Hide private vout_synchro_t.
[vlc.git] / src / video_output / vout_synchro.c
1 /*****************************************************************************
2  * vout_synchro.c : frame dropping routines
3  *****************************************************************************
4  * Copyright (C) 1999-2005 the VideoLAN team
5  * $Id$
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., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, 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 three types of machines :
59  *      14T > tauI : machines capable of decoding all I pictures
60  *      2T > tauP  : machines capable of decoding all P pictures
61  *      T > tauB   : machines capable of decoding all B pictures
62  *
63  * 4. Decoding of an I picture
64  *    ========================
65  * On fast machines, we decode all I's.
66  * Otherwise :
67  * We can decode an I picture if we simply have enough time to decode it
68  * before displaying :
69  *      t0 - t > tau´I + DELTA
70  *
71  * 5. Decoding of a P picture
72  *    =======================
73  * On fast machines, we decode all P's.
74  * Otherwise :
75  * First criterion : have time to decode it.
76  *      t2 - t > tau´P + DELTA
77  *
78  * Second criterion : it shouldn't prevent us from displaying the forthcoming
79  * I picture, which is more important.
80  *      t12 - t > tau´P + tau´I + DELTA
81  *
82  * 6. Decoding of a B picture
83  *    =======================
84  * On fast machines, we decode all B's. Otherwise :
85  *      t1 - t > tau´B + DELTA
86  * Since the next displayed I or P is already decoded, we don't have to
87  * worry about it.
88  *
89  * I hope you will have a pleasant flight and do not forget your life
90  * jacket.
91  *                                                  --Meuuh (2000-12-29)
92  */
93
94 /*****************************************************************************
95  * Preamble
96  *****************************************************************************/
97 #include <vlc/vlc.h>
98 #include <vlc_vout.h>
99 #include <vlc_input.h>
100 #include <vlc_vout_synchro.h>
101
102 /*
103  * Local prototypes
104  */
105
106 #define MAX_PIC_AVERAGE         8
107
108 struct vout_synchro_t
109 {
110     VLC_COMMON_MEMBERS
111
112     int             i_frame_rate;
113     int             i_current_rate;
114     vlc_bool_t      b_no_skip;
115     vlc_bool_t      b_quiet;
116
117     /* date of the beginning of the decoding of the current picture */
118     mtime_t         decoding_start;
119
120     /* stream properties */
121     unsigned int    i_n_p, i_n_b;
122
123     /* decoding values */
124     mtime_t         p_tau[4];                  /* average decoding durations */
125     unsigned int    pi_meaningful[4];            /* number of durations read */
126
127     /* render_time filled by SynchroChoose() */
128     int i_render_time;
129
130     /* stream context */
131     int             i_nb_ref;                /* Number of reference pictures */
132     int             i_dec_nb_ref;      /* Number of reference pictures we'll *
133                                         * have if we decode the current pic  */
134     int             i_trash_nb_ref;    /* Number of reference pictures we'll *
135                                         * have if we trash the current pic   */
136     unsigned int    i_eta_p, i_eta_b;
137     mtime_t         backward_pts, current_pts;
138     int             i_current_period;   /* period to add to the next picture */
139     int             i_backward_period;  /* period to add after the next
140                                          * reference picture
141                                          * (backward_period * period / 2) */
142
143     /* statistics */
144     unsigned int    i_trashed_pic, i_not_chosen_pic, i_pic;
145 };
146
147 /* Error margins */
148 #define DELTA                   (int)(0.075*CLOCK_FREQ)
149 #define MAX_VALID_TAU           (int)(0.3*CLOCK_FREQ)
150
151 #define DEFAULT_NB_P            5
152 #define DEFAULT_NB_B            1
153
154 /*****************************************************************************
155  * vout_SynchroInit : You know what ?
