1 /*****************************************************************************
2 * vpar_synchro.c : frame dropping routines
3 *****************************************************************************
4 * Copyright (C) 1999-2001 VideoLAN
5 * $Id: synchro.c,v 1.1 2002/08/04 17:23:42 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 *****************************************************************************/
97 #include <stdlib.h> /* free() */
98 #include <string.h> /* memcpy(), memset() */
101 #include <vlc/vout.h>
102 #include <vlc/decoder.h>
104 #include "vdec_ext-plugins.h"
113 static int SynchroType( decoder_fifo_t * );
116 #define DELTA (int)(0.075*CLOCK_FREQ)
118 #define DEFAULT_NB_P 5
119 #define DEFAULT_NB_B 1
121 /*****************************************************************************
122 * vpar_SynchroInit : You know what ?
123 *****************************************************************************/
124 void vpar_SynchroInit( vpar_thread_t * p_vpar )
126 p_vpar->synchro.i_type = SynchroType( p_vpar->p_fifo );
128 /* We use a fake stream pattern, which is often right. */
129 p_vpar->synchro.i_n_p = p_vpar->synchro.i_eta_p = DEFAULT_NB_P;
130 p_vpar->synchro.i_n_b = p_vpar->synchro.i_eta_b = DEFAULT_NB_B;
131 memset( p_vpar->synchro.p_tau, 0, 4 * sizeof(mtime_t) );
132 memset( p_vpar->synchro.pi_meaningful, 0, 4 * sizeof(unsigned int) );
133 p_vpar->synchro.b_dropped_last = 0;
134 p_vpar->synchro.current_pts = mdate() + DEFAULT_PTS_DELAY;
135 p_vpar->synchro.backward_pts = 0;
136 p_vpar->synchro.i_current_period = p_vpar->synchro.i_backward_period = 0;
137 p_vpar->synchro.i_trashed_pic = p_vpar->synchro.i_not_chosen_pic =
138 p_vpar->synchro.i_pic = 0;
141 /*****************************************************************************
142 * vpar_SynchroChoose : Decide whether we will decode a picture or not
143 *****************************************************************************/
144 vlc_bool_t vpar_SynchroChoose( vpar_thread_t * p_vpar, int i_coding_type,
147 /* For clarity reasons, we separated the special synchros code from the
148 * mathematical synchro */
150 if( p_vpar->synchro.i_type != VPAR_SYNCHRO_DEFAULT )
152 switch( i_coding_type )
155 /* I, IP, IP+, IPB */
156 if( p_vpar->synchro.i_type == VPAR_SYNCHRO_Iplus )
158 p_vpar->synchro.b_dropped_last = 1;
163 if( p_vpar->synchro.i_type == VPAR_SYNCHRO_I ) /* I */
168 if( p_vpar->synchro.i_type == VPAR_SYNCHRO_Iplus ) /* I+ */
170 if( p_vpar->synchro.b_dropped_last )
172 p_vpar->synchro.b_dropped_last = 0;
181 return( 1 ); /* IP, IP+, IPB */
184 if( p_vpar->synchro.i_type <= VPAR_SYNCHRO_IP ) /* I, IP */
188 else if( p_vpar->synchro.i_type == VPAR_SYNCHRO_IPB ) /* IPB */
193 p_vpar->synchro.b_dropped_last ^= 1; /* IP+ */
194 return( !p_vpar->synchro.b_dropped_last );
196 return( 0 ); /* never reached but gcc yells at me */
200 #define TAU_PRIME( coding_type ) (p_vpar->synchro.p_tau[(coding_type)] \
201 + (p_vpar->synchro.p_tau[(coding_type)] >> 1) \
203 #define S p_vpar->synchro
204 /* VPAR_SYNCHRO_DEFAULT */
