git.sesse.net Git - vlc/blob - src/video_parser/vpar_synchro.c

   1 /*****************************************************************************
   2  * vpar_synchro.c : frame dropping routines
   3  *****************************************************************************
   4  * Copyright (C) 1999, 2000 VideoLAN
   5  * $Id: vpar_synchro.c,v 1.66 2000/12/27 18:35:45 massiot Exp $
   6  *
   7  * Authors: Christophe Massiot <massiot@via.ecp.fr>
   8  *          Samuel Hocevar <sam@via.ecp.fr>
   9  *          Jean-Marc Dressler <polux@via.ecp.fr>
  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  * DISCUSSION : How to Write an efficient Frame-Dropping Algorithm
  28  * ==========
  29  *
  30  * This implementation is based on mathematical and statistical
  31  * developments. Older implementations used an enslavement, considering
  32  * that if we're late when reading an I picture, we will decode one frame
  33  * less. It had a tendancy to derive, and wasn't responsive enough, which
  34  * would have caused trouble with the stream control stuff.
  35  *
  36  * 1. Structure of a picture stream
  37  *    =============================
  38  * Between 2 I's, we have for instance :
  39  *    I   B   P   B   P   B   P   B   P   B   P   B   I
  40  *    t0  t1  t2  t3  t4  t5  t6  t7  t8  t9  t10 t11 t12
  41  * Please bear in mind that B's and IP's will be inverted when displaying
  42  * (decoding order != presentation order). Thus, t1 < t0.
  43  *
  44  * 2. Definitions
  45  *    ===========
  46  * t[0..12]     : Presentation timestamps of pictures 0..12.
  47  * t            : Current timestamp, at the moment of the decoding.
  48  * T            : Picture period, T = 1/frame_rate.
  49  * tau[I,P,B]   : Mean time to decode an [I,P,B] picture.
  50  * tauYUV       : Mean time to render a picture (given by the video_output).
  51  * tau´[I,P,B] = 2 * tau[I,P,B] + tauYUV
  52  *              : Mean time + typical difference (estimated to tau/2, that
  53  *                needs to be confirmed) + render time.
  54  * DELTA        : A given error margin.
  55  *
  56  * 3. General considerations
  57  *    ======================
  58  * We define to types of machines :
  59  *      2T > tauP  : machines capable of decoding all P pictures
  60  *      14T > tauI : machines capable of decoding all I pictures
  61  *
  62  * 4. Decoding of an I picture
  63  *    ========================
  64  * On fast machines, we decode all I's.
  65  * Otherwise :
  66  * We can decode an I picture if we simply have enough time to decode it
  67  * before displaying :
  68  *      t0 - t > tau´I + DELTA
  69  *
  70  * 4. Decoding of a P picture
  71  *    =======================
  72  * On fast machines, we decode all P's.
  73  * Otherwise :
  74  * First criterion : have time to decode it.
  75  *      t2 - t > tau´P + DELTA
  76  *
  77  * Second criterion : it shouldn't prevent us from displaying the forthcoming
  78  * I picture, which is more important.
  79  *      t12 - t > tau´P + tau´I + DELTA
  80  *
  81  * 5. Decoding of a B picture
  82  *    =======================
  83  * First criterion : have time to decode it.
  84  *      t1 - t > tau´B + DELTA
  85  *
  86  * Second criterion : it shouldn't prevent us from displaying the forthcoming
  87  * P picture, which is more important.
  88  *      t4 - t > tau´B + tau´P + DELTA
  89  *
  90  * I hope you will have a pleasant flight and do not forget your life
  91  * jacket.
