modules/packetizer/mpeg4video.c

   1 /*****************************************************************************
   2  * mpeg4video.c: mpeg 4 video packetizer
   3  *****************************************************************************
   4  * Copyright (C) 2001-2006 VLC authors and VideoLAN
   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 it
  12  * under the terms of the GNU Lesser General Public License as published by
  13  * the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU Lesser General Public License
  22  * along with this program; if not, write to the Free Software Foundation,
  23  * 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_common.h>
  35 #include <vlc_plugin.h>
  36 #include <vlc_sout.h>
  37 #include <vlc_codec.h>
  38 #include <vlc_block.h>
  39
  40 #include <vlc_bits.h>
  41 #include <vlc_block_helper.h>
  42 #include "packetizer_helper.h"
  43 #include "startcode_helper.h"
  44 #include "iso_color_tables.h"
  45
  46 /*****************************************************************************
  47  * Module descriptor
  48  *****************************************************************************/
  49 static int  Open ( vlc_object_t * );
  50 static void Close( vlc_object_t * );
  51
  52 vlc_module_begin ()
  53     set_category( CAT_SOUT )
  54     set_subcategory( SUBCAT_SOUT_PACKETIZER )
  55     set_description( N_("MPEG4 video packetizer") )
  56     set_capability( "packetizer", 50 )
  57     set_callbacks( Open, Close )
  58 vlc_module_end ()
  59
  60 /****************************************************************************
  61  * Local prototypes
  62  ****************************************************************************/
  63 typedef struct
  64 {
  65     /*
  66      * Input properties
  67      */
  68     packetizer_t packetizer;
  69
  70     /*
  71      * Common properties
  72      */
  73     vlc_tick_t i_interpolated_pts;
  74     vlc_tick_t i_interpolated_dts;
  75     vlc_tick_t i_last_ref_pts;
  76     int64_t i_last_time_ref;
  77     int64_t i_time_ref;
  78     int64_t i_last_time;
  79     int64_t i_last_timeincr;
  80
  81     unsigned int i_flags;
  82
  83     int         i_fps_num;
  84     int         i_fps_den;
  85
  86     bool  b_frame;
  87
  88     /* Current frame being built */
  89     block_t    *p_frame;
  90     block_t    **pp_last;
  91 } decoder_sys_t;
  92
  93 static block_t *Packetize( decoder_t *, block_t ** );
  94 static void PacketizeFlush( decoder_t * );
  95
  96 static void PacketizeReset( void *p_private, bool b_broken );
  97 static block_t *PacketizeParse( void *p_private, bool *pb_ts_used, block_t * );
  98 static int PacketizeValidate( void *p_private, block_t * );
  99
 100 static block_t *ParseMPEGBlock( decoder_t *, block_t * );
 101 static int ParseVOL( decoder_t *, es_format_t *, uint8_t *, int );
 102 static int ParseVO( decoder_t *, block_t * );
 103 static int ParseVOP( decoder_t *, block_t * );
 104 static int vlc_log2( unsigned int );
 105
 106 #define VIDEO_OBJECT_MASK                       0x01f
 107 #define VIDEO_OBJECT_LAYER_MASK                 0x00f
 108
 109 #define VIDEO_OBJECT_START_CODE                 0x100
 110 #define VIDEO_OBJECT_LAYER_START_CODE           0x120
 111 #define RESERVED_START_CODE                     0x130
 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 static const uint8_t p_mp4v_startcode[3] = { 0x00, 0x00, 0x01 };
 128
 129 /*****************************************************************************
 130  * Open: probe the packetizer and return score
 131  *****************************************************************************/
 132 static int Open( vlc_object_t *p_this )
 133 {
 134     decoder_t     *p_dec = (decoder_t*)p_this;
 135     decoder_sys_t *p_sys;
 136
 137     if( p_dec->fmt_in.i_codec != VLC_CODEC_MP4V )
