT_ASPECT_FACTOR * 16 / 9;
 281                     break;
 282                 case AR_221_1_PICTURE:
 283                     p_sys->i_aspect = VOUT_ASPECT_FACTOR * 221 / 100;
 284                     break;
 285                 case AR_SQUARE_PICTURE:
 286                     p_sys->i_aspect = VOUT_ASPECT_FACTOR *
 287                                    p_sys->p_info->sequence->width /
 288                                    p_sys->p_info->sequence->height;
 289                     break;
 290                 }
 291             }
 292             else
 293             {
 294                 /* Use the value provided in the MPEG sequence header */
 295                 if( p_sys->p_info->sequence->pixel_height > 0 )
 296                 {
 297                     p_sys->i_aspect =
 298                         ((uint64_t)p_sys->p_info->sequence->display_width) *
 299                         p_sys->p_info->sequence->pixel_width *
 300                         VOUT_ASPECT_FACTOR /
 301                         p_sys->p_info->sequence->display_height /
 302                         p_sys->p_info->sequence->pixel_height;
 303                 }
 304                 else
 305                 {
 306                     /* Invalid aspect, assume 4:3.
 307                      * This shouldn't happen and if it does it is a bug
 308                      * in libmpeg2 (likely triggered by an invalid stream) */
 309                     p_sys->i_aspect = VOUT_ASPECT_FACTOR * 4 / 3;
 310                 }
 311             }
 312
 313             msg_Dbg( p_dec, "%dx%d, aspect %d, %u.%03u fps",
 314                      p_sys->p_info->sequence->width,
 315                      p_sys->p_info->sequence->height, p_sys->i_aspect,
 316                      (uint32_t)((uint64_t)1001000000 * 27 /
 317                          p_sys->p_info->sequence->frame_period / 1001),
 318                      (uint32_t)((uint64_t)1001000000 * 27 /
 319                          p_sys->p_info->sequence->frame_period % 1001) );
 320
 321             mpeg2_custom_fbuf( p_sys->p_mpeg2dec, 1 );
 322
 323             /* Set the first 2 reference frames */
 324             mpeg2_set_buf( p_sys->p_mpeg2dec, buf, NULL );
 325
 326             if( (p_pic = GetNewPicture( p_dec, buf )) == NULL )
 327             {
 328                 block_Release( p_block );
 329                 return NULL;
 330             }
 331
 332             mpeg2_set_buf( p_sys->p_mpeg2dec, buf, p_pic );
 333
 334             /* This picture will never go through display_picture. */
 335             p_pic->date = 0;
 336
 337             /* For some reason, libmpeg2 will put this pic twice in
 338              * discard_picture. This can be considered a bug in libmpeg2. */
 339             p_dec->pf_picture_link( p_dec, p_pic );
 340
 341             if( p_sys->p_synchro )
 342             {
 343                 vout_SynchroRelease( p_sys->p_synchro );
 344             }
 345             p_sys->p_synchro = vout_SynchroInit( p_dec,
 346                 (uint32_t)((uint64_t)1001000000 * 27 /
 347                 p_sys->p_info->sequence->frame_period) );
 348             p_sys->b_after_sequence_header = 1;
 349         }
 350         break;
 351
 352         case STATE_PICTURE_2ND:
 353             vout_SynchroNewPicture( p_sys->p_synchro,
 354                 p_sys->p_info->current_picture->flags & PIC_MASK_CODING_TYPE,
 355                 p_sys->p_info->current_picture->nb_fields,
 356                 0, 0, p_sys->i_current_rate );
 357
 358             if( p_sys->b_skip )
 359             {
 360                 vout_SynchroTrash( p_sys->p_synchro );
 361             }
 362             else
 363             {
 364                 vout_SynchroDecode( p_sys->p_synchro );
 365             }
 366             break;
 367
 368         case STATE_PICTURE:
 369         {
 370             uint8_t *buf[3];
 371             mtime_t i_pts;
 372             buf[0] = buf[1] = buf[2] = NULL;
 373
 374             if ( p_sys->b_after_sequence_header &&
 375                  ((p_sys->p_info->current_picture->flags &
 376                        PIC_MASK_CODING_TYPE) == PIC_FLAG_CODING_TYPE_P) )
 377             {
 378                 /* Intra-slice refresh. Simulate a blank I picture. */
 379                 msg_Dbg( p_dec, "intra-slice refresh stream" );
 380                 vout_SynchroNewPicture( p_sys->p_synchro,
 381                     I_CODING_TYPE, 2, 0, 0, p_sys->i_current_rate );
 382                 vout_SynchroDecode( p_sys->p_synchro );
 383                 vout_SynchroEnd( p_sys->p_synchro, I_CODING_TYPE, 0 );
 384                 p_sys->b_slice_i = 1;
 385             }
 386             p_sys->b_after_sequence_header = 0;
 387
 388 #ifdef PIC_FLAG_PTS
 389             i_pts = p_sys->p_info->current_picture->flags & PIC_FLAG_PTS ?
