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