156  *****************************************************************************/
157 vout_synchro_t * __vout_SynchroInit( vlc_object_t * p_object,
158                                      int i_frame_rate )
159 {
160     vout_synchro_t * p_synchro = vlc_object_create( p_object,
161                                                   sizeof(vout_synchro_t) );
162     if ( p_synchro == NULL )
163     {
164         msg_Err( p_object, "out of memory" );
165         return NULL;
166     }
167     vlc_object_attach( p_synchro, p_object );
168
169     p_synchro->b_no_skip = !config_GetInt( p_object, "skip-frames" );
170     p_synchro->b_quiet = config_GetInt( p_object, "quiet-synchro" );
171
172     /* We use a fake stream pattern, which is often right. */
173     p_synchro->i_n_p = p_synchro->i_eta_p = DEFAULT_NB_P;
174     p_synchro->i_n_b = p_synchro->i_eta_b = DEFAULT_NB_B;
175     memset( p_synchro->p_tau, 0, 4 * sizeof(mtime_t) );
176     memset( p_synchro->pi_meaningful, 0, 4 * sizeof(unsigned int) );
177     p_synchro->i_nb_ref = 0;
178     p_synchro->i_trash_nb_ref = p_synchro->i_dec_nb_ref = 0;
179     p_synchro->current_pts = mdate() + DEFAULT_PTS_DELAY;
180     p_synchro->backward_pts = 0;
181     p_synchro->i_current_period = p_synchro->i_backward_period = 0;
182     p_synchro->i_trashed_pic = p_synchro->i_not_chosen_pic =
183         p_synchro->i_pic = 0;
184
185     p_synchro->i_frame_rate = i_frame_rate;
186
187     return p_synchro;
188 }
189
190 /*****************************************************************************
191  * vout_SynchroRelease : You know what ?
192  *****************************************************************************/
193 void vout_SynchroRelease( vout_synchro_t * p_synchro )
194 {
195     vlc_object_detach( p_synchro );
196     vlc_object_destroy( p_synchro );
197 }
198
199 /*****************************************************************************
200  * vout_SynchroReset : Reset the reference picture counter
201  *****************************************************************************/
202 void vout_SynchroReset( vout_synchro_t * p_synchro )
203 {
204     p_synchro->i_nb_ref = 0;
205     p_synchro->i_trash_nb_ref = p_synchro->i_dec_nb_ref = 0;
206 }
207
208 /*****************************************************************************
209  * vout_SynchroChoose : Decide whether we will decode a picture or not
210  *****************************************************************************/
211 vlc_bool_t vout_SynchroChoose( vout_synchro_t * p_synchro, int i_coding_type,
212                                int i_render_time, vlc_bool_t b_low_delay )
213 {
214 #define TAU_PRIME( coding_type )    (p_synchro->p_tau[(coding_type)] \
215                                     + (p_synchro->p_tau[(coding_type)] >> 1) \
216                                     + p_synchro->i_render_time)
217 #define S (*p_synchro)
218     mtime_t         now, period;
219     mtime_t         pts = 0;
220     vlc_bool_t      b_decode = 0;
221
222     if ( p_synchro->b_no_skip )
223         return 1;
224
225     now = mdate();
226     period = 1000000 * 1001 / p_synchro->i_frame_rate
227                      * p_synchro->i_current_rate / INPUT_RATE_DEFAULT;
228
229     p_synchro->i_render_time = i_render_time;
230
231     switch( i_coding_type )
232     {
233     case I_CODING_TYPE:
234         if( b_low_delay )
235         {
236             pts = S.current_pts;
237         }
238         else if( S.backward_pts )
239         {
240             pts = S.backward_pts;
241         }
242         else
243         {
244             /* displaying order : B B P B B I
245              *                      ^       ^
246              *                      |       +- current picture
247              *                      +- current PTS
248              */
249             pts = S.current_pts + period * (S.i_n_b + 2);
250         }
251
252         if( (1 + S.i_n_p * (S.i_n_b + 1)) * period >
253                 S.p_tau[I_CODING_TYPE] )
254         {
255             b_decode = 1;
256         }
257         else
258         {
259             b_decode = (pts - now) > (TAU_PRIME(I_CODING_TYPE) + DELTA);