 138         return VLC_EGENERIC;
 139
 140     /* Allocate the memory needed to store the decoder's structure */
 141     if( ( p_dec->p_sys = p_sys = malloc( sizeof(decoder_sys_t) ) ) == NULL )
 142         return VLC_ENOMEM;
 143     memset( p_sys, 0, sizeof(decoder_sys_t) );
 144
 145     /* Misc init */
 146     packetizer_Init( &p_sys->packetizer,
 147                      p_mp4v_startcode, sizeof(p_mp4v_startcode), startcode_FindAnnexB,
 148                      NULL, 0, 4,
 149                      PacketizeReset, PacketizeParse, PacketizeValidate, p_dec );
 150
 151     p_sys->p_frame = NULL;
 152     p_sys->pp_last = &p_sys->p_frame;
 153
 154     /* Setup properties */
 155     es_format_Copy( &p_dec->fmt_out, &p_dec->fmt_in );
 156     p_dec->fmt_out.i_codec = VLC_CODEC_MP4V;
 157
 158     if( p_dec->fmt_out.i_extra )
 159     {
 160         /* We have a vol */
 161         msg_Dbg( p_dec, "opening with vol size: %d", p_dec->fmt_out.i_extra );
 162         ParseVOL( p_dec, &p_dec->fmt_out,
 163                   p_dec->fmt_out.p_extra, p_dec->fmt_out.i_extra );
 164     }
 165
 166     /* Set callback */
 167     p_dec->pf_packetize = Packetize;
 168     p_dec->pf_flush = PacketizeFlush;
 169     p_dec->pf_get_cc = NULL;
 170
 171     return VLC_SUCCESS;
 172 }
 173
 174 /*****************************************************************************
 175  * Close: clean up the packetizer
 176  *****************************************************************************/
 177 static void Close( vlc_object_t *p_this )
 178 {
 179     decoder_t *p_dec = (decoder_t*)p_this;
 180     decoder_sys_t *p_sys = p_dec->p_sys;
 181
 182     packetizer_Clean( &p_sys->packetizer );
 183     if( p_sys->p_frame )
 184         block_ChainRelease( p_sys->p_frame );
 185     free( p_sys );
 186 }
 187
 188 /****************************************************************************
 189  * Packetize: the whole thing
 190  ****************************************************************************/
 191 static block_t *Packetize( decoder_t *p_dec, block_t **pp_block )
 192 {
 193     decoder_sys_t *p_sys = p_dec->p_sys;
 194
 195     return packetizer_Packetize( &p_sys->packetizer, pp_block );
 196 }
 197
 198 static void PacketizeFlush( decoder_t *p_dec )
 199 {
 200     decoder_sys_t *p_sys = p_dec->p_sys;
 201
 202     packetizer_Flush( &p_sys->packetizer );
 203 }
 204
 205 /*****************************************************************************
 206  * Helpers:
 207  *****************************************************************************/
 208 static void PacketizeReset( void *p_private, bool b_broken )
 209 {
 210     decoder_t *p_dec = p_private;
 211     decoder_sys_t *p_sys = p_dec->p_sys;
 212
 213     if( b_broken )
 214     {
 215         if( p_sys->p_frame )
 216             block_ChainRelease( p_sys->p_frame );
 217         p_sys->p_frame = NULL;
 218         p_sys->pp_last = &p_sys->p_frame;
 219     }
 220
 221     p_sys->i_interpolated_pts =
 222     p_sys->i_interpolated_dts =
 223     p_sys->i_last_ref_pts = VLC_TICK_INVALID;
 224
 225     p_sys->i_last_time_ref =
 226     p_sys->i_time_ref =
 227     p_sys->i_last_time =
 228     p_sys->i_last_timeincr = 0;
 229 }
 230
 231 static block_t *PacketizeParse( void *p_private, bool *pb_ts_used, block_t *p_block )
 232 {
 233     decoder_t *p_dec = p_private;
 234     const vlc_tick_t i_dts = p_block->i_dts;
 235     const vlc_tick_t i_pts = p_block->i_pts;
 236
 237     block_t *p_au = ParseMPEGBlock( p_dec, p_block );
 238
 239     *pb_ts_used = p_au &&  p_au->i_dts == i_dts && p_au->i_pts == i_pts;
 240
 241     return p_au;
 242 }
 243
 244
 245 static int PacketizeValidate( void *p_private, block_t *p_au )
 246 {
 247     decoder_t *p_dec = p_private;
 248     decoder_sys_t *p_sys = p_dec->p_sys;
 249
 250     /* We've just started the stream, wait for the first PTS.
