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 "i18n.h"
  40
  41 using namespace ARDOUR;
  42 using namespace PBD;
  43 using namespace std;
  44
  45 void
  46 Session::process (nframes_t nframes)
  47 {
  48         _silent = false;
  49
  50         if (synced_to_jack() && waiting_to_start) {
  51                 if ( _engine.transport_state() == AudioEngine::TransportRolling) {
  52                         actually_start_transport ();
  53                 }
  54         }
  55
  56         if (non_realtime_work_pending()) {
  57                 if (!transport_work_requested ()) {
  58                         post_transport ();
  59                 }
  60         }
  61
  62         (this->*process_function) (nframes);
  63
  64         SendFeedback (); /* EMIT SIGNAL */
  65 }
  66
  67 void
  68 Session::prepare_diskstreams ()
  69 {
  70         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
  71         for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
  72                 (*i)->prepare ();
  73         }
  74 }
  75
  76 int
  77 Session::no_roll (nframes_t nframes, nframes_t offset)
  78 {
  79         nframes_t end_frame = _transport_frame + nframes;
  80         int ret = 0;
  81         bool declick = get_transport_declick_required();
  82         boost::shared_ptr<RouteList> r = routes.reader ();
  83
  84         if (_click_io) {
  85                 _click_io->silence (nframes, offset);
  86         }
  87
  88         if (g_atomic_int_get (&processing_prohibited)) {
  89                 for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
  90                         (*i)->silence (nframes, offset);
  91                 }
  92                 return 0;
  93         }
  94
  95         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
  96
  97                 if ((*i)->hidden()) {
  98                         continue;
  99                 }
 100
 101                 (*i)->set_pending_declick (declick);
 102
 103                 if ((*i)->no_roll (nframes, _transport_frame, end_frame, offset, non_realtime_work_pending(),
 104                                    actively_recording(), declick)) {
 105                         error << string_compose(_("Session: error in no roll for %1"), (*i)->name()) << endmsg;
 106                         ret = -1;
 107                         break;
 108                 }
 109         }
 110
 111         return ret;
 112 }
 113
 114 int
 115 Session::process_routes (nframes_t nframes, nframes_t offset)
 116 {
 117         bool record_active;
 118         int  declick = get_transport_declick_required();
 119         bool rec_monitors = get_rec_monitors_input();
 120         boost::shared_ptr<RouteList> r = routes.reader ();
 121
 122         if (transport_sub_state & StopPendingCapture) {
 123                 /* force a declick out */
 124                 declick = -1;
 125         }
 126
 127         record_active = actively_recording(); // || (get_record_enabled() && get_punch_in());
 128
 129         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 130
 131                 int ret;
 132
 133                 if ((*i)->hidden()) {
 134                         continue;
 135                 }
 136
 137                 (*i)->set_pending_declick (declick);
 138
 139                 if ((ret = (*i)->roll (nframes, _transport_frame, _transport_frame + nframes, offset, declick, record_active, rec_monitors)) < 0) {
 140
 141                         /* we have to do this here. Route::roll() for an AudioTrack will have called AudioDiskstream::process(),
 142                            and the DS will expect AudioDiskstream::commit() to be called. but we're aborting from that
 143                            call path, so make sure we release any outstanding locks here before we return failure.
 144                         */
 145
 146                         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 147                         for (DiskstreamList::iterator ids = dsl->begin(); ids != dsl->end(); ++ids) {
 148                                 (*ids)->recover ();
 149                         }
 150
 151                         stop_transport ();
 152                         return -1;
 153                 }
 154         }
 155
 156         return 0;
 157 }
 158
 159 int
 160 Session::silent_process_routes (nframes_t nframes, nframes_t offset)
 161 {
 162         bool record_active = actively_recording();
 163         int  declick = get_transport_declick_required();
 164         bool rec_monitors = get_rec_monitors_input();
 165         boost::shared_ptr<RouteList> r = routes.reader ();
 166
 167         if (transport_sub_state & StopPendingCapture) {
 168                 /* force a declick out */
 169                 declick = -1;
 170         }
 171
 172         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 173
 174                 int ret;
 175
 176                 if ((*i)->hidden()) {
 177                         continue;
 178                 }
 179
 180                 if ((ret = (*i)->silent_roll (nframes, _transport_frame, _transport_frame + nframes, offset, record_active, rec_monitors)) < 0) {
 181
 182                         /* we have to do this here. Route::roll() for an AudioTrack will have called AudioDiskstream::process(),
 183                            and the DS will expect AudioDiskstream::commit() to be called. but we're aborting from that
 184                            call path, so make sure we release any outstanding locks here before we return failure.
