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

   1 /*****************************************************************************
   2  * mpegvideo.c: parse and packetize an MPEG1/2 video stream
   3  *****************************************************************************
   4  * Copyright (C) 2001, 2002 VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Laurent Aimar <fenrir@via.ecp.fr>
   8  *          Eric Petit <titer@videolan.org>
   9  *          Gildas Bazin <gbazin@netcourrier.com>
  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., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  24  *****************************************************************************/
  25
  26 /*****************************************************************************
  27  * Problem with this implementation:
  28  *
  29  * Although we should time-stamp each picture with a PTS, this isn't possible
  30  * with the current implementation.
  31  * The problem comes from the fact that for non-low-delay streams we can't
  32  * calculate the PTS of pictures used as backward reference. Even the temporal
  33  * reference number doesn't help here because all the pictures don't
  34  * necessarily have the same duration (eg. 3:2 pulldown).
  35  *
  36  * However this doesn't really matter as far as the MPEG muxers are concerned
  37  * because they allow having empty PTS fields. --gibalou
  38  *****************************************************************************/
  39
  40 /*****************************************************************************
  41  * Preamble
  42  *****************************************************************************/
  43 #include <stdlib.h>                                      /* malloc(), free() */
  44
  45 #include <vlc/vlc.h>
  46 #include <vlc/decoder.h>
  47 #include <vlc/input.h>
  48
  49 #include "vlc_block_helper.h"
  50
  51 /*****************************************************************************
  52  * Module descriptor
  53  *****************************************************************************/
  54 static int  Open ( vlc_object_t * );
  55 static void Close( vlc_object_t * );
  56
  57 vlc_module_begin();
  58     set_description( _("MPEG-I/II video packetizer") );
  59     set_capability( "packetizer", 50 );
  60     set_callbacks( Open, Close );
  61 vlc_module_end();
  62
  63 /*****************************************************************************
  64  * Local prototypes
  65  *****************************************************************************/
  66 static block_t *Packetize( decoder_t *, block_t ** );
  67 static block_t *ParseMPEGBlock( decoder_t *, block_t * );
  68
  69 struct decoder_sys_t
  70 {
  71     /*
  72      * Input properties
  73      */
  74     block_bytestream_t bytestream;
  75     int i_state;
  76     int i_offset;
  77     uint8_t p_startcode[3];
  78
  79     /* Sequence header and extension */
  80     block_t *p_seq;
  81     block_t *p_ext;
  82
  83     /* Current frame being built */
  84     block_t    *p_frame;
  85     block_t    **pp_last;
  86
  87     vlc_bool_t b_frame_slice;
  88     mtime_t i_pts;
  89     mtime_t i_dts;
  90
  91     /* Sequence properties */
  92     int         i_frame_rate;
  93     int         i_frame_rate_base;
  94     vlc_bool_t  b_seq_progressive;
  95     vlc_bool_t  b_low_delay;
  96     int         i_aspect_ratio_info;
  97     vlc_bool_t  b_inited;
  98
  99     /* Picture properties */
 100     int i_temporal_ref;
 101     int i_picture_type;
 102     int i_picture_structure;
 103     int i_top_field_first;
 104     int i_repeat_first_field;
 105     int i_progressive_frame;
 106
 107     mtime_t i_interpolated_dts;
 108     mtime_t i_old_duration;
 109     mtime_t i_last_ref_pts;
 110
 111     /* Number of pictures since last sequence header */
 112     int i_seq_old;
 113
 114 };
 115
 116 enum {
 117     STATE_NOSYNC,
 118     STATE_NEXT_SYNC
 119 };
 120
 121 /*****************************************************************************
 122  * Open:
 123  *****************************************************************************/
 124 static int Open( vlc_object_t *p_this )
 125 {
