git.sesse.net Git - vlc/blob - modules/packetizer/h264.c

   1 /*****************************************************************************
   2  * h264.c: h264/avc video packetizer
   3  *****************************************************************************
   4  * Copyright (C) 2001, 2002 VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Laurent Aimar <fenrir@via.ecp.fr>
   8  *          Eric Petit <titer@videolan.org>
   9  *          Gildas Bazin <gbazin@videolan.org>
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  24  *****************************************************************************/
  25
  26 /*****************************************************************************
  27  * Preamble
  28  *****************************************************************************/
  29 #include <stdlib.h>                                      /* malloc(), free() */
  30
  31 #include <vlc/vlc.h>
  32 #include <vlc/decoder.h>
  33 #include <vlc/sout.h>
  34
  35 #include "vlc_block_helper.h"
  36 #include "vlc_bits.h"
  37
  38 /*****************************************************************************
  39  * Module descriptor
  40  *****************************************************************************/
  41 static int  Open ( vlc_object_t * );
  42 static void Close( vlc_object_t * );
  43
  44 vlc_module_begin();
  45     set_category( CAT_SOUT );
  46     set_subcategory( SUBCAT_SOUT_PACKETIZER );
  47     set_description( _("H264 video packetizer") );
  48     set_capability( "packetizer", 50 );
  49     set_callbacks( Open, Close );
  50 vlc_module_end();
  51
  52
  53 /****************************************************************************
  54  * Local prototypes
  55  ****************************************************************************/
  56 static block_t *Packetize( decoder_t *, block_t ** );
  57 static block_t *PacketizeAVC1( decoder_t *, block_t ** );
  58
  59 struct decoder_sys_t
  60 {
  61     block_bytestream_t bytestream;
  62
  63     int     i_state;
  64     int     i_offset;
  65     uint8_t startcode[4];
  66
  67     vlc_bool_t b_slice;
  68     block_t    *p_frame;
  69
  70     vlc_bool_t   b_sps;
  71
  72     /* avcC data */
  73     int i_avcC_length_size;
  74
  75     /* Useful values of the Sequence Parameter Set */
  76     int i_log2_max_frame_num;
  77     int b_frame_mbs_only;
  78
  79     /* Useful values of the Slice Header */
  80     int i_nal_type;
  81     int i_nal_ref_idc;
  82     int i_idr_pic_id;
  83     int i_frame_num;
  84 };
  85
  86 enum
  87 {
  88     STATE_NOSYNC,
  89     STATE_NEXT_SYNC,
  90 };
  91
  92 enum nal_unit_type_e
  93 {
  94     NAL_UNKNOWN = 0,
  95     NAL_SLICE   = 1,
  96     NAL_SLICE_DPA   = 2,
  97     NAL_SLICE_DPB   = 3,
  98     NAL_SLICE_DPC   = 4,
  99     NAL_SLICE_IDR   = 5,    /* ref_idc != 0 */
 100     NAL_SEI         = 6,    /* ref_idc == 0 */
 101     NAL_SPS         = 7,
 102     NAL_PPS         = 8,
 103     NAL_AU_DELIMITER= 9
 104     /* ref_idc == 0 for 6,9,10,11,12 */
 105 };
 106
 107 enum nal_priority_e
 108 {
 109     NAL_PRIORITY_DISPOSABLE = 0,
 110     NAL_PRIORITY_LOW        = 1,
 111     NAL_PRIORITY_HIGH       = 2,
 112     NAL_PRIORITY_HIGHEST    = 3,
 113 };
 114
 115 static block_t *ParseNALBlock( decoder_t *, block_t * );
 116
 117 static block_t *nal_get_annexeb( decoder_t *, uint8_t *p, int );
 118
 119 /*****************************************************************************
 120  * Open: probe the packetizer and return score
 121  *****************************************************************************/
