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     $Id$
  19 */
  20
  21 #include <cmath>
  22 #include <cerrno>
  23 #include <algorithm>
  24 #include <unistd.h>
  25
  26 #include <pbd/error.h>
  27
  28 #include <glibmm/thread.h>
  29
  30 #include <ardour/ardour.h>
  31 #include <ardour/session.h>
  32 #include <ardour/timestamps.h>
  33 #include <ardour/audio_diskstream.h>
  34 #include <ardour/audioengine.h>
  35 #include <ardour/slave.h>
  36 #include <ardour/auditioner.h>
  37 #include <ardour/cycles.h>
  38 #include <ardour/cycle_timer.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 void
  49 Session::process (jack_nframes_t nframes)
  50 {
  51         MIDI::Manager::instance()->cycle_start(nframes);
  52
  53         if (synced_to_jack() && waiting_to_start) {
  54                 if ( _engine.transport_state() == AudioEngine::TransportRolling) {
  55                         actually_start_transport ();
  56                 }
  57         }
  58
  59         if (non_realtime_work_pending()) {
  60                 if (g_atomic_int_get (&butler_should_do_transport_work) == 0) {
  61                         post_transport ();
  62                 }
  63         }
  64
  65         (this->*process_function) (nframes);
  66
  67         MIDI::Manager::instance()->cycle_end();
  68
  69         SendFeedback (); /* EMIT SIGNAL */
  70 }
  71
  72 void
  73 Session::prepare_diskstreams ()
  74 {
  75         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
  76         for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
  77                 (*i)->prepare ();
  78         }
  79 }
  80
  81 int
  82 Session::no_roll (jack_nframes_t nframes, jack_nframes_t offset)
  83 {
  84         jack_nframes_t end_frame = _transport_frame + nframes; // FIXME: varispeed + no_roll ??
  85         int ret = 0;
  86         bool declick = get_transport_declick_required();
  87         boost::shared_ptr<RouteList> r = routes.reader ();
  88
  89         if (_click_io) {
  90                 _click_io->silence (nframes, offset);
  91         }
  92
  93         if (g_atomic_int_get (&processing_prohibited)) {
  94                 for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
  95                         (*i)->silence (nframes, offset);
  96                 }
  97                 return 0;
  98         }
  99
 100         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 101
 102                 if ((*i)->hidden()) {
 103                         continue;
 104                 }
 105
 106                 (*i)->set_pending_declick (declick);
 107
 108                 if ((*i)->no_roll (nframes, _transport_frame, end_frame, offset, non_realtime_work_pending(),
 109                                    actively_recording(), declick)) {
 110                         error << string_compose(_("Session: error in no roll for %1"), (*i)->name()) << endmsg;
 111                         ret = -1;
 112                         break;
 113                 }
 114         }
 115
 116         return ret;
 117 }
 118
 119 int
 120 Session::process_routes (jack_nframes_t nframes, jack_nframes_t offset)
 121 {
 122         bool record_active;
 123         int  declick = get_transport_declick_required();
 124         bool rec_monitors = get_rec_monitors_input();
 125         boost::shared_ptr<RouteList> r = routes.reader ();
 126
 127         if (transport_sub_state & StopPendingCapture) {
 128                 /* force a declick out */
 129                 declick = -1;
 130         }
 131
 132         record_active = actively_recording(); // || (get_record_enabled() && get_punch_in());
 133
 134         const jack_nframes_t start_frame = _transport_frame;
 135         const jack_nframes_t end_frame = _transport_frame + (jack_nframes_t)floor(nframes * _transport_speed);
 136
 137         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 138
 139                 int ret;
 140
 141                 if ((*i)->hidden()) {
 142                         continue;
 143                 }
 144
 145                 (*i)->set_pending_declick (declick);
 146
 147                 if ((ret = (*i)->roll (nframes, start_frame, end_frame, offset, declick, record_active, rec_monitors)) < 0) {
 148
 149                         /* we have to do this here. Route::roll() for an AudioTrack will have called AudioDiskstream::process(),
 150                            and the DS will expect AudioDiskstream::commit() to be called. but we're aborting from that
 151                            call path, so make sure we release any outstanding locks here before we return failure.