260         }
261         if( !b_decode && !p_synchro->b_quiet )
262         {
263             msg_Warn( p_synchro,
264                       "synchro trashing I ("I64Fd")", pts - now );
265         }
266         break;
267
268     case P_CODING_TYPE:
269         if( b_low_delay )
270         {
271             pts = S.current_pts;
272         }
273         else if( S.backward_pts )
274         {
275             pts = S.backward_pts;
276         }
277         else
278         {
279             pts = S.current_pts + period * (S.i_n_b + 1);
280         }
281
282         if( p_synchro->i_nb_ref < 1 )
283         {
284             b_decode = 0;
285         }
286         else if( (1 + S.i_n_p * (S.i_n_b + 1)) * period >
287                 S.p_tau[I_CODING_TYPE] )
288         {
289             if( (S.i_n_b + 1) * period > S.p_tau[P_CODING_TYPE] )
290             {
291                 /* Security in case we're _really_ late */
292                 b_decode = (pts - now > 0);
293             }
294             else
295             {
296                 b_decode = (pts - now) > (TAU_PRIME(P_CODING_TYPE) + DELTA);
297                 /* next I */
298                 b_decode &= (pts - now
299                               + period
300                           * ( (S.i_n_p - S.i_eta_p) * (1 + S.i_n_b) - 1 ))
301                             > (TAU_PRIME(P_CODING_TYPE)
302                                 + TAU_PRIME(I_CODING_TYPE) + DELTA);
303             }
304         }
305         else
306         {
307             b_decode = 0;
308         }
309         break;
310
311     case B_CODING_TYPE:
312         pts = S.current_pts;
313
314         if( p_synchro->i_nb_ref < 2 )
315         {
316             b_decode = 0;
317         }
318         else if( (S.i_n_b + 1) * period > S.p_tau[P_CODING_TYPE] )
319         {
320             b_decode = (pts - now) > (TAU_PRIME(B_CODING_TYPE) + DELTA);
321         }
322         else
323         {
324             b_decode = 0;
325         }
326     }
327
328     if( !b_decode )
329     {
330         S.i_not_chosen_pic++;
331     }
332     return( b_decode );
333 #undef S
334 #undef TAU_PRIME
335 }
336
337 /*****************************************************************************
338  * vout_SynchroTrash : Update counters when we trash a picture
339  *****************************************************************************/
340 void vout_SynchroTrash( vout_synchro_t * p_synchro )
341 {
342     p_synchro->i_trashed_pic++;
343     p_synchro->i_nb_ref = p_synchro->i_trash_nb_ref;
344 }
345
346 /*****************************************************************************
347  * vout_SynchroDecode : Update timers when we decide to decode a picture
348  *****************************************************************************/
349 void vout_SynchroDecode( vout_synchro_t * p_synchro )
350 {
351     p_synchro->decoding_start = mdate();
352     p_synchro->i_nb_ref = p_synchro->i_dec_nb_ref;
353 }
354
355 /*****************************************************************************
356  * vout_SynchroEnd : Called when the image is totally decoded
357  *****************************************************************************/
358 void vout_SynchroEnd( vout_synchro_t * p_synchro, int i_coding_type,
359                       vlc_bool_t b_garbage )
360 {
361     mtime_t     tau;
362
363     if( !b_garbage )
364     {
365         tau = mdate() - p_synchro->decoding_start;
366
367         /* If duration too high, something happened (pause ?), so don't
368          * take it into account. */
369         if( tau < 3 * p_synchro->p_tau[i_coding_type]
370              || ( !p_synchro->pi_meaningful[i_coding_type]
371                    && tau < MAX_VALID_TAU ) )
372         {
373             /* Mean with average tau, to ensure stability. */
374             p_synchro->p_tau[i_coding_type] =
375                 (p_synchro->pi_meaningful[i_coding_type]
376                  * p_synchro->p_tau[i_coding_type] + tau)
377                 / (p_synchro->pi_meaningful[i_coding_type] + 1);
378             if( p_synchro->pi_meaningful[i_coding_type] < MAX_PIC_AVERAGE )