 122 static int Open( 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_FOURCC( 'h', '2', '6', '4') &&
 128         p_dec->fmt_in.i_codec != VLC_FOURCC( 'H', '2', '6', '4') &&
 129         p_dec->fmt_in.i_codec != VLC_FOURCC( 'V', 'S', 'S', 'H') &&
 130         p_dec->fmt_in.i_codec != VLC_FOURCC( 'v', 's', 's', 'h') &&
 131         ( p_dec->fmt_in.i_codec != VLC_FOURCC( 'a', 'v', 'c', '1') ||
 132           p_dec->fmt_in.i_extra < 7 ) )
 133     {
 134         return VLC_EGENERIC;
 135     }
 136
 137     /* Allocate the memory needed to store the decoder's structure */
 138     if( ( p_dec->p_sys = p_sys = malloc( sizeof(decoder_sys_t) ) ) == NULL )
 139     {
 140         msg_Err( p_dec, "out of memory" );
 141         return VLC_EGENERIC;
 142     }
 143     p_sys->i_state = STATE_NOSYNC;
 144     p_sys->i_offset = 0;
 145     p_sys->startcode[0] = 0;
 146     p_sys->startcode[1] = 0;
 147     p_sys->startcode[2] = 0;
 148     p_sys->startcode[3] = 1;
 149     p_sys->bytestream = block_BytestreamInit( p_dec );
 150     p_sys->b_slice = VLC_FALSE;
 151     p_sys->p_frame = NULL;
 152     p_sys->b_sps   = VLC_FALSE;
 153
 154     p_sys->i_nal_type = -1;
 155     p_sys->i_nal_ref_idc = -1;
 156     p_sys->i_idr_pic_id = -1;
 157     p_sys->i_frame_num = -1;
 158
 159     /* Setup properties */
 160     es_format_Copy( &p_dec->fmt_out, &p_dec->fmt_in );
 161     p_dec->fmt_out.i_codec = VLC_FOURCC( 'h', '2', '6', '4' );
 162     /* FIXME: FFMPEG isn't happy at all if you leave this */
 163     if( p_dec->fmt_out.i_extra ) free( p_dec->fmt_out.p_extra );
 164     p_dec->fmt_out.i_extra = 0; p_dec->fmt_out.p_extra = 0;
 165
 166     if( p_dec->fmt_in.i_codec == VLC_FOURCC( 'a', 'v', 'c', '1' ) )
 167     {
 168         uint8_t *p = &((uint8_t*)p_dec->fmt_in.p_extra)[4];
 169         int i_sps, i_pps;
 170         int i;
 171
 172         /* Parse avcC */
 173         p_sys->i_avcC_length_size = 1 + ((*p++)&0x03);
 174
 175         /* Read SPS */
 176         i_sps = (*p++)&0x1f;
 177
 178         for( i = 0; i < i_sps; i++ )
 179         {
 180             int i_length = GetWBE( p );
 181             block_t *p_sps = nal_get_annexeb( p_dec, p + 2, i_length );
 182
 183             ParseNALBlock( p_dec, p_sps );
 184             p += 2 + i_length;
 185         }
 186         /* Read PPS */
 187         i_pps = *p++;
 188         for( i = 0; i < i_pps; i++ )
 189         {
 190             int i_length = GetWBE( p );
 191             block_t *p_pps = nal_get_annexeb( p_dec, p + 2, i_length );
 192
 193             ParseNALBlock( p_dec, p_pps );
 194             p += 2 + i_length;
 195         }
 196         msg_Dbg( p_dec, "avcC length size=%d sps=%d pps=%d",
 197                  p_sys->i_avcC_length_size, i_sps, i_pps );
 198
 199         /* Set callback */
 200         p_dec->pf_packetize = PacketizeAVC1;
 201     }
 202     else
 203     {
 204         /* Set callback */
 205         p_dec->pf_packetize = Packetize;
 206     }
 207
 208     return VLC_SUCCESS;
 209 }
 210
 211 /*****************************************************************************
 212  * Close: clean up the packetizer
 213  *****************************************************************************/
 214 static void Close( vlc_object_t *p_this )
 215 {
 216     decoder_t *p_dec = (decoder_t*)p_this;
 217     decoder_sys_t *p_sys = p_dec->p_sys;
 218
 219     block_BytestreamRelease( &p_sys->bytestream );
 220     free( p_sys );
 221 }
 222
 223 /****************************************************************************
 224  * Packetize: the whole thing
 225  ****************************************************************************/
