1 /*****************************************************************************
2 * vpar_synchro.c : frame dropping routines
3 *****************************************************************************
4 * Copyright (C) 1999, 2000 VideoLAN
5 * $Id: vpar_synchro.c,v 1.1 2001/11/13 12:09:18 henri Exp $
7 * Authors: Christophe Massiot <massiot@via.ecp.fr>
8 * Samuel Hocevar <sam@via.ecp.fr>
9 * Jean-Marc Dressler <polux@via.ecp.fr>
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.
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.
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 *****************************************************************************/
27 * DISCUSSION : How to Write an efficient Frame-Dropping Algorithm
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.
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.
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.
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
63 * 4. Decoding of an I picture
64 * ========================
65 * On fast machines, we decode all I's.
67 * We can decode an I picture if we simply have enough time to decode it
69 * t0 - t > tau´I + DELTA
71 * 5. Decoding of a P picture
72 * =======================
73 * On fast machines, we decode all P's.
75 * First criterion : have time to decode it.
76 * t2 - t > tau´P + DELTA
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
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
89 * I hope you will have a pleasant flight and do not forget your life
91 * --Meuuh (2000-12-29)
94 /*****************************************************************************
96 *****************************************************************************/
99 #include <string.h> /* memcpy(), memset() */
105 #include "intf_msg.h"
110 #include "video_output.h"
112 #include "modules_export.h"
113 #include "stream_control.h"
114 #include "input_ext-dec.h"
116 #include "vdec_ext-plugins.h"
117 #include "vpar_pool.h"
118 #include "video_parser.h"
124 static int SynchroType( void );
127 #define DELTA (int)(0.075*CLOCK_FREQ)
129 #define DEFAULT_NB_P 5
130 #define DEFAULT_NB_B 1
132 /*****************************************************************************
133 * vpar_SynchroInit : You know what ?
134 *****************************************************************************/
135 void vpar_SynchroInit( vpar_thread_t * p_vpar )
137 p_vpar->synchro.i_type = SynchroType();
139 /* We use a fake stream pattern, which is often right. */
140 p_vpar->synchro.i_n_p = p_vpar->synchro.i_eta_p = DEFAULT_NB_P;
141 p_vpar->synchro.i_n_b = p_vpar->synchro.i_eta_b = DEFAULT_NB_B;
142 memset( p_vpar->synchro.p_tau, 0, 4 * sizeof(mtime_t) );
143 memset( p_vpar->synchro.pi_meaningful, 0, 4 * sizeof(unsigned int) );
144 p_vpar->synchro.b_dropped_last = 0;
145 p_vpar->synchro.current_pts = mdate() + DEFAULT_PTS_DELAY;
146 p_vpar->synchro.backward_pts = 0;
147 p_vpar->synchro.i_current_period = p_vpar->synchro.i_backward_period = 0;
148 p_vpar->synchro.i_trashed_pic = p_vpar->synchro.i_not_chosen_pic =
149 p_vpar->synchro.i_pic = 0;
152 /*****************************************************************************
153 * vpar_SynchroChoose : Decide whether we will decode a picture or not
154 *****************************************************************************/
155 boolean_t vpar_SynchroChoose( vpar_thread_t * p_vpar, int i_coding_type,
158 /* For clarity reasons, we separated the special synchros code from the