205 mtime_t now, period, tau_yuv;
207 vlc_bool_t b_decode = 0;
210 period = 1000000 * 1001 / p_vpar->sequence.i_frame_rate
211 * p_vpar->sequence.i_current_rate / DEFAULT_RATE;
213 vlc_mutex_lock( &p_vpar->p_vout->change_lock );
214 tau_yuv = p_vpar->p_vout->render_time;
215 vlc_mutex_unlock( &p_vpar->p_vout->change_lock );
217 switch( i_coding_type )
222 pts = S.backward_pts;
226 /* displaying order : B B P B B I
228 * | +- current picture
231 pts = S.current_pts + period * (S.i_n_b + 2);
234 if( (1 + S.i_n_p * (S.i_n_b + 1)) * period >
235 S.p_tau[I_CODING_TYPE] )
241 b_decode = (pts - now) > (TAU_PRIME(I_CODING_TYPE) + DELTA);
244 msg_Warn( p_vpar->p_fifo,
245 "synchro trashing I (%lld)", pts - now );
251 pts = S.backward_pts;
255 pts = S.current_pts + period * (S.i_n_b + 1);
258 if( (1 + S.i_n_p * (S.i_n_b + 1)) * period >
259 S.p_tau[I_CODING_TYPE] )
261 if( (S.i_n_b + 1) * period > S.p_tau[P_CODING_TYPE] )
263 /* Security in case we're _really_ late */
264 b_decode = (pts - now > 0);
268 b_decode = (pts - now) > (TAU_PRIME(P_CODING_TYPE) + DELTA);
270 b_decode &= (pts - now
272 * ( (S.i_n_p - S.i_eta_p) * (1 + S.i_n_b) - 1 ))
273 > (TAU_PRIME(P_CODING_TYPE)
274 + TAU_PRIME(I_CODING_TYPE) + DELTA);
286 if( (S.i_n_b + 1) * period > S.p_tau[P_CODING_TYPE] )
288 b_decode = (pts - now) > (TAU_PRIME(B_CODING_TYPE) + DELTA);
298 S.i_not_chosen_pic++;
306 /*****************************************************************************
307 * vpar_SynchroTrash : Update counters when we trash a picture
308 *****************************************************************************/
309 void vpar_SynchroTrash( vpar_thread_t * p_vpar, int i_coding_type,
312 p_vpar->synchro.i_trashed_pic++;
315 /*****************************************************************************
316 * vpar_SynchroDecode : Update timers when we decide to decode a picture
317 *****************************************************************************/
318 void vpar_SynchroDecode( vpar_thread_t * p_vpar, int i_coding_type,
321 p_vpar->synchro.decoding_start = mdate();
324 /*****************************************************************************
325 * vpar_SynchroEnd : Called when the image is totally decoded
326 *****************************************************************************/
327 void vpar_SynchroEnd( vpar_thread_t * p_vpar, int i_coding_type,
328 int i_structure, int i_garbage )
334 tau = mdate() - p_vpar->synchro.decoding_start;
336 /* If duration too high, something happened (pause ?), so don't
337 * take it into account. */
338 if( tau < 3 * p_vpar->synchro.p_tau[i_coding_type]
339 || !p_vpar->synchro.pi_meaningful[i_coding_type] )
341 /* Mean with average tau, to ensure stability. */
342 p_vpar->synchro.p_tau[i_coding_type] =
343 (p_vpar->synchro.pi_meaningful[i_coding_type]
344 * p_vpar->synchro.p_tau[i_coding_type] + tau)
345 / (p_vpar->synchro.pi_meaningful[i_coding_type] + 1);
346 if( p_vpar->synchro.pi_meaningful[i_coding_type] < MAX_PIC_AVERAGE )
348 p_vpar->synchro.pi_meaningful[i_coding_type]++;
