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/decoder.h>
  33 #include <vlc/sout.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 )
 227     {
 228         p_sys->i_state = STATE_NOSYNC;
 229         if( p_sys->p_frame ) block_ChainRelease( p_sys->p_frame );
 230         p_sys->p_frame = NULL;
 231         p_sys->pp_last = &p_sys->p_frame;
 232         block_Release( *pp_block );
 233         return NULL;
 234     }
 235
 236     block_BytestreamPush( &p_sys->bytestream, *pp_block );
 237
 238     while( 1 )
 239     {
 240         switch( p_sys->i_state )
 241         {
 242
 243         case STATE_NOSYNC:
 244             if( block_FindStartcodeFromOffset( &p_sys->bytestream,
 245                     &p_sys->i_offset, p_sys->p_startcode, 3 ) == VLC_SUCCESS )
 246             {
 247                 p_sys->i_state = STATE_NEXT_SYNC;
 248             }
 249
 250             if( p_sys->i_offset )
 251             {
 252                 block_SkipBytes( &p_sys->bytestream, p_sys->i_offset );
 253                 p_sys->i_offset = 0;
 254                 block_BytestreamFlush( &p_sys->bytestream );
 255             }
 256
 257             if( p_sys->i_state != STATE_NEXT_SYNC )
 258             {
 259                 /* Need more data */
 260                 return NULL;
 261             }
 262
 263             p_sys->i_offset = 1; /* To find next startcode */
 264
 265         case STATE_NEXT_SYNC:
 266             /* TODO: If p_block == NULL, flush the buffer without checking the
 267              * next sync word */
 268
 269             /* Find the next startcode */
 270             if( block_FindStartcodeFromOffset( &p_sys->bytestream,
 271                     &p_sys->i_offset, p_sys->p_startcode, 3 ) != VLC_SUCCESS )
 272             {
 273                 /* Need more data */
 274                 return NULL;
 275             }
 276
 277             /* Get the new fragment and set the pts/dts */
 278             p_pic = block_New( p_dec, p_sys->i_offset );
 279             block_BytestreamFlush( &p_sys->bytestream );
 280             p_pic->i_pts = i_pts = p_sys->bytestream.p_block->i_pts;
 281             p_pic->i_dts = i_dts = p_sys->bytestream.p_block->i_dts;
 282             p_pic->i_rate = p_sys->bytestream.p_block->i_rate;
 283
 284             block_GetBytes( &p_sys->bytestream, p_pic->p_buffer,
 285                             p_pic->i_buffer );
 286
 287             p_sys->i_offset = 0;
 288
 289             /* Get picture if any */
 290             if( !( p_pic = ParseMPEGBlock( p_dec, p_pic ) ) )
 291             {
 292                 p_sys->i_state = STATE_NOSYNC;
 293                 break;
 294             }
 295
 296             /* don't reuse the same timestamps several times */
 297             if( i_pts == p_sys->bytestream.p_block->i_pts &&
 298                 i_dts == p_sys->bytestream.p_block->i_dts )
 299             {
 300                 p_sys->bytestream.p_block->i_pts = 0;
 301                 p_sys->bytestream.p_block->i_dts = 0;
 302             }
 303
 304             /* We've just started the stream, wait for the first PTS.