 251      * We discard here so we can still get the sequence header. */
 252     if( p_sys->i_interpolated_pts == VLC_TICK_INVALID &&
 253         p_sys->i_interpolated_dts == VLC_TICK_INVALID )
 254     {
 255         msg_Dbg( p_dec, "need a starting pts/dts" );
 256         return VLC_EGENERIC;
 257     }
 258
 259     /* When starting the stream we can have the first frame with
 260      * a null DTS (i_interpolated_pts is initialized to 0) */
 261     if( p_au->i_dts == VLC_TICK_INVALID )
 262         p_au->i_dts = p_au->i_pts;
 263     return VLC_SUCCESS;
 264 }
 265
 266 /*****************************************************************************
 267  * ParseMPEGBlock: Re-assemble fragments into a block containing a picture
 268  *****************************************************************************/
 269 static block_t *ParseMPEGBlock( decoder_t *p_dec, block_t *p_frag )
 270 {
 271     decoder_sys_t *p_sys = p_dec->p_sys;
 272     block_t *p_pic = NULL;
 273
 274     if( p_frag->i_buffer < 4 )
 275         return p_frag;
 276
 277     const uint32_t i_startcode = GetDWBE( p_frag->p_buffer );
 278     if( i_startcode == VISUAL_OBJECT_SEQUENCE_START_CODE ||
 279         i_startcode == VISUAL_OBJECT_SEQUENCE_END_CODE ||
 280         i_startcode == USER_DATA_START_CODE )
 281     {   /* VOS and USERDATA */
 282 #if 0
 283         /* Remove VOS start/end code from the original stream */
 284         block_Release( p_frag );
 285 #else
 286         /* Append the block for now since ts/ps muxers rely on VOL
 287          * being present in the stream */
 288         block_ChainLastAppend( &p_sys->pp_last, p_frag );
 289 #endif
 290         return NULL;
 291     }
 292     else if( i_startcode >= VIDEO_OBJECT_LAYER_START_CODE &&
 293              i_startcode < RESERVED_START_CODE )
 294     {
 295         /* Copy the complete VOL */
 296         if( (size_t)p_dec->fmt_out.i_extra != p_frag->i_buffer )
 297         {
 298             p_dec->fmt_out.p_extra =
 299                 xrealloc( p_dec->fmt_out.p_extra, p_frag->i_buffer );
 300             p_dec->fmt_out.i_extra = p_frag->i_buffer;
 301         }
 302         memcpy( p_dec->fmt_out.p_extra, p_frag->p_buffer, p_frag->i_buffer );
 303         ParseVOL( p_dec, &p_dec->fmt_out,
 304                   p_dec->fmt_out.p_extra, p_dec->fmt_out.i_extra );
 305
 306 #if 0
 307         /* Remove from the original stream */
 308         block_Release( p_frag );
 309 #else
 310         /* Append the block for now since ts/ps muxers rely on VOL
 311          * being present in the stream */
 312         block_ChainLastAppend( &p_sys->pp_last, p_frag );
 313 #endif
 314         return NULL;
 315     }
 316     else
 317     {
 318         if( !p_dec->fmt_out.i_extra )
 319         {
 320             msg_Warn( p_dec, "waiting for VOL" );
 321             block_Release( p_frag );
 322             return NULL;
 323         }
 324
 325         /* Append the block */
 326         block_ChainLastAppend( &p_sys->pp_last, p_frag );
 327     }
 328
 329     if( i_startcode == VISUAL_OBJECT_START_CODE )
 330     {
 331         ParseVO( p_dec, p_frag );
 332     }
 333     else
 334     if( i_startcode == VOP_START_CODE &&
