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
  27 #include <glibmm/thread.h>
  28
  29 #include <ardour/ardour.h>
  30 #include <ardour/session.h>
  31 #include <ardour/timestamps.h>
  32 #include <ardour/audio_diskstream.h>
  33 #include <ardour/audioengine.h>
  34 #include <ardour/slave.h>
  35 #include <ardour/auditioner.h>
  36 #include <ardour/cycles.h>
  37 #include <ardour/cycle_timer.h>
  38
  39 #include <midi++/manager.h>
  40
  41 #include "i18n.h"
  42
  43 using namespace ARDOUR;
  44 using namespace PBD;
  45 using namespace std;
  46
  47 /** Called by the audio engine when there is work to be done with JACK.
  48  * @param nframes Number of frames to process.
  49  */
  50 void
  51 Session::process (nframes_t nframes)
  52 {
  53         // This is no more the appriopriate place to call cycle
  54         // start. cycle_start needs to be called at the Route::roll()
  55         // where the signals which we want to mixdown have been calculated.
  56         //
  57         MIDI::Manager::instance()->cycle_start(nframes);
  58
  59         _silent = false;
  60
  61         if (non_realtime_work_pending()) {
  62                 if (!transport_work_requested ()) {
  63                         post_transport ();
  64                 }
  65         }
  66
  67         (this->*process_function) (nframes);
  68
  69         // the ticker is for sending time information like MidiClock
  70         nframes_t transport_frames = transport_frame();
  71         BBT_Time  transport_bbt;
  72         bbt_time(transport_frames, transport_bbt);
  73         SMPTE::Time transport_smpte;
  74         smpte_time(transport_frames, transport_smpte);
  75         tick (transport_frames, transport_bbt, transport_smpte); /* EMIT SIGNAL */
  76
  77         SendFeedback (); /* EMIT SIGNAL */
  78
  79         MIDI::Manager::instance()->cycle_end();
  80 }
  81
  82 void
  83 Session::prepare_diskstreams ()
  84 {
  85         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
  86         for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
  87                 (*i)->prepare ();
  88         }
  89 }
  90
  91 int
  92 Session::no_roll (nframes_t nframes, nframes_t offset)
  93 {
  94         nframes_t end_frame = _transport_frame + nframes; // FIXME: varispeed + no_roll ??
  95         int ret = 0;
  96         bool declick = get_transport_declick_required();
  97         boost::shared_ptr<RouteList> r = routes.reader ();
  98
  99         if (_click_io) {
 100                 _click_io->silence (nframes, offset);
 101         }
 102
 103         if (g_atomic_int_get (&processing_prohibited)) {
 104                 for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 105                         (*i)->silence (nframes, offset);
 106                 }
 107                 return 0;
 108         }
 109
 110         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 111
 112                 if ((*i)->is_hidden()) {
 113                         continue;
 114                 }
 115
 116                 (*i)->set_pending_declick (declick);
 117
 118                 if ((*i)->no_roll (nframes, _transport_frame, end_frame, offset, non_realtime_work_pending(),
 119                                    actively_recording(), declick)) {
 120                         error << string_compose(_("Session: error in no roll for %1"), (*i)->name()) << endmsg;
 121                         ret = -1;
 122                         break;
 123                 }
 124         }
 125
 126         return ret;
 127 }
 128
 129 int
 130 Session::process_routes (nframes_t nframes, nframes_t offset)
 131 {
 132         bool record_active;
 133         int  declick = get_transport_declick_required();
 134         bool rec_monitors = get_rec_monitors_input();
 135         boost::shared_ptr<RouteList> r = routes.reader ();
 136
 137         if (transport_sub_state & StopPendingCapture) {
 138                 /* force a declick out */
 139                 declick = -1;
 140         }
 141
 142         record_active = actively_recording(); // || (get_record_enabled() && get_punch_in());
 143
 144         const nframes_t start_frame = _transport_frame;
 145         const nframes_t end_frame = _transport_frame + (nframes_t)floor(nframes * _transport_speed);
 146
 147         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 148
 149                 int ret;
 150
 151                 if ((*i)->is_hidden()) {
 152                         continue;
 153                 }
 154
 155                 (*i)->set_pending_declick (declick);
 156
 157                 if ((ret = (*i)->roll (nframes, start_frame, end_frame, offset, declick, record_active, rec_monitors)) < 0) {
 158
 159                         /* we have to do this here. Route::roll() for an AudioTrack will have called AudioDiskstream::process(),
 160                            and the DS will expect AudioDiskstream::commit() to be called. but we're aborting from that
 161                            call path, so make sure we release any outstanding locks here before we return failure.
