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[ardour.git] / libs / ardour / session_transport.cc
index 4a729700abba183faf0dfbc4a0284dc1bc545688..49354dad60e873b68470ce66b76bb430cbda9149 100644 (file)
 
 #include "ardour/audioengine.h"
 #include "ardour/auditioner.h"
+#include "ardour/automation_watch.h"
 #include "ardour/butler.h"
 #include "ardour/click.h"
 #include "ardour/debug.h"
+#include "ardour/disk_reader.h"
 #include "ardour/location.h"
+#include "ardour/playlist.h"
 #include "ardour/profile.h"
 #include "ardour/scene_changer.h"
 #include "ardour/session.h"
-#include "ardour/slave.h"
+#include "ardour/transport_master.h"
+#include "ardour/transport_master_manager.h"
 #include "ardour/tempo.h"
 #include "ardour/operations.h"
+#include "ardour/vca.h"
+#include "ardour/vca_manager.h"
 
 #include "pbd/i18n.h"
 
@@ -73,42 +79,39 @@ Session::add_post_transport_work (PostTransportWork ptw)
        error << "Could not set post transport work! Crazy thread madness, call the programmers" << endmsg;
 }
 
-void
-Session::request_input_change_handling ()
+bool
+Session::should_ignore_transport_request (TransportRequestSource src, TransportRequestType type) const
 {
-       if (!(_state_of_the_state & (InitialConnecting|Deletion))) {
-               SessionEvent* ev = new SessionEvent (SessionEvent::InputConfigurationChange, SessionEvent::Add, SessionEvent::Immediate, 0, 0.0);
-               queue_event (ev);
+       if (config.get_external_sync()) {
+               if (TransportMasterManager::instance().current()->allow_request (src, type)) {
+                       return false;
+               } else {
+                       return true;
+               }
        }
+       return false;
+}
+
+bool
+Session::synced_to_engine() const {
+       return config.get_external_sync() && TransportMasterManager::instance().current()->type() == Engine;
 }
 
 void
-Session::request_sync_source (Slave* new_slave)
+Session::request_sync_source (boost::shared_ptr<TransportMaster> tm)
 {
-       SessionEvent* ev = new SessionEvent (SessionEvent::SetSyncSource, SessionEvent::Add, SessionEvent::Immediate, 0, 0.0);
-       bool seamless;
-
-       seamless = Config->get_seamless_loop ();
-
-       if (dynamic_cast<Engine_Slave*>(new_slave)) {
-               /* JACK cannot support seamless looping at present */
-               Config->set_seamless_loop (false);
-       } else {
-               /* reset to whatever the value was before we last switched slaves */
-               Config->set_seamless_loop (_was_seamless);
-       }
-
-       /* save value of seamless from before the switch */
-       _was_seamless = seamless;
-
-       ev->slave = new_slave;
-       DEBUG_TRACE (DEBUG::Slave, "sent request for new slave\n");
+       SessionEvent* ev = new SessionEvent (SessionEvent::SetTransportMaster, SessionEvent::Add, SessionEvent::Immediate, 0, 0.0);
+       ev->transport_master = tm;
+       DEBUG_TRACE (DEBUG::Slave, "sent request for new transport master\n");
        queue_event (ev);
 }
 
 void
-Session::request_transport_speed (double speed, bool as_default)
+Session::request_transport_speed (double speed, bool as_default, TransportRequestSource origin)
 {
+       if (should_ignore_transport_request (origin, TR_Speed)) {
+               return;
+       }
        SessionEvent* ev = new SessionEvent (SessionEvent::SetTransportSpeed, SessionEvent::Add, SessionEvent::Immediate, 0, speed);
        ev->third_yes_or_no = as_default; // as_default
        DEBUG_TRACE (DEBUG::Transport, string_compose ("Request transport speed = %1 as default = %2\n", speed, as_default));
@@ -120,8 +123,12 @@ Session::request_transport_speed (double speed, bool as_default)
  *  be used by callers who are varying transport speed but don't ever want to stop it.
  */
 void
-Session::request_transport_speed_nonzero (double speed, bool as_default)
+Session::request_transport_speed_nonzero (double speed, bool as_default, TransportRequestSource origin)
 {
+       if (should_ignore_transport_request (origin, TransportRequestType (TR_Speed|TR_Start))) {
+               return;
+       }
+
        if (speed == 0) {
                speed = DBL_EPSILON;
        }
@@ -130,44 +137,35 @@ Session::request_transport_speed_nonzero (double speed, bool as_default)
 }
 
 void
-Session::request_track_speed (Track* tr, double speed)
+Session::request_stop (bool abort, bool clear_state, TransportRequestSource origin)
 {
-       SessionEvent* ev = new SessionEvent (SessionEvent::SetTrackSpeed, SessionEvent::Add, SessionEvent::Immediate, 0, speed);
-       ev->set_ptr (tr);
-       queue_event (ev);
-}
+       if (should_ignore_transport_request (origin, TR_Stop)) {
+               return;
+       }
 
-void
-Session::request_stop (bool abort, bool clear_state)
-{
-       SessionEvent* ev = new SessionEvent (SessionEvent::SetTransportSpeed, SessionEvent::Add, SessionEvent::Immediate, audible_frame(), 0.0, abort, clear_state);
-       DEBUG_TRACE (DEBUG::Transport, string_compose ("Request transport stop, audible %3 transport %4 abort = %1, clear state = %2\n", abort, clear_state, audible_frame(), _transport_frame));
+       SessionEvent* ev = new SessionEvent (SessionEvent::SetTransportSpeed, SessionEvent::Add, SessionEvent::Immediate, audible_sample(), 0.0, abort, clear_state);
+       DEBUG_TRACE (DEBUG::Transport, string_compose ("Request transport stop, audible %3 transport %4 abort = %1, clear state = %2\n", abort, clear_state, audible_sample(), _transport_sample));
        queue_event (ev);
 }
 
 void
-Session::request_locate (framepos_t target_frame, bool with_roll)
+Session::request_locate (samplepos_t target_sample, bool with_roll, TransportRequestSource origin)
 {
-       SessionEvent *ev = new SessionEvent (with_roll ? SessionEvent::LocateRoll : SessionEvent::Locate, SessionEvent::Add, SessionEvent::Immediate, target_frame, 0, false);
-       DEBUG_TRACE (DEBUG::Transport, string_compose ("Request locate to %1\n", target_frame));
-       queue_event (ev);
-}
+       if (should_ignore_transport_request (origin, TR_Locate)) {
+               return;
+       }
 
-void
-Session::force_locate (framepos_t target_frame, bool with_roll)
-{
-       SessionEvent *ev = new SessionEvent (with_roll ? SessionEvent::LocateRoll : SessionEvent::Locate, SessionEvent::Add, SessionEvent::Immediate, target_frame, 0, true);
-       DEBUG_TRACE (DEBUG::Transport, string_compose ("Request forced locate to %1\n", target_frame));
+       SessionEvent *ev = new SessionEvent (with_roll ? SessionEvent::LocateRoll : SessionEvent::Locate, SessionEvent::Add, SessionEvent::Immediate, target_sample, 0, false);
+       DEBUG_TRACE (DEBUG::Transport, string_compose ("Request locate to %1\n", target_sample));
        queue_event (ev);
 }
 
 void
-Session::unset_preroll_record_punch ()
+Session::force_locate (samplepos_t target_sample, bool with_roll)
 {
-       if (_preroll_record_punch_pos >= 0) {
-               remove_event (_preroll_record_punch_pos, SessionEvent::RecordStart);
-       }
-       _preroll_record_punch_pos = -1;
+       SessionEvent *ev = new SessionEvent (with_roll ? SessionEvent::LocateRoll : SessionEvent::Locate, SessionEvent::Add, SessionEvent::Immediate, target_sample, 0, true);
+       DEBUG_TRACE (DEBUG::Transport, string_compose ("Request forced locate to %1\n", target_sample));
+       queue_event (ev);
 }
 
 void
@@ -177,49 +175,41 @@ Session::unset_preroll_record_trim ()
 }
 
 void
-Session::request_preroll_record_punch (framepos_t rec_in, framecnt_t preroll)
+Session::request_preroll_record_trim (samplepos_t rec_in, samplecnt_t preroll)
 {
        if (actively_recording ()) {
                return;
        }
-       unset_preroll_record_punch ();
        unset_preroll_record_trim ();
-       framepos_t start = std::max ((framepos_t)0, rec_in - preroll);
 