 335         ParseVOP( p_dec, p_frag ) == VLC_SUCCESS )
 336     {
 337         /* We are dealing with a VOP */
 338         p_pic = block_ChainGather( p_sys->p_frame );
 339         p_pic->i_flags = p_sys->i_flags;
 340         p_pic->i_pts = p_sys->i_interpolated_pts;
 341         p_pic->i_dts = p_sys->i_interpolated_dts;
 342
 343 #if 0
 344     msg_Err( p_dec, "output dts/pts (%"PRId64",%"PRId64")", p_pic->i_dts, p_pic->i_pts );
 345 #endif
 346         /* Reset context */
 347         p_sys->p_frame = NULL;
 348         p_sys->pp_last = &p_sys->p_frame;
 349     }
 350
 351     return p_pic;
 352 }
 353
 354 /* ParseVOL:
 355  *  TODO:
 356  *      - support aspect ratio
 357  */
 358 static int ParseVOL( decoder_t *p_dec, es_format_t *fmt,
 359                      uint8_t *p_vol, int i_vol )
 360 {
 361     decoder_sys_t *p_sys = p_dec->p_sys;
 362     int i_vo_ver_id, i_ar, i_shape;
 363     bs_t s;
 364
 365     for( ;; )
 366     {
 367         if( i_vol <= 5 )
 368             return VLC_EGENERIC;
 369
 370         if( p_vol[0] == 0x00 && p_vol[1] == 0x00 && p_vol[2] == 0x01 &&
 371             p_vol[3] >= 0x20 && p_vol[3] <= 0x2f ) break;
 372
 373         p_vol++; i_vol--;
 374     }
 375
 376     bs_init( &s, &p_vol[4], i_vol - 4 );
 377
 378     bs_skip( &s, 1 );   /* random access */
 379     bs_skip( &s, 8 );   /* vo_type */
 380     if( bs_read1( &s ) )
 381     {
 382         i_vo_ver_id = bs_read( &s, 4 );
 383         bs_skip( &s, 3 );
 384     }
 385     else
 386     {
 387         i_vo_ver_id = 1;
 388     }
 389     i_ar = bs_read( &s, 4 );
 390     if( i_ar == 0xf )
 391     {
 392         bs_skip( &s, 8 );  /* ar_width */
 393         bs_skip( &s, 8 );  /* ar_height */
 394     }
 395     if( bs_read1( &s ) )
 396     {
 397         /* vol control parameter */
 398         bs_skip( &s, 2 ); /* chroma_format */
 399         bs_read1( &s ); /* low_delay */
 400
 401         if( bs_read1( &s ) )
 402         {
 403             bs_skip( &s, 16 );
 404             bs_skip( &s, 16 );
 405             bs_skip( &s, 16 );
 406             bs_skip( &s, 3 );
 407             bs_skip( &s, 11 );
 408             bs_skip( &s, 1 );
 409             bs_skip( &s, 16 );
 410         }
 411     }
 412     /* shape 0->RECT, 1->BIN, 2->BIN_ONLY, 3->GRAY */
 413     i_shape = bs_read( &s, 2 );
 414     if( i_shape == 3 && i_vo_ver_id != 1 )
 415     {
 416         bs_skip( &s, 4 );
 417     }
 418
 419     if( !bs_read1( &s ) ) return VLC_EGENERIC; /* Marker */
 420
 421     p_sys->i_fps_num = bs_read( &s, 16 ); /* Time increment resolution*/
 422     if( !p_sys->i_fps_num ) p_sys->i_fps_num = 1;
 423
 424     if( !bs_read1( &s ) ) return VLC_EGENERIC; /* Marker */
 425
 426     if( bs_read1( &s ) )
 427     {
 428         int i_time_increment_bits = vlc_log2( p_sys->i_fps_num - 1 ) + 1;
 429
 430         if( i_time_increment_bits < 1 ) i_time_increment_bits = 1;
 431
 432         p_sys->i_fps_den = bs_read( &s, i_time_increment_bits );
 433     }
 434     if( i_shape == 0 )
 435     {
 436         bs_skip( &s, 1 );
 437         fmt->video.i_width = bs_read( &s, 13 );
 438         bs_skip( &s, 1 );
 439         fmt->video.i_height= bs_read( &s, 13 );
 440         bs_skip( &s, 1 );
 441     }
 442