 185                         */
 186
 187                         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 188                         for (DiskstreamList::iterator ids = dsl->begin(); ids != dsl->end(); ++ids) {
 189                                 (*ids)->recover ();
 190                         }
 191
 192                         stop_transport ();
 193                         return -1;
 194                 }
 195         }
 196
 197         return 0;
 198 }
 199
 200 void
 201 Session::commit_diskstreams (nframes_t nframes, bool &needs_butler)
 202 {
 203         int dret;
 204         float pworst = 1.0f;
 205         float cworst = 1.0f;
 206
 207         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 208         for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
 209
 210                 if ((*i)->hidden()) {
 211                         continue;
 212                 }
 213
 214                 /* force all diskstreams not handled by a Route to call do their stuff.
 215                    Note: the diskstreams that were handled by a route will just return zero
 216                    from this call, because they know they were processed. So in fact, this
 217                    also runs commit() for every diskstream.
 218                  */
 219
 220                 if ((dret = (*i)->process (_transport_frame, nframes, 0, actively_recording(), get_rec_monitors_input())) == 0) {
 221                         if ((*i)->commit (nframes)) {
 222                                 needs_butler = true;
 223                         }
 224
 225                 } else if (dret < 0) {
 226                         (*i)->recover();
 227                 }
 228
 229                 pworst = min (pworst, (*i)->playback_buffer_load());
 230                 cworst = min (cworst, (*i)->capture_buffer_load());
 231         }
 232
 233         uint32_t pmin = g_atomic_int_get (&_playback_load);
 234         uint32_t pminold = g_atomic_int_get (&_playback_load_min);
 235         uint32_t cmin = g_atomic_int_get (&_capture_load);
 236         uint32_t cminold = g_atomic_int_get (&_capture_load_min);
 237
 238         g_atomic_int_set (&_playback_load, (uint32_t) floor (pworst * 100.0f));
 239         g_atomic_int_set (&_capture_load, (uint32_t) floor (cworst * 100.0f));
 240         g_atomic_int_set (&_playback_load_min, min (pmin, pminold));
 241         g_atomic_int_set (&_capture_load_min, min (cmin, cminold));
 242
 243         if (actively_recording()) {
 244                 set_dirty();
 245         }
 246 }
 247
 248 void
 249 Session::process_with_events (nframes_t nframes)
 250 {
 251         Event* ev;
 252         nframes_t this_nframes;
 253         nframes_t end_frame;
 254         nframes_t offset;
 255         bool session_needs_butler = false;
 256         nframes_t stop_limit;
 257         long           frames_moved;
 258
 259         /* make sure the auditioner is silent */
 260
 261         if (auditioner) {
 262                 auditioner->silence (nframes, 0);
 263         }
 264
 265         /* handle any pending events */
 266
 267         while (pending_events.read (&ev, 1) == 1) {
 268                 merge_event (ev);
 269         }
 270
 271         /* if we are not in the middle of a state change,
 272            and there are immediate events queued up,
 273            process them.