 152                         */
 153
 154                         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 155                         for (DiskstreamList::iterator ids = dsl->begin(); ids != dsl->end(); ++ids) {
 156                                 (*ids)->recover ();
 157                         }
 158
 159                         stop_transport ();
 160                         return -1;
 161                 }
 162         }
 163
 164         return 0;
 165 }
 166
 167 int
 168 Session::silent_process_routes (jack_nframes_t nframes, jack_nframes_t offset)
 169 {
 170         bool record_active = actively_recording();
 171         int  declick = get_transport_declick_required();
 172         bool rec_monitors = get_rec_monitors_input();
 173         boost::shared_ptr<RouteList> r = routes.reader ();
 174
 175         if (transport_sub_state & StopPendingCapture) {
 176                 /* force a declick out */
 177                 declick = -1;
 178         }
 179
 180         const jack_nframes_t start_frame = _transport_frame;
 181         const jack_nframes_t end_frame = _transport_frame + lrintf(nframes * _transport_speed);
 182
 183         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 184
 185                 int ret;
 186
 187                 if ((*i)->hidden()) {
 188                         continue;
 189                 }
 190
 191                 if ((ret = (*i)->silent_roll (nframes, start_frame, end_frame, offset, record_active, rec_monitors)) < 0) {
 192
 193                         /* we have to do this here. Route::roll() for an AudioTrack will have called AudioDiskstream::process(),
 194                            and the DS will expect AudioDiskstream::commit() to be called. but we're aborting from that
 195                            call path, so make sure we release any outstanding locks here before we return failure.
 196                         */
 197
 198                         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 199                         for (DiskstreamList::iterator ids = dsl->begin(); ids != dsl->end(); ++ids) {
 200                                 (*ids)->recover ();
 201                         }
 202
 203                         stop_transport ();
 204                         return -1;
 205                 }
 206         }
 207
 208         return 0;
 209 }
 210
 211 void
 212 Session::commit_diskstreams (jack_nframes_t nframes, bool &needs_butler)
 213 {
 214         int dret;
 215         float pworst = 1.0f;
 216         float cworst = 1.0f;
 217
 218         boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 219         for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
 220
 221                 if ((*i)->hidden()) {
 222                         continue;
 223                 }
 224
 225                 /* force all diskstreams not handled by a Route to call do their stuff.
 226                  */
 227
 228                 if ((dret = (*i)->process (_transport_frame, nframes, 0, actively_recording(), get_rec_monitors_input())) == 0) {
 229                         if ((*i)->commit (nframes)) {
 230                                 needs_butler = true;
 231                         }
 232
 233                 } else if (dret < 0) {
 234                         (*i)->recover();
 235                 }
 236
 237                 pworst = min (pworst, (*i)->playback_buffer_load());
 238                 cworst = min (cworst, (*i)->capture_buffer_load());
 239         }
 240
 241         uint32_t pmin = g_atomic_int_get (&_playback_load);
 242         uint32_t pminold = g_atomic_int_get (&_playback_load_min);
 243         uint32_t cmin = g_atomic_int_get (&_capture_load);
 244         uint32_t cminold = g_atomic_int_get (&_capture_load_min);
 245
 246         g_atomic_int_set (&_playback_load, (uint32_t) floor (pworst * 100.0f));
 247         g_atomic_int_set (&_capture_load, (uint32_t) floor (cworst * 100.0f));
 248         g_atomic_int_set (&_playback_load_min, min (pmin, pminold));
 249         g_atomic_int_set (&_capture_load_min, min (cmin, cminold));
 250
 251         if (actively_recording()) {
 252                 set_dirty();
 253         }
 254 }
 255
 256
 257 void
 258 Session::process_with_events (jack_nframes_t nframes)
 259 {
 260         Event*         ev;
 261         jack_nframes_t this_nframes;
 262         jack_nframes_t end_frame;
 263         jack_nframes_t offset;
 264         jack_nframes_t stop_limit;
 265         long           frames_moved;
 266         bool           session_needs_butler = false;
 267
 268         /* make sure the auditioner is silent */
 269
 270         if (auditioner) {
 271                 auditioner->silence (nframes, 0);
 272         }
 273
 274         /* handle any pending events */
 275
 276         while (pending_events.read (&ev, 1) == 1) {
 277                 merge_event (ev);
 278         }
 279
 280         /* if we are not in the middle of a state change,
 281            and there are immediate events queued up,
 282            process them.
 283         */
 284
 285         while (!non_realtime_work_pending() && !immediate_events.empty()) {
 286                 Event *ev = immediate_events.front ();
 287                 immediate_events.pop_front ();
 288                 process_event (ev);
 289         }
 290
 291         /* Events caused a transport change, send an MTC Full Frame (SMPTE) message.