354 /*****************************************************************************
355 * vpar_SynchroDate : When an image has been decoded, ask for its date
356 *****************************************************************************/
357 mtime_t vpar_SynchroDate( vpar_thread_t * p_vpar )
359 /* No need to lock, since PTS are only used by the video parser. */
360 return( p_vpar->synchro.current_pts );
363 /*****************************************************************************
364 * vpar_SynchroNewPicture: Update stream structure and PTS
365 *****************************************************************************/
366 void vpar_SynchroNewPicture( vpar_thread_t * p_vpar, int i_coding_type,
369 mtime_t period = 1000000 * 1001 / p_vpar->sequence.i_frame_rate
370 * p_vpar->sequence.i_current_rate / DEFAULT_RATE;
372 mtime_t now = mdate();
375 switch( i_coding_type )
378 if( p_vpar->synchro.i_eta_p
379 && p_vpar->synchro.i_eta_p != p_vpar->synchro.i_n_p )
381 msg_Warn( p_vpar->p_fifo,
382 "stream periodicity changed from P[%d] to P[%d]",
383 p_vpar->synchro.i_n_p, p_vpar->synchro.i_eta_p );
384 p_vpar->synchro.i_n_p = p_vpar->synchro.i_eta_p;
386 p_vpar->synchro.i_eta_p = p_vpar->synchro.i_eta_b = 0;
388 if( p_vpar->synchro.i_type == VPAR_SYNCHRO_DEFAULT )
390 msg_Dbg( p_vpar->p_fifo, "I(%lld) P(%lld)[%d] B(%lld)[%d] YUV(%lld) : trashed %d:%d/%d",
391 p_vpar->synchro.p_tau[I_CODING_TYPE],
392 p_vpar->synchro.p_tau[P_CODING_TYPE],
393 p_vpar->synchro.i_n_p,
394 p_vpar->synchro.p_tau[B_CODING_TYPE],
395 p_vpar->synchro.i_n_b,
396 p_vpar->p_vout->render_time,
397 p_vpar->synchro.i_not_chosen_pic,
398 p_vpar->synchro.i_trashed_pic -
399 p_vpar->synchro.i_not_chosen_pic,
400 p_vpar->synchro.i_pic );
401 p_vpar->synchro.i_trashed_pic = p_vpar->synchro.i_not_chosen_pic
402 = p_vpar->synchro.i_pic = 0;
407 p_vpar->synchro.i_eta_p++;
408 if( p_vpar->synchro.i_eta_b
409 && p_vpar->synchro.i_eta_b != p_vpar->synchro.i_n_b )
411 msg_Warn( p_vpar->p_fifo,
412 "stream periodicity changed from B[%d] to B[%d]",
413 p_vpar->synchro.i_n_b, p_vpar->synchro.i_eta_b );
414 p_vpar->synchro.i_n_b = p_vpar->synchro.i_eta_b;
416 p_vpar->synchro.i_eta_b = 0;
419 p_vpar->synchro.i_eta_b++;
423 p_vpar->synchro.current_pts += p_vpar->synchro.i_current_period
426 #define PTS_THRESHOLD (period >> 2)
427 if( i_coding_type == B_CODING_TYPE )
429 /* A video frame can be displayed 1, 2 or 3 times, according to
430 * repeat_first_field, top_field_first, progressive_sequence and
431 * progressive_frame. */
432 p_vpar->synchro.i_current_period = i_repeat_field;
434 if( p_vpar->sequence.next_pts )
436 if( p_vpar->sequence.next_pts - p_vpar->synchro.current_pts
438 || p_vpar->synchro.current_pts - p_vpar->sequence.next_pts
441 msg_Warn( p_vpar->p_fifo,
442 "vpar synchro warning: pts != current_date (%lld)",
443 p_vpar->synchro.current_pts
444 - p_vpar->sequence.next_pts );
446 p_vpar->synchro.current_pts = p_vpar->sequence.next_pts;
447 p_vpar->sequence.next_pts = 0;