 305              * We discard here so we can still get the sequence header. */
 306             if( p_sys->i_interpolated_pts <= 0 &&
 307                 p_sys->i_interpolated_dts <= 0 )
 308             {
 309                 msg_Dbg( p_dec, "need a starting pts/dts" );
 310                 p_sys->i_state = STATE_NOSYNC;
 311                 block_Release( p_pic );
 312                 break;
 313             }
 314
 315             /* When starting the stream we can have the first frame with
 316              * a null DTS (i_interpolated_pts is initialized to 0) */
 317             if( !p_pic->i_dts ) p_pic->i_dts = p_pic->i_pts;
 318
 319             /* So p_block doesn't get re-added several times */
 320             *pp_block = block_BytestreamPop( &p_sys->bytestream );
 321
 322             p_sys->i_state = STATE_NOSYNC;
 323
 324             return p_pic;
 325         }
 326     }
 327 }
 328
 329 /*****************************************************************************
 330  * ParseMPEGBlock: Re-assemble fragments into a block containing a picture
 331  *****************************************************************************/
 332 static block_t *ParseMPEGBlock( decoder_t *p_dec, block_t *p_frag )
 333 {
 334     decoder_sys_t *p_sys = p_dec->p_sys;
 335     block_t *p_pic = NULL;
 336
 337     if( p_frag->p_buffer[3] == 0xB0 || p_frag->p_buffer[3] == 0xB1 )
 338     {
 339 #if 0
 340         /* Remove VOS start/end code from the original stream */
 341         block_Release( p_frag );
 342 #else
 343         /* Append the block for now since ts/ps muxers rely on VOL
 344          * being present in the stream */
 345         block_ChainLastAppend( &p_sys->pp_last, p_frag );
 346 #endif
 347         return NULL;
 348     }
 349     if( p_frag->p_buffer[3] >= 0x20 && p_frag->p_buffer[3] <= 0x2f )
 350     {
 351         /* Copy the complete VOL */
 352         if( p_dec->fmt_out.i_extra != p_frag->i_buffer )
 353         {
 354             p_dec->fmt_out.p_extra =
 355                 realloc( p_dec->fmt_out.p_extra, p_frag->i_buffer );
 356             p_dec->fmt_out.i_extra = p_frag->i_buffer;
 357         }
 358         memcpy( p_dec->fmt_out.p_extra, p_frag->p_buffer, p_frag->i_buffer );
 359         ParseVOL( p_dec, &p_dec->fmt_out,
 360                   p_dec->fmt_out.p_extra, p_dec->fmt_out.i_extra );
 361
 362 #if 0
 363         /* Remove from the original stream */
 364         block_Release( p_frag );
 365 #else
 366         /* Append the block for now since ts/ps muxers rely on VOL
 367          * being present in the stream */
 368         block_ChainLastAppend( &p_sys->pp_last, p_frag );
 369 #endif
 370         return NULL;
 371     }
 372     else
 373     {
 374         if( !p_dec->fmt_out.i_extra )
 375         {
 376             msg_Warn( p_dec, "waiting for VOL" );
 377             block_Release( p_frag );
 378             return NULL;
 379         }
 380
 381         /* Append the block */
 382         block_ChainLastAppend( &p_sys->pp_last, p_frag );
 383     }
 384
 385     if( p_frag->p_buffer[3] == 0xb6 &&
 386         ParseVOP( p_dec, p_frag ) == VLC_SUCCESS )
 387     {
 388         /* We are dealing with a VOP */
 389         p_pic = block_ChainGather( p_sys->p_frame );
 390         p_pic->i_pts = p_sys->i_interpolated_pts;
 391         p_pic->i_dts = p_sys->i_interpolated_dts;
 392
 393         /* Reset context */
 394         p_sys->p_frame = NULL;
 395         p_sys->pp_last = &p_sys->p_frame;
 396     }
 397