 126     decoder_t *p_dec = (decoder_t*)p_this;
 127     decoder_sys_t *p_sys;
 128
 129     if( p_dec->fmt_in.i_codec != VLC_FOURCC( 'm', 'p', 'g', '1' ) &&
 130         p_dec->fmt_in.i_codec != VLC_FOURCC( 'm', 'p', 'g', '2' ) &&
 131         p_dec->fmt_in.i_codec != VLC_FOURCC( 'm', 'p', 'g', 'v' ) )
 132     {
 133         return VLC_EGENERIC;
 134     }
 135
 136     es_format_Init( &p_dec->fmt_out, VIDEO_ES, VLC_FOURCC('m','p','g','v') );
 137     p_dec->pf_packetize = Packetize;
 138
 139     p_dec->p_sys = p_sys = malloc( sizeof( decoder_sys_t ) );
 140
 141     /* Misc init */
 142     p_sys->i_state = STATE_NOSYNC;
 143     p_sys->bytestream = block_BytestreamInit( p_dec );
 144     p_sys->p_startcode[0] = 0;
 145     p_sys->p_startcode[1] = 0;
 146     p_sys->p_startcode[2] = 1;
 147     p_sys->i_offset = 0;
 148
 149     p_sys->p_seq = NULL;
 150     p_sys->p_ext = NULL;
 151     p_sys->p_frame = NULL;
 152     p_sys->pp_last = &p_sys->p_frame;
 153     p_sys->b_frame_slice = VLC_FALSE;
 154
 155     p_sys->i_dts = p_sys->i_pts = 0;
 156
 157     p_sys->i_frame_rate = 1;
 158     p_sys->i_frame_rate_base = 1;
 159     p_sys->b_seq_progressive = VLC_TRUE;
 160     p_sys->b_low_delay = VLC_TRUE;
 161     p_sys->i_seq_old = 0;
 162
 163     p_sys->i_temporal_ref = 0;
 164     p_sys->i_picture_type = 0;
 165     p_sys->i_picture_structure = 0x03; /* frame */
 166     p_sys->i_top_field_first = 0;
 167     p_sys->i_repeat_first_field = 0;
 168     p_sys->i_progressive_frame = 0;
 169     p_sys->b_inited = 0;
 170
 171     p_sys->i_interpolated_dts = 0;
 172     p_sys->i_old_duration = 0;
 173     p_sys->i_last_ref_pts = 0;
 174
 175     return VLC_SUCCESS;
 176 }
 177
 178 /*****************************************************************************
 179  * Close:
 180  *****************************************************************************/
 181 static void Close( vlc_object_t *p_this )
 182 {
 183     decoder_t     *p_dec = (decoder_t*)p_this;
 184     decoder_sys_t *p_sys = p_dec->p_sys;
 185
 186     block_BytestreamRelease( &p_sys->bytestream );
 187
 188     if( p_sys->p_seq )
 189     {
 190         block_Release( p_sys->p_seq );
 191     }
 192     if( p_sys->p_ext )
 193     {
 194         block_Release( p_sys->p_ext );
 195     }
 196     if( p_sys->p_frame )
 197     {
 198         block_ChainRelease( p_sys->p_frame );
 199     }
 200
 201     free( p_sys );
 202 }
 203
 204 /*****************************************************************************
 205  * Packetize:
 206  *****************************************************************************/
 207 static block_t *Packetize( decoder_t *p_dec, block_t **pp_block )
 208 {
 209     decoder_sys_t *p_sys = p_dec->p_sys;
 210     block_t       *p_pic;
 211
 212     if( pp_block == NULL || *pp_block == NULL )
 213     {
 214         return NULL;
 215     }
 216
 217     if( (*pp_block)->i_flags & BLOCK_FLAG_DISCONTINUITY )
 218     {
 219         p_sys->i_state = STATE_NOSYNC;
 220         if( p_sys->p_frame ) block_ChainRelease( p_sys->p_frame );
 221         p_sys->p_frame = NULL;
 222         p_sys->pp_last = &p_sys->p_frame;
 223         p_sys->b_frame_slice = VLC_FALSE;
 224         block_Release( *pp_block );
 225         return NULL;
 226     }
 227
 228     block_BytestreamPush( &p_sys->bytestream, *pp_block );
 229
 230     while( 1 )
 231     {
 232         switch( p_sys->i_state )
 233         {
 234
 235         case STATE_NOSYNC:
 236             if( block_FindStartcodeFromOffset( &p_sys->bytestream,
 237                     &p_sys->i_offset, p_sys->p_startcode, 3 ) == VLC_SUCCESS )
 238             {
 239                 p_sys->i_state = STATE_NEXT_SYNC;
 240             }
 241
 242             if( p_sys->i_offset )
 243             {
 244                 block_SkipBytes( &p_sys->bytestream, p_sys->i_offset );
 245                 p_sys->i_offset = 0;
 246                 block_BytestreamFlush( &p_sys->bytestream );
 247             }
 248
 249             if( p_sys->i_state != STATE_NEXT_SYNC )
 250             {
 251                 /* Need more data */
 252                 return NULL;
 253             }
 254
 255             p_sys->i_offset = 1; /* To find next startcode */
 256
 257         case STATE_NEXT_SYNC:
