major design changes: use glib event loop for MIDI thread/UI; rework design of BaseUI...
[ardour.git] / libs / ardour / session_process.cc
1 /*
2     Copyright (C) 1999-2002 Paul Davis
3
4     This program is free software; you can redistribute it and/or modify
5     it under the terms of the GNU General Public License as published by
6     the Free Software Foundation; either version 2 of the License, or
7     (at your option) any later version.
8
9     This program is distributed in the hope that it will be useful,
10     but WITHOUT ANY WARRANTY; without even the implied warranty of
11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12     GNU General Public License for more details.
13
14     You should have received a copy of the GNU General Public License
15     along with this program; if not, write to the Free Software
16     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
17
18 */
19
20 #include <cmath>
21 #include <cerrno>
22 #include <algorithm>
23 #include <unistd.h>
24
25 #include "pbd/error.h"
26 #include "pbd/enumwriter.h"
27
28 #include <glibmm/thread.h>
29
30 #include "ardour/ardour.h"
31 #include "ardour/audio_diskstream.h"
32 #include "ardour/audioengine.h"
33 #include "ardour/auditioner.h"
34 #include "ardour/butler.h"
35 #include "ardour/debug.h"
36 #include "ardour/session.h"
37 #include "ardour/slave.h"
38 #include "ardour/timestamps.h"
39
40 #include "midi++/manager.h"
41
42 #include "i18n.h"
43
44 using namespace ARDOUR;
45 using namespace PBD;
46 using namespace std;
47
48 /** Called by the audio engine when there is work to be done with JACK.
49  * @param nframes Number of frames to process.
50  */
51 void
52 Session::process (nframes_t nframes)
53 {
54         MIDI::Manager::instance()->cycle_start(nframes);
55
56         _silent = false;
57
58         if (processing_blocked()) {
59                 _silent = true;
60                 return;
61         }
62
63         if (non_realtime_work_pending()) {
64                 if (!_butler->transport_work_requested ()) {
65                         post_transport ();
66                 }
67         }
68
69         (this->*process_function) (nframes);
70
71         // the ticker is for sending time information like MidiClock
72         nframes_t transport_frames = transport_frame();
73         BBT_Time  transport_bbt;
74         bbt_time(transport_frames, transport_bbt);
75         Timecode::Time transport_timecode;
76         timecode_time(transport_frames, transport_timecode);
77         tick (transport_frames, transport_bbt, transport_timecode); /* EMIT SIGNAL */
78
79         SendFeedback (); /* EMIT SIGNAL */
80
81         MIDI::Manager::instance()->cycle_end();
82 }
83
84 void
85 Session::prepare_diskstreams ()
86 {
87         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
88         for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
89                 (*i)->prepare ();
90         }
91 }
92
93 int
94 Session::fail_roll (nframes_t nframes)
95 {
96         return no_roll (nframes);
97 }
98
99 int
100 Session::no_roll (nframes_t nframes)
101 {
102         nframes_t end_frame = _transport_frame + nframes; // FIXME: varispeed + no_roll ??
103         int ret = 0;
104         bool declick = get_transport_declick_required();
105         boost::shared_ptr<RouteList> r = routes.reader ();
106
107         if (_click_io) {
108                 _click_io->silence (nframes);
109         }
110
111         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
112
113                 if ((*i)->is_hidden()) {
114                         continue;
115                 }
116
117                 (*i)->set_pending_declick (declick);
118
119                 if ((*i)->no_roll (nframes, _transport_frame, end_frame, non_realtime_work_pending(),
120                                    actively_recording(), declick)) {
121                         error << string_compose(_("Session: error in no roll for %1"), (*i)->name()) << endmsg;
122                         ret = -1;
123                         break;
124                 }
125         }
126
127         return ret;
128 }
129
130 int
131 Session::process_routes (nframes_t nframes)
132 {
133         bool record_active;
134         int  declick = get_transport_declick_required();
135         bool rec_monitors = get_rec_monitors_input();
136         boost::shared_ptr<RouteList> r = routes.reader ();
137
138         if (transport_sub_state & StopPendingCapture) {
139                 /* force a declick out */
140                 declick = -1;
141         }
142
143         record_active = actively_recording(); // || (get_record_enabled() && get_punch_in());
144
145         const nframes_t start_frame = _transport_frame;
146         const nframes_t end_frame = _transport_frame + (nframes_t)floor(nframes * _transport_speed);
147
148         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
149
150                 int ret;
151
152                 if ((*i)->is_hidden()) {
153                         continue;
154                 }
155
156                 (*i)->set_pending_declick (declick);
157
158                 if ((ret = (*i)->roll (nframes, start_frame, end_frame, declick, record_active, rec_monitors)) < 0) {
159
160                         /* we have to do this here. Route::roll() for an AudioTrack will have called AudioDiskstream::process(),
161                            and the DS will expect AudioDiskstream::commit() to be called. but we're aborting from that
162                            call path, so make sure we release any outstanding locks here before we return failure.