 226 static block_t *Packetize( decoder_t *p_dec, block_t **pp_block )
 227 {
 228     decoder_sys_t *p_sys = p_dec->p_sys;
 229     block_t       *p_pic;
 230
 231     if( !pp_block || !*pp_block ) return NULL;
 232
 233     block_BytestreamPush( &p_sys->bytestream, *pp_block );
 234
 235     for( ;; )
 236     {
 237         switch( p_sys->i_state )
 238         {
 239             case STATE_NOSYNC:
 240                 if( block_FindStartcodeFromOffset( &p_sys->bytestream,
 241                       &p_sys->i_offset, p_sys->startcode+1, 3 ) == VLC_SUCCESS)
 242                 {
 243                     p_sys->i_state = STATE_NEXT_SYNC;
 244                 }
 245
 246                 if( p_sys->i_offset )
 247                 {
 248                     block_SkipBytes( &p_sys->bytestream, p_sys->i_offset );
 249                     p_sys->i_offset = 0;
 250                     block_BytestreamFlush( &p_sys->bytestream );
 251                 }
 252
 253                 if( p_sys->i_state != STATE_NEXT_SYNC )
 254                 {
 255                     /* Need more data */
 256                     return NULL;
 257                 }
 258
 259                 p_sys->i_offset = 1; /* To find next startcode */
 260
 261             case STATE_NEXT_SYNC:
 262                 /* Find the next startcode */
 263                 if( block_FindStartcodeFromOffset( &p_sys->bytestream,
 264                       &p_sys->i_offset, p_sys->startcode, 3 ) != VLC_SUCCESS)
 265                 {
 266                     if( block_FindStartcodeFromOffset( &p_sys->bytestream,
 267                           &p_sys->i_offset, p_sys->startcode+1, 3 ) !=
 268                         VLC_SUCCESS )
 269                     {
 270                         /* Need more data */
 271                         return NULL;
 272                     }
 273                 }
 274
 275                 /* Get the new fragment and set the pts/dts */
 276                 p_pic = block_New( p_dec, p_sys->i_offset );
 277                 p_pic->i_pts = p_sys->bytestream.p_block->i_pts;
 278                 p_pic->i_dts = p_sys->bytestream.p_block->i_dts;
 279
 280                 block_GetBytes( &p_sys->bytestream, p_pic->p_buffer,
 281                                 p_pic->i_buffer );
 282
 283                 p_sys->i_offset = 0;
 284
 285                 /* Parse the NAL */
 286                 if( !( p_pic = ParseNALBlock( p_dec, p_pic ) ) )
 287                 {
 288                     p_sys->i_state = STATE_NOSYNC;
 289                     break;
 290                 }
 291 #if 0
 292                 msg_Dbg( p_dec, "pts="I64Fd" dts="I64Fd,
 293                          p_pic->i_pts, p_pic->i_dts );
 294 #endif
 295
 296                 /* So p_block doesn't get re-added several times */
 297                 *pp_block = block_BytestreamPop( &p_sys->bytestream );
 298
 299                 p_sys->i_state = STATE_NOSYNC;
 300
 301                 return p_pic;
 302         }
 303     }
 304 }
 305
 306 /****************************************************************************
 307  * PacketizeAVC1: the whole thing
 308  ****************************************************************************/
 309 static block_t *PacketizeAVC1( decoder_t *p_dec, block_t **pp_block )
 310 {
 311     decoder_sys_t *p_sys = p_dec->p_sys;
 312     block_t       *p_block;
 313     block_t       *p_ret = NULL;
 314     uint8_t       *p;
 315
 316     if( !pp_block || !*pp_block ) return NULL;
 317
 318     p_block = *pp_block;
 319     *pp_block = NULL;
 320
 321     for( p = p_block->p_buffer; p < &p_block->p_buffer[p_block->i_buffer]; )