 443     return VLC_SUCCESS;
 444 }
 445
 446 static int ParseVO( decoder_t *p_dec, block_t *p_vo )
 447 {
 448     bs_t s;
 449     bs_init( &s, &p_vo->p_buffer[4], p_vo->i_buffer - 4 );
 450     if( bs_read1( &s ) )
 451         bs_skip( &s, 7 );
 452
 453     const uint8_t visual_object_type = bs_read( &s, 4 );
 454     if( visual_object_type == 1 /* video ID */ ||
 455         visual_object_type == 2 /* still texture ID */ )
 456     {
 457         uint8_t colour_primaries = 1;
 458         uint8_t colour_xfer = 1;
 459         uint8_t colour_matrix_coeff = 1;
 460         uint8_t full_range = 0;
 461         if( bs_read1( &s ) ) /* video_signal_type */
 462         {
 463             bs_read( &s, 3 );
 464             full_range = bs_read( &s, 1 );
 465             if( bs_read( &s, 1 ) ) /* colour description */
 466             {
 467                 colour_primaries = bs_read( &s, 8 );
 468                 colour_xfer = bs_read( &s, 8 );
 469                 colour_matrix_coeff = bs_read( &s, 8 );
 470             }
 471         }
 472
 473         if( p_dec->fmt_in.video.primaries == COLOR_PRIMARIES_UNDEF )
 474         {
 475             p_dec->fmt_out.video.primaries = iso_23001_8_cp_to_vlc_primaries( colour_primaries );
 476             p_dec->fmt_out.video.transfer = iso_23001_8_tc_to_vlc_xfer( colour_xfer );
 477             p_dec->fmt_out.video.space = iso_23001_8_mc_to_vlc_coeffs( colour_matrix_coeff );
 478             p_dec->fmt_out.video.color_range = full_range ? COLOR_RANGE_FULL : COLOR_RANGE_LIMITED;
 479         }
 480     }
 481
 482     return VLC_SUCCESS;
 483 }
 484
 485 static int ParseVOP( decoder_t *p_dec, block_t *p_vop )
 486 {
 487     decoder_sys_t *p_sys = p_dec->p_sys;
 488     int64_t i_time_increment, i_time_ref;
 489     int i_modulo_time_base = 0, i_time_increment_bits;
 490     bs_t s;
 491
 492     bs_init( &s, &p_vop->p_buffer[4], p_vop->i_buffer - 4 );
 493
 494     switch( bs_read( &s, 2 ) )
 495     {
 496     case 0:
 497         p_sys->i_flags = BLOCK_FLAG_TYPE_I;
 498         break;
 499     case 1:
 500         p_sys->i_flags = BLOCK_FLAG_TYPE_P;
 501         break;
 502     case 2:
 503         p_sys->i_flags = BLOCK_FLAG_TYPE_B;
 504         p_sys->b_frame = true;
 505         break;
 506     case 3: /* gni ? */
 507         p_sys->i_flags = BLOCK_FLAG_TYPE_PB;
 508         break;
 509     }
 510
 511     while( bs_read( &s, 1 ) ) i_modulo_time_base++;
 512     if( !bs_read1( &s ) ) return VLC_EGENERIC; /* Marker */
 513
 514     /* VOP time increment */
 515     i_time_increment_bits = vlc_log2(p_sys->i_fps_num - 1) + 1;
 516     if( i_time_increment_bits < 1 ) i_time_increment_bits = 1;
 517     i_time_increment = bs_read( &s, i_time_increment_bits );
 518
 519     /* Interpolate PTS/DTS */
 520     if( !(p_sys->i_flags & BLOCK_FLAG_TYPE_B) )
 521     {
 522         p_sys->i_last_time_ref = p_sys->i_time_ref;
 523         p_sys->i_time_ref +=
 524             (i_modulo_time_base * p_sys->i_fps_num);
 525         i_time_ref = p_sys->i_time_ref;
 526     }
 527     else
 528     {
 529         i_time_ref = p_sys->i_last_time_ref +
 530             (i_modulo_time_base * p_sys->i_fps_num);
 531     }
 532
