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: libmpeg2.c,v 1.43 2004/02/25 17:48:52 fenrir Exp $
   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 #define PIC_FLAG_PTS
  33 #include <mpeg2dec/mpeg2.h>
  34
  35 #include "vout_synchro.h"
  36
  37 /* Aspect ratio (ISO/IEC 13818-2 section 6.3.3, table 6-3) */
  38 #define AR_SQUARE_PICTURE       1                           /* square pixels */
  39 #define AR_3_4_PICTURE          2                        /* 3:4 picture (TV) */
  40 #define AR_16_9_PICTURE         3              /* 16:9 picture (wide screen) */
  41 #define AR_221_1_PICTURE        4                  /* 2.21:1 picture (movie) */
  42
  43 /*****************************************************************************
  44  * decoder_sys_t : libmpeg2 decoder descriptor
  45  *****************************************************************************/
  46 struct decoder_sys_t
  47 {
  48     /*
  49      * libmpeg2 properties
  50      */
  51     mpeg2dec_t          *p_mpeg2dec;
  52     const mpeg2_info_t  *p_info;
  53     vlc_bool_t          b_skip;
  54
  55     /*
  56      * Input properties
  57      */
  58     pes_packet_t     *p_pes;                  /* current PES we are decoding */
  59     mtime_t          i_pts;
  60     mtime_t          i_previous_pts;
  61     mtime_t          i_current_pts;
  62     int              i_current_rate;
  63     picture_t *      p_picture_to_destroy;
  64     vlc_bool_t       b_garbage_pic;
  65     vlc_bool_t       b_after_sequence_header; /* is it the next frame after
  66                                                * the sequence header ?    */
  67     vlc_bool_t       b_slice_i;             /* intra-slice refresh stream */
  68
  69     /*
  70      * Output properties
  71      */
  72     vout_synchro_t *p_synchro;
  73     int i_aspect;
  74
  75 };
  76
  77 /*****************************************************************************
  78  * Local prototypes
  79  *****************************************************************************/
  80 static int  OpenDecoder( vlc_object_t * );
  81 static void CloseDecoder( vlc_object_t * );
  82
  83 static picture_t *DecodeBlock( decoder_t *, block_t ** );
  84
  85 static picture_t *GetNewPicture( decoder_t *, uint8_t ** );
  86
  87 /*****************************************************************************
  88  * Module descriptor
  89  *****************************************************************************/
  90 vlc_module_begin();
  91     set_description( _("MPEG I/II video decoder (using libmpeg2)") );
  92     set_capability( "decoder", 150 );
  93     set_callbacks( OpenDecoder, CloseDecoder );
  94     add_shortcut( "libmpeg2" );
  95 vlc_module_end();
  96
  97 /*****************************************************************************
  98  * OpenDecoder: probe the decoder and return score
  99  *****************************************************************************/
 100 static int OpenDecoder( vlc_object_t *p_this )
 101 {
 102     decoder_t *p_dec = (decoder_t*)p_this;
 103     decoder_sys_t *p_sys;
 104     uint32_t i_accel = 0;
 105
 106     if( p_dec->fmt_in.i_codec != VLC_FOURCC('m','p','g','v') &&
 107         p_dec->fmt_in.i_codec != VLC_FOURCC('m','p','g','1') &&
 108         /* Pinnacle hardware-mpeg1 */
 109         p_dec->fmt_in.i_codec != VLC_FOURCC('P','I','M','1') &&
 110         /* ATI Video */
 111         p_dec->fmt_in.i_codec != VLC_FOURCC('V','C','R','2') &&
 112         p_dec->fmt_in.i_codec != VLC_FOURCC('m','p','g','2') )
 113     {
