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 $
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 to types of machines :
59 * 2T > tauP : machines capable of decoding all P pictures
60 * 14T > tauI : machines capable of decoding all I pictures
62 * 4. Decoding of an I picture
63 * ========================
64 * On fast machines, we decode all I's.
66 * We can decode an I picture if we simply have enough time to decode it
68 * t0 - t > tau´I + DELTA
70 * 4. Decoding of a P picture
71 * =======================
72 * On fast machines, we decode all P's.
74 * First criterion : have time to decode it.
75 * t2 - t > tau´P + DELTA
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
81 * 5. Decoding of a B picture
82 * =======================
83 * First criterion : have time to decode it.
84 * t1 - t > tau´B + DELTA
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
90 * I hope you will have a pleasant flight and do not forget your life
92 * --Meuuh (2000-11-09)
95 /*****************************************************************************
97 *****************************************************************************/
106 #include "intf_msg.h"
108 #include "stream_control.h"
109 #include "input_ext-dec.h"
112 #include "video_output.h"
114 #include "../video_decoder/vdec_idct.h"
115 #include "../video_decoder/video_decoder.h"
116 #include "../video_decoder/vdec_motion.h"
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"
128 static int SynchroType( void );
131 #define DELTA (int)(0.040*CLOCK_FREQ)
133 #define DEFAULT_NB_P 5
134 #define DEFAULT_NB_B 1
136 /*****************************************************************************
137 * vpar_SynchroInit : You know what ?
138 *****************************************************************************/
139 void vpar_SynchroInit( vpar_thread_t * p_vpar )
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 );
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;
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,
161 /* For clarity reasons, we separated the special synchros code from the
162 * mathematical synchro */
164 if( p_vpar->synchro.i_type != VPAR_SYNCHRO_DEFAULT )
166 switch( i_coding_type )
169 /* I, IP, IP+, IPB */
170 if( p_vpar->synchro.i_type == VPAR_SYNCHRO_Iplus )
172 p_vpar->synchro.b_dropped_last = 1;
177 if( p_vpar->synchro.i_type == VPAR_SYNCHRO_I ) /* I */
182 if( p_vpar->synchro.i_type == VPAR_SYNCHRO_Iplus ) /* I+ */
184 if( p_vpar->synchro.b_dropped_last )
186 p_vpar->synchro.b_dropped_last = 0;
195 return( 1 ); /* IP, IP+, IPB */
198 if( p_vpar->synchro.i_type <= VPAR_SYNCHRO_IP ) /* I, IP */
202 else if( p_vpar->synchro.i_type == VPAR_SYNCHRO_IPB ) /* IPB */
207 p_vpar->synchro.b_dropped_last ^= 1; /* IP+ */
208 return( !p_vpar->synchro.b_dropped_last );
210 return( 0 ); /* never reached but gcc yells at me */
214 #define TAU_PRIME( coding_type ) (p_vpar->synchro.p_tau[(coding_type)] \
215 + (p_vpar->synchro.p_tau[(coding_type)] >> 1) \
217 #define S p_vpar->synchro
218 /* VPAR_SYNCHRO_DEFAULT */
219 mtime_t now, pts, period, tau_yuv;
220 boolean_t b_decode = 0;
222 char p_date[MSTRTIME_MAX_SIZE];
226 period = 1000000 / (p_vpar->sequence.i_frame_rate) * 1001;
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 );
232 vlc_mutex_lock( &p_vpar->synchro.fifo_lock );
234 switch( i_coding_type )
239 pts = S.backward_pts;
243 /* displaying order : B B P B B I
245 * | +- current picture
248 pts = S.current_pts + period * (S.i_n_b + 2);
251 if( (1 + S.i_n_p * (S.i_n_b + 1)) * period >
252 S.p_tau[I_CODING_TYPE] )
258 b_decode = (pts - now) > (TAU_PRIME(I_CODING_TYPE) + DELTA);
261 intf_WarnMsg( 3, "vpar synchro warning: trashing I" );
267 pts = S.backward_pts;
271 pts = S.current_pts + period * (S.i_n_b + 1);
274 if( (1 + S.i_n_p * (S.i_n_b + 1)) * period >
275 S.p_tau[I_CODING_TYPE] )
277 if( (S.i_n_b + 1) * period > S.p_tau[P_CODING_TYPE] )
279 /* Security in case we're _really_ late */
280 b_decode = (pts - now > 0);
284 b_decode = (pts - now) > (TAU_PRIME(P_CODING_TYPE) + DELTA);
286 b_decode &= (pts - now
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);
302 if( (S.i_n_b + 1) * period > S.p_tau[P_CODING_TYPE] )
304 if( period > S.p_tau[B_CODING_TYPE] )
306 /* Security in case we're _really_ late */