 292          * This is sent whether rolling or not, to give slaves an idea of ardour time
 293          * on locates (and allow slow slaves to position and prepare for rolling)
 294          */
 295         if (_send_smpte_update) {
 296                 send_full_time_code(nframes);
 297         }
 298
 299         if (!process_can_proceed()) {
 300                 no_roll (nframes, 0);
 301                 return;
 302         }
 303
 304         if (events.empty() || next_event == events.end()) {
 305                 process_without_events (nframes);
 306                 return;
 307         }
 308
 309         end_frame = _transport_frame + nframes;
 310
 311         {
 312                 Event* this_event;
 313                 Events::iterator the_next_one;
 314
 315                 if (post_transport_work & (PostTransportLocate|PostTransportStop)) {
 316                         no_roll (nframes, 0);
 317                         return;
 318                 }
 319
 320                 if (!_exporting && _slave) {
 321                         if (!follow_slave (nframes, 0)) {
 322                                 return;
 323                         }
 324                 }
 325
 326                 if (_transport_speed == 0) {
 327                         no_roll (nframes, 0);
 328                         return;
 329                 }
 330
 331                 send_midi_time_code_for_cycle(nframes);
 332
 333                 if (actively_recording()) {
 334                         stop_limit = max_frames;
 335                 } else {
 336
 337                         if (Config->get_stop_at_session_end()) {
 338                                 stop_limit = current_end_frame();
 339                         } else {
 340                                 stop_limit = max_frames;
 341                         }
 342                 }
 343
 344                 if (maybe_stop (stop_limit)) {
 345                         no_roll (nframes, 0);
 346                         return;
 347                 }
 348
 349                 this_event = *next_event;
 350                 the_next_one = next_event;
 351                 ++the_next_one;
 352
 353                 offset = 0;
 354
 355                 while (nframes) {
 356
 357                         if (this_event == 0 || this_event->action_frame > end_frame || this_event->action_frame < _transport_frame) {
 358
 359                                 this_nframes = nframes;
 360
 361                         } else {
 362
 363                                 /* compute nframes to next event */
 364
 365                                 if (this_event->action_frame < end_frame) {
 366                                         this_nframes = nframes - (end_frame - this_event->action_frame);
 367                                 } else {
 368                                         this_nframes = nframes;
 369                                 }
 370                         }
 371
 372                         if (this_nframes) {
 373
 374                                 click (_transport_frame, nframes, offset);
 375
 376                                 /* now process frames between now and the first event in this block */
 377                                 prepare_diskstreams ();
 378
 379                                 if (process_routes (this_nframes, offset)) {
 380                                         no_roll (nframes, 0);
 381                                         return;
 382                                 }
 383
 384                                 commit_diskstreams (this_nframes, session_needs_butler);
 385
 386                                 nframes -= this_nframes;
 387                                 offset += this_nframes;
 388
 389                                 frames_moved = (jack_nframes_t) floor (_transport_speed * this_nframes);
 390
 391                                 if (frames_moved < 0) {
 392                                         decrement_transport_position (-frames_moved);
 393                                 } else {
 394                                         increment_transport_position (frames_moved);
 395                                 }
 396
 397                                 maybe_stop (stop_limit);
 398                                 check_declick_out ();
 399                         }
 400
 401                         /* now handle this event and all others scheduled for the same time */
 402
 403                         while (this_event && this_event->action_frame == _transport_frame) {
 404                                 process_event (this_event);
 405
 406                                 if (the_next_one == events.end()) {
 407                                         this_event = 0;
 408                                 } else {
 409                                         this_event = *the_next_one;
 410                                         ++the_next_one;
 411                                 }
 412                         }
 413
 414                         /* if an event left our state changing, do the right thing */
 415
 416                         if (non_realtime_work_pending()) {
 417                                 no_roll (nframes, offset);
 418                                 break;
 419                         }
 420
 421                         /* this is necessary to handle the case of seamless looping */