163                         */
164
165                         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
166                         for (DiskstreamList::iterator ids = dsl->begin(); ids != dsl->end(); ++ids) {
167                                 (*ids)->recover ();
168                         }
169
170                         stop_transport ();
171                         return -1;
172                 }
173         }
174
175         return 0;
176 }
177
178 int
179 Session::silent_process_routes (nframes_t nframes)
180 {
181         bool record_active = actively_recording();
182         int  declick = get_transport_declick_required();
183         bool rec_monitors = get_rec_monitors_input();
184         boost::shared_ptr<RouteList> r = routes.reader ();
185
186         if (transport_sub_state & StopPendingCapture) {
187                 /* force a declick out */
188                 declick = -1;
189         }
190
191         const nframes_t start_frame = _transport_frame;
192         const nframes_t end_frame = _transport_frame + lrintf(nframes * _transport_speed);
193
194         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
195
196                 int ret;
197
198                 if ((*i)->is_hidden()) {
199                         continue;
200                 }
201
202                 if ((ret = (*i)->silent_roll (nframes, start_frame, end_frame, record_active, rec_monitors)) < 0) {
203
204                         /* we have to do this here. Route::roll() for an AudioTrack will have called AudioDiskstream::process(),
205                            and the DS will expect AudioDiskstream::commit() to be called. but we're aborting from that
206                            call path, so make sure we release any outstanding locks here before we return failure.
207                         */
208
209                         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
210                         for (DiskstreamList::iterator ids = dsl->begin(); ids != dsl->end(); ++ids) {
211                                 (*ids)->recover ();
212                         }
213
214                         stop_transport ();
215                         return -1;
216                 }
217         }
218
219         return 0;
220 }
221
222 void
223 Session::commit_diskstreams (nframes_t nframes, bool &needs_butler)
224 {
225         int dret;
226         float pworst = 1.0f;
227         float cworst = 1.0f;
228
229         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
230         for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
231
232                 if ((*i)->hidden()) {
233                         continue;
234                 }
235
236                 /* force all diskstreams not handled by a Route to call do their stuff.
237                    Note: the diskstreams that were handled by a route will just return zero
238                    from this call, because they know they were processed. So in fact, this
239                    also runs commit() for every diskstream.
240                  */
241
242                 if ((dret = (*i)->process (_transport_frame, nframes, actively_recording(), get_rec_monitors_input())) == 0) {
243                         if ((*i)->commit (nframes)) {
244                                 needs_butler = true;
245                         }
246
247                 } else if (dret < 0) {
248                         (*i)->recover();
249                 }
250
251                 pworst = min (pworst, (*i)->playback_buffer_load());
252                 cworst = min (cworst, (*i)->capture_buffer_load());
253         }
254
255         uint32_t pmin = g_atomic_int_get (&_playback_load);
256         uint32_t pminold = g_atomic_int_get (&_playback_load_min);
257         uint32_t cmin = g_atomic_int_get (&_capture_load);
258         uint32_t cminold = g_atomic_int_get (&_capture_load_min);
259
260         g_atomic_int_set (&_playback_load, (uint32_t) floor (pworst * 100.0f));
261         g_atomic_int_set (&_capture_load, (uint32_t) floor (cworst * 100.0f));
262         g_atomic_int_set (&_playback_load_min, min (pmin, pminold));
263         g_atomic_int_set (&_capture_load_min, min (cmin, cminold));
264
265         if (actively_recording()) {
266                 set_dirty();
267         }
268 }
269
270 /** Process callback used when the auditioner is not active */
271 void
272 Session::process_with_events (nframes_t nframes)
273 {
274         SessionEvent*         ev;
275         nframes_t      this_nframes;
276         nframes_t      end_frame;
277         bool           session_needs_butler = false;
278         nframes_t      stop_limit;
279         long           frames_moved;
280
281         /* make sure the auditioner is silent */
282
283         if (auditioner) {
284                 auditioner->silence (nframes);
285         }
286
287         /* handle any pending events */
288
289         while (pending_events.read (&ev, 1) == 1) {
290                 merge_event (ev);
291         }
292
293         /* if we are not in the middle of a state change,
294            and there are immediate events queued up,
295            process them.