 114         return VLC_EGENERIC;
 115     }
 116
 117     /* Allocate the memory needed to store the decoder's structure */
 118     if( ( p_dec->p_sys = p_sys =
 119           (decoder_sys_t *)malloc(sizeof(decoder_sys_t)) ) == NULL )
 120     {
 121         msg_Err( p_dec, "out of memory" );
 122         return VLC_EGENERIC;
 123     }
 124
 125     /* Initialize the thread properties */
 126     memset( p_sys, 0, sizeof(decoder_sys_t) );
 127     p_sys->p_pes      = NULL;
 128     p_sys->p_mpeg2dec = NULL;
 129     p_sys->p_synchro  = NULL;
 130     p_sys->p_info     = NULL;
 131     p_sys->i_pts      = mdate() + DEFAULT_PTS_DELAY;
 132     p_sys->i_current_pts  = 0;
 133     p_sys->i_previous_pts = 0;
 134     p_sys->p_picture_to_destroy = NULL;
 135     p_sys->b_garbage_pic = 0;
 136     p_sys->b_slice_i  = 0;
 137     p_sys->b_skip     = 0;
 138
 139 #if defined( __i386__ )
 140     if( p_dec->p_libvlc->i_cpu & CPU_CAPABILITY_MMX )
 141     {
 142         i_accel |= MPEG2_ACCEL_X86_MMX;
 143     }
 144
 145     if( p_dec->p_libvlc->i_cpu & CPU_CAPABILITY_3DNOW )
 146     {
 147         i_accel |= MPEG2_ACCEL_X86_3DNOW;
 148     }
 149
 150     if( p_dec->p_libvlc->i_cpu & CPU_CAPABILITY_MMXEXT )
 151     {
 152         i_accel |= MPEG2_ACCEL_X86_MMXEXT;
 153     }
 154
 155 #elif defined( __powerpc__ ) || defined( SYS_DARWIN )
 156     if( p_dec->p_libvlc->i_cpu & CPU_CAPABILITY_ALTIVEC )
 157     {
 158         i_accel |= MPEG2_ACCEL_PPC_ALTIVEC;
 159     }
 160
 161 #else
 162     /* If we do not know this CPU, trust libmpeg2's feature detection */
 163     i_accel = MPEG2_ACCEL_DETECT;
 164
 165 #endif
 166
 167     /* Set CPU acceleration features */
 168     mpeg2_accel( i_accel );
 169
 170     /* Initialize decoder */
 171     p_sys->p_mpeg2dec = mpeg2_init();
 172     if( p_sys->p_mpeg2dec == NULL)
 173     {
 174         msg_Err( p_dec, "mpeg2_init() failed" );
 175         free( p_sys );
 176         return VLC_EGENERIC;
 177     }
 178
 179     p_sys->p_info = mpeg2_info( p_sys->p_mpeg2dec );
 180
 181     p_dec->pf_decode_video = DecodeBlock;
 182
 183     return VLC_SUCCESS;
 184 }
 185
 186 /*****************************************************************************
 187  * RunDecoder: the libmpeg2 decoder
 188  *****************************************************************************/
 189 static picture_t *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
 190 {
 191     decoder_sys_t   *p_sys = p_dec->p_sys;
 192     mpeg2_state_t   state;
 193     picture_t       *p_pic;
 194
 195     block_t *p_block;
 196
 197     if( !pp_block || !*pp_block ) return NULL;
 198
 199     p_block = *pp_block;
 200
 201     while( 1 )
 202     {
 203         state = mpeg2_parse( p_sys->p_mpeg2dec );
 204
 205         switch( state )
 206         {
 207         case STATE_BUFFER:
 208             if( !p_block->i_buffer )
 209             {
 210                 block_Release( p_block );
 211                 return NULL;
 212             }
 213
 214             if( (p_block->i_flags&BLOCK_FLAG_DISCONTINUITY) &&
 215                 p_sys->p_synchro &&
 216                 p_sys->p_info->sequence &&
 217                 p_sys->p_info->sequence->width != (unsigned)-1 )
 218             {
 219                 vout_SynchroReset( p_sys->p_synchro );
 220                 if( p_sys->p_info->current_fbuf != NULL
 221                     && p_sys->p_info->current_fbuf->id != NULL )
 222                 {
 223                     p_sys->b_garbage_pic = 1;
 224                     p_pic = p_sys->p_info->current_fbuf->id;