 274         */
 275
 276         while (!non_realtime_work_pending() && !immediate_events.empty()) {
 277                 Event *ev = immediate_events.front ();
 278                 immediate_events.pop_front ();
 279                 process_event (ev);
 280         }
 281
 282         if (!process_can_proceed()) {
 283                 _silent = true;
 284                 return;
 285         }
 286
 287         if (events.empty() || next_event == events.end()) {
 288                 process_without_events (nframes);
 289                 return;
 290         }
 291
 292         end_frame = _transport_frame + (nframes_t)abs(floor(nframes * _transport_speed));
 293
 294         {
 295                 Event* this_event;
 296                 Events::iterator the_next_one;
 297
 298                 if (!process_can_proceed()) {
 299                         _silent = true;
 300                         return;
 301                 }
 302
 303                 if (!_exporting && _slave) {
 304                         if (!follow_slave (nframes, 0)) {
 305                                 return;
 306                         }
 307                 }
 308
 309                 if (_transport_speed == 0) {
 310                         no_roll (nframes, 0);
 311                         return;
 312                 }
 313
 314                 if (actively_recording()) {
 315                         stop_limit = max_frames;
 316                 } else {
 317
 318                         if (Config->get_stop_at_session_end()) {
 319                                 stop_limit = current_end_frame();
 320                         } else {
 321                                 stop_limit = max_frames;
 322                         }
 323                 }
 324
 325                 if (maybe_stop (stop_limit)) {
 326                         no_roll (nframes, 0);
 327                         return;
 328                 }
 329
 330                 this_event = *next_event;
 331                 the_next_one = next_event;
 332                 ++the_next_one;
 333
 334                 offset = 0;
 335
 336                 while (nframes) {
 337
 338                         this_nframes = nframes; /* real (jack) time relative */
 339                         frames_moved = (long) floor (_transport_speed * nframes); /* transport relative */
 340
 341                         /* running an event, position transport precisely to its time */
 342                         if (this_event && this_event->action_frame <= end_frame && this_event->action_frame >= _transport_frame) {
 343                                 /* this isn't quite right for reverse play */
 344                                 frames_moved = (long) (this_event->action_frame - _transport_frame);
 345                                 this_nframes = (nframes_t) abs( floor(frames_moved / _transport_speed) );
 346                         }
 347
 348                         if (this_nframes) {
 349
 350                                 click (_transport_frame, nframes, offset);
 351
 352                                 /* now process frames between now and the first event in this block */
 353                                 prepare_diskstreams ();
 354
 355                                 if (process_routes (this_nframes, offset)) {
 356                                         no_roll (nframes, 0);
 357                                         return;
 358                                 }
 359
 360                                 commit_diskstreams (this_nframes, session_needs_butler);
 361
 362                                 nframes -= this_nframes;
 363                                 offset += this_nframes;
 364
 365                                 if (frames_moved < 0) {
 366                                         decrement_transport_position (-frames_moved);
 367                                 } else {
 368                                         increment_transport_position (frames_moved);
 369                                 }
 370
 371                                 maybe_stop (stop_limit);
 372                                 check_declick_out ();
 373                         }
 374
 375                         /* now handle this event and all others scheduled for the same time */
 376
 377                         while (this_event && this_event->action_frame == _transport_frame) {
 378                                 process_event (this_event);
 379
 380                                 if (the_next_one == events.end()) {
 381                                         this_event = 0;
 382                                 } else {
 383                                         this_event = *the_next_one;
 384                                         ++the_next_one;
 385                                 }
 386                         }
 387
 388                         /* if an event left our state changing, do the right thing */
 389
 390                         if (non_realtime_work_pending()) {
 391                                 no_roll (nframes, offset);
 392                                 break;
 393                         }
 394
 395                         /* this is necessary to handle the case of seamless looping */
 396                         end_frame = _transport_frame + (nframes_t) floor (nframes * _transport_speed);
 397
 398                 }
 399
 400                 set_next_event ();
 401
 402         } /* implicit release of route lock */