 258             /* TODO: If p_block == NULL, flush the buffer without checking the
 259              * next sync word */
 260
 261             /* Find the next startcode */
 262             if( block_FindStartcodeFromOffset( &p_sys->bytestream,
 263                     &p_sys->i_offset, p_sys->p_startcode, 3 ) != VLC_SUCCESS )
 264             {
 265                 /* Need more data */
 266                 return NULL;
 267             }
 268
 269             /* Get the new fragment and set the pts/dts */
 270             p_pic = block_New( p_dec, p_sys->i_offset );
 271             p_pic->i_pts = p_sys->bytestream.p_block->i_pts;
 272             p_pic->i_dts = p_sys->bytestream.p_block->i_dts;
 273
 274             /* FIXME ? Should we flush the bytestream chain before ? */
 275             if( p_sys->bytestream.p_block->i_buffer ==
 276                 p_sys->bytestream.i_offset &&
 277                 p_sys->bytestream.p_block->p_next )
 278             {
 279                 p_pic->i_pts = p_sys->bytestream.p_block->p_next->i_pts;
 280                 p_pic->i_dts = p_sys->bytestream.p_block->p_next->i_dts;
 281             }
 282
 283             block_GetBytes( &p_sys->bytestream, p_pic->p_buffer,
 284                             p_pic->i_buffer );
 285
 286             /* don't reuse the same timestamps several times */
 287             if( p_pic->i_buffer >= 4 && p_pic->p_buffer[3] == 0x00 )
 288             {
 289                 /* We have a picture start code */
 290                 p_sys->bytestream.p_block->i_pts = 0;
 291                 p_sys->bytestream.p_block->i_dts = 0;
 292             }
 293
 294             p_sys->i_offset = 0;
 295
 296             /* Get picture if any */
 297             if( !( p_pic = ParseMPEGBlock( p_dec, p_pic ) ) )
 298             {
 299                 p_sys->i_state = STATE_NOSYNC;
 300                 break;
 301             }
 302
 303             /* We've just started the stream, wait for the first PTS.
 304              * We discard here so we can still get the sequence header. */
 305             if( p_sys->i_dts <= 0 && p_sys->i_pts <= 0 &&
 306                 p_sys->i_interpolated_dts <= 0 )
 307             {
 308                 msg_Dbg( p_dec, "need a starting pts/dts" );
 309                 p_sys->i_state = STATE_NOSYNC;
 310                 block_Release( p_pic );
 311                 break;
 312             }
 313
 314             /* When starting the stream we can have the first frame with
 315              * a null DTS (i_interpolated_pts is initialized to 0) */
 316             if( !p_pic->i_dts ) p_pic->i_dts = p_pic->i_pts;
 317
 318             /* So p_block doesn't get re-added several times */
 319             *pp_block = block_BytestreamPop( &p_sys->bytestream );
 320
 321             p_sys->i_state = STATE_NOSYNC;
 322
 323             return p_pic;
 324         }
 325     }
 326 }
 327
 328 /*****************************************************************************
 329  * ParseMPEGBlock: Re-assemble fragments into a block containing a picture
 330  *****************************************************************************/
 331 static block_t *ParseMPEGBlock( decoder_t *p_dec, block_t *p_frag )
 332 {
 333     decoder_sys_t *p_sys = p_dec->p_sys;
 334     block_t *p_pic = NULL;
 335
 336     /*
 337      * Check if previous picture is finished
 338      */
 339     if( ( p_sys->b_frame_slice &&
 340           (p_frag->p_buffer[3] == 0x00 || p_frag->p_buffer[3] > 0xaf) ) &&
 341           p_sys->p_seq == NULL )
 342     {
 343         /* We have a picture but without a sequence header we can't
 344          * do anything */
 345         msg_Dbg( p_dec, "waiting for sequence start" );
 346         if( p_sys->p_frame ) block_ChainRelease( p_sys->p_frame );
 347         p_sys->p_frame = NULL;
 348         p_sys->pp_last = &p_sys->p_frame;
 349         p_sys->b_frame_slice = VLC_FALSE;
 350
 351     }
 352     else if( p_sys->b_frame_slice &&
 353              (p_frag->p_buffer[3] == 0x00 || p_frag->p_buffer[3] > 0xaf) )
 354     {
 355         mtime_t i_duration;
 356
 357         p_pic = block_ChainGather( p_sys->p_frame );
 358
 359         i_duration = (mtime_t)( 1000000 * p_sys->i_frame_rate_base /