 225                 }
 226                 else
 227                 {
 228                     uint8_t *buf[3];
 229                     buf[0] = buf[1] = buf[2] = NULL;
 230                     if( (p_pic = GetNewPicture( p_dec, buf )) == NULL )
 231                         break;
 232                     mpeg2_set_buf( p_sys->p_mpeg2dec, buf, p_pic );
 233                 }
 234                 p_sys->p_picture_to_destroy = p_pic;
 235
 236                 if ( p_sys->b_slice_i )
 237                 {
 238                     vout_SynchroNewPicture( p_sys->p_synchro,
 239                         I_CODING_TYPE, 2, 0, 0, p_sys->i_current_rate );
 240                     vout_SynchroDecode( p_sys->p_synchro );
 241                     vout_SynchroEnd( p_sys->p_synchro, I_CODING_TYPE, 0 );
 242                 }
 243             }
 244
 245             if( p_block->i_pts )
 246             {
 247 #ifdef PIC_FLAG_PTS
 248                 mpeg2_pts( p_sys->p_mpeg2dec, (uint32_t)p_block->i_pts );
 249
 250 #else /* New interface */
 251                 mpeg2_tag_picture( p_sys->p_mpeg2dec,
 252                                    (uint32_t)p_block->i_pts, 0/*dts*/ );
 253 #endif
 254                 p_sys->i_previous_pts = p_sys->i_current_pts;
 255                 p_sys->i_current_pts = p_block->i_pts;
 256             }
 257
 258             p_sys->i_current_rate = p_block->i_rate;
 259
 260             mpeg2_buffer( p_sys->p_mpeg2dec, p_block->p_buffer,
 261                           p_block->p_buffer + p_block->i_buffer );
 262
 263             p_block->i_buffer = 0;
 264             break;
 265
 266         case STATE_SEQUENCE:
 267         {
 268             /* Initialize video output */
 269             uint8_t *buf[3];
 270             buf[0] = buf[1] = buf[2] = NULL;
 271
 272             /* Check whether the input gave a particular aspect ratio */
 273             if( p_dec->fmt_in.video.i_aspect )
 274             {
 275                 p_sys->i_aspect = p_dec->fmt_in.video.i_aspect;
 276                 if( p_sys->i_aspect <= AR_221_1_PICTURE )
 277                 switch( p_sys->i_aspect )
 278                 {
 279                 case AR_3_4_PICTURE:
 280                     p_sys->i_aspect = VOUT_ASPECT_FACTOR * 4 / 3;
 281                     break;
 282                 case AR_16_9_PICTURE:
 283                     p_sys->i_aspect = VOUT_ASPECT_FACTOR * 16 / 9;
 284                     break;
 285                 case AR_221_1_PICTURE:
 286                     p_sys->i_aspect = VOUT_ASPECT_FACTOR * 221 / 100;
 287                     break;
 288                 case AR_SQUARE_PICTURE:
 289                     p_sys->i_aspect = VOUT_ASPECT_FACTOR *
 290                                    p_sys->p_info->sequence->width /
 291                                    p_sys->p_info->sequence->height;
 292                     break;
 293                 }
 294             }
 295             else
 296             {
 297                 /* Use the value provided in the MPEG sequence header */
 298                 p_sys->i_aspect =
 299                     ((uint64_t)p_sys->p_info->sequence->display_width) *
 300                     p_sys->p_info->sequence->pixel_width * VOUT_ASPECT_FACTOR /
 301                     p_sys->p_info->sequence->display_height /
 302                     p_sys->p_info->sequence->pixel_height;
 303             }
 304
 305             msg_Dbg( p_dec, "%dx%d, aspect %d, %u.%03u fps",
 306                      p_sys->p_info->sequence->width,
 307                      p_sys->p_info->sequence->height, p_sys->i_aspect,
