X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=libs%2Fardour%2Fsession_process.cc;h=766ce395e51fc16edc60afbd46ba93526bcaf6e3;hb=e12e8716ba10ba337e298739cf59b401df805ae1;hp=801e1037b56110bd973d974058b1e552da246b48;hpb=1ab566216617d12b932699081836135fa2ab36d3;p=ardour.git

diff --git a/libs/ardour/session_process.cc b/libs/ardour/session_process.cc
index 801e1037b5..766ce395e5 100644
--- a/libs/ardour/session_process.cc
+++ b/libs/ardour/session_process.cc
@@ -23,22 +23,27 @@
 #include <unistd.h>
 
 #include "pbd/error.h"
+#include "pbd/enumwriter.h"
 
-#include <glibmm/thread.h>
+#include <glibmm/threads.h>
 
-#include "ardour/ardour.h"
-#include "ardour/audio_diskstream.h"
 #include "ardour/audioengine.h"
 #include "ardour/auditioner.h"
 #include "ardour/butler.h"
+#include "ardour/cycle_timer.h"
 #include "ardour/debug.h"
+#include "ardour/graph.h"
+#include "ardour/port.h"
+#include "ardour/process_thread.h"
+#include "ardour/scene_changer.h"
 #include "ardour/session.h"
 #include "ardour/slave.h"
-#include "ardour/timestamps.h"
+#include "ardour/ticker.h"
+#include "ardour/types.h"
 
-#include "midi++/manager.h"
+#include "midi++/mmc.h"
 
-#include "i18n.h"
+#include "pbd/i18n.h"
 
 using namespace ARDOUR;
 using namespace PBD;
@@ -47,14 +52,11 @@ using namespace std;
 /** Called by the audio engine when there is work to be done with JACK.
  * @param nframes Number of frames to process.
  */
+
 void
-Session::process (nframes_t nframes)
+Session::process (pframes_t nframes)
 {
-	// This is no more the appropriate place to call cycle
-	// start. cycle_start needs to be called at the Route::roll()
-	// where the signals which we want to mixdown have been calculated.
-	//
-	MIDI::Manager::instance()->cycle_start(nframes);
+	framepos_t transport_at_start = _transport_frame;
 
 	_silent = false;
 
@@ -69,153 +71,181 @@ Session::process (nframes_t nframes)
 		}
 	}
 
+	_engine.main_thread()->get_buffers ();
+
 	(this->*process_function) (nframes);
 
-	// the ticker is for sending time information like MidiClock
-	nframes_t transport_frames = transport_frame();
-	BBT_Time  transport_bbt;
-	bbt_time(transport_frames, transport_bbt);
-	Timecode::Time transport_timecode;
-	timecode_time(transport_frames, transport_timecode);
-	tick (transport_frames, transport_bbt, transport_timecode); /* EMIT SIGNAL */
+	/* realtime-safe meter-position and processor-order changes
+	 *
+	 * ideally this would be done in
+	 * Route::process_output_buffers() but various functions
+	 * callig it hold a _processor_lock reader-lock
+	 */
+	boost::shared_ptr<RouteList> r = routes.reader ();
+	for (RouteList::const_iterator i = r->begin(); i != r->end(); ++i) {
+		if ((*i)->apply_processor_changes_rt()) {
+			_rt_emit_pending = true;
+		}
+	}
+	if (_rt_emit_pending) {
+		if (!_rt_thread_active) {
+			emit_route_signals ();
+		}
+		if (pthread_mutex_trylock (&_rt_emit_mutex) == 0) {
+			pthread_cond_signal (&_rt_emit_cond);
+			pthread_mutex_unlock (&_rt_emit_mutex);
+			_rt_emit_pending = false;
+		}
+	}
 
-	SendFeedback (); /* EMIT SIGNAL */
+	_engine.main_thread()->drop_buffers ();
 
-	MIDI::Manager::instance()->cycle_end();
-}
+	/* deliver MIDI clock. Note that we need to use the transport frame
+	 * position at the start of process(), not the value at the end of
+	 * it. We may already have ticked() because of a transport state
+	 * change, for example.
+	 */
 
-void
-Session::prepare_diskstreams ()
-{
-	boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
-	for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
-		(*i)->prepare ();
+	try {
+		if (!_silent && !_engine.freewheeling() && Config->get_send_midi_clock() && (transport_speed() == 1.0f || transport_speed() == 0.0f) && midi_clock->has_midi_port()) {
+			midi_clock->tick (transport_at_start, nframes);
+		}
+
+		_scene_changer->run (transport_at_start, transport_at_start + nframes);
+
+	} catch (...) {
+		/* don't bother with a message */
 	}
+
+	SendFeedback (); /* EMIT SIGNAL */
 }
 
 int
-Session::fail_roll (nframes_t nframes)
+Session::fail_roll (pframes_t nframes)
 {
 	return no_roll (nframes);
 }
 
 int
-Session::no_roll (nframes_t nframes)
+Session::no_roll (pframes_t nframes)
 {
-	nframes_t end_frame = _transport_frame + nframes; // FIXME: varispeed + no_roll ??
+	PT_TIMING_CHECK (4);
+
+	framepos_t end_frame = _transport_frame + nframes; // FIXME: varispeed + no_roll ??
 	int ret = 0;
-	bool declick = get_transport_declick_required();
+	int declick = (config.get_use_transport_fades() ? get_transport_declick_required() : false);
 	boost::shared_ptr<RouteList> r = routes.reader ();
 
 	if (_click_io) {
 		_click_io->silence (nframes);
 	}
 
-	for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
+	ltc_tx_send_time_code_for_cycle (_transport_frame, end_frame, _target_transport_speed, _transport_speed, nframes);
 
-		if ((*i)->is_hidden()) {
-			continue;
-		}
+	if (_process_graph) {
+		DEBUG_TRACE(DEBUG::ProcessThreads,"calling graph/no-roll\n");
+		_process_graph->routes_no_roll( nframes, _transport_frame, end_frame, non_realtime_work_pending(), declick);
+	} else {
+		PT_TIMING_CHECK (10);
+		for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 
-		(*i)->set_pending_declick (declick);
+			if ((*i)->is_auditioner()) {
+				continue;
+			}
 