 403
 404
 405         if (session_needs_butler) {
 406                 summon_butler ();
 407         }
 408
 409         if (!_engine.freewheeling() && session_send_mtc) {
 410                 send_midi_time_code_in_another_thread ();
 411         }
 412
 413         return;
 414 }
 415
 416 void
 417 Session::reset_slave_state ()
 418 {
 419         average_slave_delta = 1800;
 420         delta_accumulator_cnt = 0;
 421         have_first_delta_accumulator = false;
 422         slave_state = Stopped;
 423 }
 424
 425 bool
 426 Session::transport_locked () const
 427 {
 428         Slave* sl = _slave;
 429
 430         if (!locate_pending() && ((Config->get_slave_source() == None) || (sl && sl->ok() && sl->locked()))) {
 431                 return true;
 432         }
 433
 434         return false;
 435 }
 436
 437 bool
 438 Session::follow_slave (nframes_t nframes, nframes_t offset)
 439 {
 440         float slave_speed;
 441         nframes_t slave_transport_frame;
 442         nframes_t this_delta;
 443         int dir;
 444         bool starting;
 445
 446         if (!_slave->ok()) {
 447                 stop_transport ();
 448                 Config->set_slave_source (None);
 449                 goto noroll;
 450         }
 451
 452         _slave->speed_and_position (slave_speed, slave_transport_frame);
 453
 454         if (!_slave->locked()) {
 455                 cerr << "Slave not locked, not rolling\n";
 456                 goto noroll;
 457         }
 458
 459         if (slave_transport_frame > _transport_frame) {
 460                 this_delta = slave_transport_frame - _transport_frame;
 461                 dir = 1;
 462         } else {
 463                 this_delta = _transport_frame - slave_transport_frame;
 464                 dir = -1;
 465         }
 466
 467         if ((starting = _slave->starting())) {
 468                 slave_speed = 0.0f;
 469         }
 470
 471 #if 0
 472         cerr << "delta = " << (int) (dir * this_delta)
 473              << " speed = " << slave_speed
 474              << " ts = " << _transport_speed
 475              << " M@ "<< slave_transport_frame << " S@ " << _transport_frame
 476              << " avgdelta = " << average_slave_delta
 477              << endl;
 478 #endif
 479
 480         if (_slave->is_always_synced() || Config->get_timecode_source_is_synced()) {
 481
 482                 /* if the TC source is synced, then we assume that its
 483                    speed is binary: 0.0 or 1.0
 484                 */
 485
 486                 if (slave_speed != 0.0f) {
 487                         slave_speed = 1.0f;
 488                 }
 489
 490         } else {
 491
 492                 /* TC source is able to drift relative to us (slave)
 493                    so we need to keep track of the drift and adjust
 494                    our speed to remain locked.
 495                 */
 496
 497                 if (delta_accumulator_cnt >= delta_accumulator_size) {
 498                         have_first_delta_accumulator = true;
 499                         delta_accumulator_cnt = 0;
 500                 }
 501
 502                 if (delta_accumulator_cnt != 0 || this_delta < _current_frame_rate) {
 503                         delta_accumulator[delta_accumulator_cnt++] = dir*this_delta;
 504                 }
 505
 506                 if (have_first_delta_accumulator) {
 507                         average_slave_delta = 0;
 508                         for (int i = 0; i < delta_accumulator_size; ++i) {
 509                                 average_slave_delta += delta_accumulator[i];
 510                         }
 511                         average_slave_delta /= delta_accumulator_size;
 512                         if (average_slave_delta < 0) {
 513                                 average_dir = -1;
 514                                 average_slave_delta = -average_slave_delta;
 515                         } else {
 516                                 average_dir = 1;
 517                         }
 518                         // cerr << "avgdelta = " << average_slave_delta*average_dir << endl;
 519                 }
 520         }
 521
 522         if (slave_speed != 0.0f) {
 523
 524                 /* slave is running */
 525
 526                 switch (slave_state) {
 527                 case Stopped:
 528                         if (_slave->requires_seekahead()) {
 529                                 slave_wait_end = slave_transport_frame + _current_frame_rate;
 530                                 locate (slave_wait_end, false, false);
 531                                 slave_state = Waiting;
 532                                 starting = true;
 533
 534                         } else {
 535
 536                                 slave_state = Running;
 537
 538                                 Location* al = _locations.auto_loop_location();
 539
 540                                 if (al && play_loop && (slave_transport_frame < al->start() || slave_transport_frame > al->end())) {
 541                                         // cancel looping
 542                                         request_play_loop(false);
 543                                 }
 544
 545                                 if (slave_transport_frame != _transport_frame) {
 546                                         locate (slave_transport_frame, false, false);
 547                                 }
 548                         }