296         */
297
298         while (!non_realtime_work_pending() && !immediate_events.empty()) {
299                 SessionEvent *ev = immediate_events.front ();
300                 immediate_events.pop_front ();
301                 process_event (ev);
302         }
303
304         /* Events caused a transport change, send an MTC Full Frame (Timecode) message.
305          * This is sent whether rolling or not, to give slaves an idea of ardour time
306          * on locates (and allow slow slaves to position and prepare for rolling)
307          */
308         if (_send_timecode_update) {
309                 send_full_time_code(nframes);
310                 deliver_mmc (MIDI::MachineControl::cmdLocate, _transport_frame);
311         }
312
313         if (!process_can_proceed()) {
314                 _silent = true;
315                 return;
316         }
317
318         if (events.empty() || next_event == events.end()) {
319                 process_without_events (nframes);
320                 return;
321         }
322
323         if (_transport_speed == 1.0) {
324                 frames_moved = (long) nframes;
325         } else {
326                 interpolation.set_target_speed (fabs(_target_transport_speed));
327                 interpolation.set_speed (fabs(_transport_speed));
328                 frames_moved = (long) interpolation.interpolate (0, nframes, 0, 0);
329         }
330
331         end_frame = _transport_frame + (nframes_t)frames_moved;
332
333         {
334                 SessionEvent* this_event;
335                 Events::iterator the_next_one;
336
337                 if (!process_can_proceed()) {
338                         _silent = true;
339                         return;
340                 }
341
342                 if (!_exporting && _slave) {
343                         if (!follow_slave (nframes)) {
344                                 return;
345                         }
346                 }
347
348                 if (_transport_speed == 0) {
349                         no_roll (nframes);
350                         return;
351                 }
352
353                 if (!_exporting) {
354                         send_midi_time_code_for_cycle (nframes);
355                 }
356
357                 if (actively_recording()) {
358                         stop_limit = max_frames;
359                 } else {
360
361                         if (Config->get_stop_at_session_end()) {
362                                 stop_limit = current_end_frame();
363                         } else {
364                                 stop_limit = max_frames;
365                         }
366                 }
367
368                 if (maybe_stop (stop_limit)) {
369                         no_roll (nframes);
370                         return;
371                 }
372
373                 this_event = *next_event;
374                 the_next_one = next_event;
375                 ++the_next_one;
376
377                 /* yes folks, here it is, the actual loop where we really truly
378                    process some audio
379                 */
380
381                 while (nframes) {
382
383                         this_nframes = nframes; /* real (jack) time relative */
384                         frames_moved = (long) floor (_transport_speed * nframes); /* transport relative */
385
386                         /* running an event, position transport precisely to its time */
387                         if (this_event && this_event->action_frame <= end_frame && this_event->action_frame >= _transport_frame) {
388                                 /* this isn't quite right for reverse play */
389                                 frames_moved = (long) (this_event->action_frame - _transport_frame);
390                                 this_nframes = (nframes_t) abs( floor(frames_moved / _transport_speed) );
391                         }
392
393                         if (this_nframes) {
394
395                                 click (_transport_frame, this_nframes);
396
397                                 /* now process frames between now and the first event in this block */
398                                 prepare_diskstreams ();
399
400                                 if (process_routes (this_nframes)) {
401                                         fail_roll (nframes);
402                                         return;
403                                 }
404
405                                 commit_diskstreams (this_nframes, session_needs_butler);
406
407                                 nframes -= this_nframes;
408
409                                 if (frames_moved < 0) {
410                                         decrement_transport_position (-frames_moved);
411                                 } else {
412                                         increment_transport_position (frames_moved);
413                                 }
414
415                                 maybe_stop (stop_limit);
416                                 check_declick_out ();
417                         }
418
419                         _engine.split_cycle (this_nframes);
420
421                         /* now handle this event and all others scheduled for the same time */
422
423                         while (this_event && this_event->action_frame == _transport_frame) {
424                                 process_event (this_event);