-		if ((*i)->no_roll (nframes, _transport_frame, end_frame, non_realtime_work_pending(),
-				   actively_recording(), declick)) {
-			error << string_compose(_("Session: error in no roll for %1"), (*i)->name()) << endmsg;
-			ret = -1;
-			break;
+			(*i)->set_pending_declick (declick);
+
+			if ((*i)->no_roll (nframes, _transport_frame, end_frame, non_realtime_work_pending())) {
+				error << string_compose(_("Session: error in no roll for %1"), (*i)->name()) << endmsg;
+				ret = -1;
+				break;
+			}
 		}
+		PT_TIMING_CHECK (11);
 	}
 
+	PT_TIMING_CHECK (5);
 	return ret;
 }
 
+/** @param need_butler to be set to true by this method if it needs the butler,
+ *  otherwise it must be left alone.
+ */
 int
-Session::process_routes (nframes_t nframes)
+Session::process_routes (pframes_t nframes, bool& need_butler)
 {
-	bool record_active;
-	int  declick = get_transport_declick_required();
-	bool rec_monitors = get_rec_monitors_input();
+	int declick = (config.get_use_transport_fades() ? get_transport_declick_required() : false);
 	boost::shared_ptr<RouteList> r = routes.reader ();
 
-	if (transport_sub_state & StopPendingCapture) {
-		/* force a declick out */
-		declick = -1;
-	}
-
-	record_active = actively_recording(); // || (get_record_enabled() && get_punch_in());
+	const framepos_t start_frame = _transport_frame;
+	const framepos_t end_frame = _transport_frame + floor (nframes * _transport_speed);
 
-	const nframes_t start_frame = _transport_frame;
-	const nframes_t end_frame = _transport_frame + (nframes_t)floor(nframes * _transport_speed);
-
-	for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
+	if (_process_graph) {
+		DEBUG_TRACE(DEBUG::ProcessThreads,"calling graph/process-routes\n");
+		if (_process_graph->process_routes (nframes, start_frame, end_frame, declick, need_butler) < 0) {
+			stop_transport ();
+			return -1;
+		}
+	} else {
 
-		int ret;
+		for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 
-		if ((*i)->is_hidden()) {
-			continue;
-		}
+			int ret;
 
-		(*i)->set_pending_declick (declick);
+			if ((*i)->is_auditioner()) {
+				continue;
+			}
 
-		if ((ret = (*i)->roll (nframes, start_frame, end_frame, declick, record_active, rec_monitors)) < 0) {
+			(*i)->set_pending_declick (declick);
 
-			/* we have to do this here. Route::roll() for an AudioTrack will have called AudioDiskstream::process(),
-			   and the DS will expect AudioDiskstream::commit() to be called. but we're aborting from that
-			   call path, so make sure we release any outstanding locks here before we return failure.
-			*/
+			bool b = false;
 
-			boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
-			for (DiskstreamList::iterator ids = dsl->begin(); ids != dsl->end(); ++ids) {
-				(*ids)->recover ();
+			if ((ret = (*i)->roll (nframes, start_frame, end_frame, declick, b)) < 0) {
+				stop_transport ();
+				return -1;
 			}
 
-			stop_transport ();
-			return -1;
+			if (b) {
+				need_butler = true;
+			}
 		}
 	}
 
 	return 0;
 }
 
+/** @param need_butler to be set to true by this method if it needs the butler,
+ *  otherwise it must be left alone.
+ */
 int
-Session::silent_process_routes (nframes_t nframes)
+Session::silent_process_routes (pframes_t nframes, bool& need_butler)
 {
-	bool record_active = actively_recording();
-	int  declick = get_transport_declick_required();
-	bool rec_monitors = get_rec_monitors_input();
 	boost::shared_ptr<RouteList> r = routes.reader ();
 
-	if (transport_sub_state & StopPendingCapture) {
-		/* force a declick out */
-		declick = -1;
-	}
-
-	const nframes_t start_frame = _transport_frame;
-	const nframes_t end_frame = _transport_frame + lrintf(nframes * _transport_speed);
-
-	for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
+	const framepos_t start_frame = _transport_frame;
+	const framepos_t end_frame = _transport_frame + lrintf(nframes * _transport_speed);
 
-		int ret;
+	if (_process_graph) {
+		_process_graph->silent_process_routes (nframes, start_frame, end_frame, need_butler);
+	} else {
+		for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 
-		if ((*i)->is_hidden()) {
-			continue;
-		}
+			int ret;
 
-		if ((ret = (*i)->silent_roll (nframes, start_frame, end_frame, record_active, rec_monitors)) < 0) {
+			if ((*i)->is_auditioner()) {
+				continue;
+			}
 
-			/* we have to do this here. Route::roll() for an AudioTrack will have called AudioDiskstream::process(),
-			   and the DS will expect AudioDiskstream::commit() to be called. but we're aborting from that
-			   call path, so make sure we release any outstanding locks here before we return failure.
-			*/
+			bool b = false;
 
-			boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
-			for (DiskstreamList::iterator ids = dsl->begin(); ids != dsl->end(); ++ids) {
-				(*ids)->recover ();
+			if ((ret = (*i)->silent_roll (nframes, start_frame, end_frame, b)) < 0) {
+				stop_transport ();
+				return -1;
 			}
 
-			stop_transport ();
-			return -1;
+			if (b) {
+				need_butler = true;
+			}
 		}
 	}
 
@@ -223,47 +253,26 @@ Session::silent_process_routes (nframes_t nframes)
 }
 
 void
-Session::commit_diskstreams (nframes_t nframes, bool &needs_butler)
+Session::get_track_statistics ()
 {
-	int dret;
 	float pworst = 1.0f;
 	float cworst = 1.0f;
 
-	boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
-	for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
+	boost::shared_ptr<RouteList> rl = routes.reader();
+	for (RouteList::iterator i = rl->begin(); i != rl->end(); ++i) {
 
-		if ((*i)->hidden()) {
-			continue;
-		}
+		boost::shared_ptr<Track> tr = boost::dynamic_pointer_cast<Track> (*i);
 