  92  *                                                  --Meuuh (2000-11-09)
  93  */
  94
  95 /*****************************************************************************
  96  * Preamble
  97  *****************************************************************************/
  98 #include "defs.h"
  99
 100 #include "config.h"
 101 #include "common.h"
 102 #include "threads.h"
 103 #include "mtime.h"
 104 #include "plugins.h"
 105
 106 #include "intf_msg.h"
 107
 108 #include "stream_control.h"
 109 #include "input_ext-dec.h"
 110
 111 #include "video.h"
 112 #include "video_output.h"
 113
 114 #include "../video_decoder/vdec_idct.h"
 115 #include "../video_decoder/video_decoder.h"
 116 #include "../video_decoder/vdec_motion.h"
 117
 118 #include "../video_decoder/vpar_blocks.h"
 119 #include "../video_decoder/vpar_headers.h"
 120 #include "../video_decoder/vpar_synchro.h"
 121 #include "../video_decoder/video_parser.h"
 122
 123 #include "main.h"
 124
 125 /*
 126  * Local prototypes
 127  */
 128 static int  SynchroType( void );
 129
 130 /* Error margins */
 131 #define DELTA                   (int)(0.040*CLOCK_FREQ)
 132
 133 #define DEFAULT_NB_P            5
 134 #define DEFAULT_NB_B            1
 135
 136 /*****************************************************************************
 137  * vpar_SynchroInit : You know what ?
 138  *****************************************************************************/
 139 void vpar_SynchroInit( vpar_thread_t * p_vpar )
 140 {
 141     p_vpar->synchro.i_type = SynchroType();
 142     p_vpar->synchro.i_start = p_vpar->synchro.i_end = 0;
 143     vlc_mutex_init( &p_vpar->synchro.fifo_lock );
 144
 145     /* We use a fake stream pattern, which is often right. */
 146     p_vpar->synchro.i_n_p = p_vpar->synchro.i_eta_p = DEFAULT_NB_P;
 147     p_vpar->synchro.i_n_b = p_vpar->synchro.i_eta_b = DEFAULT_NB_B;
 148     memset( p_vpar->synchro.p_tau, 0, 4 * sizeof(mtime_t) );
 149     memset( p_vpar->synchro.pi_meaningful, 0, 4 * sizeof(unsigned int) );
 150     p_vpar->synchro.b_dropped_last = 0;
 151     p_vpar->synchro.current_pts = mdate() + DEFAULT_PTS_DELAY;
 152     p_vpar->synchro.backward_pts = 0;
 153 }
 154
 155 /*****************************************************************************
 156  * vpar_SynchroChoose : Decide whether we will decode a picture or not
 157  *****************************************************************************/
 158 boolean_t vpar_SynchroChoose( vpar_thread_t * p_vpar, int i_coding_type,
 159                               int i_structure )
 160 {
 161     /* For clarity reasons, we separated the special synchros code from the
 162      * mathematical synchro */
 163
 164     if( p_vpar->synchro.i_type != VPAR_SYNCHRO_DEFAULT )
 165     {
 166         switch( i_coding_type )
 167         {
 168         case I_CODING_TYPE:
 169             /* I, IP, IP+, IPB */
 170             if( p_vpar->synchro.i_type == VPAR_SYNCHRO_Iplus )
 171             {
 172                 p_vpar->synchro.b_dropped_last = 1;
 173             }
 174             return( 1 );
 175
 176         case P_CODING_TYPE:
 177             if( p_vpar->synchro.i_type == VPAR_SYNCHRO_I ) /* I */
 178             {
 179                 return( 0 );
 180             }
 181
 182             if( p_vpar->synchro.i_type == VPAR_SYNCHRO_Iplus ) /* I+ */
 183             {
 184                 if( p_vpar->synchro.b_dropped_last )
 185                 {
 186                     p_vpar->synchro.b_dropped_last = 0;
 187                     return( 1 );
 188                 }
 189                 else
 190                 {
 191                     return( 0 );
 192                 }
 193             }