 390                 ( ( p_sys->p_info->current_picture->pts ==
 391                     (uint32_t)p_sys->i_current_pts ) ?
 392                   p_sys->i_current_pts : p_sys->i_previous_pts ) : 0;
 393
 394 #else /* New interface */
 395
 396             i_pts = p_sys->p_info->current_picture->flags & PIC_FLAG_TAGS ?
 397                 ( ( p_sys->p_info->current_picture->tag ==
 398                     (uint32_t)p_sys->i_current_pts ) ?
 399                   p_sys->i_current_pts : p_sys->i_previous_pts ) : 0;
 400 #endif
 401
 402             /* Hack to handle demuxers which only have DTS timestamps */
 403             if( !i_pts && !p_block->i_pts && p_block->i_dts > 0 )
 404             {
 405                 if( p_sys->p_info->sequence->flags & SEQ_FLAG_LOW_DELAY ||
 406                     (p_sys->p_info->current_picture->flags &
 407                       PIC_MASK_CODING_TYPE) == PIC_FLAG_CODING_TYPE_B )
 408                 {
 409                     i_pts = p_block->i_dts;
 410                 }
 411             }
 412             p_block->i_pts = p_block->i_dts = 0;
 413             /* End hack */
 414
 415             vout_SynchroNewPicture( p_sys->p_synchro,
 416                 p_sys->p_info->current_picture->flags & PIC_MASK_CODING_TYPE,
 417                 p_sys->p_info->current_picture->nb_fields, i_pts,
 418                 0, p_sys->i_current_rate );
 419
 420             if ( !(p_sys->b_slice_i
 421                    && ((p_sys->p_info->current_picture->flags
 422                          & PIC_MASK_CODING_TYPE) == P_CODING_TYPE))
 423                    && !vout_SynchroChoose( p_sys->p_synchro,
 424                               p_sys->p_info->current_picture->flags
 425                                 & PIC_MASK_CODING_TYPE,
 426                               /*p_sys->p_vout->render_time*/ 0 /*FIXME*/ ) )
 427             {
 428                 mpeg2_skip( p_sys->p_mpeg2dec, 1 );
 429                 p_sys->b_skip = 1;
 430                 vout_SynchroTrash( p_sys->p_synchro );
 431                 mpeg2_set_buf( p_sys->p_mpeg2dec, buf, NULL );
 432             }
 433             else
 434             {
 435                 mpeg2_skip( p_sys->p_mpeg2dec, 0 );
 436                 p_sys->b_skip = 0;
 437                 vout_SynchroDecode( p_sys->p_synchro );
 438
 439                 if( (p_pic = GetNewPicture( p_dec, buf )) == NULL )
 440                 {
 441                     block_Release( p_block );
 442                     return NULL;
 443                 }
 444
 445                 mpeg2_set_buf( p_sys->p_mpeg2dec, buf, p_pic );
 446             }
 447         }
 448         break;
 449
 450         case STATE_END:
 451         case STATE_SLICE:
 452             p_pic = NULL;
 453             if( p_sys->p_info->display_fbuf
 454                 && p_sys->p_info->display_fbuf->id )
 455             {
 456                 p_pic = (picture_t *)p_sys->p_info->display_fbuf->id;
 457
 458                 vout_SynchroEnd( p_sys->p_synchro,
 459                             p_sys->p_info->display_picture->flags
 460                              & PIC_MASK_CODING_TYPE,
 461                             p_sys->b_garbage_pic );
 462                 p_sys->b_garbage_pic = 0;
 463
 464                 if ( p_sys->p_picture_to_destroy != p_pic )
 465                 {
 466                     p_pic->date = vout_SynchroDate( p_sys->p_synchro );
 467                 }
 468                 else
 469                 {
 470                     p_sys->p_picture_to_destroy = NULL;
 471                     p_pic->date = 0;
 472                 }
 473             }
 474
 475             if( p_sys->p_info->discard_fbuf &&
 476                 p_sys->p_info->discard_fbuf->id )
 477             {
 478                 p_dec->pf_picture_unlink( p_dec,
 479                                           p_sys->p_info->discard_fbuf->id );
 480             }
 481
 482             if( p_pic ) return p_pic;
 483
 484             break;
 485
 486         case STATE_INVALID:
 487         {
 488             uint8_t *buf[3];
 489             buf[0] = buf[1] = buf[2] = NULL;
 490
 491             msg_Warn( p_dec, "invalid picture encountered" );
 492             if ( ( p_sys->p_info->current_picture == NULL ) ||