-		/* force all diskstreams not handled by a Route to call do their stuff.
-		   Note: the diskstreams that were handled by a route will just return zero
-		   from this call, because they know they were processed. So in fact, this
-		   also runs commit() for every diskstream.
-		 */
-
-		if ((dret = (*i)->process (_transport_frame, nframes, actively_recording(), get_rec_monitors_input())) == 0) {
-			if ((*i)->commit (nframes)) {
-				needs_butler = true;
-			}
-
-		} else if (dret < 0) {
-			(*i)->recover();
+		if (!tr || tr->hidden()) {
+			continue;
 		}
 
-		pworst = min (pworst, (*i)->playback_buffer_load());
-		cworst = min (cworst, (*i)->capture_buffer_load());
+		pworst = min (pworst, tr->playback_buffer_load());
+		cworst = min (cworst, tr->capture_buffer_load());
 	}
 
-	uint32_t pmin = g_atomic_int_get (&_playback_load);
-	uint32_t pminold = g_atomic_int_get (&_playback_load_min);
-	uint32_t cmin = g_atomic_int_get (&_capture_load);
-	uint32_t cminold = g_atomic_int_get (&_capture_load_min);
-
 	g_atomic_int_set (&_playback_load, (uint32_t) floor (pworst * 100.0f));
 	g_atomic_int_set (&_capture_load, (uint32_t) floor (cworst * 100.0f));
-	g_atomic_int_set (&_playback_load_min, min (pmin, pminold));
-	g_atomic_int_set (&_capture_load_min, min (cmin, cminold));
 
 	if (actively_recording()) {
 		set_dirty();
@@ -272,14 +281,15 @@ Session::commit_diskstreams (nframes_t nframes, bool &needs_butler)
 
 /** Process callback used when the auditioner is not active */
 void
-Session::process_with_events (nframes_t nframes)
+Session::process_with_events (pframes_t nframes)
 {
-	Event*         ev;
-	nframes_t      this_nframes;
-	nframes_t      end_frame;
+	PT_TIMING_CHECK (3);
+
+	SessionEvent*  ev;
+	pframes_t      this_nframes;
+	framepos_t     end_frame;
 	bool           session_needs_butler = false;
-	nframes_t      stop_limit;
-	long           frames_moved;
+	framecnt_t     frames_moved;
 
 	/* make sure the auditioner is silent */
 
@@ -299,18 +309,88 @@ Session::process_with_events (nframes_t nframes)
 	*/
 
 	while (!non_realtime_work_pending() && !immediate_events.empty()) {
-		Event *ev = immediate_events.front ();
+		SessionEvent *ev = immediate_events.front ();
 		immediate_events.pop_front ();
 		process_event (ev);
 	}
 
-	/* Events caused a transport change, send an MTC Full Frame (Timecode) message.
-	 * This is sent whether rolling or not, to give slaves an idea of ardour time
-	 * on locates (and allow slow slaves to position and prepare for rolling)
+	/* count in */
+	if (_transport_speed != 1.0 && _count_in_samples > 0) {
+		_count_in_samples = 0;
+	}
+
+	if (_count_in_samples > 0) {
+		framecnt_t ns = std::min ((framecnt_t)nframes, _count_in_samples);
+
+		no_roll (ns);
+		run_click (_transport_frame - _count_in_samples, ns);
+
+		_count_in_samples -= ns;
+		nframes -= ns;
+
+		/* process events.. */
+		if (!events.empty() && next_event != events.end()) {
+			SessionEvent* this_event = *next_event;
+			Events::iterator the_next_one = next_event;
+			++the_next_one;
+
+			while (this_event && this_event->action_frame == _transport_frame) {
+				process_event (this_event);
+				if (the_next_one == events.end()) {
+					this_event = 0;
+				} else {
+					this_event = *the_next_one;
+					++the_next_one;
+				}
+			}
+			set_next_event ();
+		}
+
+		check_declick_out ();
+
+		if (nframes == 0) {
+			return;
+		} else {
+			_engine.split_cycle (ns);
+		}
+	}
+
+	/* Decide on what to do with quarter-frame MTC during this cycle */
+
+	bool const was_sending_qf_mtc = _send_qf_mtc;
+	double const tolerance = Config->get_mtc_qf_speed_tolerance() / 100.0;
+
+	if (_transport_speed != 0) {
+		_send_qf_mtc = (
+			Config->get_send_mtc () &&
+			_transport_speed >= (1 - tolerance) &&
+			_transport_speed <= (1 + tolerance)
+			);
+
+		if (_send_qf_mtc && !was_sending_qf_mtc) {
+			/* we will re-start quarter-frame MTC this cycle, so send a full update to set things up */
+			_send_timecode_update = true;
+		}
+
+		if (Config->get_send_mtc() && !_send_qf_mtc && _pframes_since_last_mtc > (frame_rate () / 4)) {
+			/* we're sending MTC, but we're not sending QF MTC at the moment, and it's been
+			   a quarter of a second since we sent anything at all, so send a full MTC update
+			   this cycle.
+			*/
+			_send_timecode_update = true;
+		}
+
+		_pframes_since_last_mtc += nframes;
+	}
+
+	/* Events caused a transport change (or we re-started sending
+	 * MTC), so send an MTC Full Frame (Timecode) message.  This
+	 * is sent whether rolling or not, to give slaves an idea of
+	 * ardour time on locates (and allow slow slaves to position
+	 * and prepare for rolling)
 	 */
 	if (_send_timecode_update) {
-		send_full_time_code(nframes);
-		deliver_mmc (MIDI::MachineControl::cmdLocate, _transport_frame);
+		send_full_time_code (_transport_frame, nframes);
 	}
 
 	if (!process_can_proceed()) {
@@ -319,22 +399,29 @@ Session::process_with_events (nframes_t nframes)
 	}
 
 	if (events.empty() || next_event == events.end()) {
-		process_without_events (nframes);
-		return;
+		try_run_lua (nframes); // also during export ?? ->move to process_without_events()
+		/* lua scripts may inject events */
+		while (_n_lua_scripts > 0 && pending_events.read (&ev, 1) == 1) {
+			merge_event (ev);
+		}
+		if (events.empty() || next_event == events.end()) {
+			process_without_events (nframes);
+			return;
+		}
 	}
 
 	if (_transport_speed == 1.0) {
-		frames_moved = (long) nframes;
+		frames_moved = (framecnt_t) nframes;
 	} else {
-		interpolation.set_target_speed (fabs(_target_transport_speed));
-		interpolation.set_speed (fabs(_transport_speed));
-		frames_moved = (long) interpolation.interpolate (0, nframes, 0, 0);
+		interpolation.set_target_speed (_target_transport_speed);
+		interpolation.set_speed (_transport_speed);
+		frames_moved = (framecnt_t) interpolation.interpolate (0, nframes, 0, 0);
 	}
 