425
426                                 if (the_next_one == events.end()) {
427                                         this_event = 0;
428                                 } else {
429                                         this_event = *the_next_one;
430                                         ++the_next_one;
431                                 }
432                         }
433
434                         /* if an event left our state changing, do the right thing */
435
436                         if (nframes && non_realtime_work_pending()) {
437                                 no_roll (nframes);
438                                 break;
439                         }
440
441                         /* this is necessary to handle the case of seamless looping */
442                         end_frame = _transport_frame + (nframes_t) floor (nframes * _transport_speed);
443
444                 }
445
446                 set_next_event ();
447
448         } /* implicit release of route lock */
449
450         if (session_needs_butler) {
451                 _butler->summon ();
452         }
453 }
454
455 void
456 Session::reset_slave_state ()
457 {
458         average_slave_delta = 1800;
459         delta_accumulator_cnt = 0;
460         have_first_delta_accumulator = false;
461         _slave_state = Stopped;
462 }
463
464 bool
465 Session::transport_locked () const
466 {
467         Slave* sl = _slave;
468
469         if (!locate_pending() && (!config.get_external_sync() || (sl && sl->ok() && sl->locked()))) {
470                 return true;
471         }
472
473         return false;
474 }
475
476 bool
477 Session::follow_slave (nframes_t nframes)
478 {
479         double slave_speed;
480         nframes64_t slave_transport_frame;
481         nframes_t this_delta;
482         int dir;
483
484         if (!_slave->ok()) {
485                 stop_transport ();
486                 config.set_external_sync (false);
487                 goto noroll;
488         }
489
490         _slave->speed_and_position (slave_speed, slave_transport_frame);
491
492         DEBUG_TRACE (DEBUG::Slave, string_compose ("Slave position %1 speed %2\n", slave_transport_frame, slave_speed));
493
494         if (!_slave->locked()) {
495                 DEBUG_TRACE (DEBUG::Slave, "slave not locked\n");
496                 goto noroll;
497         }
498
499         if (slave_transport_frame > _transport_frame) {
500                 this_delta = slave_transport_frame - _transport_frame;
501                 dir = 1;
502         } else {
503                 this_delta = _transport_frame - slave_transport_frame;
504                 dir = -1;
505         }
506
507         if (_slave->starting()) {
508                 slave_speed = 0.0f;
509         }
510
511         if (_slave->is_always_synced() || config.get_timecode_source_is_synced()) {
512
513                 /* if the TC source is synced, then we assume that its
514                    speed is binary: 0.0 or 1.0
515                 */
516
517                 if (slave_speed != 0.0f) {
518                         slave_speed = 1.0f;
519                 }
520
521         } else {
522
523                 /* if we are chasing and the average delta between us and the
524                    master gets too big, we want to switch to silent
525                    motion. so keep track of that here.
526                 */
527
528                 if (_slave_state == Running) {
529                         calculate_moving_average_of_slave_delta(dir, this_delta);
530                 }
531         }
532
533         track_slave_state (slave_speed, slave_transport_frame, this_delta);
534
535         DEBUG_TRACE (DEBUG::Slave, string_compose ("slave state %1 @ %2 speed %3 cur delta %4 avg delta %5\n",
536                                                    _slave_state, slave_transport_frame, slave_speed, this_delta, average_slave_delta));
537                      
538
539         if (_slave_state == Running && !_slave->is_always_synced() && !config.get_timecode_source_is_synced()) {
540
541                 if (_transport_speed != 0.0f) {
542
543                         /*
544                            note that average_dir is +1 or -1
545                         */
546
547                         float delta;
548
549                         if (average_slave_delta == 0) {
550                                 delta = this_delta;
551                                 delta *= dir;
552                         } else {
553                                 delta = average_slave_delta;
554                                 delta *= average_dir;
555                         }
556
557 #ifndef NDEBUG
558                         if (slave_speed != 0.0) {
559                                 DEBUG_TRACE (DEBUG::Slave, string_compose ("delta = %1 speed = %2 ts = %3 M@%4 S@%5 avgdelta %6\n",
560                                                                            (int) (dir * this_delta),
561                                                                            slave_speed,
562                                                                            _transport_speed,
563                                                                            _transport_frame,
564                                                                            slave_transport_frame, 
