1 /*****************************************************************************
2 * vpar_synchro.c : frame dropping routines
3 *****************************************************************************
4 * Copyright (C) 1999-2001 VideoLAN
5 * $Id: vpar_synchro.c,v 1.3 2001/12/07 18:33:08 sam 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() */
102 #include "intf_msg.h"
107 #include "video_output.h"
109 #include "modules_export.h"
110 #include "stream_control.h"
111 #include "input_ext-dec.h"
113 #include "vdec_ext-plugins.h"
114 #include "vpar_pool.h"
115 #include "video_parser.h"
121 static int SynchroType( void );
124 #define DELTA (int)(0.075*CLOCK_FREQ)
126 #define DEFAULT_NB_P 5
127 #define DEFAULT_NB_B 1
129 /*****************************************************************************
130 * vpar_SynchroInit : You know what ?
131 *****************************************************************************/
132 void vpar_SynchroInit( vpar_thread_t * p_vpar )
134 p_vpar->synchro.i_type = SynchroType();
136 /* We use a fake stream pattern, which is often right. */
137 p_vpar->synchro.i_n_p = p_vpar->synchro.i_eta_p = DEFAULT_NB_P;
138 p_vpar->synchro.i_n_b = p_vpar->synchro.i_eta_b = DEFAULT_NB_B;
139 memset( p_vpar->synchro.p_tau, 0, 4 * sizeof(mtime_t) );
140 memset( p_vpar->synchro.pi_meaningful, 0, 4 * sizeof(unsigned int) );
141 p_vpar->synchro.b_dropped_last = 0;
142 p_vpar->synchro.current_pts = mdate() + DEFAULT_PTS_DELAY;
143 p_vpar->synchro.backward_pts = 0;
144 p_vpar->synchro.i_current_period = p_vpar->synchro.i_backward_period = 0;
145 p_vpar->synchro.i_trashed_pic = p_vpar->synchro.i_not_chosen_pic =
146 p_vpar->synchro.i_pic = 0;
149 /*****************************************************************************
150 * vpar_SynchroChoose : Decide whether we will decode a picture or not
151 *****************************************************************************/
152 boolean_t vpar_SynchroChoose( vpar_thread_t * p_vpar, int i_coding_type,
155 /* For clarity reasons, we separated the special synchros code from the
156 * mathematical synchro */
158 if( p_vpar->synchro.i_type != VPAR_SYNCHRO_DEFAULT )
160 switch( i_coding_type )
163 /* I, IP, IP+, IPB */
164 if( p_vpar->synchro.i_type == VPAR_SYNCHRO_Iplus )
166 p_vpar->synchro.b_dropped_last = 1;
171 if( p_vpar->synchro.i_type == VPAR_SYNCHRO_I ) /* I */
176 if( p_vpar->synchro.i_type == VPAR_SYNCHRO_Iplus ) /* I+ */
178 if( p_vpar->synchro.b_dropped_last )
180 p_vpar->synchro.b_dropped_last = 0;
189 return( 1 ); /* IP, IP+, IPB */
192 if( p_vpar->synchro.i_type <= VPAR_SYNCHRO_IP ) /* I, IP */
196 else if( p_vpar->synchro.i_type == VPAR_SYNCHRO_IPB ) /* IPB */
201 p_vpar->synchro.b_dropped_last ^= 1; /* IP+ */
202 return( !p_vpar->synchro.b_dropped_last );
204 return( 0 ); /* never reached but gcc yells at me */
208 #define TAU_PRIME( coding_type ) (p_vpar->synchro.p_tau[(coding_type)] \
209 + (p_vpar->synchro.p_tau[(coding_type)] >> 1) \
211 #define S p_vpar->synchro
212 /* VPAR_SYNCHRO_DEFAULT */
213 mtime_t now, period, tau_yuv;
215 boolean_t b_decode = 0;
217 char p_date[MSTRTIME_MAX_SIZE];