 308                      (uint32_t)((uint64_t)1001000000 * 27 /
 309                          p_sys->p_info->sequence->frame_period / 1001),
 310                      (uint32_t)((uint64_t)1001000000 * 27 /
 311                          p_sys->p_info->sequence->frame_period % 1001) );
 312
 313             mpeg2_custom_fbuf( p_sys->p_mpeg2dec, 1 );
 314
 315             /* Set the first 2 reference frames */
 316             mpeg2_set_buf( p_sys->p_mpeg2dec, buf, NULL );
 317
 318             if( (p_pic = GetNewPicture( p_dec, buf )) == NULL )
 319             {
 320                 block_Release( p_block );
 321                 return NULL;
 322             }
 323
 324             mpeg2_set_buf( p_sys->p_mpeg2dec, buf, p_pic );
 325
 326             /* This picture will never go through display_picture. */
 327             p_pic->date = 0;
 328
 329             /* For some reason, libmpeg2 will put this pic twice in
 330              * discard_picture. This can be considered a bug in libmpeg2. */
 331             p_dec->pf_picture_link( p_dec, p_pic );
 332
 333             if( p_sys->p_synchro )
 334             {
 335                 vout_SynchroRelease( p_sys->p_synchro );
 336             }
 337             p_sys->p_synchro = vout_SynchroInit( p_dec,
 338                 (uint32_t)((uint64_t)1001000000 * 27 /
 339                 p_sys->p_info->sequence->frame_period) );
 340             p_sys->b_after_sequence_header = 1;
 341         }
 342         break;
 343
 344         case STATE_PICTURE_2ND:
 345             vout_SynchroNewPicture( p_sys->p_synchro,
 346                 p_sys->p_info->current_picture->flags & PIC_MASK_CODING_TYPE,
 347                 p_sys->p_info->current_picture->nb_fields,
 348                 0, 0, p_sys->i_current_rate );
 349
 350             if( p_sys->b_skip )
 351             {
 352                 vout_SynchroTrash( p_sys->p_synchro );
 353             }
 354             else
 355             {
 356                 vout_SynchroDecode( p_sys->p_synchro );
 357             }
 358             break;
 359
 360         case STATE_PICTURE:
 361         {
 362             uint8_t *buf[3];
 363             mtime_t i_pts;
 364             buf[0] = buf[1] = buf[2] = NULL;
 365
 366             if ( p_sys->b_after_sequence_header &&
 367                  ((p_sys->p_info->current_picture->flags &
 368                        PIC_MASK_CODING_TYPE) == PIC_FLAG_CODING_TYPE_P) )
 369             {
 370                 /* Intra-slice refresh. Simulate a blank I picture. */
 371                 msg_Dbg( p_dec, "intra-slice refresh stream" );
 372                 vout_SynchroNewPicture( p_sys->p_synchro,
 373                     I_CODING_TYPE, 2, 0, 0, p_sys->i_current_rate );
 374                 vout_SynchroDecode( p_sys->p_synchro );
 375                 vout_SynchroEnd( p_sys->p_synchro, I_CODING_TYPE, 0 );
 376                 p_sys->b_slice_i = 1;
 377             }
 378             p_sys->b_after_sequence_header = 0;
 379
 380 #ifdef PIC_FLAG_PTS
 381             i_pts = p_sys->p_info->current_picture->flags & PIC_FLAG_PTS ?
 382                 ( ( p_sys->p_info->current_picture->pts ==
 383                     (uint32_t)p_sys->i_current_pts ) ?
 384                   p_sys->i_current_pts : p_sys->i_previous_pts ) : 0;
 385
 386 #else /* New interface */
 387
 388             i_pts = p_sys->p_info->current_picture->flags & PIC_FLAG_TAGS ?
 389                 ( ( p_sys->p_info->current_picture->tag ==
 390                     (uint32_t)p_sys->i_current_pts ) ?