565                                                                            average_slave_delta));
566                         }
567 #endif
568                         
569                         if (_slave->give_slave_full_control_over_transport_speed()) {
570                                 set_transport_speed (slave_speed, false, false);
571                         } else {
572                                 float adjusted_speed = slave_speed + (1.5 * (delta /  float(_current_frame_rate)));
573                                 request_transport_speed (adjusted_speed);
574                                 DEBUG_TRACE (DEBUG::Slave, string_compose ("adjust using %1 towards %2 ratio %3 current %4 slave @ %5\n",
575                                                                            delta, adjusted_speed, adjusted_speed/slave_speed, _transport_speed,
576                                                                            slave_speed));
577                         }
578                         
579                         if (abs(average_slave_delta) > _slave->resolution()) {
580                                 cerr << "average slave delta greater than slave resolution (" << _slave->resolution() << "), going to silent motion\n";
581                                 goto silent_motion;
582                         }
583                 }
584         }
585
586
587         if (_slave_state == Running && !non_realtime_work_pending()) {
588                 /* speed is set, we're locked, and good to go */
589                 return true;
590         }
591
592   silent_motion:
593         DEBUG_TRACE (DEBUG::Slave, "silent motion\n")
594         follow_slave_silently (nframes, slave_speed);
595
596   noroll:
597         /* don't move at all */
598         DEBUG_TRACE (DEBUG::Slave, "no roll\n")
599         no_roll (nframes);
600         return false;
601 }
602
603 void
604 Session::calculate_moving_average_of_slave_delta(int dir, nframes_t this_delta)
605 {
606         if (delta_accumulator_cnt >= delta_accumulator_size) {
607                 have_first_delta_accumulator = true;
608                 delta_accumulator_cnt = 0;
609         }
610
611         if (delta_accumulator_cnt != 0 || this_delta < _current_frame_rate) {
612                 delta_accumulator[delta_accumulator_cnt++] = long(dir) * long(this_delta);
613         }
614
615         if (have_first_delta_accumulator) {
616                 average_slave_delta = 0L;
617                 for (int i = 0; i < delta_accumulator_size; ++i) {
618                         average_slave_delta += delta_accumulator[i];
619                 }
620                 average_slave_delta /= long(delta_accumulator_size);
621                 if (average_slave_delta < 0L) {
622                         average_dir = -1;
623                         average_slave_delta = abs(average_slave_delta);
624                 } else {
625                         average_dir = 1;
626                 }
627         }
628 }
629
630 void
631 Session::track_slave_state (float slave_speed, nframes_t slave_transport_frame, nframes_t this_delta)
632 {
633         if (slave_speed != 0.0f) {
634
635                 /* slave is running */
636
637                 switch (_slave_state) {
638                 case Stopped:
639                         if (_slave->requires_seekahead()) {
640                                 slave_wait_end = slave_transport_frame + _slave->seekahead_distance ();
641                                 DEBUG_TRACE (DEBUG::Slave, string_compose ("slave stopped, but running, requires seekahead to %1\n", slave_wait_end));
642                                 /* we can call locate() here because we are in process context */
643                                 locate (slave_wait_end, false, false);
644                                 _slave_state = Waiting;
645
646                         } else {
647
648                                 _slave_state = Running;
649
650                                 Location* al = _locations.auto_loop_location();
651
652                                 if (al && play_loop && (slave_transport_frame < al->start() || slave_transport_frame > al->end())) {
653                                         // cancel looping
654                                         request_play_loop(false);
655                                 }
656
657                                 if (slave_transport_frame != _transport_frame) {
658                                         locate (slave_transport_frame, false, false);
659                                 }
660                         }
661                         break;
662
663                 case Waiting:
664                 default:
665                         break;
666                 }
667
668                 if (_slave_state == Waiting) {
669
670                         DEBUG_TRACE (DEBUG::Slave, string_compose ("slave waiting at %1\n", slave_transport_frame));
671
672                         if (slave_transport_frame >= slave_wait_end) {
673
674                                 DEBUG_TRACE (DEBUG::Slave, string_compose ("slave start at %1 vs %2\n", slave_transport_frame, _transport_frame));
675
676                                 _slave_state = Running;
677
678                                 /* now perform a "micro-seek" within the disk buffers to realign ourselves
679                                    precisely with the master.