221 period = 1000000 * 1001 / p_vpar->sequence.i_frame_rate
222 * p_vpar->sequence.i_current_rate / DEFAULT_RATE;
224 vlc_mutex_lock( &p_vpar->p_vout->change_lock );
225 tau_yuv = p_vpar->p_vout->render_time;
226 vlc_mutex_unlock( &p_vpar->p_vout->change_lock );
228 switch( i_coding_type )
233 pts = S.backward_pts;
237 /* displaying order : B B P B B I
239 * | +- current picture
242 pts = S.current_pts + period * (S.i_n_b + 2);
245 if( (1 + S.i_n_p * (S.i_n_b + 1)) * period >
246 S.p_tau[I_CODING_TYPE] )
252 b_decode = (pts - now) > (TAU_PRIME(I_CODING_TYPE) + DELTA);
255 intf_WarnMsg( 1, "vpar synchro warning: trashing I (%lld)",
262 pts = S.backward_pts;
266 pts = S.current_pts + period * (S.i_n_b + 1);
269 if( (1 + S.i_n_p * (S.i_n_b + 1)) * period >
270 S.p_tau[I_CODING_TYPE] )
272 if( (S.i_n_b + 1) * period > S.p_tau[P_CODING_TYPE] )
274 /* Security in case we're _really_ late */
275 b_decode = (pts - now > 0);
279 b_decode = (pts - now) > (TAU_PRIME(P_CODING_TYPE) + DELTA);
281 b_decode &= (pts - now
283 * ( (S.i_n_p - S.i_eta_p) * (1 + S.i_n_b) - 1 ))
284 > (TAU_PRIME(P_CODING_TYPE)
285 + TAU_PRIME(I_CODING_TYPE) + DELTA);
297 if( (S.i_n_b + 1) * period > S.p_tau[P_CODING_TYPE] )
299 b_decode = (pts - now) > (TAU_PRIME(B_CODING_TYPE) + DELTA);
308 intf_DbgMsg("vpar synchro debug: %s picture scheduled for %s, %s (%lld)",
309 i_coding_type == B_CODING_TYPE ? "B" :
310 (i_coding_type == P_CODING_TYPE ? "P" : "I"),
311 mstrtime(p_date, pts), b_decode ? "decoding" : "trashed",
312 S.p_tau[i_coding_type]);
316 S.i_not_chosen_pic++;
324 /*****************************************************************************
325 * vpar_SynchroTrash : Update counters when we trash a picture
326 *****************************************************************************/
327 void vpar_SynchroTrash( vpar_thread_t * p_vpar, int i_coding_type,
330 p_vpar->synchro.i_trashed_pic++;
333 /*****************************************************************************
334 * vpar_SynchroDecode : Update timers when we decide to decode a picture
335 *****************************************************************************/
336 void vpar_SynchroDecode( vpar_thread_t * p_vpar, int i_coding_type,
339 p_vpar->synchro.decoding_start = mdate();
342 /*****************************************************************************
343 * vpar_SynchroEnd : Called when the image is totally decoded
344 *****************************************************************************/
345 void vpar_SynchroEnd( vpar_thread_t * p_vpar, int i_coding_type,
346 int i_structure, int i_garbage )
352 tau = mdate() - p_vpar->synchro.decoding_start;
354 /* If duration too high, something happened (pause ?), so don't
355 * take it into account. */
356 if( tau < 3 * p_vpar->synchro.p_tau[i_coding_type]
357 || !p_vpar->synchro.pi_meaningful[i_coding_type] )
359 /* Mean with average tau, to ensure stability. */
360 p_vpar->synchro.p_tau[i_coding_type] =
361 (p_vpar->synchro.pi_meaningful[i_coding_type]
362 * p_vpar->synchro.p_tau[i_coding_type] + tau)
363 / (p_vpar->synchro.pi_meaningful[i_coding_type] + 1);
364 if( p_vpar->synchro.pi_meaningful[i_coding_type] < MAX_PIC_AVERAGE )