-       _preroll_record_punch_pos = rec_in;
-       if (_preroll_record_punch_pos >= 0) {
-               replace_event (SessionEvent::RecordStart, _preroll_record_punch_pos);
-               config.set_punch_in (false);
-               config.set_punch_out (false);
-       }
+       config.set_punch_in (false);
+       config.set_punch_out (false);
+
+       samplepos_t pos = std::max ((samplepos_t)0, rec_in - preroll);
+       _preroll_record_trim_len = preroll;
        maybe_enable_record ();
-       request_locate (start, true);
-       set_requested_return_frame (rec_in);
+       request_locate (pos, true);
+       set_requested_return_sample (rec_in);
 }
 
 void
-Session::request_preroll_record_trim (framepos_t rec_in, framecnt_t preroll)
+Session::request_count_in_record ()
 {
        if (actively_recording ()) {
                return;
        }
-       unset_preroll_record_punch ();
-       unset_preroll_record_trim ();
-
-       config.set_punch_in (false);
-       config.set_punch_out (false);
-
-       framepos_t pos = std::max ((framepos_t)0, rec_in - preroll);
-       _preroll_record_trim_len = preroll;
+       if (transport_rolling()) {
+               return;
+       }
        maybe_enable_record ();
-       request_locate (pos, true);
-       set_requested_return_frame (rec_in);
+       _count_in_once = true;
+       request_transport_speed (1.0, true);
 }
 
 void
 Session::request_play_loop (bool yn, bool change_transport_roll)
 {
-       if (_slave && yn) {
+       if (transport_master_is_external() && yn) {
                // don't attempt to loop when not using Internal Transport
                // see also gtk2_ardour/ardour_ui_options.cc parameter_changed()
                return;
@@ -271,7 +261,7 @@ Session::request_play_loop (bool yn, bool change_transport_roll)
                if (!change_transport_roll && Config->get_seamless_loop() && transport_rolling()) {
                        // request an immediate locate to refresh the tracks
                        // after disabling looping
-                       request_locate (_transport_frame-1, false);
+                       request_locate (_transport_sample-1, false);
                }
        }
 }
@@ -297,10 +287,62 @@ Session::request_cancel_play_range ()
 }
 
 
+bool
+Session::solo_selection_active ()
+{
+       if ( _soloSelection.empty() ) {
+               return false;
+       }
+       return true;
+}
+
+void
+Session::solo_selection ( StripableList &list, bool new_state  )
+{
+       boost::shared_ptr<ControlList> solo_list (new ControlList);
+       boost::shared_ptr<ControlList> unsolo_list (new ControlList);
+
+       if (new_state)
+               _soloSelection = list;
+       else
+               _soloSelection.clear();
+
+       boost::shared_ptr<RouteList> rl = get_routes();
+
+       for (ARDOUR::RouteList::iterator i = rl->begin(); i != rl->end(); ++i) {
+
+               if ( !(*i)->is_track() ) {
+                       continue;
+               }
+
+               boost::shared_ptr<Stripable> s (*i);
+
+               bool found = (std::find(list.begin(), list.end(), s) != list.end());
+               if ( new_state && found ) {
+
+                       solo_list->push_back (s->solo_control());
+
+                       //must invalidate playlists on selected tracks, so only selected regions get heard
+                       boost::shared_ptr<Track> track = boost::dynamic_pointer_cast<Track> (*i);
+                       if (track) {
+                               boost::shared_ptr<Playlist> playlist = track->playlist();
+                               if (playlist) {
+                                       playlist->ContentsChanged();
+                               }
+                       }
+               } else {
+                       unsolo_list->push_back (s->solo_control());
+               }
+       }
+
+       set_controls (solo_list, 1.0, Controllable::NoGroup);
+       set_controls (unsolo_list, 0.0, Controllable::NoGroup);
+}
+
 void
 Session::realtime_stop (bool abort, bool clear_state)
 {
-       DEBUG_TRACE (DEBUG::Transport, string_compose ("realtime stop @ %1\n", _transport_frame));
+       DEBUG_TRACE (DEBUG::Transport, string_compose ("realtime stop @ %1\n", _transport_sample));
        PostTransportWork todo = PostTransportWork (0);
 
        /* assume that when we start, we'll be moving forwards */
@@ -320,7 +362,7 @@ Session::realtime_stop (bool abort, bool clear_state)
                (*i)->realtime_handle_transport_stopped ();
        }
 
-       DEBUG_TRACE (DEBUG::Transport, string_compose ("stop complete, auto-return scheduled for return to %1\n", _requested_return_frame));
+       DEBUG_TRACE (DEBUG::Transport, string_compose ("stop complete, auto-return scheduled for return to %1\n", _requested_return_sample));
 
        /* the duration change is not guaranteed to have happened, but is likely */
 
@@ -342,6 +384,11 @@ Session::realtime_stop (bool abort, bool clear_state)
        _clear_event_type (SessionEvent::RangeStop);
        _clear_event_type (SessionEvent::RangeLocate);
 
+       //clear our solo-selection, if there is one
+       if ( solo_selection_active() ) {
+               solo_selection ( _soloSelection, false );
+       }
+
        /* if we're going to clear loop state, then force disabling record BUT only if we're not doing latched rec-enable */
        disable_record (true, (!Config->get_latched_record_enable() && clear_state));
 
@@ -353,6 +400,7 @@ Session::realtime_stop (bool abort, bool clear_state)
 
        _transport_speed = 0;
        _target_transport_speed = 0;
+       _engine_speed = 1.0;
 
        g_atomic_int_set (&_playback_load, 100);
        g_atomic_int_set (&_capture_load, 100);
@@ -429,24 +477,24 @@ Session::butler_transport_work ()
        }
 
        if (ptw & PostTransportAdjustPlaybackBuffering) {
-               /* non_realtime_locate() calls Automatable::transport_located()
-                * for every route. This eventually calls
-                * ARDOUR::AutomationList::state () which has a LocaleGuard,
-                * and would switch locales forth/back every time.
-                */
-               LocaleGuard lg;
                for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
                        boost::shared_ptr<Track> tr = boost::dynamic_pointer_cast<Track> (*i);
                        if (tr) {
                                tr->adjust_playback_buffering ();
                                /* and refill those buffers ... */
                        }
-                       (*i)->non_realtime_locate (_transport_frame);
+                       (*i)->non_realtime_locate (_transport_sample);
+               }
+               VCAList v = _vca_manager->vcas ();
+               for (VCAList::const_iterator i = v.begin(); i != v.end(); ++i) {
+                       (*i)->non_realtime_locate (_transport_sample);
                }
-
        }
 
        if (ptw & PostTransportAdjustCaptureBuffering) {
+               /* need to prevent concurrency with ARDOUR::DiskWriter::run(),
+                * DiskWriter::adjust_buffering() re-allocates the ringbuffer */
+               Glib::Threads::Mutex::Lock lx (AudioEngine::instance()->process_lock ());
                for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
                        boost::shared_ptr<Track> tr = boost::dynamic_pointer_cast<Track> (*i);
                        if (tr) {
@@ -461,19 +509,6 @@ Session::butler_transport_work ()
                }
        }
 
-       if (ptw & PostTransportInputChange) {
-               for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
-                       boost::shared_ptr<Track> tr = boost::dynamic_pointer_cast<Track> (*i);
-                       if (tr) {
-                               tr->non_realtime_input_change ();
-                       }
-               }
-       }
-
-       if (ptw & PostTransportSpeed) {
-               non_realtime_set_speed ();
-       }
-
        if (ptw & PostTransportReverse) {
 
                clear_clicks();
@@ -483,9 +518,8 @@ Session::butler_transport_work ()
                /* don't seek if locate will take care of that in non_realtime_stop() */
 
                if (!(ptw & PostTransportLocate)) {
-                       LocaleGuard lg; // see note for non_realtime_locate() above
                        for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
-                               (*i)->non_realtime_locate (_transport_frame);
+                               (*i)->non_realtime_locate (_transport_sample);
 
                                if (on_entry != g_atomic_int_get (&_butler->should_do_transport_work)) {
                                        /* new request, stop seeking, and start again */
@@ -493,6 +527,10 @@ Session::butler_transport_work ()
                                        goto restart;
                                }
                        }
+                       VCAList v = _vca_manager->vcas ();
+                       for (VCAList::const_iterator i = v.begin(); i != v.end(); ++i) {
+                               (*i)->non_realtime_locate (_transport_sample);
+                       }
                }
        }
 
@@ -523,20 +561,7 @@ Session::butler_transport_work ()
 
        g_atomic_int_dec_and_test (&_butler->should_do_transport_work);
 