307 b_decode = (pts - now > 0);
311 b_decode = (pts - now) > (TAU_PRIME(B_CODING_TYPE) + DELTA);
314 b_decode &= (pts - now
316 * ( 2 * S.i_n_b - S.i_eta_b + 3))
317 > (TAU_PRIME(B_CODING_TYPE)
318 + TAU_PRIME(P_CODING_TYPE) + DELTA);
327 vlc_mutex_unlock( &p_vpar->synchro.fifo_lock );
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]);
338 S.i_not_chosen_pic++;
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,
354 p_vpar->synchro.i_trashed_pic++;
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,
364 vlc_mutex_lock( &p_vpar->synchro.fifo_lock );
366 if( ((p_vpar->synchro.i_end + 1 - p_vpar->synchro.i_start)
367 % MAX_DECODING_PIC) )
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;
372 FIFO_INCREMENT( i_end );
376 /* FIFO full, panic() */
377 intf_ErrMsg("vpar error: synchro fifo full, estimations will be biased");
379 vlc_mutex_unlock( &p_vpar->synchro.fifo_lock );
382 /*****************************************************************************
383 * vpar_SynchroEnd : Called when the image is totally decoded
384 *****************************************************************************/
385 void vpar_SynchroEnd( vpar_thread_t * p_vpar, int i_garbage )
390 vlc_mutex_lock( &p_vpar->synchro.fifo_lock );
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];
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 )
404 p_vpar->synchro.pi_meaningful[i_coding_type]++;
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);
413 FIFO_INCREMENT( i_start );
415 vlc_mutex_unlock( &p_vpar->synchro.fifo_lock );
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 )
423 /* No need to lock, since PTS are only used by the video parser. */
424 return( p_vpar->synchro.current_pts );
427 /*****************************************************************************
428 * vpar_SynchroNewPicture: Update stream structure and PTS
429 *****************************************************************************/
430 void vpar_SynchroNewPicture( vpar_thread_t * p_vpar, int i_coding_type )
432 /* FIXME: use decoder_fifo callback */
433 pes_packet_t * p_pes;
435 switch( 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 )
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;
447 if( p_vpar->synchro.i_type == VPAR_SYNCHRO_DEFAULT )
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;
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 )
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;
474 p_vpar->synchro.i_eta_b = 0;
477 p_vpar->synchro.i_eta_b++;
481 p_pes = DECODER_FIFO_START( *p_vpar->bit_stream.p_decoder_fifo );
483 if( i_coding_type == B_CODING_TYPE )
487 if( p_pes->i_pts < p_vpar->synchro.current_pts )
490 "vpar synchro warning: pts_date < current_date" );
492 p_vpar->synchro.current_pts = p_pes->i_pts;
497 p_vpar->synchro.current_pts += 1000000
498 / (p_vpar->sequence.i_frame_rate) * 1001;
503 if( p_vpar->synchro.backward_pts == 0 )
505 p_vpar->synchro.current_pts += 1000000
506 / (p_vpar->sequence.i_frame_rate) * 1001;
510 if( p_vpar->synchro.backward_pts < p_vpar->synchro.current_pts )
513 "vpar warning: backward_date < current_date" );
515 p_vpar->synchro.current_pts = p_vpar->synchro.backward_pts;
516 p_vpar->synchro.backward_pts = 0;
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;
528 p_vpar->synchro.i_pic++;
532 /*****************************************************************************
533 * SynchroType: Get the user's synchro type
534 *****************************************************************************
535 * This function is called at initialization.
536 *****************************************************************************/
537 static int SynchroType( void )
539 char * psz_synchro = main_GetPszVariable( VPAR_SYNCHRO_VAR, NULL );
541 if( psz_synchro == NULL )
543 return VPAR_SYNCHRO_DEFAULT;
546 switch( *psz_synchro++ )
550 switch( *psz_synchro++ )
553 return VPAR_SYNCHRO_I;
556 if( *psz_synchro ) return 0;
557 return VPAR_SYNCHRO_Iplus;
561 switch( *psz_synchro++ )
564 return VPAR_SYNCHRO_IP;
567 if( *psz_synchro ) return 0;
568 return VPAR_SYNCHRO_IPplus;
572 if( *psz_synchro ) return 0;
573 return VPAR_SYNCHRO_IPB;
576 return VPAR_SYNCHRO_DEFAULT;
581 return VPAR_SYNCHRO_DEFAULT;
585 return VPAR_SYNCHRO_DEFAULT;