 391                   p_sys->i_current_pts : p_sys->i_previous_pts ) : 0;
 392 #endif
 393
 394             /* Hack to handle demuxers which only have DTS timestamps */
 395             if( !i_pts && !p_block->i_pts && p_block->i_dts > 0 )
 396             {
 397                 if( p_sys->p_info->sequence->flags & SEQ_FLAG_LOW_DELAY ||
 398                     (p_sys->p_info->current_picture->flags &
 399                       PIC_MASK_CODING_TYPE) == PIC_FLAG_CODING_TYPE_B )
 400                 {
 401                     i_pts = p_block->i_dts;
 402                 }
 403             }
 404             p_block->i_pts = p_block->i_dts = 0;
 405             /* End hack */
 406
 407             vout_SynchroNewPicture( p_sys->p_synchro,
 408                 p_sys->p_info->current_picture->flags & PIC_MASK_CODING_TYPE,
 409                 p_sys->p_info->current_picture->nb_fields, i_pts,
 410                 0, p_sys->i_current_rate );
 411
 412             if ( !(p_sys->b_slice_i
 413                    && ((p_sys->p_info->current_picture->flags
 414                          & PIC_MASK_CODING_TYPE) == P_CODING_TYPE))
 415                    && !vout_SynchroChoose( p_sys->p_synchro,
 416                               p_sys->p_info->current_picture->flags
 417                                 & PIC_MASK_CODING_TYPE,
 418                               /*p_sys->p_vout->render_time*/ 0 /*FIXME*/ ) )
 419             {
 420                 mpeg2_skip( p_sys->p_mpeg2dec, 1 );
 421                 p_sys->b_skip = 1;
 422                 vout_SynchroTrash( p_sys->p_synchro );
 423                 mpeg2_set_buf( p_sys->p_mpeg2dec, buf, NULL );
 424             }
 425             else
 426             {
 427                 mpeg2_skip( p_sys->p_mpeg2dec, 0 );
 428                 p_sys->b_skip = 0;
 429                 vout_SynchroDecode( p_sys->p_synchro );
 430
 431                 if( (p_pic = GetNewPicture( p_dec, buf )) == NULL )
 432                 {
 433                     block_Release( p_block );
 434                     return NULL;
 435                 }
 436
 437                 mpeg2_set_buf( p_sys->p_mpeg2dec, buf, p_pic );
 438             }
 439         }
 440         break;
 441
 442         case STATE_END:
 443         case STATE_SLICE:
 444             p_pic = NULL;
 445             if( p_sys->p_info->display_fbuf
 446                 && p_sys->p_info->display_fbuf->id )
 447             {
 448                 p_pic = (picture_t *)p_sys->p_info->display_fbuf->id;
 449
 450                 vout_SynchroEnd( p_sys->p_synchro,
 451                             p_sys->p_info->display_picture->flags
 452                              & PIC_MASK_CODING_TYPE,
 453                             p_sys->b_garbage_pic );
 454                 p_sys->b_garbage_pic = 0;
 455
 456                 if ( p_sys->p_picture_to_destroy != p_pic )
 457                 {
 458                     p_pic->date = vout_SynchroDate( p_sys->p_synchro );
 459                 }
 460                 else
 461                 {
 462                     p_sys->p_picture_to_destroy = NULL;
 463                     p_pic->date = 0;
 464                 }
 465             }
 466
 467             if( p_sys->p_info->discard_fbuf &&
 468                 p_sys->p_info->discard_fbuf->id )
 469             {
 470                 p_dec->pf_picture_unlink( p_dec,
 471                                           p_sys->p_info->discard_fbuf->id );
 472             }
 473
 474             if( p_pic ) return p_pic;
 475
 476             break;
 477
 478         case STATE_INVALID:
 479         {
 480             uint8_t *buf[3];
 481             buf[0] = buf[1] = buf[2] = NULL;
 482
 483             msg_Warn( p_dec, "invalid picture encountered" );
 484             if ( ( p_sys->p_info->current_picture == NULL ) ||
 485                ( ( p_sys->p_info->current_picture->flags &
 486                    PIC_MASK_CODING_TYPE) != B_CODING_TYPE ) )
 487             {
 488                 if( p_sys->p_synchro ) vout_SynchroReset( p_sys->p_synchro );
