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@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., 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             block_BytestreamFlush( &p_sys->bytestream );
 272             p_pic->i_pts = p_sys->bytestream.p_block->i_pts;
 273             p_pic->i_dts = p_sys->bytestream.p_block->i_dts;
 274
 275             block_GetBytes( &p_sys->bytestream, p_pic->p_buffer,
 276                             p_pic->i_buffer );
 277
 278             /* don't reuse the same timestamps several times */
 279             if( p_pic->i_buffer >= 4 && p_pic->p_buffer[3] == 0x00 )
 280             {
 281                 /* We have a picture start code */
 282                 p_sys->bytestream.p_block->i_pts = 0;
 283                 p_sys->bytestream.p_block->i_dts = 0;
 284             }
 285
 286             p_sys->i_offset = 0;
 287
 288             /* Get picture if any */
 289             if( !( p_pic = ParseMPEGBlock( p_dec, p_pic ) ) )
 290             {
 291                 p_sys->i_state = STATE_NOSYNC;
 292                 break;
 293             }
 294
 295             /* We've just started the stream, wait for the first PTS.
 296              * We discard here so we can still get the sequence header. */
 297             if( p_sys->i_dts <= 0 && p_sys->i_pts <= 0 &&
 298                 p_sys->i_interpolated_dts <= 0 )
 299             {
 300                 msg_Dbg( p_dec, "need a starting pts/dts" );
 301                 p_sys->i_state = STATE_NOSYNC;
 302                 block_Release( p_pic );
 303                 break;
 304             }
 305
 306             /* When starting the stream we can have the first frame with
 307              * a null DTS (i_interpolated_pts is initialized to 0) */
 308             if( !p_pic->i_dts ) p_pic->i_dts = p_pic->i_pts;
 309
 310             /* So p_block doesn't get re-added several times */
 311             *pp_block = block_BytestreamPop( &p_sys->bytestream );
 312
 313             p_sys->i_state = STATE_NOSYNC;
 314
 315             return p_pic;
 316         }
 317     }
 318 }
 319
 320 /*****************************************************************************
 321  * ParseMPEGBlock: Re-assemble fragments into a block containing a picture
 322  *****************************************************************************/
 323 static block_t *ParseMPEGBlock( decoder_t *p_dec, block_t *p_frag )
 324 {
 325     decoder_sys_t *p_sys = p_dec->p_sys;
 326     block_t *p_pic = NULL;
 327
 328     /*
 329      * Check if previous picture is finished
 330      */
 331     if( ( p_sys->b_frame_slice &&
 332           (p_frag->p_buffer[3] == 0x00 || p_frag->p_buffer[3] > 0xaf) ) &&
 333           p_sys->p_seq == NULL )
 334     {
 335         /* We have a picture but without a sequence header we can't
 336          * do anything */
 337         msg_Dbg( p_dec, "waiting for sequence start" );
 338         if( p_sys->p_frame ) block_ChainRelease( p_sys->p_frame );
 339         p_sys->p_frame = NULL;
 340         p_sys->pp_last = &p_sys->p_frame;
 341         p_sys->b_frame_slice = VLC_FALSE;
 342
 343     }
 344     else if( p_sys->b_frame_slice &&
 345              (p_frag->p_buffer[3] == 0x00 || p_frag->p_buffer[3] > 0xaf) )
 346     {
 347         mtime_t i_duration;
 348
 349         p_pic = block_ChainGather( p_sys->p_frame );
 350
 351         i_duration = (mtime_t)( 1000000 * p_sys->i_frame_rate_base /
 352                                 p_sys->i_frame_rate );
 353
 354         if( !p_sys->b_seq_progressive && p_sys->i_picture_structure != 0x03 )
 355         {
 356             i_duration /= 2;
 357         }
 358
 359         if( p_sys->b_seq_progressive )
 360         {
 361             if( p_sys->i_top_field_first == 0 &&
 362                 p_sys->i_repeat_first_field == 1 )
 363             {
 364                 i_duration *= 2;
 365             }
 366             else if( p_sys->i_top_field_first == 1 &&
 367                      p_sys->i_repeat_first_field == 1 )