 162                         */
 163
 164                         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 165                         for (DiskstreamList::iterator ids = dsl->begin(); ids != dsl->end(); ++ids) {
 166                                 (*ids)->recover ();
 167                         }
 168
 169                         stop_transport ();
 170                         return -1;
 171                 }
 172         }
 173
 174         return 0;
 175 }
 176
 177 int
 178 Session::silent_process_routes (nframes_t nframes, nframes_t offset)
 179 {
 180         bool record_active = actively_recording();
 181         int  declick = get_transport_declick_required();
 182         bool rec_monitors = get_rec_monitors_input();
 183         boost::shared_ptr<RouteList> r = routes.reader ();
 184
 185         if (transport_sub_state & StopPendingCapture) {
 186                 /* force a declick out */
 187                 declick = -1;
 188         }
 189
 190         const nframes_t start_frame = _transport_frame;
 191         const nframes_t end_frame = _transport_frame + lrintf(nframes * _transport_speed);
 192
 193         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 194
 195                 int ret;
 196
 197                 if ((*i)->is_hidden()) {
 198                         continue;
 199                 }
 200
 201                 if ((ret = (*i)->silent_roll (nframes, start_frame, end_frame, offset, record_active, rec_monitors)) < 0) {
 202
 203                         /* we have to do this here. Route::roll() for an AudioTrack will have called AudioDiskstream::process(),
 204                            and the DS will expect AudioDiskstream::commit() to be called. but we're aborting from that
 205                            call path, so make sure we release any outstanding locks here before we return failure.
 206                         */
 207
 208                         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 209                         for (DiskstreamList::iterator ids = dsl->begin(); ids != dsl->end(); ++ids) {
 210                                 (*ids)->recover ();
 211                         }
 212
 213                         stop_transport ();
 214                         return -1;
 215                 }
 216         }
 217
 218         return 0;
 219 }
 220
 221 void
 222 Session::commit_diskstreams (nframes_t nframes, bool &needs_butler)
 223 {
 224         int dret;
 225         float pworst = 1.0f;
 226         float cworst = 1.0f;
 227
 228         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 229         for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
 230
 231                 if ((*i)->hidden()) {
 232                         continue;
 233                 }
 234
 235                 /* force all diskstreams not handled by a Route to call do their stuff.
 236                    Note: the diskstreams that were handled by a route will just return zero
 237                    from this call, because they know they were processed. So in fact, this
 238                    also runs commit() for every diskstream.