379             {
380                 p_synchro->pi_meaningful[i_coding_type]++;
381             }
382         }
383     }
384 }
385
386 /*****************************************************************************
387  * vout_SynchroDate : When an image has been decoded, ask for its date
388  *****************************************************************************/
389 mtime_t vout_SynchroDate( vout_synchro_t * p_synchro )
390 {
391     /* No need to lock, since PTS are only used by the video parser. */
392     return p_synchro->current_pts;
393 }
394
395 /*****************************************************************************
396  * vout_SynchroNewPicture: Update stream structure and PTS
397  *****************************************************************************/
398 void vout_SynchroNewPicture( vout_synchro_t * p_synchro, int i_coding_type,
399                              int i_repeat_field, mtime_t next_pts,
400                              mtime_t next_dts, int i_current_rate,
401                              vlc_bool_t b_low_delay )
402 {
403     mtime_t         period = 1000000 * 1001 / p_synchro->i_frame_rate
404                               * i_current_rate / INPUT_RATE_DEFAULT;
405 #if 0
406     mtime_t         now = mdate();
407 #endif
408     p_synchro->i_current_rate = i_current_rate;
409
410     switch( i_coding_type )
411     {
412     case I_CODING_TYPE:
413         if( p_synchro->i_eta_p
414              && p_synchro->i_eta_p != p_synchro->i_n_p )
415         {
416 #if 0
417             if( !p_synchro->b_quiet )
418                 msg_Dbg( p_synchro,
419                          "stream periodicity changed from P[%d] to P[%d]",
420                          p_synchro->i_n_p, p_synchro->i_eta_p );
421 #endif
422             p_synchro->i_n_p = p_synchro->i_eta_p;
423         }
424         p_synchro->i_eta_p = p_synchro->i_eta_b = 0;
425         p_synchro->i_trash_nb_ref = 0;
426         if( p_synchro->i_nb_ref < 2 )
427             p_synchro->i_dec_nb_ref = p_synchro->i_nb_ref + 1;
428         else
429             p_synchro->i_dec_nb_ref = p_synchro->i_nb_ref;
430
431 #if 0
432         if( !p_synchro->b_quiet )
433             msg_Dbg( p_synchro, "I("I64Fd") P("I64Fd")[%d] B("I64Fd")"
434                   "[%d] YUV("I64Fd") : trashed %d:%d/%d",
435                   p_synchro->p_tau[I_CODING_TYPE],
436                   p_synchro->p_tau[P_CODING_TYPE],
437                   p_synchro->i_n_p,
438                   p_synchro->p_tau[B_CODING_TYPE],
439                   p_synchro->i_n_b,
440                   p_synchro->i_render_time,
441                   p_synchro->i_not_chosen_pic,
442                   p_synchro->i_trashed_pic -
443                   p_synchro->i_not_chosen_pic,
444                   p_synchro->i_pic );
445         p_synchro->i_trashed_pic = p_synchro->i_not_chosen_pic
446             = p_synchro->i_pic = 0;
447 #else
448         if( p_synchro->i_pic >= 100 )
449         {
450             if( !p_synchro->b_quiet && p_synchro->i_trashed_pic != 0 )
451                 msg_Dbg( p_synchro, "decoded %d/%d pictures",
452                          p_synchro->i_pic
453                            - p_synchro->i_trashed_pic,
454                          p_synchro->i_pic );
455             p_synchro->i_trashed_pic = p_synchro->i_not_chosen_pic
456                 = p_synchro->i_pic = 0;
457         }
458 #endif
459         break;
460
461     case P_CODING_TYPE:
462         p_synchro->i_eta_p++;
463         if( p_synchro->i_eta_b
464              && p_synchro->i_eta_b != p_synchro->i_n_b )
465         {
466 #if 0
467             if( !p_synchro->b_quiet )
468                 msg_Dbg( p_synchro,
469                          "stream periodicity changed from B[%d] to B[%d]",
470                          p_synchro->i_n_b, p_synchro->i_eta_b );
471 #endif
472             p_synchro->i_n_b = p_synchro->i_eta_b;
473         }
474         p_synchro->i_eta_b = 0;
475         p_synchro->i_dec_nb_ref = 2;
476         p_synchro->i_trash_nb_ref = 0;
477         break;
478
479     case B_CODING_TYPE:
480         p_synchro->i_eta_b++;