 194
 195             return( 1 ); /* IP, IP+, IPB */
 196
 197         case B_CODING_TYPE:
 198             if( p_vpar->synchro.i_type <= VPAR_SYNCHRO_IP ) /* I, IP */
 199             {
 200                 return( 0 );
 201             }
 202             else if( p_vpar->synchro.i_type == VPAR_SYNCHRO_IPB ) /* IPB */
 203             {
 204                 return( 1 );
 205             }
 206
 207             p_vpar->synchro.b_dropped_last ^= 1; /* IP+ */
 208             return( !p_vpar->synchro.b_dropped_last );
 209         }
 210         return( 0 ); /* never reached but gcc yells at me */
 211     }
 212     else
 213     {
 214 #define TAU_PRIME( coding_type )    (p_vpar->synchro.p_tau[(coding_type)] \
 215                                  + (p_vpar->synchro.p_tau[(coding_type)] >> 1) \
 216                                             + tau_yuv)
 217 #define S                           p_vpar->synchro
 218         /* VPAR_SYNCHRO_DEFAULT */
 219         mtime_t         now, pts, period, tau_yuv;
 220         boolean_t       b_decode = 0;
 221 #ifdef DEBUG_VPAR
 222         char            p_date[MSTRTIME_MAX_SIZE];
 223 #endif
 224
 225         now = mdate();
 226         period = 1000000 / (p_vpar->sequence.i_frame_rate) * 1001;
 227
 228         vlc_mutex_lock( &p_vpar->p_vout->change_lock );
 229         tau_yuv = p_vpar->p_vout->render_time;
 230         vlc_mutex_unlock( &p_vpar->p_vout->change_lock );
 231
 232         vlc_mutex_lock( &p_vpar->synchro.fifo_lock );
 233
 234         switch( i_coding_type )
 235         {
 236         case I_CODING_TYPE:
 237             if( S.backward_pts )
 238             {
 239                 pts = S.backward_pts;
 240             }
 241             else
 242             {
 243                 /* displaying order : B B P B B I
 244                  *                      ^       ^
 245                  *                      |       +- current picture
 246                  *                      +- current PTS
 247                  */
 248                 pts = S.current_pts + period * (S.i_n_b + 2);
 249             }
 250
 251             if( (1 + S.i_n_p * (S.i_n_b + 1)) * period >
 252                     S.p_tau[I_CODING_TYPE] )
 253             {
 254                 b_decode = 1;
 255             }
 256             else
 257             {
 258                 b_decode = (pts - now) > (TAU_PRIME(I_CODING_TYPE) + DELTA);
 259             }
 260             if( !b_decode )
 261                 intf_WarnMsg( 3, "vpar synchro warning: trashing I" );
 262             break;
 263
 264         case P_CODING_TYPE:
 265             if( S.backward_pts )
 266             {
 267                 pts = S.backward_pts;
 268             }
 269             else
 270             {
 271                 pts = S.current_pts + period * (S.i_n_b + 1);
 272             }
 273
 274             if( (1 + S.i_n_p * (S.i_n_b + 1)) * period >
 275                     S.p_tau[I_CODING_TYPE] )
 276             {
 277                 if( (S.i_n_b + 1) * period > S.p_tau[P_CODING_TYPE] )
 278                 {
 279                     /* Security in case we're _really_ late */
 280                     b_decode = (pts - now > 0);
 281                 }
 282                 else
 283                 {
 284                     b_decode = (pts - now) > (TAU_PRIME(P_CODING_TYPE) + DELTA);
 285                     /* next I */
 286                     b_decode &= (pts - now
 287                                   + period
 288                               * ( (S.i_n_p - S.i_eta_p) * (1 + S.i_n_b) - 1 ))
 289                                 > (TAU_PRIME(P_CODING_TYPE)
 290                                     + TAU_PRIME(I_CODING_TYPE) + DELTA);