 239                  */
 240
 241                 if ((dret = (*i)->process (_transport_frame, nframes, 0, actively_recording(), get_rec_monitors_input())) == 0) {
 242                         if ((*i)->commit (nframes)) {
 243                                 needs_butler = true;
 244                         }
 245
 246                 } else if (dret < 0) {
 247                         (*i)->recover();
 248                 }
 249
 250                 pworst = min (pworst, (*i)->playback_buffer_load());
 251                 cworst = min (cworst, (*i)->capture_buffer_load());
 252         }
 253
 254         uint32_t pmin = g_atomic_int_get (&_playback_load);
 255         uint32_t pminold = g_atomic_int_get (&_playback_load_min);
 256         uint32_t cmin = g_atomic_int_get (&_capture_load);
 257         uint32_t cminold = g_atomic_int_get (&_capture_load_min);
 258
 259         g_atomic_int_set (&_playback_load, (uint32_t) floor (pworst * 100.0f));
 260         g_atomic_int_set (&_capture_load, (uint32_t) floor (cworst * 100.0f));
 261         g_atomic_int_set (&_playback_load_min, min (pmin, pminold));
 262         g_atomic_int_set (&_capture_load_min, min (cmin, cminold));
 263
 264         if (actively_recording()) {
 265                 set_dirty();
 266         }
 267 }
 268
 269 /** Process callback used when the auditioner is not active */
 270 void
 271 Session::process_with_events (nframes_t nframes)
 272 {
 273         Event*         ev;
 274         nframes_t this_nframes;
 275         nframes_t end_frame;
 276         nframes_t offset;
 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, 0);
 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                 Event *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 (SMPTE) 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_smpte_update) {
 309                 send_full_time_code(nframes);
 310         }
 311
 312         if (!process_can_proceed()) {
 313                 _silent = true;
 314                 return;
 315         }
 316
 317         if (events.empty() || next_event == events.end()) {
 318                 process_without_events (nframes);
 319                 return;
 320         }
 321
 322         end_frame = _transport_frame + (nframes_t)abs(floor(nframes * _transport_speed));
 323
 324         {
 325                 Event* this_event;
 326                 Events::iterator the_next_one;
 327
 328                 if (!process_can_proceed()) {
 329                         _silent = true;
 330                         return;
 331                 }
 332
 333                 if (!_exporting && _slave) {
 334                         if (!follow_slave (nframes, 0)) {
 335                                 return;
 336                         }
 337                 }
 338
 339                 if (_transport_speed == 0) {
 340                         no_roll (nframes, 0);
 341                         return;
 342                 }
 343
 344                 if (!_exporting) {
 345                         send_midi_time_code_for_cycle (nframes);
 346                 }
 347
 348                 if (actively_recording()) {
 349                         stop_limit = max_frames;
 350                 } else {
 351
 352                         if (Config->get_stop_at_session_end()) {
 353                                 stop_limit = current_end_frame();
 354                         } else {
 355                                 stop_limit = max_frames;
 356                         }
 357                 }
 358
 359                 if (maybe_stop (stop_limit)) {
 360                         no_roll (nframes, 0);
 361                         return;
 362                 }
 363
 364                 this_event = *next_event;
 365                 the_next_one = next_event;
 366                 ++the_next_one;
 367
 368                 offset = 0;
 369
 370                 /* yes folks, here it is, the actual loop where we really truly
 371                    process some audio */
 372                 while (nframes) {
 373
 374                         this_nframes = nframes; /* real (jack) time relative */
 375                         frames_moved = (long) floor (_transport_speed * nframes); /* transport relative */
 376
 377                         /* running an event, position transport precisely to its time */
 378                         if (this_event && this_event->action_frame <= end_frame && this_event->action_frame >= _transport_frame) {
 379                                 /* this isn't quite right for reverse play */
 380                                 frames_moved = (long) (this_event->action_frame - _transport_frame);
 381                                 this_nframes = (nframes_t) abs( floor(frames_moved / _transport_speed) );
 382                         }
 383
 384                         if (this_nframes) {
 385
 386                                 click (_transport_frame, nframes, offset);
 387