 533     int64_t i_time_diff = (i_time_ref + i_time_increment) - (p_sys->i_last_time + p_sys->i_last_timeincr);
 534     if( p_sys->i_fps_num && i_modulo_time_base == 0 && i_time_diff < 0 && -i_time_diff > p_sys->i_fps_num )
 535     {
 536         msg_Warn(p_dec, "missing modulo_time_base update");
 537         i_modulo_time_base += -i_time_diff / p_sys->i_fps_num;
 538         p_sys->i_time_ref += (i_modulo_time_base * p_sys->i_fps_num);
 539         p_sys->i_time_ref += p_sys->i_last_timeincr % p_sys->i_fps_num;
 540         i_time_ref = p_sys->i_time_ref;
 541     }
 542
 543     if( p_sys->i_fps_num < 5 && /* Work-around buggy streams */
 544         p_dec->fmt_in.video.i_frame_rate > 0 &&
 545         p_dec->fmt_in.video.i_frame_rate_base > 0 )
 546     {
 547         p_sys->i_interpolated_pts += vlc_tick_from_samples(
 548         p_dec->fmt_in.video.i_frame_rate_base,
 549         p_dec->fmt_in.video.i_frame_rate);
 550     }
 551     else if( p_sys->i_fps_num )
 552     {
 553         i_time_diff = (i_time_ref + i_time_increment) - (p_sys->i_last_time + p_sys->i_last_timeincr);
 554         p_sys->i_interpolated_pts += vlc_tick_from_samples( i_time_diff, p_sys->i_fps_num );
 555     }
 556
 557 #if 0
 558     msg_Err( p_dec, "interp dts/pts (%"PRId64",%"PRId64"), dts/pts (%"PRId64",%"PRId64") %"PRId64" mod %d inc %"PRId64,
 559              p_sys->i_interpolated_dts, p_sys->i_interpolated_pts,
 560              p_vop->i_dts, p_vop->i_pts, p_sys->i_time_ref, i_modulo_time_base, i_time_increment );
 561 #endif
 562
 563     p_sys->i_last_time = i_time_ref;
 564     p_sys->i_last_timeincr = i_time_increment;
 565
 566     /* Correct interpolated dts when we receive a new pts/dts */
 567     if( p_vop->i_pts != VLC_TICK_INVALID )
 568         p_sys->i_interpolated_pts = p_vop->i_pts;
 569     if( p_vop->i_dts != VLC_TICK_INVALID )
 570         p_sys->i_interpolated_dts = p_vop->i_dts;
 571
 572     if( (p_sys->i_flags & BLOCK_FLAG_TYPE_B) || !p_sys->b_frame )
 573     {
 574         /* Trivial case (DTS == PTS) */
 575
 576         p_sys->i_interpolated_dts = p_sys->i_interpolated_pts;
 577
 578         if( p_vop->i_pts != VLC_TICK_INVALID )
 579             p_sys->i_interpolated_dts = p_vop->i_pts;
 580         if( p_vop->i_dts != VLC_TICK_INVALID )
 581             p_sys->i_interpolated_dts = p_vop->i_dts;
 582
 583         p_sys->i_interpolated_pts = p_sys->i_interpolated_dts;
 584     }
 585     else
 586     {
 587         if( p_sys->i_last_ref_pts != VLC_TICK_INVALID )
 588             p_sys->i_interpolated_dts = p_sys->i_last_ref_pts;
 589
 590         p_sys->i_last_ref_pts = p_sys->i_interpolated_pts;
 591     }
 592
 593     return VLC_SUCCESS;
 594 }
 595
 596 /* look at libavutil av_log2 ;) */
 597 static int vlc_log2( unsigned int v )
 598 {
 599     int n = 0;
 600     static const int vlc_log2_table[16] =
 601     {
 602         0,0,1,1,2,2,2,2, 3,3,3,3,3,3,3,3
 603     };
 604
 605     if( v&0xffff0000 )
 606     {
 607         v >>= 16;
 608         n += 16;
 609     }
 610     if( v&0xff00 )
 611     {
 612         v >>= 8;
 613         n += 8;
 614     }
 615     if( v&0xf0 )
 616     {
 617         v >>= 4;
 618         n += 4;
 619     }
 620     n += vlc_log2_table[v];
 621
 622     return n;
 623 }