366 p_vpar->synchro.pi_meaningful[i_coding_type]++;
371 intf_DbgMsg("vpar synchro debug: finished decoding %s (%lld)",
372 i_coding_type == B_CODING_TYPE ? "B" :
373 (i_coding_type == P_CODING_TYPE ? "P" : "I"), tau);
378 intf_DbgMsg("vpar synchro debug: aborting %s",
379 i_coding_type == B_CODING_TYPE ? "B" :
380 (i_coding_type == P_CODING_TYPE ? "P" : "I"));
384 /*****************************************************************************
385 * vpar_SynchroDate : When an image has been decoded, ask for its date
386 *****************************************************************************/
387 mtime_t vpar_SynchroDate( vpar_thread_t * p_vpar )
389 /* No need to lock, since PTS are only used by the video parser. */
390 return( p_vpar->synchro.current_pts );
393 /*****************************************************************************
394 * vpar_SynchroNewPicture: Update stream structure and PTS
395 *****************************************************************************/
396 void vpar_SynchroNewPicture( vpar_thread_t * p_vpar, int i_coding_type,
399 mtime_t period = 1000000 * 1001 / p_vpar->sequence.i_frame_rate
400 * p_vpar->sequence.i_current_rate / DEFAULT_RATE;
402 mtime_t now = mdate();
405 switch( i_coding_type )
408 if( p_vpar->synchro.i_eta_p
409 && p_vpar->synchro.i_eta_p != p_vpar->synchro.i_n_p )
411 intf_WarnMsg( 3, "vpar info: stream periodicity changed "
412 "from P[%d] to P[%d]",
413 p_vpar->synchro.i_n_p, p_vpar->synchro.i_eta_p );
414 p_vpar->synchro.i_n_p = p_vpar->synchro.i_eta_p;
416 p_vpar->synchro.i_eta_p = p_vpar->synchro.i_eta_b = 0;
418 if( p_main->b_stats && p_vpar->synchro.i_type == VPAR_SYNCHRO_DEFAULT )
420 intf_Msg( "vpar synchro stats: I(%lld) P(%lld)[%d] B(%lld)[%d] YUV(%lld) : trashed %d:%d/%d",
421 p_vpar->synchro.p_tau[I_CODING_TYPE],
422 p_vpar->synchro.p_tau[P_CODING_TYPE],
423 p_vpar->synchro.i_n_p,
424 p_vpar->synchro.p_tau[B_CODING_TYPE],
425 p_vpar->synchro.i_n_b,
426 p_vpar->p_vout->render_time,
427 p_vpar->synchro.i_not_chosen_pic,
428 p_vpar->synchro.i_trashed_pic -
429 p_vpar->synchro.i_not_chosen_pic,
430 p_vpar->synchro.i_pic );
431 p_vpar->synchro.i_trashed_pic = p_vpar->synchro.i_not_chosen_pic
432 = p_vpar->synchro.i_pic = 0;
437 p_vpar->synchro.i_eta_p++;
438 if( p_vpar->synchro.i_eta_b
439 && p_vpar->synchro.i_eta_b != p_vpar->synchro.i_n_b )
441 intf_WarnMsg( 3, "vpar info: stream periodicity changed "
442 "from B[%d] to B[%d]",
443 p_vpar->synchro.i_n_b, p_vpar->synchro.i_eta_b );
444 p_vpar->synchro.i_n_b = p_vpar->synchro.i_eta_b;
446 p_vpar->synchro.i_eta_b = 0;
449 p_vpar->synchro.i_eta_b++;
453 p_vpar->synchro.current_pts += p_vpar->synchro.i_current_period
456 #define PTS_THRESHOLD (period >> 2)
457 if( i_coding_type == B_CODING_TYPE )
459 /* A video frame can be displayed 1, 2 or 3 times, according to
460 * repeat_first_field, top_field_first, progressive_sequence and
461 * progressive_frame. */
462 p_vpar->synchro.i_current_period = i_repeat_field;
464 if( p_vpar->sequence.next_pts )
466 if( p_vpar->sequence.next_pts - p_vpar->synchro.current_pts
468 || p_vpar->synchro.current_pts - p_vpar->sequence.next_pts