 388                                 /* now process frames between now and the first event in this block */
 389                                 prepare_diskstreams ();
 390
 391                                 if (process_routes (this_nframes, offset)) {
 392                                         no_roll (nframes, 0);
 393                                         return;
 394                                 }
 395
 396                                 commit_diskstreams (this_nframes, session_needs_butler);
 397
 398                                 nframes -= this_nframes;
 399                                 offset += this_nframes;
 400
 401                                 if (frames_moved < 0) {
 402                                         decrement_transport_position (-frames_moved);
 403                                 } else {
 404                                         increment_transport_position (frames_moved);
 405                                 }
 406
 407                                 maybe_stop (stop_limit);
 408                                 check_declick_out ();
 409                         }
 410
 411                         /* now handle this event and all others scheduled for the same time */
 412
 413                         while (this_event && this_event->action_frame == _transport_frame) {
 414                                 process_event (this_event);
 415
 416                                 if (the_next_one == events.end()) {
 417                                         this_event = 0;
 418                                 } else {
 419                                         this_event = *the_next_one;
 420                                         ++the_next_one;
 421                                 }
 422                         }
 423
 424                         /* if an event left our state changing, do the right thing */
 425
 426                         if (non_realtime_work_pending()) {
 427                                 no_roll (nframes, offset);
 428                                 break;
 429                         }
 430
 431                         /* this is necessary to handle the case of seamless looping */
 432                         end_frame = _transport_frame + (nframes_t) floor (nframes * _transport_speed);
 433
 434                 }
 435
 436                 set_next_event ();
 437
 438         } /* implicit release of route lock */
 439
 440         if (session_needs_butler)
 441                 summon_butler ();
 442 }
 443
 444 void
 445 Session::reset_slave_state ()
 446 {
 447         average_slave_delta = 1800;
 448         delta_accumulator_cnt = 0;
 449         have_first_delta_accumulator = false;
 450         slave_state = Stopped;
 451 }
 452
 453 bool
 454 Session::transport_locked () const
 455 {
 456         Slave* sl = _slave;
 457
 458         if (!locate_pending() && ((Config->get_slave_source() == None) || (sl && sl->ok() && sl->locked()))) {
 459                 return true;
 460         }
 461
 462         return false;
 463 }
 464
 465 bool
 466 Session::follow_slave (nframes_t nframes, nframes_t offset)
 467 {
 468         float slave_speed;
 469         nframes_t slave_transport_frame;
 470         nframes_t this_delta;
 471         int dir;
 472         bool starting;
 473
 474         if (!_slave->ok()) {
 475                 stop_transport ();
 476                 Config->set_slave_source (None);
 477                 goto noroll;
 478         }
 479
 480         _slave->speed_and_position (slave_speed, slave_transport_frame);
 481
 482         if (!_slave->locked()) {
 483                 goto noroll;
 484         }
 485
 486         if (slave_transport_frame > _transport_frame) {
 487                 this_delta = slave_transport_frame - _transport_frame;
 488                 dir = 1;
 489         } else {
 490                 this_delta = _transport_frame - slave_transport_frame;
 491                 dir = -1;
 492         }
 493
 494         if ((starting = _slave->starting())) {
 495                 slave_speed = 0.0f;
 496         }
 497
 498 #if 0
 499         cerr << "delta = " << (int) (dir * this_delta)
 500              << " speed = " << slave_speed
 501              << " ts = " << _transport_speed
 502              << " M@ "<< slave_transport_frame << " S@ " << _transport_frame
 503              << " avgdelta = " << average_slave_delta
 504              << endl;
 505 #endif
 506
 507         if (_slave->is_always_synced() || Config->get_timecode_source_is_synced()) {
 508
 509                 /* if the TC source is synced, then we assume that its
 510                    speed is binary: 0.0 or 1.0
 511                 */
 512
 513                 if (slave_speed != 0.0f) {
 514                         slave_speed = 1.0f;
 515                 }
 516
 517         } else {
 518
 519                 /* TC source is able to drift relative to us (slave)
 520                    so we need to keep track of the drift and adjust
 521                    our speed to remain locked.