481         p_synchro->i_dec_nb_ref = p_synchro->i_trash_nb_ref
482             = p_synchro->i_nb_ref;
483         break;
484     }
485
486     p_synchro->current_pts += p_synchro->i_current_period
487                                         * (period >> 1);
488
489 #define PTS_THRESHOLD   (period >> 2)
490     if( i_coding_type == B_CODING_TYPE || b_low_delay )
491     {
492         /* A video frame can be displayed 1, 2 or 3 times, according to
493          * repeat_first_field, top_field_first, progressive_sequence and
494          * progressive_frame. */
495         p_synchro->i_current_period = i_repeat_field;
496
497         if( next_pts )
498         {
499             if( (next_pts - p_synchro->current_pts
500                     > PTS_THRESHOLD
501                   || p_synchro->current_pts - next_pts
502                     > PTS_THRESHOLD) && !p_synchro->b_quiet )
503             {
504                 msg_Warn( p_synchro, "vout synchro warning: pts != "
505                           "current_date ("I64Fd")",
506                           p_synchro->current_pts
507                               - next_pts );
508             }
509             p_synchro->current_pts = next_pts;
510         }
511     }
512     else
513     {
514         p_synchro->i_current_period = p_synchro->i_backward_period;
515         p_synchro->i_backward_period = i_repeat_field;
516
517         if( p_synchro->backward_pts )
518         {
519             if( next_dts &&
520                 (next_dts - p_synchro->backward_pts
521                     > PTS_THRESHOLD
522                   || p_synchro->backward_pts - next_dts
523                     > PTS_THRESHOLD) && !p_synchro->b_quiet )
524             {
525                 msg_Warn( p_synchro, "backward_pts != dts ("I64Fd")",
526                            next_dts
527                                - p_synchro->backward_pts );
528             }
529             if( (p_synchro->backward_pts - p_synchro->current_pts
530                     > PTS_THRESHOLD
531                   || p_synchro->current_pts - p_synchro->backward_pts
532                     > PTS_THRESHOLD) && !p_synchro->b_quiet )
533             {
534                 msg_Warn( p_synchro,
535                           "backward_pts != current_pts ("I64Fd")",
536                           p_synchro->current_pts
537                               - p_synchro->backward_pts );
538             }
539             p_synchro->current_pts = p_synchro->backward_pts;
540             p_synchro->backward_pts = 0;
541         }
542         else if( next_dts )
543         {
544             if( (next_dts - p_synchro->current_pts
545                     > PTS_THRESHOLD
546                   || p_synchro->current_pts - next_dts
547                     > PTS_THRESHOLD) && !p_synchro->b_quiet )
548             {
549                 msg_Warn( p_synchro, "dts != current_pts ("I64Fd")",
550                           p_synchro->current_pts
551                               - next_dts );
552             }
553             /* By definition of a DTS. */
554             p_synchro->current_pts = next_dts;
555             next_dts = 0;
556         }
557
558         if( next_pts )
559         {
560             /* Store the PTS for the next time we have to date an I picture. */
561             p_synchro->backward_pts = next_pts;
562             next_pts = 0;
563         }
564     }
565 #undef PTS_THRESHOLD
566
567 #if 0
568     /* Removed for incompatibility with slow motion */
569     if( p_synchro->current_pts + DEFAULT_PTS_DELAY < now )
570     {
571         /* We cannot be _that_ late, something must have happened, reinit
572          * the dates. */
573         if( !p_synchro->b_quiet )
574             msg_Warn( p_synchro, "PTS << now ("I64Fd"), resetting",
575                       now - p_synchro->current_pts - DEFAULT_PTS_DELAY );
576         p_synchro->current_pts = now + DEFAULT_PTS_DELAY;
577     }
578     if( p_synchro->backward_pts
579          && p_synchro->backward_pts + DEFAULT_PTS_DELAY < now )
580     {
581         /* The same. */
582         p_synchro->backward_pts = 0;
583     }
584 #endif
585
586     p_synchro->i_pic++;
587 }