 549                         break;
 550
 551                 case Waiting:
 552                         break;
 553
 554                 default:
 555                         break;
 556
 557                 }
 558
 559                 if (slave_state == Waiting) {
 560
 561                         // cerr << "waiting at " << slave_transport_frame << endl;
 562
 563                         if (slave_transport_frame >= slave_wait_end) {
 564                                 // cerr << "\tstart at " << _transport_frame << endl;
 565
 566                                 slave_state = Running;
 567
 568                                 bool ok = true;
 569                                 nframes_t frame_delta = slave_transport_frame - _transport_frame;
 570
 571                                 boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 572
 573                                 for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
 574                                         if (!(*i)->can_internal_playback_seek (frame_delta)) {
 575                                                 ok = false;
 576                                                 break;
 577                                         }
 578                                 }
 579
 580                                 if (ok) {
 581                                         for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
 582                                                 (*i)->internal_playback_seek (frame_delta);
 583                                         }
 584                                         _transport_frame += frame_delta;
 585
 586                                 } else {
 587                                         // cerr << "cannot micro-seek\n";
 588                                         /* XXX what? */
 589                                 }
 590
 591                                 memset (delta_accumulator, 0, sizeof (nframes_t) * delta_accumulator_size);
 592                                 average_slave_delta = 0;
 593                                 this_delta = 0;
 594                         }
 595                 }
 596
 597                 if (slave_state == Running && _transport_speed == 0.0f) {
 598
 599                         // cerr << "slave starts transport\n";
 600
 601                         start_transport ();
 602                 }
 603
 604         } else {
 605
 606                 /* slave has stopped */
 607
 608                 if (_transport_speed != 0.0f) {
 609
 610                         // cerr << "slave stops transport: " << slave_speed << " frame: " << slave_transport_frame
 611                         // << " tf = " << _transport_frame
 612                         // << endl;
 613
 614                         if (Config->get_slave_source() == JACK) {
 615                                 last_stop_frame = _transport_frame;
 616                         }
 617
 618                         stop_transport();
 619                 }
 620
 621                 if (slave_transport_frame != _transport_frame) {
 622                         // cerr << "slave stopped, move to " << slave_transport_frame << endl;
 623                         force_locate (slave_transport_frame, false);
 624                 }
 625
 626                 slave_state = Stopped;
 627         }
 628
 629         if (slave_state == Running && !_slave->is_always_synced() && !Config->get_timecode_source_is_synced()) {
 630
 631
 632                 if (_transport_speed != 0.0f) {
 633
 634                         /*
 635                            note that average_dir is +1 or -1
 636                         */
 637
 638                         const float adjust_seconds = 1.0f;
 639                         float delta;
 640
 641                         //if (average_slave_delta == 0) {
 642                                 delta = this_delta;
 643                                 delta *= dir;
 644 //                      } else {
 645 //                              delta = average_slave_delta;
 646 //                              delta *= average_dir;
 647 //                      }
 648
 649                         float adjusted_speed = slave_speed +
 650                                 (delta / (adjust_seconds * _current_frame_rate));
 651
 652                         // cerr << "adjust using " << delta
 653                         // << " towards " << adjusted_speed
 654                         // << " ratio = " << adjusted_speed / slave_speed
 655                         // << " current = " << _transport_speed
 656                         // << " slave @ " << slave_speed
 657                         // << endl;
 658
 659                         request_transport_speed (adjusted_speed);
 660
 661 #if 1
 662                         if ((nframes_t) average_slave_delta > _slave->resolution()) {
 663                                 // cerr << "not locked\n";
 664                                 goto silent_motion;
 665                         }
 666 #endif
 667                 }
 668         }
 669
 670         if (!starting && !non_realtime_work_pending()) {
 671                 /* speed is set, we're locked, and good to go */
 672                 return true;
 673         }
 674
 675   silent_motion:
 676
 677         if (slave_speed && _transport_speed) {
 678
 679                 /* something isn't right, but we should move with the master
 680                    for now.