 522                 */
 523
 524                 if (delta_accumulator_cnt >= delta_accumulator_size) {
 525                         have_first_delta_accumulator = true;
 526                         delta_accumulator_cnt = 0;
 527                 }
 528
 529                 if (delta_accumulator_cnt != 0 || this_delta < _current_frame_rate) {
 530                         delta_accumulator[delta_accumulator_cnt++] = long(dir) * long(this_delta);
 531                 }
 532
 533                 if (have_first_delta_accumulator) {
 534                         average_slave_delta = 0L;
 535                         for (int i = 0; i < delta_accumulator_size; ++i) {
 536                                 average_slave_delta += delta_accumulator[i];
 537                         }
 538                         average_slave_delta /= long(delta_accumulator_size);
 539                         if (average_slave_delta < 0L) {
 540                                 average_dir = -1;
 541                                 average_slave_delta = abs(average_slave_delta);
 542                         } else {
 543                                 average_dir = 1;
 544                         }
 545                         // cerr << "avgdelta = " << average_slave_delta*average_dir << endl;
 546                 }
 547         }
 548
 549         if (slave_speed != 0.0f) {
 550
 551                 /* slave is running */
 552
 553                 switch (slave_state) {
 554                 case Stopped:
 555                         if (_slave->requires_seekahead()) {
 556                                 slave_wait_end = slave_transport_frame + _current_frame_rate;
 557                                 locate (slave_wait_end, false, false);
 558                                 slave_state = Waiting;
 559                                 starting = true;
 560
 561                         } else {
 562
 563                                 slave_state = Running;
 564
 565                                 Location* al = _locations.auto_loop_location();
 566
 567                                 if (al && play_loop && (slave_transport_frame < al->start() || slave_transport_frame > al->end())) {
 568                                         // cancel looping
 569                                         request_play_loop(false);
 570                                 }
 571
 572                                 if (slave_transport_frame != _transport_frame) {
 573                                         locate (slave_transport_frame, false, false);
 574                                 }
 575                         }
 576                         break;
 577
 578                 case Waiting:
 579                         break;
 580
 581                 default:
 582                         break;
 583
 584                 }
 585
 586                 if (slave_state == Waiting) {
 587
 588                         // cerr << "waiting at " << slave_transport_frame << endl;
 589                         if (slave_transport_frame >= slave_wait_end) {
 590                                 // cerr << "\tstart at " << _transport_frame << endl;
 591
 592                                 slave_state = Running;
 593
 594                                 bool ok = true;
 595                                 nframes_t frame_delta = slave_transport_frame - _transport_frame;
 596
 597                                 boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 598
 599                                 for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
 600                                         if (!(*i)->can_internal_playback_seek (frame_delta)) {
 601                                                 ok = false;
 602                                                 break;
 603                                         }
 604                                 }
 605
 606                                 if (ok) {
 607                                         for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
 608                                                 (*i)->internal_playback_seek (frame_delta);
 609                                         }
 610                                         _transport_frame += frame_delta;
 611
 612                                 } else {
 613                                         // cerr << "cannot micro-seek\n";
 614                                         /* XXX what? */
 615                                 }
 616
 617                                 memset (delta_accumulator, 0, sizeof (long) * delta_accumulator_size);
 618                                 average_slave_delta = 0L;
 619                                 this_delta = 0;
 620                         }
 621                 }
 622
 623                 if (slave_state == Running && _transport_speed == 0.0f) {
 624
 625                         // cerr << "slave starts transport\n";
 626
 627                         start_transport ();
 628                 }
 629
 630         } else {
 631
 632                 /* slave has stopped */
 633
 634                 if (_transport_speed != 0.0f) {
 635
 636                         // cerr << "slave stops transport: " << slave_speed << " frame: " << slave_transport_frame
 637                         // << " tf = " << _transport_frame
 638                         // << endl;
 639
 640                         if (Config->get_slave_source() == JACK) {
 641                                 last_stop_frame = _transport_frame;
 642                         }
 643
 644                         stop_transport();
 645                 }
 646
 647                 if (slave_transport_frame != _transport_frame) {
 648                         // cerr << "slave stopped, move to " << slave_transport_frame << endl;
 649                         force_locate (slave_transport_frame, false);
 650                 }