 489             }
 490             mpeg2_skip( p_sys->p_mpeg2dec, 1 );
 491             p_sys->b_skip = 1;
 492
 493             if( p_sys->p_info->current_fbuf &&
 494                 p_sys->p_info->current_fbuf->id )
 495             {
 496                 p_sys->b_garbage_pic = 1;
 497                 p_pic = p_sys->p_info->current_fbuf->id;
 498             }
 499             else if( !p_sys->p_info->sequence )
 500             {
 501                 break;
 502             }
 503             else
 504             {
 505                 if( (p_pic = GetNewPicture( p_dec, buf )) == NULL )
 506                     break;
 507                 mpeg2_set_buf( p_sys->p_mpeg2dec, buf, p_pic );
 508             }
 509             p_sys->p_picture_to_destroy = p_pic;
 510
 511             memset( p_pic->p[0].p_pixels, 0,
 512                     p_sys->p_info->sequence->width
 513                      * p_sys->p_info->sequence->height );
 514             memset( p_pic->p[1].p_pixels, 0x80,
 515                     p_sys->p_info->sequence->width
 516                      * p_sys->p_info->sequence->height / 4 );
 517             memset( p_pic->p[2].p_pixels, 0x80,
 518                     p_sys->p_info->sequence->width
 519                      * p_sys->p_info->sequence->height / 4 );
 520
 521             if( p_sys->b_slice_i )
 522             {
 523                 vout_SynchroNewPicture( p_sys->p_synchro,
 524                             I_CODING_TYPE, 2, 0, 0, p_sys->i_current_rate );
 525                 vout_SynchroDecode( p_sys->p_synchro );
 526                 vout_SynchroEnd( p_sys->p_synchro, I_CODING_TYPE, 0 );
 527             }
 528             break;
 529         }
 530
 531         default:
 532             break;
 533         }
 534     }
 535
 536     /* Never reached */
 537     return NULL;
 538 }
 539
 540 /*****************************************************************************
 541  * CloseDecoder: libmpeg2 decoder destruction
 542  *****************************************************************************/
 543 static void CloseDecoder( vlc_object_t *p_this )
 544 {
 545     decoder_t *p_dec = (decoder_t *)p_this;
 546     decoder_sys_t *p_sys = p_dec->p_sys;
 547
 548     if( p_sys->p_synchro ) vout_SynchroRelease( p_sys->p_synchro );
 549
 550     if( p_sys->p_mpeg2dec ) mpeg2_close( p_sys->p_mpeg2dec );
 551
 552     free( p_sys );
 553 }
 554
 555 /*****************************************************************************
 556  * GetNewPicture: Get a new picture from the vout and set the buf struct
 557  *****************************************************************************/
 558 static picture_t *GetNewPicture( decoder_t *p_dec, uint8_t **pp_buf )
 559 {
 560     decoder_sys_t *p_sys = p_dec->p_sys;
 561     picture_t *p_pic;
 562
 563     p_dec->fmt_out.video.i_width = p_sys->p_info->sequence->width;
 564     p_dec->fmt_out.video.i_height = p_sys->p_info->sequence->height;
 565     p_dec->fmt_out.video.i_aspect = p_sys->i_aspect;
 566
 567     p_dec->fmt_out.i_codec =
 568         ( p_sys->p_info->sequence->chroma_height <
 569           p_sys->p_info->sequence->height ) ?
 570         VLC_FOURCC('I','4','2','0') : VLC_FOURCC('I','4','2','2');
 571
 572     /* Get a new picture */
 573     p_pic = p_dec->pf_vout_buffer_new( p_dec );
 574
 575     if( p_pic == NULL ) return NULL;
 576
 577     p_pic->b_progressive = p_sys->p_info->current_picture != NULL ?
 578         p_sys->p_info->current_picture->flags & PIC_FLAG_PROGRESSIVE_FRAME : 1;
 579     p_pic->b_top_field_first = p_sys->p_info->current_picture != NULL ?
 580         p_sys->p_info->current_picture->flags & PIC_FLAG_TOP_FIELD_FIRST : 1;
 581     p_pic->i_nb_fields = p_sys->p_info->current_picture != NULL ?
 582         p_sys->p_info->current_picture->nb_fields : 2;
 583
 584     p_dec->pf_picture_link( p_dec, p_pic );
 585
 586     pp_buf[0] = p_pic->p[0].p_pixels;
 587     pp_buf[1] = p_pic->p[1].p_pixels;
 588     pp_buf[2] = p_pic->p[2].p_pixels;
 589
 590     return p_pic;
 591 }