 360                                 p_sys->i_frame_rate );
 361
 362         if( !p_sys->b_seq_progressive && p_sys->i_picture_structure != 0x03 )
 363         {
 364             i_duration /= 2;
 365         }
 366
 367         if( p_sys->b_seq_progressive )
 368         {
 369             if( p_sys->i_top_field_first == 0 &&
 370                 p_sys->i_repeat_first_field == 1 )
 371             {
 372                 i_duration *= 2;
 373             }
 374             else if( p_sys->i_top_field_first == 1 &&
 375                      p_sys->i_repeat_first_field == 1 )
 376             {
 377                 i_duration *= 3;
 378             }
 379         }
 380         else
 381         {
 382             if( p_sys->i_picture_structure == 0x03 )
 383             {
 384                 if( p_sys->i_progressive_frame && p_sys->i_repeat_first_field )
 385                 {
 386                     i_duration += i_duration / 2;
 387                 }
 388             }
 389         }
 390
 391         if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
 392         {
 393             /* Trivial case (DTS == PTS) */
 394             /* Correct interpolated dts when we receive a new pts/dts */
 395             if( p_sys->i_pts > 0 ) p_sys->i_interpolated_dts = p_sys->i_pts;
 396             if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
 397         }
 398         else
 399         {
 400             /* Correct interpolated dts when we receive a new pts/dts */
 401             if( p_sys->i_last_ref_pts > 0 )
 402                 p_sys->i_interpolated_dts = p_sys->i_last_ref_pts;
 403             if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
 404
 405             p_sys->i_last_ref_pts = p_sys->i_pts;
 406         }
 407
 408         p_pic->i_dts = p_sys->i_interpolated_dts;
 409
 410         /* Set PTS only if we have a B frame or if it comes from the stream */
 411         if( p_sys->i_pts > 0 )
 412         {
 413             p_pic->i_pts = p_sys->i_pts;
 414         }
 415         else if( p_sys->i_picture_type == 0x03 )
 416         {
 417             p_pic->i_pts = p_pic->i_dts;
 418         }
 419         else
 420         {
 421             p_pic->i_pts = 0;
 422         }
 423
 424         if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
 425         {
 426             /* Trivial case (DTS == PTS) */
 427             p_sys->i_interpolated_dts += i_duration;
 428         }
 429         else
 430         {
 431             p_sys->i_interpolated_dts += p_sys->i_old_duration;
 432             p_sys->i_old_duration = i_duration;
 433         }
 434
 435         switch ( p_sys->i_picture_type )
 436         {
 437         case 0x01:
 438             p_pic->i_flags |= BLOCK_FLAG_TYPE_I;
 439             break;
 440         case 0x02:
 441             p_pic->i_flags |= BLOCK_FLAG_TYPE_P;
 442             break;
 443         case 0x03:
 444             p_pic->i_flags |= BLOCK_FLAG_TYPE_B;
 445             break;
 446         }
 447
 448         p_pic->i_length = p_sys->i_interpolated_dts - p_pic->i_dts;
 449
 450 #if 0
 451         msg_Dbg( p_dec, "pic: type=%d dts="I64Fd" pts-dts="I64Fd,
 452         p_sys->i_picture_type, p_pic->i_dts, p_pic->i_pts - p_pic->i_dts);
 453 #endif
 454
 455         /* Reset context */
 456         p_sys->p_frame = NULL;
 457         p_sys->pp_last = &p_sys->p_frame;
 458         p_sys->b_frame_slice = VLC_FALSE;
 459     }
 460
 461     /*
 462      * Check info of current fragment
 463      */
 464     if( p_frag->p_buffer[3] == 0xb8 )
 465     {
 466         /* Group start code */
 467         if( p_sys->p_seq &&
 468             p_sys->i_seq_old > p_sys->i_frame_rate/p_sys->i_frame_rate_base )
 469         {
 470             /* Usefull for mpeg1: repeat sequence header every second */
 471             block_ChainLastAppend( &p_sys->pp_last, block_Duplicate( p_sys->p_seq ) );
 472             if( p_sys->p_ext )
 473             {
 474                 block_ChainLastAppend( &p_sys->pp_last, block_Duplicate( p_sys->p_ext ) );
 475             }
 476
 477             p_sys->i_seq_old = 0;
 478         }
 479     }
 480     else if( p_frag->p_buffer[3] == 0xb3 && p_frag->i_buffer >= 8 )
 481     {
 482         /* Sequence header code */