 681                 */
 682
 683                 bool need_butler;
 684
 685                 prepare_diskstreams ();
 686                 silent_process_routes (nframes, offset);
 687                 commit_diskstreams (nframes, need_butler);
 688
 689                 if (need_butler) {
 690                         summon_butler ();
 691                 }
 692
 693                 int32_t frames_moved = (int32_t) floor (_transport_speed * nframes);
 694
 695                 if (frames_moved < 0) {
 696                         decrement_transport_position (-frames_moved);
 697                 } else {
 698                         increment_transport_position (frames_moved);
 699                 }
 700
 701                 nframes_t stop_limit;
 702
 703                 if (actively_recording()) {
 704                         stop_limit = max_frames;
 705                 } else {
 706                         if (Config->get_stop_at_session_end()) {
 707                                 stop_limit = current_end_frame();
 708                         } else {
 709                                 stop_limit = max_frames;
 710                         }
 711                 }
 712
 713                 maybe_stop (stop_limit);
 714         }
 715
 716   noroll:
 717         /* don't move at all */
 718         no_roll (nframes, 0);
 719         return false;
 720 }
 721
 722 void
 723 Session::process_without_events (nframes_t nframes)
 724 {
 725         bool session_needs_butler = false;
 726         nframes_t stop_limit;
 727         long frames_moved;
 728         nframes_t offset = 0;
 729
 730         if (!process_can_proceed()) {
 731                 _silent = true;
 732                 return;
 733         }
 734
 735         if (!_exporting && _slave) {
 736                 if (!follow_slave (nframes, 0)) {
 737                         return;
 738                 }
 739         }
 740
 741         if (_transport_speed == 0) {
 742                 no_roll (nframes, 0);
 743                 return;
 744         }
 745
 746         if (actively_recording()) {
 747                 stop_limit = max_frames;
 748         } else {
 749                 if (Config->get_stop_at_session_end()) {
 750                         stop_limit = current_end_frame();
 751                 } else {
 752                         stop_limit = max_frames;
 753                 }
 754         }
 755
 756         if (maybe_stop (stop_limit)) {
 757                 no_roll (nframes, 0);
 758                 return;
 759         }
 760
 761         if (maybe_sync_start (nframes, offset)) {
 762                 return;
 763         }
 764
 765         click (_transport_frame, nframes, offset);
 766
 767         prepare_diskstreams ();
 768
 769         frames_moved = (long) floor (_transport_speed * nframes);
 770
 771         if (process_routes (nframes, offset)) {
 772                 no_roll (nframes, offset);
 773                 return;
 774         }
 775
 776         commit_diskstreams (nframes, session_needs_butler);
 777
 778         if (frames_moved < 0) {
 779                 decrement_transport_position (-frames_moved);
 780         } else {
 781                 increment_transport_position (frames_moved);
 782         }
 783
 784         maybe_stop (stop_limit);
 785         check_declick_out ();
 786
 787         if (session_needs_butler) {
 788                 summon_butler ();
 789         }
 790
 791         if (!_engine.freewheeling() && session_send_mtc) {
 792                 send_midi_time_code_in_another_thread ();
 793         }
 794
 795         return;
 796 }
 797
 798 void
 799 Session::process_audition (nframes_t nframes)
 800 {
 801         Event* ev;
 802         boost::shared_ptr<RouteList> r = routes.reader ();
 803
 804         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 805                 if (!(*i)->hidden()) {
 806                         (*i)->silence (nframes, 0);
 807                 }
 808         }
 809
 810         /* run the auditioner, and if it says we need butler service, ask for it */
 811
 812         if (auditioner->play_audition (nframes) > 0) {
 813                 summon_butler ();
 814         }
 815
 816         /* handle pending events */
 817
 818         while (pending_events.read (&ev, 1) == 1) {
 819                 merge_event (ev);
 820         }
 821
 822         /* if we are not in the middle of a state change,
 823            and there are immediate events queued up,
 824            process them.
 825         */
 826
 827         while (!non_realtime_work_pending() && !immediate_events.empty()) {
 828                 Event *ev = immediate_events.front ();
 829                 immediate_events.pop_front ();
 830                 process_event (ev);
 831         }
 832
 833         if (!auditioner->active()) {
 834                 process_function = &Session::process_with_events;
 835         }
 836 }
 837
 838 bool
 839 Session::maybe_sync_start (nframes_t& nframes, nframes_t& offset)
 840 {
 841         nframes_t sync_offset;
 842
 843         if (!waiting_for_sync_offset) {
 844                 return false;
 845         }
 846
 847         if (_engine.get_sync_offset (sync_offset) && sync_offset < nframes) {
 848
 849                 no_roll (sync_offset, 0);
 850                 nframes -= sync_offset;
 851                 offset += sync_offset;
 852                 waiting_for_sync_offset = false;
 853
 854                 if (nframes == 0) {
 855                         return true; // done
 856                 }
 857
 858         } else {
 859                 no_roll (nframes, 0);
 860                 return true; // done
 861         }
 862
 863         return false;
 864 }
 865