-       DEBUG_TRACE (DEBUG::Transport, string_compose (X_("Butler transport work all done after %1 usecs\n"), g_get_monotonic_time() - before));
-       DEBUG_TRACE (DEBUG::Transport, X_(string_compose ("Frame %1\n", _transport_frame)));
-}
-
-void
-Session::non_realtime_set_speed ()
-{
-       boost::shared_ptr<RouteList> rl = routes.reader();
-       for (RouteList::iterator i = rl->begin(); i != rl->end(); ++i) {
-               boost::shared_ptr<Track> tr = boost::dynamic_pointer_cast<Track> (*i);
-               if (tr) {
-                       tr->non_realtime_set_speed ();
-               }
-       }
+       DEBUG_TRACE (DEBUG::Transport, string_compose (X_("Butler transport work all done after %1 usecs @ %2 trw = %3\n"), g_get_monotonic_time() - before, _transport_sample, _butler->transport_work_requested()));
 }
 
 void
@@ -559,21 +584,21 @@ Session::non_realtime_overwrite (int on_entry, bool& finished)
 void
 Session::non_realtime_locate ()
 {
-       DEBUG_TRACE (DEBUG::Transport, string_compose ("locate tracks to %1\n", _transport_frame));
+       DEBUG_TRACE (DEBUG::Transport, string_compose ("locate tracks to %1\n", _transport_sample));
 
        if (Config->get_loop_is_mode() && get_play_loop()) {
 
                Location *loc  = _locations->auto_loop_location();
 
-               if (!loc || (_transport_frame < loc->start() || _transport_frame >= loc->end())) {
+               if (!loc || (_transport_sample < loc->start() || _transport_sample >= loc->end())) {
                        /* jumped out of loop range: stop tracks from looping,
                           but leave loop (mode) enabled.
                         */
                        set_track_loop (false);
 
                } else if (loc && Config->get_seamless_loop() &&
-                   ((loc->start() <= _transport_frame) ||
-                   (loc->end() > _transport_frame) ) ) {
+                   ((loc->start() <= _transport_sample) ||
+                   (loc->end() > _transport_sample) ) ) {
 
                        /* jumping to start of loop. This  might have been done before but it is
                         * idempotent and cheap. Doing it here ensures that when we start playback
@@ -592,15 +617,36 @@ Session::non_realtime_locate ()
        }
 
 
+       samplepos_t tf;
+
        {
-               LocaleGuard lg; // see note for non_realtime_locate() above
                boost::shared_ptr<RouteList> rl = routes.reader();
+
+         restart:
+               gint sc = g_atomic_int_get (&_seek_counter);
+               tf = _transport_sample;
+
                for (RouteList::iterator i = rl->begin(); i != rl->end(); ++i) {
-                       (*i)->non_realtime_locate (_transport_frame);
+                       (*i)->non_realtime_locate (tf);
+                       if (sc != g_atomic_int_get (&_seek_counter)) {
+                               goto restart;
+                       }
                }
        }
 
-       _scene_changer->locate (_transport_frame);
+       {
+               /* VCAs are quick to locate because they have no data (except
+                  automation) associated with them. Don't bother with a
+                  restart mechanism here, but do use the same transport sample
+                  that the Routes used.
+               */
+               VCAList v = _vca_manager->vcas ();
+               for (VCAList::const_iterator i = v.begin(); i != v.end(); ++i) {
+                       (*i)->non_realtime_locate (tf);
+               }
+       }
+
+       _scene_changer->locate (_transport_sample);
 
        /* XXX: it would be nice to generate the new clicks here (in the non-RT thread)
           rather than clearing them so that the RT thread has to spend time constructing
@@ -611,7 +657,7 @@ Session::non_realtime_locate ()
 
 #ifdef USE_TRACKS_CODE_FEATURES
 bool
-Session::select_playhead_priority_target (framepos_t& jump_to)
+Session::select_playhead_priority_target (samplepos_t& jump_to)
 {
        jump_to = -1;
 
@@ -687,7 +733,7 @@ Session::select_playhead_priority_target (framepos_t& jump_to)
 #else
 
 bool
-Session::select_playhead_priority_target (framepos_t& jump_to)
+Session::select_playhead_priority_target (samplepos_t& jump_to)
 {
        if (config.get_external_sync() || !config.get_auto_return()) {
                return false;
@@ -702,7 +748,7 @@ Session::select_playhead_priority_target (framepos_t& jump_to)
 void
 Session::follow_playhead_priority ()
 {
-       framepos_t target;
+       samplepos_t target;
 
        if (select_playhead_priority_target (target)) {
                request_locate (target);
@@ -724,7 +770,7 @@ Session::non_realtime_stop (bool abort, int on_entry, bool& finished)
        boost::shared_ptr<RouteList> rl = routes.reader();
        for (RouteList::iterator i = rl->begin(); i != rl->end(); ++i) {
                boost::shared_ptr<Track> tr = boost::dynamic_pointer_cast<Track> (*i);
-               if (tr && tr->get_captured_frames () != 0) {
+               if (tr && tr->get_captured_samples () != 0) {
                        did_record = true;
                        break;
                }
@@ -768,12 +814,6 @@ Session::non_realtime_stop (bool abort, int on_entry, bool& finished)
 
        boost::shared_ptr<RouteList> r = routes.reader ();
 
-       for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
-               if (!(*i)->is_auditioner()) {
-                       (*i)->set_pending_declick (0);
-               }
-       }
-
        if (did_record) {
                commit_reversible_command ();
                /* increase take name */
@@ -785,9 +825,15 @@ Session::non_realtime_stop (bool abort, int on_entry, bool& finished)
 
        if (_engine.running()) {
                PostTransportWork ptw = post_transport_work ();
+
                for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
-                       (*i)->nonrealtime_handle_transport_stopped (abort, (ptw & PostTransportLocate), (!(ptw & PostTransportLocate) || pending_locate_flush));
+                       (*i)->non_realtime_transport_stop (_transport_sample, !(ptw & PostTransportLocate));
                }
+               VCAList v = _vca_manager->vcas ();
+               for (VCAList::const_iterator i = v.begin(); i != v.end(); ++i) {
+                       (*i)->non_realtime_transport_stop (_transport_sample, !(ptw & PostTransportLocate));
+               }
+
                update_latency_compensation ();
        }
 
@@ -795,50 +841,46 @@ Session::non_realtime_stop (bool abort, int on_entry, bool& finished)
 
        if (auto_return_enabled ||
            (ptw & PostTransportLocate) ||
-           (_requested_return_frame >= 0) ||
+           (_requested_return_sample >= 0) ||
            synced_to_engine()) {
 
-               if (pending_locate_flush) {
-                       flush_all_inserts ();
-               }
-
                // rg: what is the logic behind this case?
-               // _requested_return_frame should be ignored when synced_to_engine/slaved.
-               // currently worked around in MTC_Slave by forcing _requested_return_frame to -1
+               // _requested_return_sample should be ignored when synced_to_engine/slaved.
+               // currently worked around in MTC_Slave by forcing _requested_return_sample to -1
                // 2016-01-10
-               if ((auto_return_enabled || synced_to_engine() || _requested_return_frame >= 0) &&
+               if ((auto_return_enabled || synced_to_engine() || _requested_return_sample >= 0) &&
                    !(ptw & PostTransportLocate)) {
 
                        /* no explicit locate queued */
 
                        bool do_locate = false;
 
-                       if (_requested_return_frame >= 0) {
+                       if (_requested_return_sample >= 0) {
 
                                /* explicit return request pre-queued in event list. overrides everything else */
 
-                               _transport_frame = _requested_return_frame;
+                               _transport_sample = _requested_return_sample;
                                do_locate = true;
 
                        } else {
-                               framepos_t jump_to;
+                               samplepos_t jump_to;
 
                                if (select_playhead_priority_target (jump_to)) {
 
-                                       _transport_frame = jump_to;
+                                       _transport_sample = jump_to;
                                        do_locate = true;
 
                                } else if (abort) {
 
-                                       _transport_frame = _last_roll_location;
+                                       _transport_sample = _last_roll_location;
                                        do_locate = true;
                                }
                        }
 
-                       _requested_return_frame = -1;
+                       _requested_return_sample = -1;
 
                        if (do_locate) {
-                               _engine.transport_locate (_transport_frame);
+                               _engine.transport_locate (_transport_sample);
                        }
                }
 
@@ -860,11 +902,10 @@ Session::non_realtime_stop (bool abort, int on_entry, bool& finished)
        /* this for() block can be put inside the previous if() and has the effect of ... ??? what */
 