159 * mathematical synchro */
161 if( p_vpar->synchro.i_type != VPAR_SYNCHRO_DEFAULT )
163 switch( i_coding_type )
166 /* I, IP, IP+, IPB */
167 if( p_vpar->synchro.i_type == VPAR_SYNCHRO_Iplus )
169 p_vpar->synchro.b_dropped_last = 1;
174 if( p_vpar->synchro.i_type == VPAR_SYNCHRO_I ) /* I */
179 if( p_vpar->synchro.i_type == VPAR_SYNCHRO_Iplus ) /* I+ */
181 if( p_vpar->synchro.b_dropped_last )
183 p_vpar->synchro.b_dropped_last = 0;
192 return( 1 ); /* IP, IP+, IPB */
195 if( p_vpar->synchro.i_type <= VPAR_SYNCHRO_IP ) /* I, IP */
199 else if( p_vpar->synchro.i_type == VPAR_SYNCHRO_IPB ) /* IPB */
204 p_vpar->synchro.b_dropped_last ^= 1; /* IP+ */
205 return( !p_vpar->synchro.b_dropped_last );
207 return( 0 ); /* never reached but gcc yells at me */
211 #define TAU_PRIME( coding_type ) (p_vpar->synchro.p_tau[(coding_type)] \
212 + (p_vpar->synchro.p_tau[(coding_type)] >> 1) \
214 #define S p_vpar->synchro
215 /* VPAR_SYNCHRO_DEFAULT */
216 mtime_t now, period, tau_yuv;
218 boolean_t b_decode = 0;
220 char p_date[MSTRTIME_MAX_SIZE];
224 period = 1000000 * 1001 / p_vpar->sequence.i_frame_rate
225 * p_vpar->sequence.i_current_rate / DEFAULT_RATE;
227 vlc_mutex_lock( &p_vpar->p_vout->change_lock );
228 tau_yuv = p_vpar->p_vout->render_time;
229 vlc_mutex_unlock( &p_vpar->p_vout->change_lock );
231 switch( i_coding_type )
236 pts = S.backward_pts;
240 /* displaying order : B B P B B I
242 * | +- current picture
245 pts = S.current_pts + period * (S.i_n_b + 2);
248 if( (1 + S.i_n_p * (S.i_n_b + 1)) * period >
249 S.p_tau[I_CODING_TYPE] )
255 b_decode = (pts - now) > (TAU_PRIME(I_CODING_TYPE) + DELTA);
258 intf_WarnMsg( 1, "vpar synchro warning: trashing I (%lld)",
265 pts = S.backward_pts;
269 pts = S.current_pts + period * (S.i_n_b + 1);
272 if( (1 + S.i_n_p * (S.i_n_b + 1)) * period >
273 S.p_tau[I_CODING_TYPE] )
275 if( (S.i_n_b + 1) * period > S.p_tau[P_CODING_TYPE] )
277 /* Security in case we're _really_ late */
278 b_decode = (pts - now > 0);
282 b_decode = (pts - now) > (TAU_PRIME(P_CODING_TYPE) + DELTA);
284 b_decode &= (pts - now
286 * ( (S.i_n_p - S.i_eta_p) * (1 + S.i_n_b) - 1 ))
287 > (TAU_PRIME(P_CODING_TYPE)
288 + TAU_PRIME(I_CODING_TYPE) + DELTA);
300 if( (S.i_n_b + 1) * period > S.p_tau[P_CODING_TYPE] )
302 b_decode = (pts - now) > (TAU_PRIME(B_CODING_TYPE) + DELTA);
311 intf_DbgMsg("vpar synchro debug: %s picture scheduled for %s, %s (%lld)",
312 i_coding_type == B_CODING_TYPE ? "B" :
313 (i_coding_type == P_CODING_TYPE ? "P" : "I"),
314 mstrtime(p_date, pts), b_decode ? "decoding" : "trashed",
315 S.p_tau[i_coding_type]);
319 S.i_not_chosen_pic++;
327 /*****************************************************************************
328 * vpar_SynchroTrash : Update counters when we trash a picture
329 *****************************************************************************/
330 void vpar_SynchroTrash( vpar_thread_t * p_vpar, int i_coding_type,
333 p_vpar->synchro.i_trashed_pic++;
336 /*****************************************************************************
337 * vpar_SynchroDecode : Update timers when we decide to decode a picture
338 *****************************************************************************/
339 void vpar_SynchroDecode( vpar_thread_t * p_vpar, int i_coding_type,
342 p_vpar->synchro.decoding_start = mdate();
345 /*****************************************************************************
346 * vpar_SynchroEnd : Called when the image is totally decoded
347 *****************************************************************************/