 398     return p_pic;
 399 }
 400
 401 /* ParseVOL:
 402  *  TODO:
 403  *      - support aspect ratio
 404  */
 405 static int ParseVOL( decoder_t *p_dec, es_format_t *fmt,
 406                      uint8_t *p_vol, int i_vol )
 407 {
 408     decoder_sys_t *p_sys = p_dec->p_sys;
 409     int i_vo_type, i_vo_ver_id, i_ar, i_shape;
 410     bs_t s;
 411
 412     for( ;; )
 413     {
 414         if( p_vol[0] == 0x00 && p_vol[1] == 0x00 && p_vol[2] == 0x01 &&
 415             p_vol[3] >= 0x20 && p_vol[3] <= 0x2f ) break;
 416
 417         p_vol++; i_vol--;
 418         if( i_vol <= 4 ) return VLC_EGENERIC;
 419     }
 420
 421     bs_init( &s, &p_vol[4], i_vol - 4 );
 422
 423     bs_skip( &s, 1 );   /* random access */
 424     i_vo_type = bs_read( &s, 8 );
 425     if( bs_read1( &s ) )
 426     {
 427         i_vo_ver_id = bs_read( &s, 4 );
 428         bs_skip( &s, 3 );
 429     }
 430     else
 431     {
 432         i_vo_ver_id = 1;
 433     }
 434     i_ar = bs_read( &s, 4 );
 435     if( i_ar == 0xf )
 436     {
 437         int i_ar_width, i_ar_height;
 438
 439         i_ar_width = bs_read( &s, 8 );
 440         i_ar_height= bs_read( &s, 8 );
 441     }
 442     if( bs_read1( &s ) )
 443     {
 444         int i_chroma_format;
 445         int i_low_delay;
 446
 447         /* vol control parameter */
 448         i_chroma_format = bs_read( &s, 2 );
 449         i_low_delay = bs_read1( &s );
 450
 451         if( bs_read1( &s ) )
 452         {
 453             bs_skip( &s, 16 );
 454             bs_skip( &s, 16 );
 455             bs_skip( &s, 16 );
 456             bs_skip( &s, 3 );
 457             bs_skip( &s, 11 );
 458             bs_skip( &s, 1 );
 459             bs_skip( &s, 16 );
 460         }
 461     }
 462     /* shape 0->RECT, 1->BIN, 2->BIN_ONLY, 3->GRAY */
 463     i_shape = bs_read( &s, 2 );
 464     if( i_shape == 3 && i_vo_ver_id != 1 )
 465     {
 466         bs_skip( &s, 4 );
 467     }
 468
 469     if( !bs_read1( &s ) ) return VLC_EGENERIC; /* Marker */
 470
 471     p_sys->i_fps_num = bs_read( &s, 16 ); /* Time increment resolution*/
 472     if( !p_sys->i_fps_num ) p_sys->i_fps_num = 1;
 473
 474     if( !bs_read1( &s ) ) return VLC_EGENERIC; /* Marker */
 475
 476     if( bs_read1( &s ) )
 477     {
 478         int i_time_increment_bits = vlc_log2( p_sys->i_fps_num - 1 ) + 1;
 479
 480         if( i_time_increment_bits < 1 ) i_time_increment_bits = 1;
 481
 482         p_sys->i_fps_den = bs_read( &s, i_time_increment_bits );
 483     }
 484     if( i_shape == 0 )
 485     {
 486         bs_skip( &s, 1 );
 487         fmt->video.i_width = bs_read( &s, 13 );
 488         bs_skip( &s, 1 );
 489         fmt->video.i_height= bs_read( &s, 13 );
 490         bs_skip( &s, 1 );
 491     }
 492
 493     return VLC_SUCCESS;
 494 }
 495
 496 static int ParseVOP( decoder_t *p_dec, block_t *p_vop )
 497 {
 498     decoder_sys_t *p_sys = p_dec->p_sys;
 499     int64_t i_time_increment, i_time_ref;
 500     int i_modulo_time_base = 0, i_time_increment_bits;
 501     bs_t s;
 502
 503     bs_init( &s, &p_vop->p_buffer[4], p_vop->i_buffer - 4 );
 504
 505     switch( bs_read( &s, 2 ) )
 506     {
 507     case 0:
 508         p_sys->i_flags = BLOCK_FLAG_TYPE_I;
 509         break;
 510     case 1:
 511         p_sys->i_flags = BLOCK_FLAG_TYPE_P;
 512         break;
 513     case 2:
 514         p_sys->i_flags = BLOCK_FLAG_TYPE_B;
 515         p_sys->b_frame = VLC_TRUE;
 516         break;
 517     case 3: /* gni ? */
 518         p_sys->i_flags = BLOCK_FLAG_TYPE_PB;
