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