348 void vpar_SynchroEnd( vpar_thread_t * p_vpar, int i_coding_type,
349 int i_structure, int i_garbage )
355 tau = mdate() - p_vpar->synchro.decoding_start;
357 /* If duration too high, something happened (pause ?), so don't
358 * take it into account. */
359 if( tau < 3 * p_vpar->synchro.p_tau[i_coding_type]
360 || !p_vpar->synchro.pi_meaningful[i_coding_type] )
362 /* Mean with average tau, to ensure stability. */
363 p_vpar->synchro.p_tau[i_coding_type] =
364 (p_vpar->synchro.pi_meaningful[i_coding_type]
365 * p_vpar->synchro.p_tau[i_coding_type] + tau)
366 / (p_vpar->synchro.pi_meaningful[i_coding_type] + 1);
367 if( p_vpar->synchro.pi_meaningful[i_coding_type] < MAX_PIC_AVERAGE )
369 p_vpar->synchro.pi_meaningful[i_coding_type]++;
374 intf_DbgMsg("vpar synchro debug: finished decoding %s (%lld)",
375 i_coding_type == B_CODING_TYPE ? "B" :
376 (i_coding_type == P_CODING_TYPE ? "P" : "I"), tau);
381 intf_DbgMsg("vpar synchro debug: aborting %s",
382 i_coding_type == B_CODING_TYPE ? "B" :
383 (i_coding_type == P_CODING_TYPE ? "P" : "I"));
387 /*****************************************************************************
388 * vpar_SynchroDate : When an image has been decoded, ask for its date
389 *****************************************************************************/
390 mtime_t vpar_SynchroDate( vpar_thread_t * p_vpar )
392 /* No need to lock, since PTS are only used by the video parser. */
393 return( p_vpar->synchro.current_pts );
396 /*****************************************************************************
397 * vpar_SynchroNewPicture: Update stream structure and PTS
398 *****************************************************************************/
399 void vpar_SynchroNewPicture( vpar_thread_t * p_vpar, int i_coding_type,
402 mtime_t period = 1000000 * 1001 / p_vpar->sequence.i_frame_rate
403 * p_vpar->sequence.i_current_rate / DEFAULT_RATE;
405 mtime_t now = mdate();
408 switch( i_coding_type )
411 if( p_vpar->synchro.i_eta_p
412 && p_vpar->synchro.i_eta_p != p_vpar->synchro.i_n_p )
414 intf_WarnMsg( 3, "vpar info: stream periodicity changed "
415 "from P[%d] to P[%d]",
416 p_vpar->synchro.i_n_p, p_vpar->synchro.i_eta_p );
417 p_vpar->synchro.i_n_p = p_vpar->synchro.i_eta_p;
419 p_vpar->synchro.i_eta_p = p_vpar->synchro.i_eta_b = 0;
421 if( p_main->b_stats && p_vpar->synchro.i_type == VPAR_SYNCHRO_DEFAULT )
423 intf_Msg( "vpar synchro stats: I(%lld) P(%lld)[%d] B(%lld)[%d] YUV(%lld) : trashed %d:%d/%d",
424 p_vpar->synchro.p_tau[I_CODING_TYPE],
425 p_vpar->synchro.p_tau[P_CODING_TYPE],
426 p_vpar->synchro.i_n_p,
427 p_vpar->synchro.p_tau[B_CODING_TYPE],
428 p_vpar->synchro.i_n_b,
429 p_vpar->p_vout->render_time,
430 p_vpar->synchro.i_not_chosen_pic,
431 p_vpar->synchro.i_trashed_pic -
432 p_vpar->synchro.i_not_chosen_pic,
433 p_vpar->synchro.i_pic );
434 p_vpar->synchro.i_trashed_pic = p_vpar->synchro.i_not_chosen_pic
435 = p_vpar->synchro.i_pic = 0;
440 p_vpar->synchro.i_eta_p++;
441 if( p_vpar->synchro.i_eta_b
442 && p_vpar->synchro.i_eta_b != p_vpar->synchro.i_n_b )
444 intf_WarnMsg( 3, "vpar info: stream periodicity changed "
445 "from B[%d] to B[%d]",
446 p_vpar->synchro.i_n_b, p_vpar->synchro.i_eta_b );
447 p_vpar->synchro.i_n_b = p_vpar->synchro.i_eta_b;
449 p_vpar->synchro.i_eta_b = 0;
452 p_vpar->synchro.i_eta_b++;
456 p_vpar->synchro.current_pts += p_vpar->synchro.i_current_period
459 #define PTS_THRESHOLD (period >> 2)
460 if( i_coding_type == B_CODING_TYPE )