-	end_frame = _transport_frame + (nframes_t)frames_moved;
+	end_frame = _transport_frame + frames_moved;
 
 	{
-		Event* this_event;
+		SessionEvent* this_event;
 		Events::iterator the_next_one;
 
 		if (!process_can_proceed()) {
@@ -353,20 +440,13 @@ Session::process_with_events (nframes_t nframes)
 			return;
 		}
 
-		if (!_exporting) {
-			send_midi_time_code_for_cycle (nframes);
+		if (!_exporting && !timecode_transmission_suspended()) {
+			send_midi_time_code_for_cycle (_transport_frame, end_frame, nframes);
 		}
 
-		if (actively_recording()) {
-			stop_limit = max_frames;
-		} else {
+		ltc_tx_send_time_code_for_cycle (_transport_frame, end_frame, _target_transport_speed, _transport_speed, nframes);
 
-			if (Config->get_stop_at_session_end()) {
-				stop_limit = current_end_frame();
-			} else {
-				stop_limit = max_frames;
-			}
-		}
+		framepos_t stop_limit = compute_stop_limit ();
 
 		if (maybe_stop (stop_limit)) {
 			no_roll (nframes);
@@ -384,28 +464,27 @@ Session::process_with_events (nframes_t nframes)
 		while (nframes) {
 
 			this_nframes = nframes; /* real (jack) time relative */
-			frames_moved = (long) floor (_transport_speed * nframes); /* transport relative */
+			frames_moved = (framecnt_t) floor (_transport_speed * nframes); /* transport relative */
 
 			/* running an event, position transport precisely to its time */
 			if (this_event && this_event->action_frame <= end_frame && this_event->action_frame >= _transport_frame) {
 				/* this isn't quite right for reverse play */
-				frames_moved = (long) (this_event->action_frame - _transport_frame);
-				this_nframes = (nframes_t) abs( floor(frames_moved / _transport_speed) );
+				frames_moved = (framecnt_t) (this_event->action_frame - _transport_frame);
+				this_nframes = abs (floor(frames_moved / _transport_speed));
 			}
 
+			try_run_lua (this_nframes);
+
 			if (this_nframes) {
 
 				click (_transport_frame, this_nframes);
 
-				/* now process frames between now and the first event in this block */
-				prepare_diskstreams ();
-
-				if (process_routes (this_nframes)) {
+				if (process_routes (this_nframes, session_needs_butler)) {
 					fail_roll (nframes);
 					return;
 				}
 
-				commit_diskstreams (this_nframes, session_needs_butler);
+				get_track_statistics ();
 
 				nframes -= this_nframes;
 
@@ -419,7 +498,9 @@ Session::process_with_events (nframes_t nframes)
 				check_declick_out ();
 			}
 
-			_engine.split_cycle (this_nframes);
+			if (nframes > 0) {
+				_engine.split_cycle (this_nframes);
+			}
 
 			/* now handle this event and all others scheduled for the same time */
 
@@ -442,8 +523,7 @@ Session::process_with_events (nframes_t nframes)
 			}
 
 			/* this is necessary to handle the case of seamless looping */
-			end_frame = _transport_frame + (nframes_t) floor (nframes * _transport_speed);
-
+			end_frame = _transport_frame + floor (nframes * _transport_speed);
 		}
 
 		set_next_event ();
@@ -461,7 +541,7 @@ Session::reset_slave_state ()
 	average_slave_delta = 1800;
 	delta_accumulator_cnt = 0;
 	have_first_delta_accumulator = false;
-	slave_state = Stopped;
+	_slave_state = Stopped;
 }
 
 bool
@@ -477,13 +557,12 @@ Session::transport_locked () const
 }
 
 bool
-Session::follow_slave (nframes_t nframes)
+Session::follow_slave (pframes_t nframes)
 {
 	double slave_speed;
-	nframes64_t slave_transport_frame;
-	nframes_t this_delta;
+	framepos_t slave_transport_frame;
+	framecnt_t this_delta;
 	int dir;
-	bool starting;
 
 	if (!_slave->ok()) {
 		stop_transport ();
@@ -493,9 +572,10 @@ Session::follow_slave (nframes_t nframes)
 
 	_slave->speed_and_position (slave_speed, slave_transport_frame);
 
-	DEBUG_TRACE (DEBUG::Slave, string_compose ("Slave @ %2 speed %1\n", slave_speed, slave_transport_frame));
+	DEBUG_TRACE (DEBUG::Slave, string_compose ("Slave position %1 speed %2\n", slave_transport_frame, slave_speed));
 
 	if (!_slave->locked()) {
+		DEBUG_TRACE (DEBUG::Slave, "slave not locked\n");
 		goto noroll;
 	}
 
@@ -507,11 +587,13 @@ Session::follow_slave (nframes_t nframes)
 		dir = -1;
 	}
 
-	if ((starting = _slave->starting())) {
+	if (_slave->starting()) {
 		slave_speed = 0.0f;
 	}
 
-	if (_slave->is_always_synced() || config.get_timecode_source_is_synced()) {
+	if (_slave->is_always_synced() ||
+			(Config->get_timecode_source_is_synced() && (dynamic_cast<TimecodeSlave*>(_slave)) != 0)
+			) {
 
 		/* if the TC source is synced, then we assume that its
 		   speed is binary: 0.0 or 1.0
@@ -523,17 +605,25 @@ Session::follow_slave (nframes_t nframes)
 