 322     {
 323         block_t *p_pic;
 324         int i_size = 0;
 325         int i;
 326
 327         for( i = 0; i < p_sys->i_avcC_length_size; i++ )
 328         {
 329             i_size = (i_size << 8) | (*p++);
 330         }
 331
 332         if( i_size > 0 )
 333         {
 334             block_t *p_part = nal_get_annexeb( p_dec, p, i_size );
 335
 336             p_part->i_dts = p_block->i_dts;
 337             p_part->i_pts = p_block->i_pts;
 338
 339             /* Parse the NAL */
 340             if( ( p_pic = ParseNALBlock( p_dec, p_part ) ) )
 341             {
 342                 block_ChainAppend( &p_ret, p_pic );
 343             }
 344         }
 345         p += i_size;
 346     }
 347
 348     return p_ret;
 349 }
 350
 351 static block_t *nal_get_annexeb( decoder_t *p_dec, uint8_t *p, int i_size )
 352 {
 353     block_t *p_nal;
 354
 355     p_nal = block_New( p_dec, 3 + i_size );
 356
 357     /* Add start code */
 358     p_nal->p_buffer[0] = 0x00;
 359     p_nal->p_buffer[1] = 0x00;
 360     p_nal->p_buffer[2] = 0x01;
 361
 362     /* Copy nalu */
 363     memcpy( &p_nal->p_buffer[3], p, i_size );
 364
 365     return p_nal;
 366 }
 367
 368 static void nal_get_decoded( uint8_t **pp_ret, int *pi_ret,
 369                              uint8_t *src, int i_src )
 370 {
 371     uint8_t *end = &src[i_src];
 372     uint8_t *dst = malloc( i_src );
 373
 374     *pp_ret = dst;
 375
 376     while( src < end )
 377     {
 378         if( src < end - 3 && src[0] == 0x00 && src[1] == 0x00 &&
 379             src[2] == 0x03 )
 380         {
 381             *dst++ = 0x00;
 382             *dst++ = 0x00;
 383
 384             src += 3;
 385             continue;
 386         }
 387         *dst++ = *src++;
 388     }
 389
 390     *pi_ret = dst - *pp_ret;
 391 }
 392
 393 static inline int bs_read_ue( bs_t *s )
 394 {
 395     int i = 0;
 396
 397     while( bs_read1( s ) == 0 && s->p < s->p_end && i < 32 )
 398     {
 399         i++;
 400     }
 401     return( ( 1 << i) - 1 + bs_read( s, i ) );
 402 }
 403
 404 static inline int bs_read_se( bs_t *s )
 405 {
 406     int val = bs_read_ue( s );
 407
 408     return val&0x01 ? (val+1)/2 : -(val/2);
 409 }
 410
 411
 412 static block_t *ParseNALBlock( decoder_t *p_dec, block_t *p_frag )
 413 {
 414     decoder_sys_t *p_sys = p_dec->p_sys;
 415     block_t *p_pic = NULL;
 416
 417     const int i_nal_ref_idc = (p_frag->p_buffer[3] >> 5)&0x03;
 418     const int i_nal_type = p_frag->p_buffer[3]&0x1f;
 419
 420 #define OUTPUT \
 421     do {                                                \
 422         p_pic = block_ChainGather( p_sys->p_frame );    \
 423         p_pic->i_length = 0;    /* FIXME */             \
 424                                                         \
 425         p_sys->p_frame = NULL;                          \
 426         p_sys->b_slice = VLC_FALSE;                     \
 427     } while(0)
 428
 429
 430     if( p_sys->b_slice && !p_sys->b_sps )
 431     {
 432         block_ChainRelease( p_sys->p_frame );
 433         msg_Warn( p_dec, "waiting for SPS" );
 434
 435         /* Reset context */
 436         p_sys->p_frame = NULL;
 437         p_sys->b_slice = VLC_FALSE;
 438     }
 439
 440     if( !p_sys->b_sps &&
 441         i_nal_type >= NAL_SLICE && i_nal_type <= NAL_SLICE_IDR )
 442     {
 443         p_sys->b_slice = VLC_TRUE;
 444         /* Fragment will be discarded later on */
 445     }
 446     else if( i_nal_type >= NAL_SLICE && i_nal_type <= NAL_SLICE_IDR )
 447     {
 448         uint8_t *dec;
 449         int i_dec, i_first_mb, i_slice_type, i_frame_num, i_pic_flags = 0;