472 "vpar synchro warning: pts != current_date (%lld)",
473 p_vpar->synchro.current_pts
474 - p_vpar->sequence.next_pts );
476 p_vpar->synchro.current_pts = p_vpar->sequence.next_pts;
477 p_vpar->sequence.next_pts = 0;
482 p_vpar->synchro.i_current_period = p_vpar->synchro.i_backward_period;
483 p_vpar->synchro.i_backward_period = i_repeat_field;
485 if( p_vpar->synchro.backward_pts )
487 if( p_vpar->sequence.next_dts &&
488 (p_vpar->sequence.next_dts - p_vpar->synchro.backward_pts
490 || p_vpar->synchro.backward_pts - p_vpar->sequence.next_dts
494 "vpar synchro warning: backward_pts != dts (%lld)",
495 p_vpar->sequence.next_dts
496 - p_vpar->synchro.backward_pts );
498 if( p_vpar->synchro.backward_pts - p_vpar->synchro.current_pts
500 || p_vpar->synchro.current_pts - p_vpar->synchro.backward_pts
504 "vpar synchro warning: backward_pts != current_pts (%lld)",
505 p_vpar->synchro.current_pts - p_vpar->synchro.backward_pts );
507 p_vpar->synchro.current_pts = p_vpar->synchro.backward_pts;
508 p_vpar->synchro.backward_pts = 0;
510 else if( p_vpar->sequence.next_dts )
512 if( p_vpar->sequence.next_dts - p_vpar->synchro.current_pts
514 || p_vpar->synchro.current_pts - p_vpar->sequence.next_dts
518 "vpar synchro warning: dts != current_pts (%lld)",
519 p_vpar->synchro.current_pts
520 - p_vpar->sequence.next_dts );
522 /* By definition of a DTS. */
523 p_vpar->synchro.current_pts = p_vpar->sequence.next_dts;
524 p_vpar->sequence.next_dts = 0;
527 if( p_vpar->sequence.next_pts )
529 /* Store the PTS for the next time we have to date an I picture. */
530 p_vpar->synchro.backward_pts = p_vpar->sequence.next_pts;
531 p_vpar->sequence.next_pts = 0;
537 /* Removed for incompatibility with slow motion */
538 if( p_vpar->synchro.current_pts + DEFAULT_PTS_DELAY < now )
540 /* We cannot be _that_ late, something must have happened, reinit
542 intf_WarnMsg( 2, "PTS << now (%lld), resetting",
543 now - p_vpar->synchro.current_pts - DEFAULT_PTS_DELAY );
544 p_vpar->synchro.current_pts = now + DEFAULT_PTS_DELAY;
546 if( p_vpar->synchro.backward_pts
547 && p_vpar->synchro.backward_pts + DEFAULT_PTS_DELAY < now )
550 p_vpar->synchro.backward_pts = 0;
554 p_vpar->synchro.i_pic++;
557 /*****************************************************************************
558 * SynchroType: Get the user's synchro type
559 *****************************************************************************
560 * This function is called at initialization.
561 *****************************************************************************/
562 static int SynchroType( void )
564 char * psz_synchro = main_GetPszVariable( VPAR_SYNCHRO_VAR, NULL );
566 if( psz_synchro == NULL )
568 return VPAR_SYNCHRO_DEFAULT;
571 switch( *psz_synchro++ )
575 switch( *psz_synchro++ )
578 return VPAR_SYNCHRO_I;
581 if( *psz_synchro ) return 0;
582 return VPAR_SYNCHRO_Iplus;
586 switch( *psz_synchro++ )
589 return VPAR_SYNCHRO_IP;
592 if( *psz_synchro ) return 0;
593 return VPAR_SYNCHRO_IPplus;
597 if( *psz_synchro ) return 0;
598 return VPAR_SYNCHRO_IPB;
601 return VPAR_SYNCHRO_DEFAULT;
606 return VPAR_SYNCHRO_DEFAULT;
610 return VPAR_SYNCHRO_DEFAULT;