452 p_vpar->synchro.i_current_period = p_vpar->synchro.i_backward_period;
453 p_vpar->synchro.i_backward_period = i_repeat_field;
455 if( p_vpar->synchro.backward_pts )
457 if( p_vpar->sequence.next_dts &&
458 (p_vpar->sequence.next_dts - p_vpar->synchro.backward_pts
460 || p_vpar->synchro.backward_pts - p_vpar->sequence.next_dts
463 msg_Warn( p_vpar->p_fifo, "backward_pts != dts (%lld)",
464 p_vpar->sequence.next_dts
465 - p_vpar->synchro.backward_pts );
467 if( p_vpar->synchro.backward_pts - p_vpar->synchro.current_pts
469 || p_vpar->synchro.current_pts - p_vpar->synchro.backward_pts
472 msg_Warn( p_vpar->p_fifo,
473 "backward_pts != current_pts (%lld)",
474 p_vpar->synchro.current_pts
475 - p_vpar->synchro.backward_pts );
477 p_vpar->synchro.current_pts = p_vpar->synchro.backward_pts;
478 p_vpar->synchro.backward_pts = 0;
480 else if( p_vpar->sequence.next_dts )
482 if( p_vpar->sequence.next_dts - p_vpar->synchro.current_pts
484 || p_vpar->synchro.current_pts - p_vpar->sequence.next_dts
487 msg_Warn( p_vpar->p_fifo, "dts != current_pts (%lld)",
488 p_vpar->synchro.current_pts
489 - p_vpar->sequence.next_dts );
491 /* By definition of a DTS. */
492 p_vpar->synchro.current_pts = p_vpar->sequence.next_dts;
493 p_vpar->sequence.next_dts = 0;
496 if( p_vpar->sequence.next_pts )
498 /* Store the PTS for the next time we have to date an I picture. */
499 p_vpar->synchro.backward_pts = p_vpar->sequence.next_pts;
500 p_vpar->sequence.next_pts = 0;
506 /* Removed for incompatibility with slow motion */
507 if( p_vpar->synchro.current_pts + DEFAULT_PTS_DELAY < now )
509 /* We cannot be _that_ late, something must have happened, reinit
511 msg_Warn( p_vpar->p_fifo, "PTS << now (%lld), resetting",
512 now - p_vpar->synchro.current_pts - DEFAULT_PTS_DELAY );
513 p_vpar->synchro.current_pts = now + DEFAULT_PTS_DELAY;
515 if( p_vpar->synchro.backward_pts
516 && p_vpar->synchro.backward_pts + DEFAULT_PTS_DELAY < now )
519 p_vpar->synchro.backward_pts = 0;
523 p_vpar->synchro.i_pic++;
526 /*****************************************************************************
527 * SynchroType: Get the user's synchro type
528 *****************************************************************************
529 * This function is called at initialization.
530 *****************************************************************************/
531 static int SynchroType( decoder_fifo_t *p_this )
533 char psz_synchro_tmp[5];
534 char * psz_synchro = config_GetPsz( p_this, "vpar-synchro" );
536 if( psz_synchro == NULL )
538 return VPAR_SYNCHRO_DEFAULT;
541 strncpy( psz_synchro_tmp, psz_synchro, 5);
543 psz_synchro = psz_synchro_tmp;
545 switch( *psz_synchro++ )
549 switch( *psz_synchro++ )
552 return VPAR_SYNCHRO_I;
555 if( *psz_synchro ) return 0;
556 return VPAR_SYNCHRO_Iplus;
560 switch( *psz_synchro++ )
563 return VPAR_SYNCHRO_IP;
566 if( *psz_synchro ) return 0;
567 return VPAR_SYNCHRO_IPplus;
571 if( *psz_synchro ) return 0;
572 return VPAR_SYNCHRO_IPB;
575 return VPAR_SYNCHRO_DEFAULT;
580 return VPAR_SYNCHRO_DEFAULT;
584 return VPAR_SYNCHRO_DEFAULT;