680                                 */
681
682
683                                 bool ok = true;
684                                 nframes_t frame_delta = slave_transport_frame - _transport_frame;
685
686                                 boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
687
688                                 for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
689                                         if (!(*i)->can_internal_playback_seek (frame_delta)) {
690                                                 ok = false;
691                                                 break;
692                                         }
693                                 }
694
695                                 if (ok) {
696                                         for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
697                                                 (*i)->internal_playback_seek (frame_delta);
698                                         }
699                                         _transport_frame += frame_delta;
700
701                                 } else {
702                                         cerr << "cannot micro-seek\n";
703                                         /* XXX what? */
704                                 }
705
706                                 memset (delta_accumulator, 0, sizeof (long) * delta_accumulator_size);
707                                 average_slave_delta = 0L;
708                                 this_delta = 0;
709                         }
710                 }
711
712                 if (_slave_state == Running && _transport_speed == 0.0f) {
713                         DEBUG_TRACE (DEBUG::Slave, "slave starts transport\n");
714                         start_transport ();
715                 }
716
717         } else { // slave_speed is 0
718
719                 /* slave has stopped */
720
721                 if (_transport_speed != 0.0f) {
722                         DEBUG_TRACE (DEBUG::Slave, string_compose ("slave stops transport: %1 frame %2 tf %3\n", slave_speed, slave_transport_frame, _transport_frame));
723                         stop_transport();
724                 }
725
726                 if (slave_transport_frame != _transport_frame) {
727                         DEBUG_TRACE (DEBUG::Slave, string_compose ("slave stopped, move to %1\n", slave_transport_frame));
728                         force_locate (slave_transport_frame, false);
729                 }
730
731                 _slave_state = Stopped;
732         }
733 }
734
735 void
736 Session::follow_slave_silently (nframes_t nframes, float slave_speed)
737 {
738         if (slave_speed && _transport_speed) {
739
740                 /* something isn't right, but we should move with the master
741                    for now.
742                 */
743
744                 bool need_butler;
745
746                 prepare_diskstreams ();
747                 silent_process_routes (nframes);
748                 commit_diskstreams (nframes, need_butler);
749
750                 if (need_butler) {
751                         _butler->summon ();
752                 }
753
754                 int32_t frames_moved = (int32_t) floor (_transport_speed * nframes);
755
756                 if (frames_moved < 0) {
757                         decrement_transport_position (-frames_moved);
758                 } else {
759                         increment_transport_position (frames_moved);
760                 }
761
762                 nframes_t stop_limit;
763
764                 if (actively_recording()) {
765                         stop_limit = max_frames;
766                 } else {
767                         if (Config->get_stop_at_session_end()) {
768                                 stop_limit = current_end_frame();
769                         } else {
770                                 stop_limit = max_frames;
771                         }
772                 }
773
774                 maybe_stop (stop_limit);
775         }
776 }
777
778 void
779 Session::process_without_events (nframes_t nframes)
780 {
781         bool session_needs_butler = false;
782         nframes_t stop_limit;
783         long frames_moved;
784
785         if (!process_can_proceed()) {
786                 _silent = true;
787                 return;
788         }
789
790         if (!_exporting && _slave) {
791                 if (!follow_slave (nframes)) {
792                         return;
793                 }
794         }
795
796         if (_transport_speed == 0) {
797                 fail_roll (nframes);
798                 return;
799         }
800
801         if (!_exporting) {
802                 send_midi_time_code_for_cycle (nframes);
803         }
804
805         if (actively_recording()) {
806                 stop_limit = max_frames;
807         } else {
808                 if (Config->get_stop_at_session_end()) {
809                         stop_limit = current_end_frame();
810                 } else {
811                         stop_limit = max_frames;
812                 }
813         }
814
815         if (maybe_stop (stop_limit)) {
816                 fail_roll (nframes);
817                 return;
818         }
819
820         if (maybe_sync_start (nframes)) {
821                 return;
822         }
823
824         click (_transport_frame, nframes);
825
826         prepare_diskstreams ();
827
828         if (_transport_speed == 1.0) {
829                 frames_moved = (long) nframes;
830         } else {
831                 interpolation.set_target_speed (fabs(_target_transport_speed));
832                 interpolation.set_speed (fabs(_transport_speed));
833                 frames_moved = (long) interpolation.interpolate (0, nframes, 0, 0);
834         }
835
836         if (process_routes (nframes)) {
837                 fail_roll (nframes);
838                 return;
839         }
840
841         commit_diskstreams (nframes, session_needs_butler);
842
843         if (frames_moved < 0) {
844                 decrement_transport_position (-frames_moved);
845         } else {
846                 increment_transport_position (frames_moved);
847         }
848
849         maybe_stop (stop_limit);
850         check_declick_out ();
851
852         if (session_needs_butler) {
853                 _butler->summon ();
854         }
855 }
856
857 /** Process callback used when the auditioner is active.