 291                 }
 292             }
 293             else
 294             {
 295                 b_decode = 0;
 296             }
 297             break;
 298
 299         case B_CODING_TYPE:
 300             pts = S.current_pts;
 301
 302             if( (S.i_n_b + 1) * period > S.p_tau[P_CODING_TYPE] )
 303             {
 304                 if( period > S.p_tau[B_CODING_TYPE] )
 305                 {
 306                     /* Security in case we're _really_ late */
 307                     b_decode = (pts - now > 0);
 308                 }
 309                 else
 310                 {
 311                     b_decode = (pts - now) > (TAU_PRIME(B_CODING_TYPE) + DELTA);
 312
 313                     /* next P or I */
 314                     b_decode &= (pts - now
 315                                  + period
 316                                  * ( 2 * S.i_n_b - S.i_eta_b + 3))
 317                                    > (TAU_PRIME(B_CODING_TYPE)
 318                                        + TAU_PRIME(P_CODING_TYPE) + DELTA);
 319                 }
 320             }
 321             else
 322             {
 323                 b_decode = 0;
 324             }
 325         }
 326
 327         vlc_mutex_unlock( &p_vpar->synchro.fifo_lock );
 328 #ifdef DEBUG_VPAR
 329         intf_DbgMsg("vpar synchro debug: %s picture scheduled for %s, %s (%lld)",
 330                     i_coding_type == B_CODING_TYPE ? "B" :
 331                     (i_coding_type == P_CODING_TYPE ? "P" : "I"),
 332                     mstrtime(p_date, pts), b_decode ? "decoding" : "trashed",
 333                     S.p_tau[i_coding_type]);
 334 #endif
 335 #ifdef STATS
 336         if( !b_decode )
 337         {
 338             S.i_not_chosen_pic++;
 339         }
 340 #endif
 341         return( b_decode );
 342 #undef S
 343 #undef TAU_PRIME
 344     }
 345 }
 346
 347 /*****************************************************************************
 348  * vpar_SynchroTrash : Update counters when we trash a picture
 349  *****************************************************************************/
 350 void vpar_SynchroTrash( vpar_thread_t * p_vpar, int i_coding_type,
 351                         int i_structure )
 352 {
 353 #ifdef STATS
 354     p_vpar->synchro.i_trashed_pic++;
 355 #endif
 356 }
 357
 358 /*****************************************************************************
 359  * vpar_SynchroDecode : Update timers when we decide to decode a picture
 360  *****************************************************************************/
 361 void vpar_SynchroDecode( vpar_thread_t * p_vpar, int i_coding_type,
 362                          int i_structure )
 363 {
 364     vlc_mutex_lock( &p_vpar->synchro.fifo_lock );
 365
 366     if( ((p_vpar->synchro.i_end + 1 - p_vpar->synchro.i_start)
 367             % MAX_DECODING_PIC) )
 368     {
 369         p_vpar->synchro.p_date_fifo[p_vpar->synchro.i_end] = mdate();
 370         p_vpar->synchro.pi_coding_types[p_vpar->synchro.i_end] = i_coding_type;
 371
 372         FIFO_INCREMENT( i_end );
 373     }
 374     else
 375     {
 376         /* FIFO full, panic() */
 377         intf_ErrMsg("vpar error: synchro fifo full, estimations will be biased");
 378     }
 379     vlc_mutex_unlock( &p_vpar->synchro.fifo_lock );
 380 }
 381
 382 /*****************************************************************************
 383  * vpar_SynchroEnd : Called when the image is totally decoded
 384  *****************************************************************************/
 385 void vpar_SynchroEnd( vpar_thread_t * p_vpar, int i_garbage )
 386 {
 387     mtime_t     tau;