 	} else {
 
-		/* TC source is able to drift relative to us (slave)
-		   so we need to keep track of the drift and adjust
-		   our speed to remain locked.
+		/* if we are chasing and the average delta between us and the
+		   master gets too big, we want to switch to silent
+		   motion. so keep track of that here.
 		*/
 
-		calculate_moving_average_of_slave_delta(dir, this_delta);
+		if (_slave_state == Running) {
+			calculate_moving_average_of_slave_delta(dir, this_delta);
+		}
 	}
 
-	track_slave_state(slave_speed, slave_transport_frame, this_delta, starting);
+	track_slave_state (slave_speed, slave_transport_frame, this_delta);
+
+	DEBUG_TRACE (DEBUG::Slave, string_compose ("slave state %1 @ %2 speed %3 cur delta %4 avg delta %5\n",
+						   _slave_state, slave_transport_frame, slave_speed, this_delta, average_slave_delta));
+
 
-	if (slave_state == Running && !_slave->is_always_synced() && !config.get_timecode_source_is_synced()) {
+	if (_slave_state == Running && !_slave->is_always_synced() &&
+			!(Config->get_timecode_source_is_synced() && (dynamic_cast<TimecodeSlave*>(_slave)) != 0)
+			) {
 
 		if (_transport_speed != 0.0f) {
 
@@ -543,7 +633,6 @@ Session::follow_slave (nframes_t nframes)
 
 			float delta;
 
-#ifdef USE_MOVING_AVERAGE_OF_SLAVE
 			if (average_slave_delta == 0) {
 				delta = this_delta;
 				delta *= dir;
@@ -551,48 +640,41 @@ Session::follow_slave (nframes_t nframes)
 				delta = average_slave_delta;
 				delta *= average_dir;
 			}
-#else
-			delta = this_delta;
-			delta *= dir;
+
+#ifndef NDEBUG
+			if (slave_speed != 0.0) {
+				DEBUG_TRACE (DEBUG::Slave, string_compose ("delta = %1 speed = %2 ts = %3 M@%4 S@%5 avgdelta %6\n",
+									   (int) (dir * this_delta),
+									   slave_speed,
+									   _transport_speed,
+									   _transport_frame,
+									   slave_transport_frame,
+									   average_slave_delta));
+			}
 #endif
 
-			if (fabs(delta) > frames_per_cycle()) {
-				/* too far off, so locate and keep rolling */
-				DEBUG_TRACE (DEBUG::Slave, string_compose ("slave delta is too big, locate to %1\n", slave_transport_frame));
-				request_locate (slave_transport_frame, true);
+			if (_slave->give_slave_full_control_over_transport_speed()) {
+				set_transport_speed (slave_speed, 0, false, false);
+				//std::cout << "set speed = " << slave_speed << "\n";
 			} else {
-				float adjusted_speed = slave_speed + (delta /  float(_current_frame_rate));
-				
-				if (_slave->give_slave_full_control_over_transport_speed()) {
-					request_transport_speed(slave_speed);
-				} else {
-					request_transport_speed(adjusted_speed);
-					DEBUG_TRACE (DEBUG::Slave, string_compose ("adjust using %1 towards %2 ratio %3 current %4 slave @ %5\n",
-										   delta, adjusted_speed, adjusted_speed/slave_speed, _transport_speed,
-										   slave_speed));
-				}
+				float adjusted_speed = slave_speed + (1.5 * (delta /  float(_current_frame_rate)));
+				request_transport_speed (adjusted_speed);
+				DEBUG_TRACE (DEBUG::Slave, string_compose ("adjust using %1 towards %2 ratio %3 current %4 slave @ %5\n",
+									   delta, adjusted_speed, adjusted_speed/slave_speed, _transport_speed,
+									   slave_speed));
 			}
-			
-			if (abs(average_slave_delta) > (long) _slave->resolution()) {
-				cerr << "average slave delta greater than slave resolution, going to silent motion\n";
+
+#if 1
+			if (!actively_recording() && (framecnt_t) abs(average_slave_delta) > _slave->resolution()) {
+				cerr << "average slave delta greater than slave resolution (" << _slave->resolution() << "), going to silent motion\n";
 				goto silent_motion;
 			}
+#endif
 		}
 	}
 
-#ifndef NDEBUG
-	if (slave_speed != 0.0) {
-		DEBUG_TRACE (DEBUG::Slave, string_compose ("delta = %1 speed = %2 ts = %3 M@%4 S@%5 avgdelta %6\n",
-							   (int) (dir * this_delta),
-							   slave_speed,
-							   _transport_speed,
-							   slave_transport_frame, 
-							   _transport_frame,
-							   average_slave_delta));
-	}
-#endif
 
-	if (!starting && !non_realtime_work_pending()) {
+	if (_slave_state == Running && !non_realtime_work_pending()) {
 		/* speed is set, we're locked, and good to go */
 		return true;
 	}
@@ -609,7 +691,7 @@ Session::follow_slave (nframes_t nframes)
 }
 
 void
-Session::calculate_moving_average_of_slave_delta(int dir, nframes_t this_delta)
+Session::calculate_moving_average_of_slave_delta (int dir, framecnt_t this_delta)
 {
 	if (delta_accumulator_cnt >= delta_accumulator_size) {
 		have_first_delta_accumulator = true;
@@ -617,7 +699,7 @@ Session::calculate_moving_average_of_slave_delta(int dir, nframes_t this_delta)
 	}
 
 	if (delta_accumulator_cnt != 0 || this_delta < _current_frame_rate) {
-		delta_accumulator[delta_accumulator_cnt++] = long(dir) * long(this_delta);
+		delta_accumulator[delta_accumulator_cnt++] = (framecnt_t) dir *  (framecnt_t) this_delta;
 	}
 
 	if (have_first_delta_accumulator) {
@@ -625,7 +707,7 @@ Session::calculate_moving_average_of_slave_delta(int dir, nframes_t this_delta)
 		for (int i = 0; i < delta_accumulator_size; ++i) {
 			average_slave_delta += delta_accumulator[i];
 		}
-		average_slave_delta /= long(delta_accumulator_size);
+		average_slave_delta /= (int32_t) delta_accumulator_size;
 		if (average_slave_delta < 0L) {
 			average_dir = -1;
 			average_slave_delta = abs(average_slave_delta);
@@ -636,29 +718,29 @@ Session::calculate_moving_average_of_slave_delta(int dir, nframes_t this_delta)
 }
 
 void
-Session::track_slave_state(
-		float slave_speed,
-		nframes_t slave_transport_frame,
-		nframes_t this_delta,
-		bool starting)
+Session::track_slave_state (float slave_speed, framepos_t slave_transport_frame, framecnt_t /*this_delta*/)
 {
 	if (slave_speed != 0.0f) {
 