 483         static const int code_to_frame_rate[16][2] =
 484         {
 485             { 1, 1 },  /* invalid */
 486             { 24000, 1001 }, { 24, 1 }, { 25, 1 },       { 30000, 1001 },
 487             { 30, 1 },       { 50, 1 }, { 60000, 1001 }, { 60, 1 },
 488             /* Unofficial 15fps from Xing*/
 489             { 15, 1001 },
 490             /* Unofficial economy rates from libmpeg3 */
 491             { 5, 1001 }, { 10, 1001 }, { 12, 1001 }, { 15, 1001 },
 492             { 1, 1 },  { 1, 1 }  /* invalid */
 493         };
 494
 495         if( p_sys->p_seq ) block_Release( p_sys->p_seq );
 496         if( p_sys->p_ext ) block_Release( p_sys->p_ext );
 497
 498         p_sys->p_seq = block_Duplicate( p_frag );
 499         p_sys->i_seq_old = 0;
 500         p_sys->p_ext = NULL;
 501
 502         p_dec->fmt_out.video.i_width =
 503             ( p_frag->p_buffer[4] << 4)|(p_frag->p_buffer[5] >> 4 );
 504         p_dec->fmt_out.video.i_height =
 505             ( (p_frag->p_buffer[5]&0x0f) << 8 )|p_frag->p_buffer[6];
 506         p_sys->i_aspect_ratio_info = p_frag->p_buffer[7] >> 4;
 507
 508         /* TODO: MPEG1 aspect ratio */
 509
 510         p_sys->i_frame_rate = code_to_frame_rate[p_frag->p_buffer[7]&0x0f][0];
 511         p_sys->i_frame_rate_base =
 512             code_to_frame_rate[p_frag->p_buffer[7]&0x0f][1];
 513
 514         p_sys->b_seq_progressive = VLC_TRUE;
 515         p_sys->b_low_delay = VLC_TRUE;
 516
 517         if ( !p_sys->b_inited )
 518         {
 519             msg_Dbg( p_dec, "Size %dx%d fps=%.3f",
 520                  p_dec->fmt_out.video.i_width, p_dec->fmt_out.video.i_height,
 521                  p_sys->i_frame_rate / (float)p_sys->i_frame_rate_base );
 522             p_sys->b_inited = 1;
 523         }
 524     }
 525     else if( p_frag->p_buffer[3] == 0xb5 )
 526     {
 527         int i_type = p_frag->p_buffer[4] >> 4;
 528
 529         /* Extention start code */
 530         if( i_type == 0x01 )
 531         {
 532             static const int mpeg2_aspect[16][2] =
 533             {
 534                 {0,1}, {1,1}, {4,3}, {16,9}, {221,100},
 535                 {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1},
 536                 {0,1}, {0,1}
 537             };
 538
 539             /* sequence extention */
 540             if( p_sys->p_ext) block_Release( p_sys->p_ext );
 541             p_sys->p_ext = block_Duplicate( p_frag );
 542
 543             if( p_frag->i_buffer >= 10 )
 544             {
 545                 p_sys->b_seq_progressive =
 546                     p_frag->p_buffer[5]&0x08 ? VLC_TRUE : VLC_FALSE;
 547                 p_sys->b_low_delay =
 548                     p_frag->p_buffer[9]&0x80 ? VLC_TRUE : VLC_FALSE;
 549             }
 550
 551             p_dec->fmt_out.video.i_aspect =
 552                 mpeg2_aspect[p_sys->i_aspect_ratio_info][0] *
 553                 VOUT_ASPECT_FACTOR /
 554                 mpeg2_aspect[p_sys->i_aspect_ratio_info][1];
 555
 556         }
 557         else if( i_type == 0x08 )
 558         {
 559             /* picture extention */
 560             p_sys->i_picture_structure = p_frag->p_buffer[6]&0x03;
 561             p_sys->i_top_field_first   = p_frag->p_buffer[7] >> 7;
 562             p_sys->i_repeat_first_field= (p_frag->p_buffer[7]>>1)&0x01;
 563             p_sys->i_progressive_frame = p_frag->p_buffer[8] >> 7;
 564         }
 565     }
 566     else if( p_frag->p_buffer[3] == 0x00 )
 567     {
 568         /* Picture start code */
 569         p_sys->i_seq_old++;
 570
 571         if( p_frag->i_buffer >= 6 )
 572         {
 573             p_sys->i_temporal_ref =
 574                 ( p_frag->p_buffer[4] << 2 )|(p_frag->p_buffer[5] >> 6);
 575             p_sys->i_picture_type = ( p_frag->p_buffer[5] >> 3 ) & 0x03;
 576         }
 577
 578         p_sys->i_dts = p_frag->i_dts;
 579         p_sys->i_pts = p_frag->i_pts;
 580     }
 581     else if( p_frag->p_buffer[3] >= 0x01 && p_frag->p_buffer[3] <= 0xaf )
 582     {
 583         /* Slice start code */
 584         p_sys->b_frame_slice = VLC_TRUE;
 585     }
 586
 587     /* Append the block */
 588     block_ChainLastAppend( &p_sys->pp_last, p_frag );
 589
 590     return p_pic;
 591 }