 388     int         i_coding_type;
 389
 390     vlc_mutex_lock( &p_vpar->synchro.fifo_lock );
 391
 392     if (!i_garbage)
 393     {
 394         tau = mdate() - p_vpar->synchro.p_date_fifo[p_vpar->synchro.i_start];
 395         i_coding_type = p_vpar->synchro.pi_coding_types[p_vpar->synchro.i_start];
 396
 397         /* Mean with average tau, to ensure stability. */
 398         p_vpar->synchro.p_tau[i_coding_type] =
 399             (p_vpar->synchro.pi_meaningful[i_coding_type]
 400              * p_vpar->synchro.p_tau[i_coding_type] + tau)
 401             / (p_vpar->synchro.pi_meaningful[i_coding_type] + 1);
 402         if( p_vpar->synchro.pi_meaningful[i_coding_type] < MAX_PIC_AVERAGE )
 403         {
 404             p_vpar->synchro.pi_meaningful[i_coding_type]++;
 405         }
 406 #ifdef DEBUG_VPAR
 407         intf_DbgMsg("vpar synchro debug: finished decoding %s (%lld)",
 408                     i_coding_type == B_CODING_TYPE ? "B" :
 409                     (i_coding_type == P_CODING_TYPE ? "P" : "I"), tau);
 410 #endif
 411     }
 412
 413     FIFO_INCREMENT( i_start );
 414
 415     vlc_mutex_unlock( &p_vpar->synchro.fifo_lock );
 416 }
 417
 418 /*****************************************************************************
 419  * vpar_SynchroDate : When an image has been decoded, ask for its date
 420  *****************************************************************************/
 421 mtime_t vpar_SynchroDate( vpar_thread_t * p_vpar )
 422 {
 423     /* No need to lock, since PTS are only used by the video parser. */
 424     return( p_vpar->synchro.current_pts );
 425 }
 426
 427 /*****************************************************************************
 428  * vpar_SynchroNewPicture: Update stream structure and PTS
 429  *****************************************************************************/
 430 void vpar_SynchroNewPicture( vpar_thread_t * p_vpar, int i_coding_type )
 431 {
 432     /* FIXME: use decoder_fifo callback */
 433     pes_packet_t * p_pes;
 434
 435     switch( i_coding_type )
 436     {
 437     case I_CODING_TYPE:
 438         p_vpar->synchro.i_eta_p = p_vpar->synchro.i_eta_b = 0;
 439         if( p_vpar->synchro.i_eta_p
 440                 && p_vpar->synchro.i_eta_p != p_vpar->synchro.i_n_p )
 441         {
 442             intf_WarnMsg( 1, "Stream periodicity changed from P[%d] to P[%d]",
 443                           p_vpar->synchro.i_n_p, p_vpar->synchro.i_eta_p );
 444             p_vpar->synchro.i_n_p = p_vpar->synchro.i_eta_p;
 445         }
 446 #ifdef STATS
 447         if( p_vpar->synchro.i_type == VPAR_SYNCHRO_DEFAULT )
 448         {
 449             intf_Msg( "vpar synchro stats: I(%lld) P(%lld)[%d] B(%lld)[%d] YUV(%lld) : trashed %d:%d/%d",
 450                   p_vpar->synchro.p_tau[I_CODING_TYPE],
 451                   p_vpar->synchro.p_tau[P_CODING_TYPE],
 452                   p_vpar->synchro.i_n_p,
 453                   p_vpar->synchro.p_tau[B_CODING_TYPE],
 454                   p_vpar->synchro.i_n_b,
 455                   p_vpar->p_vout->render_time,
 456                   p_vpar->synchro.i_not_chosen_pic,
 457                   p_vpar->synchro.i_trashed_pic -
 458                   p_vpar->synchro.i_not_chosen_pic,
 459                   p_vpar->synchro.i_pic );
 460             p_vpar->synchro.i_trashed_pic = p_vpar->synchro.i_not_chosen_pic
 461                 = p_vpar->synchro.i_pic = 0;
 462         }
 463 #endif
 464         break;
 465     case P_CODING_TYPE:
 466         p_vpar->synchro.i_eta_p++;
 467         if( p_vpar->synchro.i_eta_b
 468                 && p_vpar->synchro.i_eta_b != p_vpar->synchro.i_n_b )
 469         {
 470             intf_WarnMsg( 1, "Stream periodicity changed from B[%d] to B[%d]",