 		/* slave is running */
 
-		switch (slave_state) {
+		switch (_slave_state) {
 		case Stopped:
 			if (_slave->requires_seekahead()) {
-				slave_wait_end = slave_transport_frame + _current_frame_rate;
+				slave_wait_end = slave_transport_frame + _slave->seekahead_distance ();
+				DEBUG_TRACE (DEBUG::Slave, string_compose ("slave stopped, but running, requires seekahead to %1\n", slave_wait_end));
+				/* we can call locate() here because we are in process context */
 				locate (slave_wait_end, false, false);
-				slave_state = Waiting;
-				starting = true;
+				_slave_state = Waiting;
 
 			} else {
 
-				slave_state = Running;
+				DEBUG_TRACE (DEBUG::Slave, string_compose ("slave stopped -> running at %1\n", slave_transport_frame));
+
+				memset (delta_accumulator, 0, sizeof (int32_t) * delta_accumulator_size);
+				average_slave_delta = 0L;
 
-				Location* al = _locations.auto_loop_location();
+				Location* al = _locations->auto_loop_location();
 
 				if (al && play_loop && (slave_transport_frame < al->start() || slave_transport_frame > al->end())) {
 					// cancel looping
@@ -666,45 +748,51 @@ Session::track_slave_state(
 				}
 
 				if (slave_transport_frame != _transport_frame) {
+					DEBUG_TRACE (DEBUG::Slave, string_compose ("require locate to run. eng: %1 -> sl: %2\n", _transport_frame, slave_transport_frame));
 					locate (slave_transport_frame, false, false);
 				}
+				_slave_state = Running;
 			}
 			break;
 
 		case Waiting:
-			break;
-
 		default:
 			break;
-
 		}
 
-		if (slave_state == Waiting) {
+		if (_slave_state == Waiting) {
+
+			DEBUG_TRACE (DEBUG::Slave, string_compose ("slave waiting at %1\n", slave_transport_frame));
 
-		#ifdef DEBUG_SLAVES
-			cerr << "waiting at " << slave_transport_frame << endl;
-		#endif
 			if (slave_transport_frame >= slave_wait_end) {
-#ifdef DEBUG_SLAVES
-				cerr << "\tstart at " << _transport_frame << endl;
-#endif
-				slave_state = Running;
 
-				bool ok = true;
-				nframes_t frame_delta = slave_transport_frame - _transport_frame;
+				DEBUG_TRACE (DEBUG::Slave, string_compose ("slave start at %1 vs %2\n", slave_transport_frame, _transport_frame));
+
+				_slave_state = Running;
+
+				/* now perform a "micro-seek" within the disk buffers to realign ourselves
+				   precisely with the master.
+				*/
+
 
-				boost::shared_ptr<DiskstreamList> dsl = diskstreams.reader();
+				bool ok = true;
+				framecnt_t frame_delta = slave_transport_frame - _transport_frame;
 
-				for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
-					if (!(*i)->can_internal_playback_seek (frame_delta)) {
+				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->can_internal_playback_seek (frame_delta)) {
 						ok = false;
 						break;
 					}
 				}
 
 				if (ok) {
-					for (DiskstreamList::iterator i = dsl->begin(); i != dsl->end(); ++i) {
-						(*i)->internal_playback_seek (frame_delta);
+					for (RouteList::iterator i = rl->begin(); i != rl->end(); ++i) {
+						boost::shared_ptr<Track> tr = boost::dynamic_pointer_cast<Track> (*i);
+						if (tr) {
+							tr->internal_playback_seek (frame_delta);
+						}
 					}
 					_transport_frame += frame_delta;
 
@@ -712,14 +800,10 @@ Session::track_slave_state(
 					cerr << "cannot micro-seek\n";
 					/* XXX what? */
 				}
-
-				memset (delta_accumulator, 0, sizeof (long) * delta_accumulator_size);
-				average_slave_delta = 0L;
-				this_delta = 0;
 			}
 		}
 
-		if (slave_state == Running && _transport_speed == 0.0f) {
+		if (_slave_state == Running && _transport_speed == 0.0f) {
 			DEBUG_TRACE (DEBUG::Slave, "slave starts transport\n");
 			start_transport ();
 		}
@@ -730,7 +814,7 @@ Session::track_slave_state(
 
 		if (_transport_speed != 0.0f) {
 			DEBUG_TRACE (DEBUG::Slave, string_compose ("slave stops transport: %1 frame %2 tf %3\n", slave_speed, slave_transport_frame, _transport_frame));
-			stop_transport();
+			stop_transport ();
 		}
 
 		if (slave_transport_frame != _transport_frame) {
@@ -738,12 +822,12 @@ Session::track_slave_state(
 			force_locate (slave_transport_frame, false);
 		}
 
-		slave_state = Stopped;
+		reset_slave_state();
 	}
 }
 
 void
-Session::follow_slave_silently (nframes_t nframes, float slave_speed)
+Session::follow_slave_silently (pframes_t nframes, float slave_speed)
 {
 	if (slave_speed && _transport_speed) {
 
@@ -751,11 +835,11 @@ Session::follow_slave_silently (nframes_t nframes, float slave_speed)
 		   for now.
 		*/
 
-		bool need_butler;
+		bool need_butler = false;
+
+		silent_process_routes (nframes, need_butler);
 
-		prepare_diskstreams ();
-		silent_process_routes (nframes);
-		commit_diskstreams (nframes, need_butler);
+		get_track_statistics ();
 
 		if (need_butler) {
 			_butler->summon ();
@@ -769,28 +853,16 @@ Session::follow_slave_silently (nframes_t nframes, float slave_speed)
 			increment_transport_position (frames_moved);
 		}
 