 368             {
 369                 i_duration *= 3;
 370             }
 371         }
 372         else
 373         {
 374             if( p_sys->i_picture_structure == 0x03 )
 375             {
 376                 if( p_sys->i_progressive_frame && p_sys->i_repeat_first_field )
 377                 {
 378                     i_duration += i_duration / 2;
 379                 }
 380             }
 381         }
 382
 383         if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
 384         {
 385             /* Trivial case (DTS == PTS) */
 386             /* Correct interpolated dts when we receive a new pts/dts */
 387             if( p_sys->i_pts > 0 ) p_sys->i_interpolated_dts = p_sys->i_pts;
 388             if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
 389         }
 390         else
 391         {
 392             /* Correct interpolated dts when we receive a new pts/dts */
 393             if( p_sys->i_last_ref_pts > 0 )
 394                 p_sys->i_interpolated_dts = p_sys->i_last_ref_pts;
 395             if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
 396
 397             p_sys->i_last_ref_pts = p_sys->i_pts;
 398         }
 399
 400         p_pic->i_dts = p_sys->i_interpolated_dts;
 401
 402         /* Set PTS only if we have a B frame or if it comes from the stream */
 403         if( p_sys->i_pts > 0 )
 404         {
 405             p_pic->i_pts = p_sys->i_pts;
 406         }
 407         else if( p_sys->i_picture_type == 0x03 )
 408         {
 409             p_pic->i_pts = p_pic->i_dts;
 410         }
 411         else
 412         {
 413             p_pic->i_pts = 0;
 414         }
 415
 416         if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
 417         {
 418             /* Trivial case (DTS == PTS) */
 419             p_sys->i_interpolated_dts += i_duration;
 420         }
 421         else
 422         {
 423             p_sys->i_interpolated_dts += p_sys->i_old_duration;
 424             p_sys->i_old_duration = i_duration;
 425         }
 426
 427         switch ( p_sys->i_picture_type )
 428         {
 429         case 0x01:
 430             p_pic->i_flags |= BLOCK_FLAG_TYPE_I;
 431             break;
 432         case 0x02:
 433             p_pic->i_flags |= BLOCK_FLAG_TYPE_P;
 434             break;
 435         case 0x03:
 436             p_pic->i_flags |= BLOCK_FLAG_TYPE_B;
 437             break;
 438         }
 439
 440         p_pic->i_length = p_sys->i_interpolated_dts - p_pic->i_dts;
 441
 442 #if 0
 443         msg_Dbg( p_dec, "pic: type=%d dts="I64Fd" pts-dts="I64Fd,
 444         p_sys->i_picture_type, p_pic->i_dts, p_pic->i_pts - p_pic->i_dts);
 445 #endif
 446
 447         /* Reset context */
 448         p_sys->p_frame = NULL;
 449         p_sys->pp_last = &p_sys->p_frame;
 450         p_sys->b_frame_slice = VLC_FALSE;
 451     }
 452
 453     /*
 454      * Check info of current fragment
 455      */
 456     if( p_frag->p_buffer[3] == 0xb8 )
 457     {
 458         /* Group start code */
 459         if( p_sys->p_seq &&
 460             p_sys->i_seq_old > p_sys->i_frame_rate/p_sys->i_frame_rate_base )
 461         {
 462             /* Usefull for mpeg1: repeat sequence header every second */
 463             block_ChainLastAppend( &p_sys->pp_last, block_Duplicate( p_sys->p_seq ) );
 464             if( p_sys->p_ext )
 465             {
 466                 block_ChainLastAppend( &p_sys->pp_last, block_Duplicate( p_sys->p_ext ) );
 467             }
 468
 469             p_sys->i_seq_old = 0;
 470         }
 471     }
 472     else if( p_frag->p_buffer[3] == 0xb3 && p_frag->i_buffer >= 8 )
 473     {
 474         /* Sequence header code */
 475         static const int code_to_frame_rate[16][2] =
 476         {
 477             { 1, 1 },  /* invalid */
 478             { 24000, 1001 }, { 24, 1 }, { 25, 1 },       { 30000, 1001 },
 479             { 30, 1 },       { 50, 1 }, { 60000, 1001 }, { 60, 1 },
 480             /* Unofficial 15fps from Xing*/
 481             { 15, 1001 },