858  * @param nframes number of frames to process.
859  */
860 void
861 Session::process_audition (nframes_t nframes)
862 {
863         SessionEvent* ev;
864         boost::shared_ptr<RouteList> r = routes.reader ();
865
866         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
867                 if (!(*i)->is_hidden()) {
868                         (*i)->silence (nframes);
869                 }
870         }
871
872         /* run the auditioner, and if it says we need butler service, ask for it */
873
874         if (auditioner->play_audition (nframes) > 0) {
875                 _butler->summon ();
876         }
877
878         /* handle pending events */
879
880         while (pending_events.read (&ev, 1) == 1) {
881                 merge_event (ev);
882         }
883
884         /* if we are not in the middle of a state change,
885            and there are immediate events queued up,
886            process them.
887         */
888
889         while (!non_realtime_work_pending() && !immediate_events.empty()) {
890                 SessionEvent *ev = immediate_events.front ();
891                 immediate_events.pop_front ();
892                 process_event (ev);
893         }
894
895         if (!auditioner->active()) {
896                 /* auditioner no longer active, so go back to the normal process callback */
897                 process_function = &Session::process_with_events;
898         }
899 }
900
901 bool
902 Session::maybe_sync_start (nframes_t& nframes)
903 {
904         nframes_t sync_offset;
905
906         if (!waiting_for_sync_offset) {
907                 return false;
908         }
909
910         if (_engine.get_sync_offset (sync_offset) && sync_offset < nframes) {
911
912                 /* generate silence up to the sync point, then
913                    adjust nframes + offset to reflect whatever
914                    is left to do.
915                 */
916
917                 no_roll (sync_offset);
918                 nframes -= sync_offset;
919                 Port::increment_port_offset (sync_offset);
920                 waiting_for_sync_offset = false;
921
922                 if (nframes == 0) {
923                         return true; // done, nothing left to process
924                 }
925
926         } else {
927
928                 /* sync offset point is not within this process()
929                    cycle, so just generate silence. and don't bother
930                    with any fancy stuff here, just the minimal silence.
931                 */
932
933                 _silent = true;
934
935                 if (Config->get_locate_while_waiting_for_sync()) {
936                         if (micro_locate (nframes)) {
937                                 /* XXX ERROR !!! XXX */
938                         }
939                 }
940
941                 return true; // done, nothing left to process
942         }
943
944         return false;
945 }
946
947 void
948 Session::queue_event (SessionEvent* ev)
949 {
950         if (_state_of_the_state & Deletion) {
951                 return;
952         } else if (_state_of_the_state & Loading) {
953                 merge_event (ev);
954         } else {
955                 pending_events.write (&ev, 1);
956         }
957 }
958
959 void
960 Session::set_next_event ()
961 {
962         if (events.empty()) {
963                 next_event = events.end();
964                 return;
965         }
966
967         if (next_event == events.end()) {
968                 next_event = events.begin();
969         }
970
971         if ((*next_event)->action_frame > _transport_frame) {
972                 next_event = events.begin();
973         }
974
975         for (; next_event != events.end(); ++next_event) {
976                 if ((*next_event)->action_frame >= _transport_frame) {
977                         break;
978                 }
979         }
980 }
981
982 void
983 Session::process_event (SessionEvent* ev)
984 {
985         bool remove = true;
986         bool del = true;
987
988         /* if we're in the middle of a state change (i.e. waiting
989            for the butler thread to complete the non-realtime
990            part of the change), we'll just have to queue this
991            event for a time when the change is complete.