 422                         /* not sure if it will work in conjuction with varispeed */
 423                         end_frame = _transport_frame + nframes;
 424
 425                 }
 426
 427                 set_next_event ();
 428
 429         } /* implicit release of route lock */
 430
 431         if (session_needs_butler)
 432                 summon_butler ();
 433 }
 434
 435 void
 436 Session::reset_slave_state ()
 437 {
 438         average_slave_delta = 1800;
 439         delta_accumulator_cnt = 0;
 440         have_first_delta_accumulator = false;
 441         slave_state = Stopped;
 442 }
 443
 444 bool
 445 Session::transport_locked () const
 446 {
 447         Slave* sl = _slave;
 448
 449         if (!locate_pending() && ((_slave_type == None) || (sl && sl->ok() && sl->locked()))) {
 450                 return true;
 451         }
 452
 453         return false;
 454 }
 455
 456 bool
 457 Session::follow_slave (jack_nframes_t nframes, jack_nframes_t offset)
 458 {
 459         float slave_speed;
 460         jack_nframes_t slave_transport_frame;
 461         jack_nframes_t this_delta;
 462         int dir;
 463         bool starting;
 464
 465         if (!_slave->ok()) {
 466                 stop_transport ();
 467                 set_slave_source (None, 0);
 468                 goto noroll;
 469         }
 470
 471         _slave->speed_and_position (slave_speed, slave_transport_frame);
 472
 473         if (!_slave->locked()) {
 474                 goto noroll;
 475         }
 476
 477         if (slave_transport_frame > _transport_frame) {
 478                 this_delta = slave_transport_frame - _transport_frame;
 479                 dir = 1;
 480         } else {
 481                 this_delta = _transport_frame - slave_transport_frame;
 482                 dir = -1;
 483         }
 484
 485         if ((starting = _slave->starting())) {
 486                 slave_speed = 0.0f;
 487         }
 488
 489 #if 0
 490         cerr << "delta = " << (int) (dir * this_delta)
 491              << " speed = " << slave_speed
 492              << " ts = " << _transport_speed
 493              << " M@"<< slave_transport_frame << " S@" << _transport_frame
 494              << " avgdelta = " << average_slave_delta
 495              << endl;
 496 #endif
 497
 498         if (Config->get_timecode_source_is_synced()) {
 499
 500                 /* if the TC source is synced, then we assume that its
 501                    speed is binary: 0.0 or 1.0
 502                 */
 503
 504                 if (slave_speed != 0.0f) {
 505                         slave_speed = 1.0f;
 506                 }
 507
 508         } else {
 509
 510                 /* TC source is able to drift relative to us (slave)
 511                    so we need to keep track of the drift and adjust
 512                    our speed to remain locked.
 513                 */
 514
 515                 if (delta_accumulator_cnt >= delta_accumulator_size) {
 516                         have_first_delta_accumulator = true;
 517                         delta_accumulator_cnt = 0;
 518                 }
 519
 520                 if (delta_accumulator_cnt != 0 || this_delta < _current_frame_rate) {
 521                         delta_accumulator[delta_accumulator_cnt++] = dir*this_delta;
 522                 }
 523
 524                 if (have_first_delta_accumulator) {
 525                         average_slave_delta = 0;
 526                         for (int i = 0; i < delta_accumulator_size; ++i) {
 527                                 average_slave_delta += delta_accumulator[i];
 528                         }
 529                         average_slave_delta /= delta_accumulator_size;
 530                         if (average_slave_delta < 0) {
 531                                 average_dir = -1;
 532                                 average_slave_delta = -average_slave_delta;
 533                         } else {
 534                                 average_dir = 1;
 535                         }
 536                         // cerr << "avgdelta = " << average_slave_delta*average_dir << endl;
 537                 }
 538         }
 539
 540         if (slave_speed != 0.0f) {
 541
 542                 /* slave is running */
 543
 544                 switch (slave_state) {
 545                 case Stopped:
 546                         if (_slave->requires_seekahead()) {
 547                                 slave_wait_end = slave_transport_frame + _current_frame_rate;
 548                                 locate (slave_wait_end, false, false);
 549                                 slave_state = Waiting;
 550                                 starting = true;
 551
 552                         } else {
 553
 554                                 slave_state = Running;
 555
 556                                 Location* al = _locations.auto_loop_location();
 557
 558                                 if (al && auto_loop && (slave_transport_frame < al->start() || slave_transport_frame > al->end())) {
 559                                         // cancel looping
 560                                         request_auto_loop(false);
 561                                 }
 562
 563                                 if (slave_transport_frame != _transport_frame) {
 564                                         locate (slave_transport_frame, false, false);
 565                                 }
 566                         }
