git.sesse.net Git - vlc/blob - modules/packetizer/mpeg4video.c

   1 /*****************************************************************************
   2  * mpeg4video.c: mpeg 4 video packetizer
   3  *****************************************************************************
   4  * Copyright (C) 2001-2006 the VideoLAN team
   5  * $Id$
   6  *
   7  * Authors: Gildas Bazin <gbazin@videolan.org>
   8  *          Laurent Aimar <fenrir@via.ecp.fr>
   9  *          Eric Petit <titer@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., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  24  *****************************************************************************/
  25
  26 /*****************************************************************************
  27  * Preamble
  28  *****************************************************************************/
  29
  30 #ifdef HAVE_CONFIG_H
  31 # include "config.h"
  32 #endif
  33
  34 #include <vlc/vlc.h>
  35 #include <vlc_sout.h>
  36 #include <vlc_codec.h>
  37 #include <vlc_block.h>
  38 #include <vlc_input.h>                  /* hmmm, just for INPUT_RATE_DEFAULT */
  39
  40 #include "vlc_bits.h"
  41 #include "vlc_block_helper.h"
  42
  43 /*****************************************************************************
  44  * Module descriptor
  45  *****************************************************************************/
  46 static int  Open ( vlc_object_t * );
  47 static void Close( vlc_object_t * );
  48
  49 vlc_module_begin();
  50     set_category( CAT_SOUT );
  51     set_subcategory( SUBCAT_SOUT_PACKETIZER );
  52     set_description( _("MPEG4 video packetizer") );
  53     set_capability( "packetizer", 50 );
  54     set_callbacks( Open, Close );
  55 vlc_module_end();
  56
  57 /****************************************************************************
  58  * Local prototypes
  59  ****************************************************************************/
  60 static block_t *Packetize( decoder_t *, block_t ** );
  61
  62 struct decoder_sys_t
  63 {
  64     /*
  65      * Input properties
  66      */
  67     block_bytestream_t bytestream;
  68     int i_state;
  69     size_t i_offset;
  70     uint8_t p_startcode[3];
  71
  72     /*
  73      * Common properties
  74      */
  75     mtime_t i_interpolated_pts;
  76     mtime_t i_interpolated_dts;
  77     mtime_t i_last_ref_pts;
  78     mtime_t i_last_time_ref;
  79     mtime_t i_time_ref;
  80     mtime_t i_last_time;
  81     mtime_t i_last_timeincr;
  82
  83     unsigned int i_flags;
  84
  85     int         i_fps_num;
  86     int         i_fps_den;
  87     int         i_last_incr;
  88     int         i_last_incr_diff;
  89
  90     vlc_bool_t  b_frame;
  91
  92     /* Current frame being built */
  93     block_t    *p_frame;
  94     block_t    **pp_last;
  95 };
  96
  97 enum {
  98     STATE_NOSYNC,
  99     STATE_NEXT_SYNC
 100 };
 101
 102 static block_t *ParseMPEGBlock( decoder_t *, block_t * );
 103 static int ParseVOL( decoder_t *, es_format_t *, uint8_t *, int );
 104 static int ParseVOP( decoder_t *, block_t * );
 105 static int vlc_log2( unsigned int );
 106
 107 #define VIDEO_OBJECT_MASK                       0x01f
 108 #define VIDEO_OBJECT_LAYER_MASK                 0x00f
 109
 110 #define VIDEO_OBJECT_START_CODE                 0x100
 111 #define VIDEO_OBJECT_LAYER_START_CODE           0x120
 112 #define VISUAL_OBJECT_SEQUENCE_START_CODE       0x1b0
 113 #define VISUAL_OBJECT_SEQUENCE_END_CODE         0x1b1
 114 #define USER_DATA_START_CODE                    0x1b2
 115 #define GROUP_OF_VOP_START_CODE                 0x1b3
 116 #define VIDEO_SESSION_ERROR_CODE                0x1b4
 117 #define VISUAL_OBJECT_START_CODE                0x1b5
 118 #define VOP_START_CODE                          0x1b6
 119 #define FACE_OBJECT_START_CODE                  0x1ba
 120 #define FACE_OBJECT_PLANE_START_CODE            0x1bb