        {
-               LocaleGuard lg; // see note for non_realtime_locate() above
                DEBUG_TRACE (DEBUG::Transport, X_("Butler PTW: locate\n"));
                for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
                        DEBUG_TRACE (DEBUG::Transport, string_compose ("Butler PTW: locate on %1\n", (*i)->name()));
-                       (*i)->non_realtime_locate (_transport_frame);
+                       (*i)->non_realtime_locate (_transport_sample);
 
                        if (on_entry != g_atomic_int_get (&_butler->should_do_transport_work)) {
                                finished = false;
@@ -874,17 +915,24 @@ Session::non_realtime_stop (bool abort, int on_entry, bool& finished)
                }
        }
 
+       {
+               VCAList v = _vca_manager->vcas ();
+               for (VCAList::const_iterator i = v.begin(); i != v.end(); ++i) {
+                       (*i)->non_realtime_locate (_transport_sample);
+               }
+       }
+
        have_looped = false;
 
        /* don't bother with this stuff if we're disconnected from the engine,
           because there will be no process callbacks to deliver stuff from
        */
 
-       if (_engine.connected() && !_engine.freewheeling()) {
+       if (_engine.running() && !_engine.freewheeling()) {
                // need to queue this in the next RT cycle
                _send_timecode_update = true;
 
-               if (!dynamic_cast<MTC_Slave*>(_slave)) {
+               if (transport_master()->type() == MTC) {
                        send_immediate_mmc (MIDI::MachineControlCommand (MIDI::MachineControl::cmdStop));
 
                        /* This (::non_realtime_stop()) gets called by main
@@ -893,7 +941,7 @@ Session::non_realtime_stop (bool abort, int on_entry, bool& finished)
 
                           Something must be done. XXX
                        */
-                       send_mmc_locate (_transport_frame);
+                       send_mmc_locate (_transport_sample);
                }
        }
 
@@ -905,7 +953,7 @@ Session::non_realtime_stop (bool abort, int on_entry, bool& finished)
                 *
                 * save state only if there's no slave or if it's not yet locked.
                 */
-               if (!_slave || !_slave->locked()) {
+               if (!transport_master_is_external() || !transport_master()->locked()) {
                        DEBUG_TRACE (DEBUG::Transport, X_("Butler PTW: requests save\n"));
                        SaveSessionRequested (_current_snapshot_name);
                        saved = true;
@@ -929,50 +977,16 @@ Session::non_realtime_stop (bool abort, int on_entry, bool& finished)
                }
        }
 
-       PositionChanged (_transport_frame); /* EMIT SIGNAL */
+       PositionChanged (_transport_sample); /* EMIT SIGNAL */
        DEBUG_TRACE (DEBUG::Transport, string_compose ("send TSC with speed = %1\n", _transport_speed));
        TransportStateChange (); /* EMIT SIGNAL */
+       AutomationWatch::instance().transport_stop_automation_watches (_transport_sample);
 
        /* and start it up again if relevant */
 
-       if ((ptw & PostTransportLocate) && !config.get_external_sync() && pending_locate_roll) {
+       if ((ptw & PostTransportLocate) && !config.get_external_sync()) {
                request_transport_speed (1.0);
        }
-
-       /* Even if we didn't do a pending locate roll this time, we don't want it hanging
-          around for next time.
-       */
-       pending_locate_roll = false;
-}
-
-void
-Session::check_declick_out ()
-{
-       bool locate_required = transport_sub_state & PendingLocate;
-
-       /* this is called after a process() iteration. if PendingDeclickOut was set,
-          it means that we were waiting to declick the output (which has just been
-          done) before maybe doing something else. this is where we do that "something else".
-
-          note: called from the audio thread.
-       */
-
-       if (transport_sub_state & PendingDeclickOut) {
-
-               if (locate_required) {
-                       start_locate (pending_locate_frame, pending_locate_roll, pending_locate_flush);
-                       transport_sub_state &= ~(PendingDeclickOut|PendingLocate);
-               } else {
-                       if (!(transport_sub_state & StopPendingCapture)) {
-                               stop_transport (pending_abort);
-                               transport_sub_state &= ~(PendingDeclickOut|PendingLocate);
-                       }
-               }
-
-       } else if (transport_sub_state & PendingLoopDeclickOut) {
-               /* Nothing else to do here; we've declicked, and the loop event will be along shortly */
-               transport_sub_state &= ~PendingLoopDeclickOut;
-       }
 }
 
 void
@@ -981,7 +995,6 @@ Session::unset_play_loop ()
        if (play_loop) {
                play_loop = false;
                clear_events (SessionEvent::AutoLoop);
-               clear_events (SessionEvent::AutoLoopDeclick);
                set_track_loop (false);
 
 
@@ -990,6 +1003,7 @@ Session::unset_play_loop ()
                        add_post_transport_work (PostTransportLocate);
                        _butler->schedule_transport_work ();
                }
+               TransportStateChange (); /* EMIT SIGNAL */
        }
 }
 
@@ -1005,9 +1019,8 @@ Session::set_track_loop (bool yn)
        boost::shared_ptr<RouteList> rl = routes.reader ();
 
        for (RouteList::iterator i = rl->begin(); i != rl->end(); ++i) {
-               boost::shared_ptr<Track> tr = boost::dynamic_pointer_cast<Track> (*i);
-               if (tr && !tr->hidden()) {
-                       tr->set_loop (yn ? loc : 0);
+               if (*i && !(*i)->is_private_route()) {
+                       (*i)->set_loop (yn ? loc : 0);
                }
        }
 }
@@ -1060,10 +1073,9 @@ Session::set_play_loop (bool yn, double speed)
                           in a fade-in when the loop restarts.  The AutoLoop event will peform the actual loop.
                        */
 
-                       framepos_t dcp;
-                       framecnt_t dcl;
+                       samplepos_t dcp;
+                       samplecnt_t dcl;
                        auto_loop_declick_range (loc, dcp, dcl);
-                       merge_event (new SessionEvent (SessionEvent::AutoLoopDeclick, SessionEvent::Replace, dcp, dcl, 0.0f));
                        merge_event (new SessionEvent (SessionEvent::AutoLoop, SessionEvent::Replace, loc->end(), loc->start(), 0.0f));
 
                        /* if requested to roll, locate to start of loop and
@@ -1105,9 +1117,9 @@ Session::flush_all_inserts ()
 }
 
 void
-Session::start_locate (framepos_t target_frame, bool with_roll, bool with_flush, bool for_loop_enabled, bool force)
+Session::start_locate (samplepos_t target_sample, bool with_roll, bool with_flush, bool for_loop_enabled, bool force)
 {
-       if (target_frame < 0) {
+       if (target_sample < 0) {
                error << _("Locate called for negative sample position - ignored") << endmsg;
                return;
        }
@@ -1115,25 +1127,26 @@ Session::start_locate (framepos_t target_frame, bool with_roll, bool with_flush,
        if (synced_to_engine()) {
 
                double sp;
-               framepos_t pos;
+               samplepos_t pos;
+               samplepos_t ignore1, ignore2;
 
-               _slave->speed_and_position (sp, pos);
+               transport_master()->speed_and_position (sp, pos, ignore1, ignore2, 0);
 
-               if (target_frame != pos) {
+               if (target_sample != pos) {
 
                        if (config.get_jack_time_master()) {
                                /* actually locate now, since otherwise jack_timebase_callback
-                                  will use the incorrect _transport_frame and report an old
+                                  will use the incorrect _transport_sample and report an old
                                   and incorrect time to Jack transport
                                */
-                               locate (target_frame, with_roll, with_flush, for_loop_enabled, force);
+                               locate (target_sample, with_roll, with_flush, for_loop_enabled, force);
                        }
 
                        /* tell JACK to change transport position, and we will
                           follow along later in ::follow_slave()
                        */
 
-                       _engine.transport_locate (target_frame);
+                       _engine.transport_locate (target_sample);
 
                        if (sp != 1.0f && with_roll) {
                                _engine.transport_start ();
@@ -1142,12 +1155,18 @@ Session::start_locate (framepos_t target_frame, bool with_roll, bool with_flush,
                }
 
        } else {
-               locate (target_frame, with_roll, with_flush, for_loop_enabled, force);
+               locate (target_sample, with_roll, with_flush, for_loop_enabled, force);
        }
 }
 
+samplecnt_t
+Session::worst_latency_preroll () const
+{
+       return _worst_output_latency + _worst_input_latency;
+}
+
 int
-Session::micro_locate (framecnt_t distance)
+Session::micro_locate (samplecnt_t distance)
 {
        boost::shared_ptr<RouteList> rl = routes.reader();
        for (RouteList::iterator i = rl->begin(); i != rl->end(); ++i) {
@@ -1157,6 +1176,8 @@ Session::micro_locate (framecnt_t distance)
                }
        }
 