 450         vlc_bool_t b_pic = VLC_FALSE;
 451         bs_t s;
 452
 453         /* do not convert the whole frame */
 454         nal_get_decoded( &dec, &i_dec, &p_frag->p_buffer[4],
 455                          __MIN( p_frag->i_buffer - 4, 60 ) );
 456         bs_init( &s, dec, i_dec );
 457
 458         /* first_mb_in_slice */
 459         i_first_mb = bs_read_ue( &s );
 460
 461         /* slice_type */
 462         switch( (i_slice_type = bs_read_ue( &s )) )
 463         {
 464             case 0: case 5:
 465                 i_pic_flags = BLOCK_FLAG_TYPE_P;
 466                 break;
 467             case 1: case 6:
 468                 i_pic_flags = BLOCK_FLAG_TYPE_B;
 469                 break;
 470             case 2: case 7:
 471                 i_pic_flags = BLOCK_FLAG_TYPE_I;
 472                 break;
 473             case 3: case 8: /* SP */
 474                 i_pic_flags = BLOCK_FLAG_TYPE_P;
 475                 break;
 476             case 4: case 9:
 477                 i_pic_flags = BLOCK_FLAG_TYPE_I;
 478                 break;
 479         }
 480
 481         /* pic_parameter_set_id */
 482         bs_read_ue( &s );
 483         /* frame_num */
 484         i_frame_num = bs_read( &s, p_sys->i_log2_max_frame_num + 4 );
 485
 486         /* Detection of the first VCL NAL unit of a primary coded picture
 487          * (cf. 7.4.1.2.4) */
 488         if( i_frame_num != p_sys->i_frame_num ||
 489             ( (i_nal_ref_idc != p_sys->i_nal_ref_idc) &&
 490               (!i_nal_ref_idc || !p_sys->i_nal_ref_idc) ) )
 491         {
 492             b_pic = VLC_TRUE;
 493         }
 494         p_sys->i_frame_num = i_frame_num;
 495         p_sys->i_nal_ref_idc = i_nal_ref_idc;
 496
 497         if( !p_sys->b_frame_mbs_only )
 498         {
 499             /* field_pic_flag */
 500             if( bs_read( &s, 1 ) )
 501             {
 502                 /* bottom_field_flag */
 503                 bs_read( &s, 1 );
 504             }
 505         }
 506
 507         if( i_nal_type == NAL_SLICE_IDR )
 508         {
 509             /* id_pic_id */
 510             int i_idr_pic_id = bs_read_ue( &s );
 511             if( p_sys->i_nal_type != i_nal_type ) b_pic = VLC_TRUE;
 512             if( p_sys->i_idr_pic_id != i_idr_pic_id ) b_pic = VLC_TRUE;
 513             p_sys->i_idr_pic_id = i_idr_pic_id;
 514         }
 515         p_sys->i_nal_type = i_nal_type;
 516
 517         if( b_pic && p_sys->b_slice )
 518             OUTPUT;
 519
 520         p_sys->b_slice = VLC_TRUE;
 521
 522         free( dec );
 523     }
 524     else if( i_nal_type == NAL_SPS )
 525     {
 526         uint8_t *dec;
 527         int     i_dec;
 528         bs_t s;
 529         int i_tmp;
 530
 531         msg_Dbg( p_dec, "found NAL_SPS" );
 532
 533         p_sys->b_sps = VLC_TRUE;
 534
 535         nal_get_decoded( &dec, &i_dec, &p_frag->p_buffer[4],
 536                          p_frag->i_buffer - 4 );
 537
 538         bs_init( &s, dec, i_dec );
 539         /* Skip profile(8), constraint_set012, reserver(5), level(8) */
 540         bs_skip( &s, 8 + 1+1+1 + 5 + 8 );
 541         /* sps id */
 542         bs_read_ue( &s );
 543         /* Skip i_log2_max_frame_num */
 544         p_sys->i_log2_max_frame_num = bs_read_ue( &s );
 545         /* Read poc_type */
 546         i_tmp = bs_read_ue( &s );
 547         if( i_tmp == 0 )
 548         {
 549             /* skip i_log2_max_poc_lsb */
 550             bs_read_ue( &s );
 551         }
 552         else if( i_tmp == 1 )
 553         {
 554             int i_cycle;
 555             /* skip b_delta_pic_order_always_zero */