 651
 652                 slave_state = Stopped;
 653         }
 654
 655         if (slave_state == Running && !_slave->is_always_synced() && !Config->get_timecode_source_is_synced()) {
 656
 657
 658                 if (_transport_speed != 0.0f) {
 659
 660                         /*
 661                            note that average_dir is +1 or -1
 662                         */
 663
 664                         const float adjust_seconds = 1.0f;
 665                         float delta;
 666
 667                         //if (average_slave_delta == 0) {
 668                                 delta = this_delta;
 669                                 delta *= dir;
 670 //                      } else {
 671 //                              delta = average_slave_delta;
 672 //                              delta *= average_dir;
 673 //                      }
 674
 675                         float adjusted_speed = slave_speed +
 676                                 (delta / (adjust_seconds * _current_frame_rate));
 677
 678 #if 0
 679                         cerr << "adjust using " << delta
 680                              << " towards " << adjusted_speed
 681                              << " ratio = " << adjusted_speed / slave_speed
 682                              << " current = " << _transport_speed
 683                              << " slave @ " << slave_speed
 684                              << endl;
 685 #endif
 686
 687                         request_transport_speed (adjusted_speed);
 688
 689 #if 1
 690                         if (abs(average_slave_delta) > (long) _slave->resolution()) {
 691                                 cerr << "average slave delta greater than slave resolution, going to silent motion\n";
 692                                 goto silent_motion;
 693                         }
 694 #endif
 695                 }
 696         }
 697
 698         if (!starting && !non_realtime_work_pending()) {
 699                 /* speed is set, we're locked, and good to go */
 700                 return true;
 701         }
 702
 703   silent_motion:
 704
 705         if (slave_speed && _transport_speed) {
 706
 707                 /* something isn't right, but we should move with the master
 708                    for now.
 709                 */
 710
 711                 bool need_butler;
 712
 713                 prepare_diskstreams ();
 714                 silent_process_routes (nframes, offset);
 715                 commit_diskstreams (nframes, need_butler);
 716
 717                 if (need_butler) {
 718                         summon_butler ();
 719                 }
 720
 721                 int32_t frames_moved = (int32_t) floor (_transport_speed * nframes);
 722
 723                 if (frames_moved < 0) {
 724                         decrement_transport_position (-frames_moved);
 725                 } else {
 726                         increment_transport_position (frames_moved);
 727                 }
 728
 729                 nframes_t stop_limit;
 730
 731                 if (actively_recording()) {
 732                         stop_limit = max_frames;
 733                 } else {
 734                         if (Config->get_stop_at_session_end()) {
 735                                 stop_limit = current_end_frame();
 736                         } else {
 737                                 stop_limit = max_frames;
 738                         }
 739                 }
 740
 741                 maybe_stop (stop_limit);
 742         }
 743
 744   noroll:
 745         /* don't move at all */
 746         no_roll (nframes, 0);
 747         return false;
 748 }
 749
 750 void
 751 Session::process_without_events (nframes_t nframes)
 752 {
 753         bool session_needs_butler = false;
 754         nframes_t stop_limit;
 755         long frames_moved;
 756         nframes_t offset = 0;
 757
 758         if (!process_can_proceed()) {
 759                 _silent = true;
 760                 return;
 761         }
 762
 763         if (!_exporting && _slave) {
 764                 if (!follow_slave (nframes, 0)) {
 765                         return;
 766                 }
 767         }
 768
 769         if (_transport_speed == 0) {
 770                 no_roll (nframes, 0);
 771                 return;
 772         }
 773
 774         if (!_exporting) {
 775                 send_midi_time_code_for_cycle (nframes);
 776         }
 777
 778         if (actively_recording()) {
 779                 stop_limit = max_frames;
 780         } else {
 781                 if (Config->get_stop_at_session_end()) {
 782                         stop_limit = current_end_frame();
 783                 } else {
 784                         stop_limit = max_frames;
 785                 }
 786         }
 787
 788         if (maybe_stop (stop_limit)) {
 789                 no_roll (nframes, 0);
 790                 return;
 791         }
 792
 793         if (maybe_sync_start (nframes, offset)) {
 794                 return;
 795         }
 796
 797         click (_transport_frame, nframes, offset);
 798
 799         prepare_diskstreams ();
 800
 801         frames_moved = (long) floor (_transport_speed * nframes);
 802
 803         if (process_routes (nframes, offset)) {
 804                 no_roll (nframes, offset);
 805                 return;
 806         }
 807
 808         commit_diskstreams (nframes, session_needs_butler);
 809
 810         if (frames_moved < 0) {
 811                 decrement_transport_position (-frames_moved);
 812         } else {
 813                 increment_transport_position (frames_moved);
 814         }
 815
 816         maybe_stop (stop_limit);
 817         check_declick_out ();
 818
 819         if (session_needs_butler)
 820                 summon_butler ();
 821 }
 822
 823 /** Process callback used when the auditioner is active.