+       DEBUG_TRACE (DEBUG::Transport, string_compose ("micro-locate by %1\n", distance));
+
        for (RouteList::iterator i = rl->begin(); i != rl->end(); ++i) {
                boost::shared_ptr<Track> tr = boost::dynamic_pointer_cast<Track> (*i);
                if (tr) {
@@ -1164,13 +1185,13 @@ Session::micro_locate (framecnt_t distance)
                }
        }
 
-       _transport_frame += distance;
+       _transport_sample += distance;
        return 0;
 }
 
 /** @param with_mmc true to send a MMC locate command when the locate is done */
 void
-Session::locate (framepos_t target_frame, bool with_roll, bool with_flush, bool for_loop_enabled, bool force, bool with_mmc)
+Session::locate (samplepos_t target_sample, bool with_roll, bool with_flush, bool for_loop_enabled, bool force, bool with_mmc)
 {
        bool need_butler = false;
 
@@ -1179,13 +1200,13 @@ Session::locate (framepos_t target_frame, bool with_roll, bool with_flush, bool
         * already have the correct data in them, and thus there is no need to
         * actually tell the tracks to locate. What does need to be done,
         * though, is all the housekeeping that is associated with non-linear
-        * changes in the value of _transport_frame.
+        * changes in the value of _transport_sample.
         */
 
        DEBUG_TRACE (DEBUG::Transport, string_compose ("rt-locate to %1, roll %2 flush %3 loop-enabled %4 force %5 mmc %6\n",
-                                                      target_frame, with_roll, with_flush, for_loop_enabled, force, with_mmc));
+                                                      target_sample, with_roll, with_flush, for_loop_enabled, force, with_mmc));
 
-       if (!force && _transport_frame == target_frame && !loop_changing && !for_loop_enabled) {
+       if (!force && _transport_sample == target_sample && !loop_changing && !for_loop_enabled) {
 
                /* already at the desired position. Not forced to locate,
                   the loop isn't changing, so unless we're told to
@@ -1201,33 +1222,24 @@ Session::locate (framepos_t target_frame, bool with_roll, bool with_flush, bool
                return;
        }
 
-       if (_transport_speed && !(for_loop_enabled && Config->get_seamless_loop())) {
-               /* Schedule a declick.  We'll be called again when its done.
-                  We only do it this way for ordinary locates, not those
-                  due to **seamless** loops.
-               */
-
-               if (!(transport_sub_state & PendingDeclickOut)) {
-                       transport_sub_state |= (PendingDeclickOut|PendingLocate);
-                       pending_locate_frame = target_frame;
-                       pending_locate_roll = with_roll;
-                       pending_locate_flush = with_flush;
-                       return;
-               }
-       }
+       cerr << "... now doing the actual locate\n";
 
        // Update Timecode time
-       _transport_frame = target_frame;
-       _last_roll_or_reversal_location = target_frame;
-       timecode_time(_transport_frame, transmitting_timecode_time);
+       _transport_sample = target_sample;
+       // Bump seek counter so that any in-process locate in the butler
+       // thread(s?) can restart.
+       g_atomic_int_inc (&_seek_counter);
+       _last_roll_or_reversal_location = target_sample;
+       _remaining_latency_preroll = worst_latency_preroll ();
+       timecode_time(_transport_sample, transmitting_timecode_time); // XXX here?
 
        /* do "stopped" stuff if:
         *
         * we are rolling AND
-        *    no autoplay in effect AND
-         *       we're not going to keep rolling after the locate AND
-         *           !(playing a loop with JACK sync)
-         *
+        * no autoplay in effect AND
+        * we're not going to keep rolling after the locate AND
+        * !(playing a loop with JACK sync)
+        *
         */
 
        bool transport_was_stopped = !transport_rolling();
@@ -1286,7 +1298,7 @@ Session::locate (framepos_t target_frame, bool with_roll, bool with_flush, bool
                Location* al = _locations->auto_loop_location();
 
                if (al) {
-                       if (_transport_frame < al->start() || _transport_frame >= al->end()) {
+                       if (_transport_sample < al->start() || _transport_sample >= al->end()) {
 
                                // located outside the loop: cancel looping directly, this is called from event handling context
 
@@ -1304,7 +1316,7 @@ Session::locate (framepos_t target_frame, bool with_roll, bool with_flush, bool
                                        }
                                }
 
-                       } else if (_transport_frame == al->start()) {
+                       } else if (_transport_sample == al->start()) {
 
                                // located to start of loop - this is looping, basically
 
@@ -1328,7 +1340,7 @@ Session::locate (framepos_t target_frame, bool with_roll, bool with_flush, bool
 
                                        if (tr && tr->rec_enable_control()->get_value()) {
                                                // tell it we've looped, so it can deal with the record state
-                                               tr->transport_looped (_transport_frame);
+                                               tr->transport_looped (_transport_sample);
                                        }
                                }
 
@@ -1347,11 +1359,13 @@ Session::locate (framepos_t target_frame, bool with_roll, bool with_flush, bool
        _send_timecode_update = true;
 
        if (with_mmc) {
-               send_mmc_locate (_transport_frame);
+               send_mmc_locate (_transport_sample);
        }
 
-       _last_roll_location = _last_roll_or_reversal_location =  _transport_frame;
-       Located (); /* EMIT SIGNAL */
+       _last_roll_location = _last_roll_or_reversal_location =  _transport_sample;
+       if (!synced_to_engine () || _transport_sample == _engine.transport_sample ()) {
+               Located (); /* EMIT SIGNAL */
+       }
 }
 
 /** Set the transport speed.
@@ -1359,36 +1373,46 @@ Session::locate (framepos_t target_frame, bool with_roll, bool with_flush, bool
  *  @param speed New speed
  */
 void
-Session::set_transport_speed (double speed, framepos_t destination_frame, bool abort, bool clear_state, bool as_default)
+Session::set_transport_speed (double speed, samplepos_t destination_sample, bool abort, bool clear_state, bool as_default)
 {
        DEBUG_TRACE (DEBUG::Transport, string_compose ("@ %5 Set transport speed to %1, abort = %2 clear_state = %3, current = %4 as_default %6\n",
-                                                      speed, abort, clear_state, _transport_speed, _transport_frame, as_default));
+                                                      speed, abort, clear_state, _transport_speed, _transport_sample, as_default));
+
+       /* max speed is somewhat arbitrary but based on guestimates regarding disk i/o capability
+          and user needs. We really need CD-style "skip" playback for ffwd and rewind.
+       */
+
+       if (speed > 0) {
+               speed = min (8.0, speed);
+       } else if (speed < 0) {
+               speed = max (-8.0, speed);
+       }
+
+       double new_engine_speed = 1.0;
+       if (speed != 0) {
+               new_engine_speed = fabs (speed);
+               if (speed < 0) speed = -1;
+               if (speed > 0) speed = 1;
+       }
 
-       if (_transport_speed == speed) {
+       if (_transport_speed == speed && new_engine_speed == _engine_speed) {
                if (as_default && speed == 0.0) { // => reset default transport speed. hacky or what?
                        _default_transport_speed = 1.0;
                }
                return;
        }
 
+#if 0 // TODO pref: allow vari-speed recording
        if (actively_recording() && speed != 1.0 && speed != 0.0) {
                /* no varispeed during recording */
-               DEBUG_TRACE (DEBUG::Transport, string_compose ("No varispeed during recording cur_speed %1, frame %2\n",
-                                                      _transport_speed, _transport_frame));
+               DEBUG_TRACE (DEBUG::Transport, string_compose ("No varispeed during recording cur_speed %1, sample %2\n",
+                                                      _transport_speed, _transport_sample));
                return;
        }
+#endif
 
        _target_transport_speed = fabs(speed);
-
-       /* 8.0 max speed is somewhat arbitrary but based on guestimates regarding disk i/o capability
-          and user needs. We really need CD-style "skip" playback for ffwd and rewind.
-       */
-
-       if (speed > 0) {
-               speed = min (8.0, speed);
-       } else if (speed < 0) {
-               speed = max (-8.0, speed);
-       }
+       _engine_speed = new_engine_speed;
 
        if (transport_rolling() && speed == 0.0) {
 
@@ -1404,6 +1428,7 @@ Session::set_transport_speed (double speed, framepos_t destination_frame, bool a
                                   take care of it.
                                */
                                _play_range = false;
+                               _count_in_once = false;
                                unset_play_loop ();
                        }
                        _engine.transport_stop ();
@@ -1411,7 +1436,7 @@ Session::set_transport_speed (double speed, framepos_t destination_frame, bool a
                        bool const auto_return_enabled = (!config.get_external_sync() && (Config->get_auto_return_target_list() || abort));
 