 121 #define MESH_OBJECT_START_CODE                  0x1bc
 122 #define MESH_OBJECT_PLANE_START_CODE            0x1bd
 123 #define STILL_TEXTURE_OBJECT_START_CODE         0x1be
 124 #define TEXTURE_SPATIAL_LAYER_START_CODE        0x1bf
 125 #define TEXTURE_SNR_LAYER_START_CODE            0x1c0
 126
 127 /*****************************************************************************
 128  * Open: probe the packetizer and return score
 129  *****************************************************************************/
 130 static int Open( vlc_object_t *p_this )
 131 {
 132     decoder_t     *p_dec = (decoder_t*)p_this;
 133     decoder_sys_t *p_sys;
 134
 135     switch( p_dec->fmt_in.i_codec )
 136     {
 137         case VLC_FOURCC( 'm', '4', 's', '2'):
 138         case VLC_FOURCC( 'M', '4', 'S', '2'):
 139         case VLC_FOURCC( 'm', 'p', '4', 's'):
 140         case VLC_FOURCC( 'M', 'P', '4', 'S'):
 141         case VLC_FOURCC( 'm', 'p', '4', 'v'):
 142         case VLC_FOURCC( 'M', 'P', '4', 'V'):
 143         case VLC_FOURCC( 'D', 'I', 'V', 'X'):
 144         case VLC_FOURCC( 'd', 'i', 'v', 'x'):
 145         case VLC_FOURCC( 'X', 'V', 'I', 'D'):
 146         case VLC_FOURCC( 'X', 'v', 'i', 'D'):
 147         case VLC_FOURCC( 'x', 'v', 'i', 'd'):
 148         case VLC_FOURCC( 'D', 'X', '5', '0'):
 149         case VLC_FOURCC( 'd', 'x', '5', '0'):
 150         case VLC_FOURCC( 0x04, 0,   0,   0):
 151         case VLC_FOURCC( '3', 'I', 'V', '2'):
 152         case VLC_FOURCC( 'm', '4', 'c', 'c'):
 153         case VLC_FOURCC( 'M', '4', 'C', 'C'):
 154             break;
 155
 156         default:
 157             return VLC_EGENERIC;
 158     }
 159
 160     /* Allocate the memory needed to store the decoder's structure */
 161     if( ( p_dec->p_sys = p_sys = malloc( sizeof(decoder_sys_t) ) ) == NULL )
 162     {
 163         msg_Err( p_dec, "out of memory" );
 164         return VLC_EGENERIC;
 165     }
 166     memset( p_sys, 0, sizeof(decoder_sys_t) );
 167
 168     /* Misc init */
 169     p_sys->i_state = STATE_NOSYNC;
 170     p_sys->bytestream = block_BytestreamInit();
 171     p_sys->p_startcode[0] = 0;
 172     p_sys->p_startcode[1] = 0;
 173     p_sys->p_startcode[2] = 1;
 174     p_sys->i_offset = 0;
 175     p_sys->p_frame = NULL;
 176     p_sys->pp_last = &p_sys->p_frame;
 177
 178     /* Setup properties */
 179     es_format_Copy( &p_dec->fmt_out, &p_dec->fmt_in );
 180     p_dec->fmt_out.i_codec = VLC_FOURCC( 'm', 'p', '4', 'v' );
 181
 182     if( p_dec->fmt_in.i_extra )
 183     {
 184         /* We have a vol */
 185         p_dec->fmt_out.i_extra = p_dec->fmt_in.i_extra;
 186         p_dec->fmt_out.p_extra = malloc( p_dec->fmt_in.i_extra );
 187         memcpy( p_dec->fmt_out.p_extra, p_dec->fmt_in.p_extra,
 188                 p_dec->fmt_in.i_extra );
 189
 190         msg_Dbg( p_dec, "opening with vol size: %d", p_dec->fmt_in.i_extra );
 191         ParseVOL( p_dec, &p_dec->fmt_out,
 192                   p_dec->fmt_out.p_extra, p_dec->fmt_out.i_extra );
 193     }
 194     else
 195     {
 196         /* No vol, we'll have to look for one later on */
 197         p_dec->fmt_out.i_extra = 0;
 198         p_dec->fmt_out.p_extra = 0;
 199     }
 200
 201     /* Set callback */
 202     p_dec->pf_packetize = Packetize;
 203
 204     return VLC_SUCCESS;
 205 }
 206
 207 /*****************************************************************************
 208  * Close: clean up the packetizer
 209  *****************************************************************************/
 210 static void Close( vlc_object_t *p_this )
 211 {
 212     decoder_t *p_dec = (decoder_t*)p_this;
 213
 214     block_BytestreamRelease( &p_dec->p_sys->bytestream );
 215     if( p_dec->p_sys->p_frame ) block_ChainRelease( p_dec->p_sys->p_frame );
 216     free( p_dec->p_sys );
 217 }
 218
 219 /****************************************************************************