 556             bs_skip( &s, 1 );
 557             /* skip i_offset_for_non_ref_pic */
 558             bs_read_se( &s );
 559             /* skip i_offset_for_top_to_bottom_field */
 560             bs_read_se( &s );
 561             /* read i_num_ref_frames_in_poc_cycle */
 562             i_cycle = bs_read_ue( &s );
 563             if( i_cycle > 256 ) i_cycle = 256;
 564             while( i_cycle > 0 )
 565             {
 566                 /* skip i_offset_for_ref_frame */
 567                 bs_read_se(&s );
 568             }
 569         }
 570         /* i_num_ref_frames */
 571         bs_read_ue( &s );
 572         /* b_gaps_in_frame_num_value_allowed */
 573         bs_skip( &s, 1 );
 574
 575         /* Read size */
 576         p_dec->fmt_out.video.i_width  = 16 * ( bs_read_ue( &s ) + 1 );
 577         p_dec->fmt_out.video.i_height = 16 * ( bs_read_ue( &s ) + 1 );
 578
 579         /* b_frame_mbs_only */
 580         p_sys->b_frame_mbs_only = bs_read( &s, 1 );
 581         if( p_sys->b_frame_mbs_only == 0 )
 582         {
 583             bs_skip( &s, 1 );
 584         }
 585         /* b_direct8x8_inference */
 586         bs_skip( &s, 1 );
 587
 588         /* crop */
 589         i_tmp = bs_read( &s, 1 );
 590         if( i_tmp )
 591         {
 592             /* left */
 593             bs_read_ue( &s );
 594             /* right */
 595             bs_read_ue( &s );
 596             /* top */
 597             bs_read_ue( &s );
 598             /* bottom */
 599             bs_read_ue( &s );
 600         }
 601
 602         /* vui */
 603         i_tmp = bs_read( &s, 1 );
 604         if( i_tmp )
 605         {
 606             /* read the aspect ratio part if any FIXME check it */
 607             i_tmp = bs_read( &s, 1 );
 608             if( i_tmp )
 609             {
 610                 static const struct { int w, h; } sar[14] =
 611                 {
 612                     { 0,   0 }, { 1,   1 }, { 12, 11 }, { 10, 11 },
 613                     { 16, 11 }, { 40, 33 }, { 24, 11 }, { 20, 11 },
 614                     { 32, 11 }, { 80, 33 }, { 18, 11 }, { 15, 11 },
 615                     { 64, 33 }, { 160,99 },
 616                 };
 617                 int i_sar = bs_read( &s, 8 );
 618                 int w, h;
 619
 620                 if( i_sar < 14 )
 621                 {
 622                     w = sar[i_sar].w;
 623                     h = sar[i_sar].h;
 624                 }
 625                 else
 626                 {
 627                     w = bs_read( &s, 16 );
 628                     h = bs_read( &s, 16 );
 629                 }
 630                 p_dec->fmt_out.video.i_aspect =
 631                     VOUT_ASPECT_FACTOR * w / h * p_dec->fmt_out.video.i_width /
 632                     p_dec->fmt_out.video.i_height;
 633             }
 634         }
 635
 636         free( dec );
 637
 638
 639         if( p_sys->b_slice )
 640             OUTPUT;
 641     }
 642     else if( i_nal_type == NAL_PPS )
 643     {
 644         bs_t s;
 645         bs_init( &s, &p_frag->p_buffer[4], p_frag->i_buffer - 4 );
 646
 647         /* TODO */
 648         msg_Dbg( p_dec, "found NAL_PPS" );
 649
 650         if( p_sys->b_slice )
 651             OUTPUT;
 652     }
 653     else if( i_nal_type == NAL_AU_DELIMITER ||
 654              i_nal_type == NAL_SEI ||
 655              ( i_nal_type >= 13 && i_nal_type <= 18 ) )
 656     {
 657         if( p_sys->b_slice )
 658             OUTPUT;
 659     }
 660
 661 #undef OUTPUT
 662
 663     /* Append the block */
 664     block_ChainAppend( &p_sys->p_frame, p_frag );
 665
 666     return p_pic;
 667 }