                        if (!auto_return_enabled) {
-                               _requested_return_frame = destination_frame;
+                               _requested_return_sample = destination_sample;
                        }
 
                        stop_transport (abort);
@@ -1428,7 +1453,7 @@ Session::set_transport_speed (double speed, framepos_t destination_frame, bool a
                        Location *location = _locations->auto_loop_location();
 
                        if (location != 0) {
-                               if (_transport_frame != location->start()) {
+                               if (_transport_sample != location->start()) {
 
                                        if (Config->get_seamless_loop()) {
                                                /* force tracks to do their thing */
@@ -1449,6 +1474,7 @@ Session::set_transport_speed (double speed, framepos_t destination_frame, bool a
 
                if (synced_to_engine()) {
                        _engine.transport_start ();
+                       _count_in_once = false;
                } else {
                        start_transport ();
                }
@@ -1457,6 +1483,9 @@ Session::set_transport_speed (double speed, framepos_t destination_frame, bool a
 
                /* not zero, not 1.0 ... varispeed */
 
+               // TODO handled transport start..  _remaining_latency_preroll
+               // and reversal of playback direction.
+
                if ((synced_to_engine()) && speed != 0.0 && speed != 1.0) {
                        warning << string_compose (
                                _("Global varispeed cannot be supported while %1 is connected to JACK transport control"),
@@ -1465,15 +1494,17 @@ Session::set_transport_speed (double speed, framepos_t destination_frame, bool a
                        return;
                }
 
+#if 0
                if (actively_recording()) {
                        return;
                }
+#endif
 
-               if (speed > 0.0 && _transport_frame == current_end_frame()) {
+               if (speed > 0.0 && _transport_sample == current_end_sample()) {
                        return;
                }
 
-               if (speed < 0.0 && _transport_frame == 0) {
+               if (speed < 0.0 && _transport_sample == 0) {
                        return;
                }
 
@@ -1487,7 +1518,7 @@ Session::set_transport_speed (double speed, framepos_t destination_frame, bool a
 
                if ((_transport_speed && speed * _transport_speed < 0.0) || (_last_transport_speed * speed < 0.0) || (_last_transport_speed == 0.0 && speed < 0.0)) {
                        todo = PostTransportWork (todo | PostTransportReverse);
-                       _last_roll_or_reversal_location = _transport_frame;
+                       _last_roll_or_reversal_location = _transport_sample;
                }
 
                _last_transport_speed = _transport_speed;
@@ -1497,14 +1528,6 @@ Session::set_transport_speed (double speed, framepos_t destination_frame, bool a
                        _default_transport_speed = speed;
                }
 
-               boost::shared_ptr<RouteList> rl = routes.reader();
-               for (RouteList::iterator i = rl->begin(); i != rl->end(); ++i) {
-                       boost::shared_ptr<Track> tr = boost::dynamic_pointer_cast<Track> (*i);
-                       if (tr && tr->realtime_set_speed (tr->speed(), true)) {
-                               todo = PostTransportWork (todo | PostTransportSpeed);
-                       }
-               }
-
                if (todo) {
                        add_post_transport_work (todo);
                        _butler->schedule_transport_work ();
@@ -1524,14 +1547,14 @@ Session::set_transport_speed (double speed, framepos_t destination_frame, bool a
                 * The 0.2% dead-zone is somewhat arbitrary. Main use-case
                 * for TransportStateChange() here is the ShuttleControl display.
                 */
-               if (fabs (_signalled_varispeed - speed) > .002
+               if (fabs (_signalled_varispeed - actual_speed ()) > .002
                    // still, signal hard changes to 1.0 and 0.0:
-                   || ( speed == 1.0 && _signalled_varispeed != 1.0)
-                   || ( speed == 0.0 && _signalled_varispeed != 0.0)
+                   || (actual_speed () == 1.0 && _signalled_varispeed != 1.0)
+                   || (actual_speed () == 0.0 && _signalled_varispeed != 0.0)
                   )
                {
                        TransportStateChange (); /* EMIT SIGNAL */
-                       _signalled_varispeed = speed;
+                       _signalled_varispeed = actual_speed ();
                }
        }
 }
@@ -1541,85 +1564,15 @@ Session::set_transport_speed (double speed, framepos_t destination_frame, bool a
 void
 Session::stop_transport (bool abort, bool clear_state)
 {
+       _count_in_once = false;
        if (_transport_speed == 0.0f) {
                return;
        }
 
-       DEBUG_TRACE (DEBUG::Transport, string_compose ("stop_transport, declick required? %1\n", get_transport_declick_required()));
-
-       if (!get_transport_declick_required()) {
-
-               /* stop has not yet been scheduled */
-
-               boost::shared_ptr<RouteList> rl = routes.reader();
-               framepos_t stop_target = audible_frame();
-
-               for (RouteList::iterator i = rl->begin(); i != rl->end(); ++i) {
-                       boost::shared_ptr<Track> tr = boost::dynamic_pointer_cast<Track> (*i);
-                       if (tr) {
-                               tr->prepare_to_stop (_transport_frame, stop_target);
-                       }
-               }
-
-               SubState new_bits;
-
-               if (actively_recording() &&                           /* we are recording */
-                   worst_input_latency() > current_block_size) {     /* input latency exceeds block size, so simple 1 cycle delay before stop is not enough */
+       DEBUG_TRACE (DEBUG::Transport, "time to actually stop\n");
 
-                       /* we need to capture the audio that is still somewhere in the pipeline between
-                          wherever it was generated and the process callback. This means that even though
-                          the user (or something else)  has asked us to stop, we have to roll
-                          past this point and then reset the playhead/transport location to
-                          the position at which the stop was requested.
-
-                          we still need playback to "stop" now, however, which is why we schedule
-                          a declick below.
-                       */
-
-                       DEBUG_TRACE (DEBUG::Transport, string_compose ("stop transport requested @ %1, scheduled for + %2 = %3, abort = %4\n",
-                                                                      _transport_frame, _worst_input_latency,
-                                                                      _transport_frame + _worst_input_latency,
-                                                                      abort));
-
-                       SessionEvent *ev = new SessionEvent (SessionEvent::StopOnce, SessionEvent::Replace,
-                                                            _transport_frame + _worst_input_latency,
-                                                            0, 0, abort);
-
-                       merge_event (ev);
-
-                       /* request a declick at the start of the next process cycle() so that playback ceases.
-                          It will remain silent until we actually stop (at the StopOnce event somewhere in
-                          the future). The extra flag (StopPendingCapture) is set to ensure that check_declick_out()
-                          does not stop the transport too early.
-                        */
-                       new_bits = SubState (PendingDeclickOut|StopPendingCapture);
-
-               } else {
-
-                       /* Not recording, schedule a declick in the next process() cycle and then stop at its end */
-
-                       new_bits = PendingDeclickOut;
-                       DEBUG_TRACE (DEBUG::Transport, string_compose ("stop scheduled for next process cycle @ %1\n", _transport_frame));
-               }
-
-               /* we'll be called again after the declick */
-               transport_sub_state = SubState (transport_sub_state|new_bits);
-               pending_abort = abort;
-
-               return;
-
-       } else {
-
-               DEBUG_TRACE (DEBUG::Transport, "time to actually stop\n");
-
-               /* declick was scheduled, but we've been called again, which means it is really time to stop
-
-                  XXX: we should probably split this off into its own method and call it explicitly.
-               */
-
-               realtime_stop (abort, clear_state);
-               _butler->schedule_transport_work ();
-       }
+       realtime_stop (abort, clear_state);
+       _butler->schedule_transport_work ();
 }
 
 /** Called from the process thread */
@@ -1628,8 +1581,9 @@ Session::start_transport ()
 {
        DEBUG_TRACE (DEBUG::Transport, "start_transport\n");
 
-       _last_roll_location = _transport_frame;
-       _last_roll_or_reversal_location = _transport_frame;
+       _last_roll_location = _transport_sample;
+       _last_roll_or_reversal_location = _transport_sample;
+       _remaining_latency_preroll = worst_latency_preroll ();
 
        have_looped = false;
 
@@ -1639,7 +1593,14 @@ Session::start_transport ()
 
        switch (record_status()) {
        case Enabled:
-               if (!config.get_punch_in() && !preroll_record_punch_enabled()) {
+               if (!config.get_punch_in()) {
+                       /* This is only for UIs (keep blinking rec-en before
+                        * punch-in, don't show rec-region etc). The UI still
+                        * depends on SessionEvent::PunchIn and ensuing signals.
+                        *
+                        * The disk-writers handle punch in/out internally
+                        * in their local delay-compensated timeframe.
+                        */
                        enable_record ();
                }
                break;
@@ -1654,55 +1615,56 @@ Session::start_transport ()
                break;
        }
 