 220  * Packetize: the whole thing
 221  ****************************************************************************/
 222 static block_t *Packetize( decoder_t *p_dec, block_t **pp_block )
 223 {
 224     decoder_sys_t *p_sys = p_dec->p_sys;
 225     block_t       *p_pic;
 226     mtime_t       i_pts, i_dts;
 227
 228     if( pp_block == NULL || *pp_block == NULL ) return NULL;
 229
 230     if( (*pp_block)->i_flags&(BLOCK_FLAG_DISCONTINUITY|BLOCK_FLAG_CORRUPTED) )
 231     {
 232         if( (*pp_block)->i_flags&BLOCK_FLAG_CORRUPTED )
 233         {
 234             p_sys->i_state = STATE_NOSYNC;
 235             block_BytestreamFlush( &p_sys->bytestream );
 236
 237             if( p_sys->p_frame )
 238                 block_ChainRelease( p_sys->p_frame );
 239             p_sys->p_frame = NULL;
 240             p_sys->pp_last = &p_sys->p_frame;
 241         }
 242 //        p_sys->i_interpolated_pts =
 243 //        p_sys->i_interpolated_dts =
 244 //        p_sys->i_last_ref_pts =
 245 //        p_sys->i_last_time_ref =
 246 //        p_sys->i_time_ref =
 247 //        p_sys->i_last_time =
 248 //        p_sys->i_last_timeincr = 0;
 249
 250         block_Release( *pp_block );
 251         return NULL;
 252     }
 253
 254     block_BytestreamPush( &p_sys->bytestream, *pp_block );
 255
 256     while( 1 )
 257     {
 258         switch( p_sys->i_state )
 259         {
 260
 261         case STATE_NOSYNC:
 262             if( block_FindStartcodeFromOffset( &p_sys->bytestream,
 263                     &p_sys->i_offset, p_sys->p_startcode, 3 ) == VLC_SUCCESS )
 264             {
 265                 p_sys->i_state = STATE_NEXT_SYNC;
 266             }
 267
 268             if( p_sys->i_offset )
 269             {
 270                 block_SkipBytes( &p_sys->bytestream, p_sys->i_offset );
 271                 p_sys->i_offset = 0;
 272                 block_BytestreamFlush( &p_sys->bytestream );
 273             }
 274
 275             if( p_sys->i_state != STATE_NEXT_SYNC )
 276             {
 277                 /* Need more data */
 278                 return NULL;
 279             }
 280
 281             p_sys->i_offset = 1; /* To find next startcode */
 282
 283         case STATE_NEXT_SYNC:
 284             /* TODO: If p_block == NULL, flush the buffer without checking the
 285              * next sync word */
 286
 287             /* Find the next startcode */
 288             if( block_FindStartcodeFromOffset( &p_sys->bytestream,
 289                     &p_sys->i_offset, p_sys->p_startcode, 3 ) != VLC_SUCCESS )
 290             {
 291                 /* Need more data */
 292                 return NULL;
 293             }
 294
 295             /* Get the new fragment and set the pts/dts */
 296             p_pic = block_New( p_dec, p_sys->i_offset );
 297             block_BytestreamFlush( &p_sys->bytestream );
 298             p_pic->i_pts = i_pts = p_sys->bytestream.p_block->i_pts;
 299             p_pic->i_dts = i_dts = p_sys->bytestream.p_block->i_dts;
 300             p_pic->i_rate = p_sys->bytestream.p_block->i_rate;
 301
 302             block_GetBytes( &p_sys->bytestream, p_pic->p_buffer,
 303                             p_pic->i_buffer );
 304
 305             p_sys->i_offset = 0;
 306
 307             /* Get picture if any */
 308             if( !( p_pic = ParseMPEGBlock( p_dec, p_pic ) ) )
 309             {
 310                 p_sys->i_state = STATE_NOSYNC;
 311                 break;
 312             }
 313
 314             /* don't reuse the same timestamps several times */
 315             if( i_pts == p_sys->bytestream.p_block->i_pts &&
 316                 i_dts == p_sys->bytestream.p_block->i_dts )
 317             {
 318                 p_sys->bytestream.p_block->i_pts = 0;
 319                 p_sys->bytestream.p_block->i_dts = 0;
 320             }
 321
 322             /* We've just started the stream, wait for the first PTS.