992         */
993
994         if (non_realtime_work_pending()) {
995
996                 /* except locates, which we have the capability to handle */
997
998                 if (ev->type != SessionEvent::Locate) {
999                         immediate_events.insert (immediate_events.end(), ev);
1000                         _remove_event (ev);
1001                         return;
1002                 }
1003         }
1004
1005         DEBUG_TRACE (DEBUG::SessionEvents, string_compose ("Processing event: %1 @ %2\n", enum_2_string (ev->type), _transport_frame));
1006
1007         switch (ev->type) {
1008         case SessionEvent::SetLoop:
1009                 set_play_loop (ev->yes_or_no);
1010                 break;
1011
1012         case SessionEvent::AutoLoop:
1013                 if (play_loop) {
1014                         start_locate (ev->target_frame, true, false, Config->get_seamless_loop());
1015                 }
1016                 remove = false;
1017                 del = false;
1018                 break;
1019
1020         case SessionEvent::Locate:
1021                 if (ev->yes_or_no) {
1022                         // cerr << "forced locate to " << ev->target_frame << endl;
1023                         locate (ev->target_frame, false, true, false);
1024                 } else {
1025                         // cerr << "soft locate to " << ev->target_frame << endl;
1026                         start_locate (ev->target_frame, false, true, false);
1027                 }
1028                 _send_timecode_update = true;
1029                 break;
1030
1031         case SessionEvent::LocateRoll:
1032                 if (ev->yes_or_no) {
1033                         // cerr << "forced locate to+roll " << ev->target_frame << endl;
1034                         locate (ev->target_frame, true, true, false);
1035                 } else {
1036                         // cerr << "soft locate to+roll " << ev->target_frame << endl;
1037                         start_locate (ev->target_frame, true, true, false);
1038                 }
1039                 _send_timecode_update = true;
1040                 break;
1041
1042         case SessionEvent::LocateRollLocate:
1043                 // locate is handled by ::request_roll_at_and_return()
1044                 _requested_return_frame = ev->target_frame;
1045                 request_locate (ev->target2_frame, true);
1046                 break;
1047
1048
1049         case SessionEvent::SetTransportSpeed:
1050                 set_transport_speed (ev->speed, ev->yes_or_no, ev->second_yes_or_no);
1051                 break;
1052
1053         case SessionEvent::PunchIn:
1054                 // cerr << "PunchIN at " << transport_frame() << endl;
1055                 if (config.get_punch_in() && record_status() == Enabled) {
1056                         enable_record ();
1057                 }
1058                 remove = false;
1059                 del = false;
1060                 break;
1061
1062         case SessionEvent::PunchOut:
1063                 // cerr << "PunchOUT at " << transport_frame() << endl;
1064                 if (config.get_punch_out()) {
1065                         step_back_from_record ();
1066                 }
1067                 remove = false;
1068                 del = false;
1069                 break;
1070
1071         case SessionEvent::StopOnce:
1072                 if (!non_realtime_work_pending()) {
1073                         stop_transport (ev->yes_or_no);
1074                         _clear_event_type (SessionEvent::StopOnce);
1075                 }
1076                 remove = false;
1077                 del = false;
1078                 break;
1079
1080         case SessionEvent::RangeStop:
1081                 if (!non_realtime_work_pending()) {
1082                         stop_transport (ev->yes_or_no);
1083                 }
1084                 remove = false;
1085                 del = false;
1086                 break;
1087
1088         case SessionEvent::RangeLocate:
1089                 start_locate (ev->target_frame, true, true, false);
1090                 remove = false;
1091                 del = false;
1092                 break;
1093
1094         case SessionEvent::Overwrite:
1095                 overwrite_some_buffers (static_cast<Diskstream*>(ev->ptr));
1096                 break;
1097
1098         case SessionEvent::SetDiskstreamSpeed:
1099                 set_diskstream_speed (static_cast<Diskstream*> (ev->ptr), ev->speed);
1100                 break;
1101
1102         case SessionEvent::SetSyncSource:
1103                 use_sync_source (ev->slave);
1104                 break;
1105
1106         case SessionEvent::Audition:
1107                 set_audition (ev->region);
1108                 // drop reference to region
1109                 ev->region.reset ();
1110                 break;
1111
1112         case SessionEvent::InputConfigurationChange:
1113                 add_post_transport_work (PostTransportInputChange);
1114                 _butler->schedule_transport_work ();
1115                 break;
1116
1117         case SessionEvent::SetPlayAudioRange:
1118                 set_play_range (ev->audio_range, (ev->speed == 1.0f));
1119                 break;
1120
1121         case SessionEvent::RealTimeOperation:
1122                 process_rtop (ev);
1123                 del = false; // other side of RT request needs to clean up
1124                 break;
1125
1126         default:
1127           fatal << string_compose(_("Programming error: illegal event type in process_event (%1)"), ev->type) << endmsg;
1128                 /*NOTREACHED*/
1129                 break;
1130         };
1131
1132         if (remove) {
1133                 del = del && !_remove_event (ev);
1134         }
1135
1136         if (del) {
1137                 delete ev;
1138         }
1139 }
1140
1141 void
1142 Session::process_rtop (SessionEvent* ev)
1143 {
1144         ev->rt_slot ();
1145         ev->rt_return (ev);
1146 }