-       transport_sub_state |= PendingDeclickIn;
-
        _transport_speed = _default_transport_speed;
        _target_transport_speed = _transport_speed;
 
-       boost::shared_ptr<RouteList> rl = routes.reader();
-       for (RouteList::iterator i = rl->begin(); i != rl->end(); ++i) {
-               boost::shared_ptr<Track> tr = boost::dynamic_pointer_cast<Track> (*i);
-               if (tr) {
-                       tr->realtime_set_speed (tr->speed(), true);
-               }
-       }
-
        if (!_engine.freewheeling()) {
                Timecode::Time time;
-               timecode_time_subframes (_transport_frame, time);
-               if (!dynamic_cast<MTC_Slave*>(_slave)) {
+               timecode_time_subframes (_transport_sample, time);
+               if (transport_master()->type() == MTC) {
                        send_immediate_mmc (MIDI::MachineControlCommand (MIDI::MachineControl::cmdDeferredPlay));
                }
 
-               if (actively_recording() && click_data && config.get_count_in ()) {
+               if (actively_recording() && click_data && (config.get_count_in () || _count_in_once)) {
+                       _count_in_once = false;
                        /* calculate count-in duration (in audio samples)
-                        * - use [fixed] tempo/meter at _transport_frame
-                        * - calc duration of 1 bar + time-to-beat before or at transport_frame
+                        * - use [fixed] tempo/meter at _transport_sample
+                        * - calc duration of 1 bar + time-to-beat before or at transport_sample
                         */
-                       const Tempo& tempo = _tempo_map->tempo_at_frame (_transport_frame);
-                       const Meter& meter = _tempo_map->meter_at_frame (_transport_frame);
+                       const Tempo& tempo = _tempo_map->tempo_at_sample (_transport_sample);
+                       const Meter& meter = _tempo_map->meter_at_sample (_transport_sample);
 
-                       double div = meter.divisions_per_bar ();
-                       double pulses = _tempo_map->exact_qn_at_frame (_transport_frame, 0) * div / 4.0;
-                       double beats_left = fmod (pulses, div);
+                       const double num = meter.divisions_per_bar ();
+                       const double den = meter.note_divisor ();
+                       const double barbeat = _tempo_map->exact_qn_at_sample (_transport_sample, 0) * den / (4. * num);
+                       const double bar_fract = fmod (barbeat, 1.0); // fraction of bar elapsed.
 
-                       _count_in_samples = meter.frames_per_bar (tempo, _current_frame_rate);
+                       _count_in_samples = meter.samples_per_bar (tempo, _current_sample_rate);
 
-                       double dt = _count_in_samples / div;
-                       if (beats_left == 0) {
+                       double dt = _count_in_samples / num;
+                       if (bar_fract == 0) {
                                /* at bar boundary, count-in 2 bars before start. */
                                _count_in_samples *= 2;
                        } else {
                                /* beats left after full bar until roll position */
-                               _count_in_samples += meter.frames_per_grid (tempo, _current_frame_rate) * beats_left;
+                               _count_in_samples *= 1. + bar_fract;
+                       }
+
+                       if (_count_in_samples > _remaining_latency_preroll) {
+                               _remaining_latency_preroll = _count_in_samples;
                        }
 
                        int clickbeat = 0;
-                       framepos_t cf = _transport_frame - _count_in_samples;
-                       while (cf < _transport_frame) {
-                               add_click (cf - _worst_track_latency, clickbeat == 0);
+                       samplepos_t cf = _transport_sample - _count_in_samples;
+                       samplecnt_t offset = _click_io->connected_latency (true);
+                       while (cf < _transport_sample + offset) {
+                               add_click (cf, clickbeat == 0);
                                cf += dt;
-                               clickbeat = fmod (clickbeat + 1, div);
+                               clickbeat = fmod (clickbeat + 1, num);
+                       }
+
+                       if (_count_in_samples < _remaining_latency_preroll) {
+                               _count_in_samples = _remaining_latency_preroll;
                        }
                }
        }
@@ -1735,6 +1697,7 @@ Session::post_transport ()
        if (ptw & PostTransportLocate) {
 
                if (((!config.get_external_sync() && (auto_play_legal && config.get_auto_play())) && !_exporting) || (ptw & PostTransportRoll)) {
+                       _count_in_once = false;
                        start_transport ();
                } else {
                        transport_sub_state = 0;
@@ -1749,15 +1712,15 @@ Session::post_transport ()
 }
 
 void
-Session::reset_rf_scale (framecnt_t motion)
+Session::reset_rf_scale (samplecnt_t motion)
 {
        cumulative_rf_motion += motion;
 
-       if (cumulative_rf_motion < 4 * _current_frame_rate) {
+       if (cumulative_rf_motion < 4 * _current_sample_rate) {
                rf_scale = 1;
-       } else if (cumulative_rf_motion < 8 * _current_frame_rate) {
+       } else if (cumulative_rf_motion < 8 * _current_sample_rate) {
                rf_scale = 4;
-       } else if (cumulative_rf_motion < 16 * _current_frame_rate) {
+       } else if (cumulative_rf_motion < 16 * _current_sample_rate) {
                rf_scale = 10;
        } else {
                rf_scale = 100;
@@ -1768,167 +1731,6 @@ Session::reset_rf_scale (framecnt_t motion)
        }
 }
 
-void
-Session::mtc_status_changed (bool yn)
-{
-       g_atomic_int_set (&_mtc_active, yn);
-       MTCSyncStateChanged( yn );
-}
-
-void
-Session::ltc_status_changed (bool yn)
-{
-       g_atomic_int_set (&_ltc_active, yn);
-       LTCSyncStateChanged( yn );
-}
-
-void
-Session::use_sync_source (Slave* new_slave)
-{
-       /* Runs in process() context */
-
-       bool non_rt_required = false;
-
-       /* XXX this deletion is problematic because we're in RT context */
-
-       delete _slave;
-       _slave = new_slave;
-
-       MTC_Slave* mtc_slave = dynamic_cast<MTC_Slave*>(_slave);
-       if (mtc_slave) {
-               mtc_slave->ActiveChanged.connect_same_thread (mtc_status_connection, boost::bind (&Session::mtc_status_changed, this, _1));
-               MTCSyncStateChanged(mtc_slave->locked() );
-       } else {
-               if (g_atomic_int_get (&_mtc_active) ){
-                       g_atomic_int_set (&_mtc_active, 0);
-                       MTCSyncStateChanged( false );
-               }
-               mtc_status_connection.disconnect ();
-       }
-
-       LTC_Slave* ltc_slave = dynamic_cast<LTC_Slave*> (_slave);
-       if (ltc_slave) {
-               ltc_slave->ActiveChanged.connect_same_thread (ltc_status_connection, boost::bind (&Session::ltc_status_changed, this, _1));
-               LTCSyncStateChanged (ltc_slave->locked() );
-       } else {
-               if (g_atomic_int_get (&_ltc_active) ){
-                       g_atomic_int_set (&_ltc_active, 0);
-                       LTCSyncStateChanged( false );
-               }
-               ltc_status_connection.disconnect ();
-       }
-
-       DEBUG_TRACE (DEBUG::Slave, string_compose ("set new slave to %1\n", _slave));
-
-       // need to queue this for next process() cycle
-       _send_timecode_update = true;
-
-       boost::shared_ptr<RouteList> rl = routes.reader();
-       for (RouteList::iterator i = rl->begin(); i != rl->end(); ++i) {
-               boost::shared_ptr<Track> tr = boost::dynamic_pointer_cast<Track> (*i);
-               if (tr && !tr->hidden()) {
-                       if (tr->realtime_set_speed (tr->speed(), true)) {
-                               non_rt_required = true;
-                       }
-                       tr->set_slaved (_slave != 0);
-               }
-       }
-
-       if (non_rt_required) {
-               add_post_transport_work (PostTransportSpeed);
-               _butler->schedule_transport_work ();
-       }
-
-       set_dirty();
-}
-
-void
-Session::drop_sync_source ()
-{
-       request_sync_source (0);
-}
-
-void
-Session::switch_to_sync_source (SyncSource src)
-{
-       Slave* new_slave;
-
-       DEBUG_TRACE (DEBUG::Slave, string_compose ("Setting up sync source %1\n", enum_2_string (src)));
-
-       switch (src) {
-       case MTC:
-               if (_slave && dynamic_cast<MTC_Slave*>(_slave)) {
-                       return;
-               }
-
-               try {
-                       new_slave = new MTC_Slave (*this, *_midi_ports->mtc_input_port());
-               }
-
-               catch (failed_constructor& err) {
-                       return;
-               }
-               break;
-
-       case LTC:
-               if (_slave && dynamic_cast<LTC_Slave*>(_slave)) {
-                       return;
-               }
-
-               try {
-                       new_slave = new LTC_Slave (*this);
-               }
-
-               catch (failed_constructor& err) {
-                       return;
-               }
-
-               break;
-
-       case MIDIClock:
-               if (_slave && dynamic_cast<MIDIClock_Slave*>(_slave)) {
-                       return;
-               }
-
-               try {
-                       new_slave = new MIDIClock_Slave (*this, *_midi_ports->midi_clock_input_port(), 24);
-               }
-
-               catch (failed_constructor& err) {
-                       return;
-               }
-               break;
-
-       case Engine:
-               if (_slave && dynamic_cast<Engine_Slave*>(_slave)) {
-                       return;
-               }
-
-               if (config.get_video_pullup() != 0.0f) {
-                       return;
-               }
-
-               new_slave = new Engine_Slave (*AudioEngine::instance());
-               break;
-
-       default:
-               new_slave = 0;
-               break;
-       };
-
-       request_sync_source (new_slave);
-}
-
-void
-Session::set_track_speed (Track* track, double speed)
-{
-       if (track->realtime_set_speed (speed, false)) {
-               add_post_transport_work (PostTransportSpeed);
-               _butler->schedule_transport_work ();
-               set_dirty ();
-       }
-}
-
 void
 Session::unset_play_range ()
 {
@@ -1977,18 +1779,18 @@ Session::set_play_range (list<AudioRange>& range, bool leave_rolling)
                        /* locating/stopping is subject to delays for declicking.
                         */
 