 482             /* Unofficial economy rates from libmpeg3 */
 483             { 5, 1001 }, { 10, 1001 }, { 12, 1001 }, { 15, 1001 },
 484             { 1, 1 },  { 1, 1 }  /* invalid */
 485         };
 486
 487         if( p_sys->p_seq ) block_Release( p_sys->p_seq );
 488         if( p_sys->p_ext ) block_Release( p_sys->p_ext );
 489
 490         p_sys->p_seq = block_Duplicate( p_frag );
 491         p_sys->i_seq_old = 0;
 492         p_sys->p_ext = NULL;
 493
 494         p_dec->fmt_out.video.i_width =
 495             ( p_frag->p_buffer[4] << 4)|(p_frag->p_buffer[5] >> 4 );
 496         p_dec->fmt_out.video.i_height =
 497             ( (p_frag->p_buffer[5]&0x0f) << 8 )|p_frag->p_buffer[6];
 498         p_sys->i_aspect_ratio_info = p_frag->p_buffer[7] >> 4;
 499
 500         /* TODO: MPEG1 aspect ratio */
 501
 502         p_sys->i_frame_rate = code_to_frame_rate[p_frag->p_buffer[7]&0x0f][0];
 503         p_sys->i_frame_rate_base =
 504             code_to_frame_rate[p_frag->p_buffer[7]&0x0f][1];
 505
 506         p_dec->fmt_out.video.i_frame_rate = p_sys->i_frame_rate;
 507         p_dec->fmt_out.video.i_frame_rate_base = p_sys->i_frame_rate_base;
 508
 509         p_sys->b_seq_progressive = VLC_TRUE;
 510         p_sys->b_low_delay = VLC_TRUE;
 511
 512         if ( !p_sys->b_inited )
 513         {
 514             msg_Dbg( p_dec, "Size %dx%d fps=%.3f",
 515                  p_dec->fmt_out.video.i_width, p_dec->fmt_out.video.i_height,
 516                  p_sys->i_frame_rate / (float)p_sys->i_frame_rate_base );
 517             p_sys->b_inited = 1;
 518         }
 519     }
 520     else if( p_frag->p_buffer[3] == 0xb5 )
 521     {
 522         int i_type = p_frag->p_buffer[4] >> 4;
 523
 524         /* Extention start code */
 525         if( i_type == 0x01 )
 526         {
 527             static const int mpeg2_aspect[16][2] =
 528             {
 529                 {0,1}, {1,1}, {4,3}, {16,9}, {221,100},
 530                 {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1},
 531                 {0,1}, {0,1}
 532             };
 533
 534             /* sequence extention */
 535             if( p_sys->p_ext) block_Release( p_sys->p_ext );
 536             p_sys->p_ext = block_Duplicate( p_frag );
 537
 538             if( p_frag->i_buffer >= 10 )
 539             {
 540                 p_sys->b_seq_progressive =
 541                     p_frag->p_buffer[5]&0x08 ? VLC_TRUE : VLC_FALSE;
 542                 p_sys->b_low_delay =
 543                     p_frag->p_buffer[9]&0x80 ? VLC_TRUE : VLC_FALSE;
 544             }
 545
 546             p_dec->fmt_out.video.i_aspect =
 547                 mpeg2_aspect[p_sys->i_aspect_ratio_info][0] *
 548                 VOUT_ASPECT_FACTOR /
 549                 mpeg2_aspect[p_sys->i_aspect_ratio_info][1];
 550
 551         }
 552         else if( i_type == 0x08 )
 553         {
 554             /* picture extention */
 555             p_sys->i_picture_structure = p_frag->p_buffer[6]&0x03;
 556             p_sys->i_top_field_first   = p_frag->p_buffer[7] >> 7;
 557             p_sys->i_repeat_first_field= (p_frag->p_buffer[7]>>1)&0x01;
 558             p_sys->i_progressive_frame = p_frag->p_buffer[8] >> 7;
 559         }
 560     }
 561     else if( p_frag->p_buffer[3] == 0x00 )
 562     {
 563         /* Picture start code */
 564         p_sys->i_seq_old++;
 565
 566         if( p_frag->i_buffer >= 6 )
 567         {
 568             p_sys->i_temporal_ref =
 569                 ( p_frag->p_buffer[4] << 2 )|(p_frag->p_buffer[5] >> 6);
 570             p_sys->i_picture_type = ( p_frag->p_buffer[5] >> 3 ) & 0x03;
 571         }
 572
 573         p_sys->i_dts = p_frag->i_dts;
 574         p_sys->i_pts = p_frag->i_pts;
 575     }
 576     else if( p_frag->p_buffer[3] >= 0x01 && p_frag->p_buffer[3] <= 0xaf )
 577     {
 578         /* Slice start code */
 579         p_sys->b_frame_slice = VLC_TRUE;
 580     }
 581
 582     /* Append the block */
 583     block_ChainLastAppend( &p_sys->pp_last, p_frag );
 584
 585     return p_pic;
 586 }