 824  * @param nframes number of frames to process.
 825  */
 826 void
 827 Session::process_audition (nframes_t nframes)
 828 {
 829         Event* ev;
 830         boost::shared_ptr<RouteList> r = routes.reader ();
 831
 832         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 833                 if (!(*i)->is_hidden()) {
 834                         (*i)->silence (nframes, 0);
 835                 }
 836         }
 837
 838         /* run the auditioner, and if it says we need butler service, ask for it */
 839
 840         if (auditioner->play_audition (nframes) > 0) {
 841                 summon_butler ();
 842         }
 843
 844         /* handle pending events */
 845
 846         while (pending_events.read (&ev, 1) == 1) {
 847                 merge_event (ev);
 848         }
 849
 850         /* if we are not in the middle of a state change,
 851            and there are immediate events queued up,
 852            process them.
 853         */
 854
 855         while (!non_realtime_work_pending() && !immediate_events.empty()) {
 856                 Event *ev = immediate_events.front ();
 857                 immediate_events.pop_front ();
 858                 process_event (ev);
 859         }
 860
 861         if (!auditioner->active()) {
 862                 /* auditioner no longer active, so go back to the normal process callback */
 863                 process_function = &Session::process_with_events;
 864         }
 865 }
 866
 867 bool
 868 Session::maybe_sync_start (nframes_t& nframes, nframes_t& offset)
 869 {
 870         nframes_t sync_offset;
 871
 872         if (!waiting_for_sync_offset) {
 873                 return false;
 874         }
 875
 876         if (_engine.get_sync_offset (sync_offset) && sync_offset < nframes) {
 877
 878                 /* generate silence up to the sync point, then
 879                    adjust nframes + offset to reflect whatever
 880                    is left to do.
 881                 */
 882
 883                 no_roll (sync_offset, 0);
 884                 nframes -= sync_offset;
 885                 offset += sync_offset;
 886                 waiting_for_sync_offset = false;
 887
 888                 if (nframes == 0) {
 889                         return true; // done, nothing left to process
 890                 }
 891
 892         } else {
 893
 894                 /* sync offset point is not within this process()
 895                    cycle, so just generate silence. and don't bother
 896                    with any fancy stuff here, just the minimal silence.
 897                 */
 898
 899                 g_atomic_int_inc (&processing_prohibited);
 900                 no_roll (nframes, 0);
 901                 g_atomic_int_dec_and_test (&processing_prohibited);
 902
 903                 if (Config->get_locate_while_waiting_for_sync()) {
 904                         if (micro_locate (nframes)) {
 905                                 /* XXX ERROR !!! XXX */
 906                         }
 907                 }
 908
 909                 return true; // done, nothing left to process
 910         }
 911
 912         return false;
 913 }
 914