 493                ( ( p_sys->p_info->current_picture->flags &
 494                    PIC_MASK_CODING_TYPE) != B_CODING_TYPE ) )
 495             {
 496                 if( p_sys->p_synchro ) vout_SynchroReset( p_sys->p_synchro );
 497             }
 498             mpeg2_skip( p_sys->p_mpeg2dec, 1 );
 499             p_sys->b_skip = 1;
 500
 501             if( p_sys->p_info->current_fbuf &&
 502                 p_sys->p_info->current_fbuf->id )
 503             {
 504                 p_sys->b_garbage_pic = 1;
 505                 p_pic = p_sys->p_info->current_fbuf->id;
 506             }
 507             else if( !p_sys->p_info->sequence )
 508             {
 509                 break;
 510             }
 511             else
 512             {
 513                 if( (p_pic = GetNewPicture( p_dec, buf )) == NULL )
 514                     break;
 515                 mpeg2_set_buf( p_sys->p_mpeg2dec, buf, p_pic );
 516             }
 517             p_sys->p_picture_to_destroy = p_pic;
 518
 519             memset( p_pic->p[0].p_pixels, 0,
 520                     p_sys->p_info->sequence->width
 521                      * p_sys->p_info->sequence->height );
 522             memset( p_pic->p[1].p_pixels, 0x80,
 523                     p_sys->p_info->sequence->width
 524                      * p_sys->p_info->sequence->height / 4 );
 525             memset( p_pic->p[2].p_pixels, 0x80,
 526                     p_sys->p_info->sequence->width
 527                      * p_sys->p_info->sequence->height / 4 );
 528
 529             if( p_sys->b_slice_i )
 530             {
 531                 vout_SynchroNewPicture( p_sys->p_synchro,
 532                             I_CODING_TYPE, 2, 0, 0, p_sys->i_current_rate );
 533                 vout_SynchroDecode( p_sys->p_synchro );
 534                 vout_SynchroEnd( p_sys->p_synchro, I_CODING_TYPE, 0 );
 535             }
 536             break;
 537         }
 538
 539         default:
 540             break;
 541         }
 542     }
 543
 544     /* Never reached */
 545     return NULL;
 546 }
 547
 548 /*****************************************************************************
 549  * CloseDecoder: libmpeg2 decoder destruction
 550  *****************************************************************************/
 551 static void CloseDecoder( vlc_object_t *p_this )
 552 {
 553     decoder_t *p_dec = (decoder_t *)p_this;
 554     decoder_sys_t *p_sys = p_dec->p_sys;
 555
 556     if( p_sys->p_synchro ) vout_SynchroRelease( p_sys->p_synchro );
 557
 558     if( p_sys->p_mpeg2dec ) mpeg2_close( p_sys->p_mpeg2dec );
 559
 560     free( p_sys );
 561 }
 562
 563 /*****************************************************************************
 564  * GetNewPicture: Get a new picture from the vout and set the buf struct
 565  *****************************************************************************/
 566 static picture_t *GetNewPicture( decoder_t *p_dec, uint8_t **pp_buf )
 567 {
 568     decoder_sys_t *p_sys = p_dec->p_sys;
 569     picture_t *p_pic;
 570
 571     p_dec->fmt_out.video.i_width = p_sys->p_info->sequence->width;
 572     p_dec->fmt_out.video.i_height = p_sys->p_info->sequence->height;
 573     p_dec->fmt_out.video.i_aspect = p_sys->i_aspect;
 574
 575     p_dec->fmt_out.i_codec =
 576         ( p_sys->p_info->sequence->chroma_height <
 577           p_sys->p_info->sequence->height ) ?
 578         VLC_FOURCC('I','4','2','0') : VLC_FOURCC('I','4','2','2');
 579
 580     /* Get a new picture */
 581     p_pic = p_dec->pf_vout_buffer_new( p_dec );
 582
 583     if( p_pic == NULL ) return NULL;
 584
 585     p_pic->b_progressive = p_sys->p_info->current_picture != NULL ?
 586         p_sys->p_info->current_picture->flags & PIC_FLAG_PROGRESSIVE_FRAME : 1;
 587     p_pic->b_top_field_first = p_sys->p_info->current_picture != NULL ?
 588         p_sys->p_info->current_picture->flags & PIC_FLAG_TOP_FIELD_FIRST : 1;
 589     p_pic->i_nb_fields = p_sys->p_info->current_picture != NULL ?
 590         p_sys->p_info->current_picture->nb_fields : 2;
 591
 592     p_dec->pf_picture_link( p_dec, p_pic );
 593
 594     pp_buf[0] = p_pic->p[0].p_pixels;
 595     pp_buf[1] = p_pic->p[1].p_pixels;
 596     pp_buf[2] = p_pic->p[2].p_pixels;
 597
 598     return p_pic;
 599 }