-		nframes_t stop_limit;
-
-		if (actively_recording()) {
-			stop_limit = max_frames;
-		} else {
-			if (Config->get_stop_at_session_end()) {
-				stop_limit = current_end_frame();
-			} else {
-				stop_limit = max_frames;
-			}
-		}
-
+		framepos_t const stop_limit = compute_stop_limit ();
 		maybe_stop (stop_limit);
 	}
 }
 
 void
-Session::process_without_events (nframes_t nframes)
+Session::process_without_events (pframes_t nframes)
 {
 	bool session_needs_butler = false;
-	nframes_t stop_limit;
-	long frames_moved;
+	framecnt_t frames_moved;
 
 	if (!process_can_proceed()) {
 		_silent = true;
@@ -799,6 +871,7 @@ Session::process_without_events (nframes_t nframes)
 
 	if (!_exporting && _slave) {
 		if (!follow_slave (nframes)) {
+			ltc_tx_send_time_code_for_cycle (_transport_frame, _transport_frame, 0, 0 , nframes);
 			return;
 		}
 	}
@@ -808,20 +881,22 @@ Session::process_without_events (nframes_t nframes)
 		return;
 	}
 
-	if (!_exporting) {
-		send_midi_time_code_for_cycle (nframes);
+	if (_transport_speed == 1.0) {
+		frames_moved = (framecnt_t) nframes;
+	} else {
+		interpolation.set_target_speed (_target_transport_speed);
+		interpolation.set_speed (_transport_speed);
+		frames_moved = (framecnt_t) interpolation.interpolate (0, nframes, 0, 0);
 	}
 
-	if (actively_recording()) {
-		stop_limit = max_frames;
-	} else {
-		if (Config->get_stop_at_session_end()) {
-			stop_limit = current_end_frame();
-		} else {
-			stop_limit = max_frames;
-		}
+	if (!_exporting && !timecode_transmission_suspended()) {
+		send_midi_time_code_for_cycle (_transport_frame, _transport_frame + frames_moved, nframes);
 	}
 
+	ltc_tx_send_time_code_for_cycle (_transport_frame, _transport_frame + frames_moved, _target_transport_speed, _transport_speed, nframes);
+
+	framepos_t const stop_limit = compute_stop_limit ();
+
 	if (maybe_stop (stop_limit)) {
 		fail_roll (nframes);
 		return;
@@ -833,22 +908,12 @@ Session::process_without_events (nframes_t nframes)
 
 	click (_transport_frame, nframes);
 
-	prepare_diskstreams ();
-
-	if (_transport_speed == 1.0) {
-		frames_moved = (long) nframes;
-	} else {
-		interpolation.set_target_speed (fabs(_target_transport_speed));
-		interpolation.set_speed (fabs(_transport_speed));
-		frames_moved = (long) interpolation.interpolate (0, nframes, 0, 0);
-	}
-
-	if (process_routes (nframes)) {
+	if (process_routes (nframes, session_needs_butler)) {
 		fail_roll (nframes);
 		return;
 	}
 
-	commit_diskstreams (nframes, session_needs_butler);
+	get_track_statistics ();
 
 	if (frames_moved < 0) {
 		decrement_transport_position (-frames_moved);
@@ -868,13 +933,13 @@ Session::process_without_events (nframes_t nframes)
  * @param nframes number of frames to process.
  */
 void
-Session::process_audition (nframes_t nframes)
+Session::process_audition (pframes_t nframes)
 {
-	Event* ev;
+	SessionEvent* ev;
 	boost::shared_ptr<RouteList> r = routes.reader ();
 
 	for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
-		if (!(*i)->is_hidden()) {
+		if (!(*i)->is_auditioner()) {
 			(*i)->silence (nframes);
 		}
 	}
@@ -885,6 +950,12 @@ Session::process_audition (nframes_t nframes)
 		_butler->summon ();
 	}
 
+	/* if using a monitor section, run it because otherwise we don't hear anything */
+
+	if (_monitor_out && auditioner->needs_monitor()) {
+		_monitor_out->monitor_run (_transport_frame, _transport_frame + nframes, nframes, false);
+	}
+
 	/* handle pending events */
 
 	while (pending_events.read (&ev, 1) == 1) {
@@ -897,21 +968,21 @@ Session::process_audition (nframes_t nframes)
 	*/
 
 	while (!non_realtime_work_pending() && !immediate_events.empty()) {
-		Event *ev = immediate_events.front ();
+		SessionEvent *ev = immediate_events.front ();
 		immediate_events.pop_front ();
 		process_event (ev);
 	}
 
-	if (!auditioner->active()) {
+	if (!auditioner->auditioning()) {
 		/* auditioner no longer active, so go back to the normal process callback */
 		process_function = &Session::process_with_events;
 	}
 }
 
 bool
-Session::maybe_sync_start (nframes_t& nframes)
+Session::maybe_sync_start (pframes_t & nframes)
 {
-	nframes_t sync_offset;
+	pframes_t sync_offset;
 
 	if (!waiting_for_sync_offset) {
 		return false;
@@ -926,7 +997,7 @@ Session::maybe_sync_start (nframes_t& nframes)
 
 		no_roll (sync_offset);
 		nframes -= sync_offset;
-		Port::increment_port_offset (sync_offset);
+		Port::increment_global_port_buffer_offset (sync_offset);
 		waiting_for_sync_offset = false;
 
 		if (nframes == 0) {
@@ -954,3 +1025,353 @@ Session::maybe_sync_start (nframes_t& nframes)
 	return false;
 }
 