 567                         break;
 568
 569                 case Waiting:
 570                         break;
 571
 572                 default:
 573                         break;
 574
 575                 }
 576
 577                 if (slave_state == Waiting) {
 578
 579                         // cerr << "waiting at " << slave_transport_frame << endl;
 580                         if (slave_transport_frame >= slave_wait_end) {
 581                                 // cerr << "\tstart at " << _transport_frame << endl;
 582
 583                                 slave_state = Running;
 584
 585                                 bool ok = true;
 586                                 jack_nframes_t frame_delta = slave_transport_frame - _transport_frame;
 587
 588                                 boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
 589
 590                                 for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
 591                                         if (!(*i)->can_internal_playback_seek (frame_delta)) {
 592                                                 ok = false;
 593                                                 break;
 594                                         }
 595                                 }
 596
 597                                 if (ok) {
 598                                         for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
 599                                                 (*i)->internal_playback_seek (frame_delta);
 600                                         }
 601                                         _transport_frame += frame_delta;
 602
 603                                 } else {
 604                                         // cerr << "cannot micro-seek\n";
 605                                         /* XXX what? */
 606                                 }
 607
 608                                 memset (delta_accumulator, 0, sizeof (jack_nframes_t) * delta_accumulator_size);
 609                                 average_slave_delta = 0;
 610                                 this_delta = 0;
 611                         }
 612                 }
 613
 614                 if (slave_state == Running && _transport_speed == 0.0f) {
 615
 616                         // cerr << "slave starts transport\n";
 617
 618                         start_transport ();
 619                 }
 620
 621         } else {
 622
 623                 /* slave has stopped */
 624
 625                 if (_transport_speed != 0.0f) {
 626
 627                         // cerr << "slave stops transport: " << slave_speed << " frame: " << slave_transport_frame
 628                         // << " tf = " << _transport_frame
 629                         // << endl;
 630
 631                         if (_slave_type == JACK) {
 632                                 last_stop_frame = _transport_frame;
 633                         }
 634
 635                         stop_transport();
 636                 }
 637
 638                 if (slave_transport_frame != _transport_frame) {
 639                         // cerr << "slave stopped, move to " << slave_transport_frame << endl;
 640                         force_locate (slave_transport_frame, false);
 641                 }
 642
 643                 slave_state = Stopped;
 644         }
 645
 646         if (slave_state == Running && !Config->get_timecode_source_is_synced()) {
 647
 648
 649                 if (_transport_speed != 0.0f) {
 650
 651                         /*
 652                            note that average_dir is +1 or -1
 653                         */
 654
 655                         const float adjust_seconds = 1.0f;
 656                         float delta;
 657
 658                         //if (average_slave_delta == 0) {
 659                                 delta = this_delta;
 660                                 delta *= dir;
 661 //                      } else {
 662 //                              delta = average_slave_delta;
 663 //                              delta *= average_dir;
 664 //                      }
 665
 666                         float adjusted_speed = slave_speed +
 667                                 (delta / (adjust_seconds * _current_frame_rate));
 668
 669                         // cerr << "adjust using " << delta
 670                         // << " towards " << adjusted_speed
 671                         // << " ratio = " << adjusted_speed / slave_speed
 672                         // << " current = " << _transport_speed
 673                         // << " slave @ " << slave_speed
 674                         // << endl;
 675
 676                         request_transport_speed (adjusted_speed);
 677
 678 #if 1
 679                         if ((jack_nframes_t) average_slave_delta > _slave->resolution()) {
 680                                 // cerr << "not locked\n";
 681                                 goto silent_motion;
 682                         }
 683 #endif
 684                 }
 685         }
 686
 687         if (!starting && !non_realtime_work_pending()) {
 688                 /* speed is set, we're locked, and good to go */
 689                 return true;
 690         }
 691
 692   silent_motion:
 693
 694         if (slave_speed && _transport_speed) {
 695
 696                 /* something isn't right, but we should move with the master
 697                    for now.