 323              * We discard here so we can still get the sequence header. */
 324             if( p_sys->i_interpolated_pts <= 0 &&
 325                 p_sys->i_interpolated_dts <= 0 )
 326             {
 327                 msg_Dbg( p_dec, "need a starting pts/dts" );
 328                 p_sys->i_state = STATE_NOSYNC;
 329                 block_Release( p_pic );
 330                 break;
 331             }
 332
 333             /* When starting the stream we can have the first frame with
 334              * a null DTS (i_interpolated_pts is initialized to 0) */
 335             if( !p_pic->i_dts ) p_pic->i_dts = p_pic->i_pts;
 336
 337             /* So p_block doesn't get re-added several times */
 338             *pp_block = block_BytestreamPop( &p_sys->bytestream );
 339
 340             p_sys->i_state = STATE_NOSYNC;
 341
 342             return p_pic;
 343         }
 344     }
 345 }
 346
 347 /*****************************************************************************
 348  * ParseMPEGBlock: Re-assemble fragments into a block containing a picture
 349  *****************************************************************************/
 350 static block_t *ParseMPEGBlock( decoder_t *p_dec, block_t *p_frag )
 351 {
 352     decoder_sys_t *p_sys = p_dec->p_sys;
 353     block_t *p_pic = NULL;
 354
 355     if( p_frag->p_buffer[3] == 0xB0 || p_frag->p_buffer[3] == 0xB1 || p_frag->p_buffer[3] == 0xB2 )
 356     {   /* VOS and USERDATA */
 357 #if 0
 358         /* Remove VOS start/end code from the original stream */
 359         block_Release( p_frag );
 360 #else
 361         /* Append the block for now since ts/ps muxers rely on VOL
 362          * being present in the stream */
 363         block_ChainLastAppend( &p_sys->pp_last, p_frag );
 364 #endif
 365         return NULL;
 366     }
 367     if( p_frag->p_buffer[3] >= 0x20 && p_frag->p_buffer[3] <= 0x2f )
 368     {
 369         /* Copy the complete VOL */
 370         if( (size_t)p_dec->fmt_out.i_extra != p_frag->i_buffer )
 371         {
 372             p_dec->fmt_out.p_extra =
 373                 realloc( p_dec->fmt_out.p_extra, p_frag->i_buffer );
 374             p_dec->fmt_out.i_extra = p_frag->i_buffer;
 375         }
 376         memcpy( p_dec->fmt_out.p_extra, p_frag->p_buffer, p_frag->i_buffer );
 377         ParseVOL( p_dec, &p_dec->fmt_out,
 378                   p_dec->fmt_out.p_extra, p_dec->fmt_out.i_extra );
 379
 380 #if 0
 381         /* Remove from the original stream */
 382         block_Release( p_frag );
 383 #else
 384         /* Append the block for now since ts/ps muxers rely on VOL
 385          * being present in the stream */
 386         block_ChainLastAppend( &p_sys->pp_last, p_frag );
 387 #endif
 388         return NULL;
 389     }
 390     else
 391     {
 392         if( !p_dec->fmt_out.i_extra )
 393         {
 394             msg_Warn( p_dec, "waiting for VOL" );
 395             block_Release( p_frag );
 396             return NULL;
 397         }
 398
 399         /* Append the block */
 400         block_ChainLastAppend( &p_sys->pp_last, p_frag );
 401     }
 402
 403     if( p_frag->p_buffer[3] == 0xb6 &&
 404         ParseVOP( p_dec, p_frag ) == VLC_SUCCESS )
 405     {
 406         /* We are dealing with a VOP */
 407         p_pic = block_ChainGather( p_sys->p_frame );
 408         p_pic->i_pts = p_sys->i_interpolated_pts;
 409         p_pic->i_dts = p_sys->i_interpolated_dts;
 410
 411         /* Reset context */
 412         p_sys->p_frame = NULL;