-                       framepos_t requested_frame = i->end;
+                       samplepos_t requested_sample = i->end;
 
-                       if (requested_frame > current_block_size) {
-                               requested_frame -= current_block_size;
+                       if (requested_sample > current_block_size) {
+                               requested_sample -= current_block_size;
                        } else {
-                               requested_frame = 0;
+                               requested_sample = 0;
                        }
 
                        if (next == range.end()) {
-                               ev = new SessionEvent (SessionEvent::RangeStop, SessionEvent::Add, requested_frame, 0, 0.0f);
+                               ev = new SessionEvent (SessionEvent::RangeStop, SessionEvent::Add, requested_sample, 0, 0.0f);
                        } else {
-                               ev = new SessionEvent (SessionEvent::RangeLocate, SessionEvent::Add, requested_frame, (*next).start, 0.0f);
+                               ev = new SessionEvent (SessionEvent::RangeLocate, SessionEvent::Add, requested_sample, (*next).start, 0.0f);
                        }
 
                        merge_event (ev);
@@ -2017,7 +1819,7 @@ Session::set_play_range (list<AudioRange>& range, bool leave_rolling)
 }
 
 void
-Session::request_bounded_roll (framepos_t start, framepos_t end)
+Session::request_bounded_roll (samplepos_t start, samplepos_t end)
 {
        AudioRange ar (start, end, 0);
        list<AudioRange> lar;
@@ -2027,16 +1829,16 @@ Session::request_bounded_roll (framepos_t start, framepos_t end)
 }
 
 void
-Session::set_requested_return_frame (framepos_t return_to)
+Session::set_requested_return_sample (samplepos_t return_to)
 {
-       _requested_return_frame = return_to;
+       _requested_return_sample = return_to;
 }
 
 void
-Session::request_roll_at_and_return (framepos_t start, framepos_t return_to)
+Session::request_roll_at_and_return (samplepos_t start, samplepos_t return_to)
 {
        SessionEvent *ev = new SessionEvent (SessionEvent::LocateRollLocate, SessionEvent::Add, SessionEvent::Immediate, return_to, 1.0);
-       ev->target2_frame = start;
+       ev->target2_sample = start;
        queue_event (ev);
 }
 
@@ -2070,7 +1872,7 @@ Session::xrun_recovery ()
 {
        ++_xrun_count;
 
-       Xrun (_transport_frame); /* EMIT SIGNAL */
+       Xrun (_transport_sample); /* EMIT SIGNAL */
 
        if (Config->get_stop_recording_on_xrun() && actively_recording()) {
 
@@ -2112,9 +1914,9 @@ Session::allow_auto_play (bool yn)
 }
 
 bool
-Session::maybe_stop (framepos_t limit)
+Session::maybe_stop (samplepos_t limit)
 {
-       if ((_transport_speed > 0.0f && _transport_frame >= limit) || (_transport_speed < 0.0f && _transport_frame == 0)) {
+       if ((_transport_speed > 0.0f && _transport_sample >= limit) || (_transport_speed < 0.0f && _transport_sample == 0)) {
                if (synced_to_engine () && config.get_jack_time_master ()) {
                        _engine.transport_stop ();
                } else if (!synced_to_engine ()) {
@@ -2126,7 +1928,7 @@ Session::maybe_stop (framepos_t limit)
 }
 
 void
-Session::send_mmc_locate (framepos_t t)
+Session::send_mmc_locate (samplepos_t t)
 {
        if (t < 0) {
                return;
@@ -2162,3 +1964,91 @@ Session::timecode_transmission_suspended () const
 {
        return g_atomic_int_get (&_suspend_timecode_transmission) == 1;
 }
+
+boost::shared_ptr<TransportMaster>
+Session::transport_master() const
+{
+       return TransportMasterManager::instance().current();
+}
+
+bool
+Session::transport_master_is_external () const
+{
+       return config.get_external_sync();
+}
+
+void
+Session::sync_source_changed (SyncSource type, samplepos_t pos, pframes_t cycle_nframes)
+{
+       /* Runs in process() context */
+
+       boost::shared_ptr<TransportMaster> master = TransportMasterManager::instance().current();
+
+       /* save value of seamless from before the switch */
+       _was_seamless = Config->get_seamless_loop ();
+
+       if (type == Engine) {
+               /* JACK cannot support seamless looping at present */
+               Config->set_seamless_loop (false);
+       } else {
+               /* reset to whatever the value was before we last switched slaves */
+               Config->set_seamless_loop (_was_seamless);
+       }
+
+       if (master->can_loop()) {
+               request_play_loop (false);
+       } else if (master->has_loop()) {
+               request_play_loop (true);
+       }
+
+       /* slave change, reset any DiskIO block on disk output because it is no
+          longer valid with a new slave.
+       */
+
+       DiskReader::set_no_disk_output (false);
+
+#if 0
+       we should not be treating specific transport masters as special cases because there maybe > 1 of a particular type
+
+       boost::shared_ptr<MTC_TransportMaster> mtc_master = boost::dynamic_pointer_cast<MTC_TransportMaster> (master);
+
+       if (mtc_master) {
+               mtc_master->ActiveChanged.connect_same_thread (mtc_status_connection, boost::bind (&Session::mtc_status_changed, this, _1));
+               MTCSyncStateChanged(mtc_master->locked() );
+       } else {
+               if (g_atomic_int_compare_and_exchange (&_mtc_active, 1, 0)) {
+                       MTCSyncStateChanged( false );
+               }
+               mtc_status_connection.disconnect ();
+       }
+
+       boost::shared_ptr<LTC_TransportMaster> ltc_master = boost::dynamic_pointer_cast<LTC_TransportMaster> (master);
+
+       if (ltc_master) {
+               ltc_master->ActiveChanged.connect_same_thread (ltc_status_connection, boost::bind (&Session::ltc_status_changed, this, _1));
+               LTCSyncStateChanged (ltc_master->locked() );
+       } else {
+               if (g_atomic_int_compare_and_exchange (&_ltc_active, 1, 0)) {
+                       LTCSyncStateChanged( false );
+               }
+               ltc_status_connection.disconnect ();
+       }
+#endif
+
+       DEBUG_TRACE (DEBUG::Slave, string_compose ("set new slave to %1\n", master));
+
+       // need to queue this for next process() cycle
+       _send_timecode_update = true;
+
+       boost::shared_ptr<RouteList> rl = routes.reader();
+       const bool externally_slaved = transport_master_is_external();
+
+       for (RouteList::iterator i = rl->begin(); i != rl->end(); ++i) {
+               boost::shared_ptr<Track> tr = boost::dynamic_pointer_cast<Track> (*i);
+               if (tr && !tr->is_private_route()) {
+                       tr->set_slaved (externally_slaved);
+               }
+       }
+
+       set_dirty();
+}