 698                 */
 699
 700                 bool need_butler;
 701
 702                 prepare_diskstreams ();
 703                 silent_process_routes (nframes, offset);
 704                 commit_diskstreams (nframes, need_butler);
 705
 706                 if (need_butler) {
 707                         summon_butler ();
 708                 }
 709
 710                 int32_t frames_moved = (int32_t) floor (_transport_speed * nframes);
 711
 712                 if (frames_moved < 0) {
 713                         decrement_transport_position (-frames_moved);
 714                 } else {
 715                         increment_transport_position (frames_moved);
 716                 }
 717
 718                 jack_nframes_t stop_limit;
 719
 720                 if (actively_recording()) {
 721                         stop_limit = max_frames;
 722                 } else {
 723                         if (Config->get_stop_at_session_end()) {
 724                                 stop_limit = current_end_frame();
 725                         } else {
 726                                 stop_limit = max_frames;
 727                         }
 728                 }
 729
 730                 maybe_stop (stop_limit);
 731         }
 732
 733   noroll:
 734         /* don't move at all */
 735         no_roll (nframes, 0);
 736         return false;
 737 }
 738
 739 void
 740 Session::process_without_events (jack_nframes_t nframes)
 741 {
 742         bool session_needs_butler = false;
 743         jack_nframes_t stop_limit;
 744         long frames_moved;
 745         jack_nframes_t offset = 0;
 746
 747         {
 748                 if (post_transport_work & (PostTransportLocate|PostTransportStop)) {
 749                         no_roll (nframes, 0);
 750                         return;
 751                 }
 752
 753                 if (!_exporting && _slave) {
 754                         if (!follow_slave (nframes, 0)) {
 755                                 return;
 756                         }
 757                 }
 758
 759                 if (_transport_speed == 0) {
 760                         no_roll (nframes, 0);
 761                         return;
 762                 }
 763
 764                 send_midi_time_code_for_cycle(nframes);
 765
 766                 if (actively_recording()) {
 767                         stop_limit = max_frames;
 768                 } else {
 769                         if (Config->get_stop_at_session_end()) {
 770                                 stop_limit = current_end_frame();
 771                         } else {
 772                                 stop_limit = max_frames;
 773                         }
 774                 }
 775
 776                 if (maybe_stop (stop_limit)) {
 777                         no_roll (nframes, 0);
 778                         return;
 779                 }
 780
 781                 if (maybe_sync_start (nframes, offset)) {
 782                         return;
 783                 }
 784
 785                 click (_transport_frame, nframes, offset);
 786
 787                 prepare_diskstreams ();
 788
 789                 frames_moved = (long) floor (_transport_speed * nframes);
 790
 791                 if (process_routes (nframes, offset)) {
 792                         no_roll (nframes, offset);
 793                         return;
 794                 }
 795
 796                 commit_diskstreams (nframes, session_needs_butler);
 797
 798                 if (frames_moved < 0) {
 799                         decrement_transport_position (-frames_moved);
 800                 } else {
 801                         increment_transport_position (frames_moved);
 802                 }
 803
 804                 maybe_stop (stop_limit);
 805                 check_declick_out ();
 806
 807         } /* implicit release of route lock */
 808
 809         if (session_needs_butler)
 810                 summon_butler ();
 811 }
 812
 813 void
 814 Session::process_audition (jack_nframes_t nframes)
 815 {
 816         Event* ev;
 817         boost::shared_ptr<RouteList> r = routes.reader ();
 818
 819         for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 820                 if (!(*i)->hidden()) {
 821                         (*i)->silence (nframes, 0);
 822                 }
 823         }
 824
 825         /* run the auditioner, and if it says we need butler service, ask for it */
 826
 827         if (auditioner->play_audition (nframes) > 0) {
 828                 summon_butler ();
 829         }
 830
 831         /* handle pending events */
 832
 833         while (pending_events.read (&ev, 1) == 1) {
 834                 merge_event (ev);
 835         }
 836
 837         /* if we are not in the middle of a state change,
 838            and there are immediate events queued up,
 839            process them.
 840         */
 841
 842         while (!non_realtime_work_pending() && !immediate_events.empty()) {
 843                 Event *ev = immediate_events.front ();
 844                 immediate_events.pop_front ();
 845                 process_event (ev);
 846         }
 847
 848         if (!auditioner->active()) {
 849                 process_function = &Session::process_with_events;
 850         }
 851 }
 852
 853 bool
 854 Session::maybe_sync_start (jack_nframes_t& nframes, jack_nframes_t& offset)
 855 {
 856         jack_nframes_t sync_offset;
 857
 858         if (!waiting_for_sync_offset) {
 859                 return false;
 860         }
 861
 862         if (_engine.get_sync_offset (sync_offset) && sync_offset < nframes) {
 863
 864                 no_roll (sync_offset, 0);
 865                 nframes -= sync_offset;
 866                 offset += sync_offset;
 867                 waiting_for_sync_offset = false;
 868
 869                 if (nframes == 0) {
 870                         return true; // done
 871                 }
 872
 873         } else {
 874                 no_roll (nframes, 0);
 875                 return true; // done
 876         }
 877
 878         return false;
 879 }
 880