 413         p_sys->pp_last = &p_sys->p_frame;
 414     }
 415
 416     return p_pic;
 417 }
 418
 419 /* ParseVOL:
 420  *  TODO:
 421  *      - support aspect ratio
 422  */
 423 static int ParseVOL( decoder_t *p_dec, es_format_t *fmt,
 424                      uint8_t *p_vol, int i_vol )
 425 {
 426     decoder_sys_t *p_sys = p_dec->p_sys;
 427     int i_vo_type, i_vo_ver_id, i_ar, i_shape;
 428     bs_t s;
 429
 430     for( ;; )
 431     {
 432         if( p_vol[0] == 0x00 && p_vol[1] == 0x00 && p_vol[2] == 0x01 &&
 433             p_vol[3] >= 0x20 && p_vol[3] <= 0x2f ) break;
 434
 435         p_vol++; i_vol--;
 436         if( i_vol <= 4 ) return VLC_EGENERIC;
 437     }
 438
 439     bs_init( &s, &p_vol[4], i_vol - 4 );
 440
 441     bs_skip( &s, 1 );   /* random access */
 442     i_vo_type = bs_read( &s, 8 );
 443     if( bs_read1( &s ) )
 444     {
 445         i_vo_ver_id = bs_read( &s, 4 );
 446         bs_skip( &s, 3 );
 447     }
 448     else
 449     {
 450         i_vo_ver_id = 1;
 451     }
 452     i_ar = bs_read( &s, 4 );
 453     if( i_ar == 0xf )
 454     {
 455         int i_ar_width, i_ar_height;
 456
 457         i_ar_width = bs_read( &s, 8 );
 458         i_ar_height= bs_read( &s, 8 );
 459     }
 460     if( bs_read1( &s ) )
 461     {
 462         int i_chroma_format;
 463         int i_low_delay;
 464
 465         /* vol control parameter */
 466         i_chroma_format = bs_read( &s, 2 );
 467         i_low_delay = bs_read1( &s );
 468
 469         if( bs_read1( &s ) )
 470         {
 471             bs_skip( &s, 16 );
 472             bs_skip( &s, 16 );
 473             bs_skip( &s, 16 );
 474             bs_skip( &s, 3 );
 475             bs_skip( &s, 11 );
 476             bs_skip( &s, 1 );
 477             bs_skip( &s, 16 );
 478         }
 479     }
 480     /* shape 0->RECT, 1->BIN, 2->BIN_ONLY, 3->GRAY */
 481     i_shape = bs_read( &s, 2 );
 482     if( i_shape == 3 && i_vo_ver_id != 1 )
 483     {
 484         bs_skip( &s, 4 );
 485     }
 486
 487     if( !bs_read1( &s ) ) return VLC_EGENERIC; /* Marker */
 488
 489     p_sys->i_fps_num = bs_read( &s, 16 ); /* Time increment resolution*/
 490     if( !p_sys->i_fps_num ) p_sys->i_fps_num = 1;
 491
 492     if( !bs_read1( &s ) ) return VLC_EGENERIC; /* Marker */
 493
 494     if( bs_read1( &s ) )
 495     {
 496         int i_time_increment_bits = vlc_log2( p_sys->i_fps_num - 1 ) + 1;
 497
 498         if( i_time_increment_bits < 1 ) i_time_increment_bits = 1;
 499
 500         p_sys->i_fps_den = bs_read( &s, i_time_increment_bits );
 501     }
 502     if( i_shape == 0 )
 503     {
 504         bs_skip( &s, 1 );
 505         fmt->video.i_width = bs_read( &s, 13 );
 506         bs_skip( &s, 1 );
 507         fmt->video.i_height= bs_read( &s, 13 );
 508         bs_skip( &s, 1 );
 509     }
 510
 511     return VLC_SUCCESS;
 512 }
 513
 514 static int ParseVOP( decoder_t *p_dec, block_t *p_vop )
 515 {
 516     decoder_sys_t *p_sys = p_dec->p_sys;
 517     int64_t i_time_increment, i_time_ref;
 518     int i_modulo_time_base = 0, i_time_increment_bits;
 519     bs_t s;
 520
 521     bs_init( &s, &p_vop->p_buffer[4], p_vop->i_buffer - 4 );
 522
 523     switch( bs_read( &s, 2 ) )
 524     {
 525     case 0:
 526         p_sys->i_flags = BLOCK_FLAG_TYPE_I;
 527         break;
 528     case 1:
 529         p_sys->i_flags = BLOCK_FLAG_TYPE_P;
 530         break;
 531     case 2:
 532         p_sys->i_flags = BLOCK_FLAG_TYPE_B;
 533         p_sys->b_frame = VLC_TRUE;
 534         break;
 535     case 3: /* gni ? */