 471                           p_vpar->synchro.i_n_b, p_vpar->synchro.i_eta_b );
 472             p_vpar->synchro.i_n_b = p_vpar->synchro.i_eta_b;
 473         }
 474         p_vpar->synchro.i_eta_b = 0;
 475         break;
 476     case B_CODING_TYPE:
 477         p_vpar->synchro.i_eta_b++;
 478         break;
 479     }
 480
 481     p_pes = DECODER_FIFO_START( *p_vpar->bit_stream.p_decoder_fifo );
 482
 483     if( i_coding_type == B_CODING_TYPE )
 484     {
 485         if( p_pes->i_pts )
 486         {
 487             if( p_pes->i_pts < p_vpar->synchro.current_pts )
 488             {
 489                 intf_WarnMsg( 2,
 490                         "vpar synchro warning: pts_date < current_date" );
 491             }
 492             p_vpar->synchro.current_pts = p_pes->i_pts;
 493             p_pes->i_pts = 0;
 494         }
 495         else
 496         {
 497             p_vpar->synchro.current_pts += 1000000
 498                     / (p_vpar->sequence.i_frame_rate) * 1001;
 499         }
 500     }
 501     else
 502     {
 503         if( p_vpar->synchro.backward_pts == 0 )
 504         {
 505             p_vpar->synchro.current_pts += 1000000
 506                     / (p_vpar->sequence.i_frame_rate) * 1001;
 507         }
 508         else
 509         {
 510             if( p_vpar->synchro.backward_pts < p_vpar->synchro.current_pts )
 511             {
 512                 intf_WarnMsg( 2,
 513                         "vpar warning: backward_date < current_date" );
 514             }
 515             p_vpar->synchro.current_pts = p_vpar->synchro.backward_pts;
 516             p_vpar->synchro.backward_pts = 0;
 517         }
 518
 519         if( p_pes->i_pts )
 520         {
 521             /* Store the PTS for the next time we have to date an I picture. */
 522             p_vpar->synchro.backward_pts = p_pes->i_pts;
 523             p_pes->i_pts = 0;
 524         }
 525     }
 526
 527 #ifdef STATS
 528     p_vpar->synchro.i_pic++;
 529 #endif
 530 }
 531
 532 /*****************************************************************************
 533  * SynchroType: Get the user's synchro type
 534  *****************************************************************************
 535  * This function is called at initialization.
 536  *****************************************************************************/
 537 static int SynchroType( void )
 538 {
 539     char * psz_synchro = main_GetPszVariable( VPAR_SYNCHRO_VAR, NULL );
 540
 541     if( psz_synchro == NULL )
 542     {
 543         return VPAR_SYNCHRO_DEFAULT;
 544     }
 545
 546     switch( *psz_synchro++ )
 547     {
 548       case 'i':
 549       case 'I':
 550         switch( *psz_synchro++ )
 551         {
 552           case '\0':
 553             return VPAR_SYNCHRO_I;
 554
 555           case '+':
 556             if( *psz_synchro ) return 0;
 557             return VPAR_SYNCHRO_Iplus;
 558
 559           case 'p':
 560           case 'P':
 561             switch( *psz_synchro++ )
 562             {
 563               case '\0':
 564                 return VPAR_SYNCHRO_IP;
 565
 566               case '+':
 567                 if( *psz_synchro ) return 0;
 568                 return VPAR_SYNCHRO_IPplus;
 569
 570               case 'b':
 571               case 'B':
 572                 if( *psz_synchro ) return 0;
 573                 return VPAR_SYNCHRO_IPB;
 574
 575               default:
 576                 return VPAR_SYNCHRO_DEFAULT;
 577
 578             }
 579
 580           default:
 581             return VPAR_SYNCHRO_DEFAULT;
 582         }
 583     }
 584
 585     return VPAR_SYNCHRO_DEFAULT;
 586 }
 587