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