 536         p_sys->i_flags = BLOCK_FLAG_TYPE_PB;
 537         break;
 538     }
 539
 540     while( bs_read( &s, 1 ) ) i_modulo_time_base++;
 541     if( !bs_read1( &s ) ) return VLC_EGENERIC; /* Marker */
 542
 543     /* VOP time increment */
 544     i_time_increment_bits = vlc_log2(p_dec->p_sys->i_fps_num - 1) + 1;
 545     if( i_time_increment_bits < 1 ) i_time_increment_bits = 1;
 546     i_time_increment = bs_read( &s, i_time_increment_bits );
 547
 548     /* Interpolate PTS/DTS */
 549     if( !(p_sys->i_flags & BLOCK_FLAG_TYPE_B) )
 550     {
 551         p_sys->i_last_time_ref = p_sys->i_time_ref;
 552         p_sys->i_time_ref +=
 553             (i_modulo_time_base * p_dec->p_sys->i_fps_num);
 554         i_time_ref = p_sys->i_time_ref;
 555     }
 556     else
 557     {
 558         i_time_ref = p_sys->i_last_time_ref +
 559             (i_modulo_time_base * p_dec->p_sys->i_fps_num);
 560     }
 561
 562 #if 0
 563     msg_Err( p_dec, "interp pts/dts (%lli,%lli), pts/dts (%lli,%lli)",
 564              p_sys->i_interpolated_pts, p_sys->i_interpolated_dts,
 565              p_vop->i_pts, p_vop->i_dts );
 566 #endif
 567
 568     if( p_dec->p_sys->i_fps_num < 5 && /* Work-around buggy streams */
 569         p_dec->fmt_in.video.i_frame_rate > 0 &&
 570         p_dec->fmt_in.video.i_frame_rate_base > 0 )
 571     {
 572         p_sys->i_interpolated_pts += I64C(1000000) *
 573         p_dec->fmt_in.video.i_frame_rate_base *
 574         p_vop->i_rate / INPUT_RATE_DEFAULT /
 575         p_dec->fmt_in.video.i_frame_rate;
 576     }
 577     else if( p_dec->p_sys->i_fps_num )
 578         p_sys->i_interpolated_pts +=
 579             ( I64C(1000000) * (i_time_ref + i_time_increment -
 580               p_sys->i_last_time - p_sys->i_last_timeincr) *
 581               p_vop->i_rate / INPUT_RATE_DEFAULT /
 582               p_dec->p_sys->i_fps_num );
 583
 584     p_sys->i_last_time = i_time_ref;
 585     p_sys->i_last_timeincr = i_time_increment;
 586
 587     /* Correct interpolated dts when we receive a new pts/dts */
 588     if( p_vop->i_pts > 0 )
 589         p_sys->i_interpolated_pts = p_vop->i_pts;
 590     if( p_vop->i_dts > 0 )
 591         p_sys->i_interpolated_dts = p_vop->i_dts;
 592
 593     if( (p_sys->i_flags & BLOCK_FLAG_TYPE_B) || !p_sys->b_frame )
 594     {
 595         /* Trivial case (DTS == PTS) */
 596
 597         p_sys->i_interpolated_dts = p_sys->i_interpolated_pts;
 598
 599         if( p_vop->i_pts > 0 )
 600             p_sys->i_interpolated_dts = p_vop->i_pts;
 601         if( p_vop->i_dts > 0 )
 602             p_sys->i_interpolated_dts = p_vop->i_dts;
 603
 604         p_sys->i_interpolated_pts = p_sys->i_interpolated_dts;
 605     }
 606     else
 607     {
 608         if( p_sys->i_last_ref_pts > 0 )
 609             p_sys->i_interpolated_dts = p_sys->i_last_ref_pts;
 610
 611         p_sys->i_last_ref_pts = p_sys->i_interpolated_pts;
 612     }
 613
 614     return VLC_SUCCESS;
 615 }
 616
 617 /* look at ffmpeg av_log2 ;) */
 618 static int vlc_log2( unsigned int v )
 619 {
 620     int n = 0;
 621     static const int vlc_log2_table[16] =
 622     {
 623         0,0,1,1,2,2,2,2, 3,3,3,3,3,3,3,3
 624     };
 625
 626     if( v&0xffff0000 )
 627     {
 628         v >>= 16;
 629         n += 16;
 630     }
 631     if( v&0xff00 )
 632     {
 633         v >>= 8;
 634         n += 8;
 635     }
 636     if( v&0xf0 )
 637     {
 638         v >>= 4;
 639         n += 4;
 640     }
 641     n += vlc_log2_table[v];
 642
 643     return n;
 644 }