 519         break;
 520     }
 521
 522     while( bs_read( &s, 1 ) ) i_modulo_time_base++;
 523     if( !bs_read1( &s ) ) return VLC_EGENERIC; /* Marker */
 524
 525     /* VOP time increment */
 526     i_time_increment_bits = vlc_log2(p_dec->p_sys->i_fps_num - 1) + 1;
 527     if( i_time_increment_bits < 1 ) i_time_increment_bits = 1;
 528     i_time_increment = bs_read( &s, i_time_increment_bits );
 529
 530     /* Interpolate PTS/DTS */
 531     if( !(p_sys->i_flags & BLOCK_FLAG_TYPE_B) )
 532     {
 533         p_sys->i_last_time_ref = p_sys->i_time_ref;
 534         p_sys->i_time_ref +=
 535             (i_modulo_time_base * p_dec->p_sys->i_fps_num);
 536         i_time_ref = p_sys->i_time_ref;
 537     }
 538     else
 539     {
 540         i_time_ref = p_sys->i_last_time_ref +
 541             (i_modulo_time_base * p_dec->p_sys->i_fps_num);
 542     }
 543
 544 #if 0
 545     msg_Err( p_dec, "interp pts/dts (%lli,%lli), pts/dts (%lli,%lli)",
 546              p_sys->i_interpolated_pts, p_sys->i_interpolated_dts,
 547              p_vop->i_pts, p_vop->i_dts );
 548 #endif
 549
 550     if( p_dec->p_sys->i_fps_num < 5 && /* Work-around buggy streams */
 551         p_dec->fmt_in.video.i_frame_rate > 0 &&
 552         p_dec->fmt_in.video.i_frame_rate_base > 0 )
 553     {
 554         p_sys->i_interpolated_pts += I64C(1000000) *
 555         p_dec->fmt_in.video.i_frame_rate_base *
 556         p_vop->i_rate / INPUT_RATE_DEFAULT /
 557         p_dec->fmt_in.video.i_frame_rate;
 558     }
 559     else if( p_dec->p_sys->i_fps_num )
 560         p_sys->i_interpolated_pts +=
 561             ( I64C(1000000) * (i_time_ref + i_time_increment -
 562               p_sys->i_last_time - p_sys->i_last_timeincr) *
 563               p_vop->i_rate / INPUT_RATE_DEFAULT /
 564               p_dec->p_sys->i_fps_num );
 565
 566     p_sys->i_last_time = i_time_ref;
 567     p_sys->i_last_timeincr = i_time_increment;
 568
 569     /* Correct interpolated dts when we receive a new pts/dts */
 570     if( p_vop->i_pts > 0 )
 571         p_sys->i_interpolated_pts = p_vop->i_pts;
 572     if( p_vop->i_dts > 0 )
 573         p_sys->i_interpolated_dts = p_vop->i_dts;
 574
 575     if( (p_sys->i_flags & BLOCK_FLAG_TYPE_B) || !p_sys->b_frame )
 576     {
 577         /* Trivial case (DTS == PTS) */
 578
 579         p_sys->i_interpolated_dts = p_sys->i_interpolated_pts;
 580
 581         if( p_vop->i_pts > 0 )
 582             p_sys->i_interpolated_dts = p_vop->i_pts;
 583         if( p_vop->i_dts > 0 )
 584             p_sys->i_interpolated_dts = p_vop->i_dts;
 585
 586         p_sys->i_interpolated_pts = p_sys->i_interpolated_dts;
 587     }
 588     else
 589     {
 590         if( p_sys->i_last_ref_pts > 0 )
 591             p_sys->i_interpolated_dts = p_sys->i_last_ref_pts;
 592
 593         p_sys->i_last_ref_pts = p_sys->i_interpolated_pts;
 594     }
 595
 596     return VLC_SUCCESS;
 597 }
 598
 599 /* look at ffmpeg av_log2 ;) */
 600 static int vlc_log2( unsigned int v )
 601 {
 602     int n = 0;
 603     static const int vlc_log2_table[16] =
 604     {
 605         0,0,1,1,2,2,2,2, 3,3,3,3,3,3,3,3
 606     };
 607
 608     if( v&0xffff0000 )
 609     {
 610         v >>= 16;
 611         n += 16;
 612     }
 613     if( v&0xff00 )
 614     {
 615         v >>= 8;
 616         n += 8;
 617     }
 618     if( v&0xf0 )
 619     {
 620         v >>= 4;
 621         n += 4;
 622     }
 623     n += vlc_log2_table[v];
 624
 625     return n;
 626 }