462 /* A video frame can be displayed 1, 2 or 3 times, according to
463 * repeat_first_field, top_field_first, progressive_sequence and
464 * progressive_frame. */
465 p_vpar->synchro.i_current_period = i_repeat_field;
467 if( p_vpar->sequence.next_pts )
469 if( p_vpar->sequence.next_pts - p_vpar->synchro.current_pts
471 || p_vpar->synchro.current_pts - p_vpar->sequence.next_pts
475 "vpar synchro warning: pts != current_date (%lld)",
476 p_vpar->synchro.current_pts
477 - p_vpar->sequence.next_pts );
479 p_vpar->synchro.current_pts = p_vpar->sequence.next_pts;
480 p_vpar->sequence.next_pts = 0;
485 p_vpar->synchro.i_current_period = p_vpar->synchro.i_backward_period;
486 p_vpar->synchro.i_backward_period = i_repeat_field;
488 if( p_vpar->synchro.backward_pts )
490 if( p_vpar->sequence.next_dts &&
491 (p_vpar->sequence.next_dts - p_vpar->synchro.backward_pts
493 || p_vpar->synchro.backward_pts - p_vpar->sequence.next_dts
497 "vpar synchro warning: backward_pts != dts (%lld)",
498 p_vpar->sequence.next_dts
499 - p_vpar->synchro.backward_pts );
501 if( p_vpar->synchro.backward_pts - p_vpar->synchro.current_pts
503 || p_vpar->synchro.current_pts - p_vpar->synchro.backward_pts
507 "vpar synchro warning: backward_pts != current_pts (%lld)",
508 p_vpar->synchro.current_pts - p_vpar->synchro.backward_pts );
510 p_vpar->synchro.current_pts = p_vpar->synchro.backward_pts;
511 p_vpar->synchro.backward_pts = 0;
513 else if( p_vpar->sequence.next_dts )
515 if( p_vpar->sequence.next_dts - p_vpar->synchro.current_pts
517 || p_vpar->synchro.current_pts - p_vpar->sequence.next_dts
521 "vpar synchro warning: dts != current_pts (%lld)",
522 p_vpar->synchro.current_pts
523 - p_vpar->sequence.next_dts );
525 /* By definition of a DTS. */
526 p_vpar->synchro.current_pts = p_vpar->sequence.next_dts;
527 p_vpar->sequence.next_dts = 0;
530 if( p_vpar->sequence.next_pts )
532 /* Store the PTS for the next time we have to date an I picture. */
533 p_vpar->synchro.backward_pts = p_vpar->sequence.next_pts;
534 p_vpar->sequence.next_pts = 0;
540 /* Removed for incompatibility with slow motion */
541 if( p_vpar->synchro.current_pts + DEFAULT_PTS_DELAY < now )
543 /* We cannot be _that_ late, something must have happened, reinit
545 intf_WarnMsg( 2, "PTS << now (%lld), resetting",
546 now - p_vpar->synchro.current_pts - DEFAULT_PTS_DELAY );
547 p_vpar->synchro.current_pts = now + DEFAULT_PTS_DELAY;
549 if( p_vpar->synchro.backward_pts
550 && p_vpar->synchro.backward_pts + DEFAULT_PTS_DELAY < now )
553 p_vpar->synchro.backward_pts = 0;
557 p_vpar->synchro.i_pic++;
560 /*****************************************************************************
561 * SynchroType: Get the user's synchro type
562 *****************************************************************************
563 * This function is called at initialization.
564 *****************************************************************************/
565 static int SynchroType( void )
567 char * psz_synchro = main_GetPszVariable( VPAR_SYNCHRO_VAR, NULL );
569 if( psz_synchro == NULL )
571 return VPAR_SYNCHRO_DEFAULT;
574 switch( *psz_synchro++ )
578 switch( *psz_synchro++ )
581 return VPAR_SYNCHRO_I;
584 if( *psz_synchro ) return 0;
585 return VPAR_SYNCHRO_Iplus;
589 switch( *psz_synchro++ )
592 return VPAR_SYNCHRO_IP;
595 if( *psz_synchro ) return 0;
596 return VPAR_SYNCHRO_IPplus;
600 if( *psz_synchro ) return 0;
601 return VPAR_SYNCHRO_IPB;
604 return VPAR_SYNCHRO_DEFAULT;
609 return VPAR_SYNCHRO_DEFAULT;
613 return VPAR_SYNCHRO_DEFAULT;