+void
+Session::queue_event (SessionEvent* ev)
+{
+	if (_state_of_the_state & Deletion) {
+		return;
+	} else if (_state_of_the_state & Loading) {
+		merge_event (ev);
+	} else {
+		pending_events.write (&ev, 1);
+	}
+}
+
+void
+Session::set_next_event ()
+{
+	if (events.empty()) {
+		next_event = events.end();
+		return;
+	}
+
+	if (next_event == events.end()) {
+		next_event = events.begin();
+	}
+
+	if ((*next_event)->action_frame > _transport_frame) {
+		next_event = events.begin();
+	}
+
+	for (; next_event != events.end(); ++next_event) {
+		if ((*next_event)->action_frame >= _transport_frame) {
+			break;
+		}
+	}
+}
+
+void
+Session::process_event (SessionEvent* ev)
+{
+	bool remove = true;
+	bool del = true;
+
+	/* if we're in the middle of a state change (i.e. waiting
+	   for the butler thread to complete the non-realtime
+	   part of the change), we'll just have to queue this
+	   event for a time when the change is complete.
+	*/
+
+	if (non_realtime_work_pending()) {
+
+		/* except locates, which we have the capability to handle */
+
+		if (ev->type != SessionEvent::Locate) {
+			immediate_events.insert (immediate_events.end(), ev);
+			_remove_event (ev);
+			return;
+		}
+	}
+
+	DEBUG_TRACE (DEBUG::SessionEvents, string_compose ("Processing event: %1 @ %2\n", enum_2_string (ev->type), _transport_frame));
+
+	switch (ev->type) {
+	case SessionEvent::SetLoop:
+		set_play_loop (ev->yes_or_no, ev->speed);
+		break;
+
+	case SessionEvent::AutoLoop:
+		if (play_loop) {
+			/* roll after locate, do not flush, set "with loop"
+			   true only if we are seamless looping
+			*/
+			start_locate (ev->target_frame, true, false, Config->get_seamless_loop());
+		}
+		remove = false;
+		del = false;
+		break;
+
+	case SessionEvent::AutoLoopDeclick:
+		if (play_loop) {
+			/* Request a declick fade-out and a fade-in; the fade-out will happen
+			   at the end of the loop, and the fade-in at the start.
+			*/
+			transport_sub_state |= (PendingLoopDeclickOut | PendingLoopDeclickIn);
+		}
+		remove = false;
+		del = false;
+		break;
+
+	case SessionEvent::Locate:
+		if (ev->yes_or_no) {
+			/* args: do not roll after locate, do flush, not with loop */
+			locate (ev->target_frame, false, true, false);
+		} else {
+			/* args: do not roll after locate, do flush, not with loop */
+			start_locate (ev->target_frame, false, true, false);
+		}
+		_send_timecode_update = true;
+		break;
+
+	case SessionEvent::LocateRoll:
+		if (ev->yes_or_no) {
+			/* args: roll after locate, do flush, not with loop */
+			locate (ev->target_frame, true, true, false);
+		} else {
+			/* args: roll after locate, do flush, not with loop */
+			start_locate (ev->target_frame, true, true, false);
+		}
+		_send_timecode_update = true;
+		break;
+
+	case SessionEvent::Skip:
+		if (Config->get_skip_playback()) {
+			start_locate (ev->target_frame, true, true, false);
+			_send_timecode_update = true;
+		}
+		remove = false;
+		del = false;
+		break;
+
+	case SessionEvent::LocateRollLocate:
+		// locate is handled by ::request_roll_at_and_return()
+		_requested_return_frame = ev->target_frame;
+		request_locate (ev->target2_frame, true);
+		break;
+
+
+	case SessionEvent::SetTransportSpeed:
+		set_transport_speed (ev->speed, ev->target_frame, ev->yes_or_no, ev->second_yes_or_no, ev->third_yes_or_no);
+		break;
+
+	case SessionEvent::PunchIn:
+		// cerr << "PunchIN at " << transport_frame() << endl;
+		if (config.get_punch_in() && record_status() == Enabled && !preroll_record_punch_enabled()) {
+			enable_record ();
+		}
+		remove = false;
+		del = false;
+		break;
+
+	case SessionEvent::PunchOut:
+		// cerr << "PunchOUT at " << transport_frame() << endl;
+		if (config.get_punch_out() && !preroll_record_punch_enabled()) {
+			step_back_from_record ();
+		}
+		remove = false;
+		del = false;
+		break;
+
+	case SessionEvent::RecordStart:
+		if (preroll_record_punch_enabled() && record_status() == Enabled) {
+			enable_record ();
+		}
+		remove = false;
+		del = false;
+		break;
+
+	case SessionEvent::StopOnce:
+		if (!non_realtime_work_pending()) {
+			_clear_event_type (SessionEvent::StopOnce);
+			stop_transport (ev->yes_or_no);
+		}
+		remove = false;
+		del = false;
+		break;
+
+	case SessionEvent::RangeStop:
+		if (!non_realtime_work_pending()) {
+			stop_transport (ev->yes_or_no);
+		}
+		remove = false;
+		del = false;
+		break;
+
+	case SessionEvent::RangeLocate:
+		/* args: roll after locate, do flush, not with loop */
+		start_locate (ev->target_frame, true, true, false);
+		remove = false;
+		del = false;
+		break;
+
+	case SessionEvent::Overwrite:
+		overwrite_some_buffers (static_cast<Track*>(ev->ptr));
+		break;
+
+	case SessionEvent::SetTrackSpeed:
+		set_track_speed (static_cast<Track*> (ev->ptr), ev->speed);
+		break;
+
+	case SessionEvent::SetSyncSource:
+		DEBUG_TRACE (DEBUG::Slave, "seen request for new slave\n");
+		use_sync_source (ev->slave);
+		break;
+
+	case SessionEvent::Audition:
+		set_audition (ev->region);
+		// drop reference to region
+		ev->region.reset ();
+		break;
+
+	case SessionEvent::InputConfigurationChange:
+		add_post_transport_work (PostTransportInputChange);
+		_butler->schedule_transport_work ();
+		break;
+
+	case SessionEvent::SetPlayAudioRange:
+		set_play_range (ev->audio_range, (ev->speed == 1.0f));
+		break;
+
+	case SessionEvent::CancelPlayAudioRange:
+		unset_play_range();
+		break;
+
+	case SessionEvent::RealTimeOperation:
+		process_rtop (ev);
+		del = false; // other side of RT request needs to clean up
+		break;
+
+	case SessionEvent::AdjustPlaybackBuffering:
+		schedule_playback_buffering_adjustment ();
+		break;
+
+	case SessionEvent::AdjustCaptureBuffering:
+		schedule_capture_buffering_adjustment ();
+		break;
+
+	case SessionEvent::SetTimecodeTransmission:
+		g_atomic_int_set (&_suspend_timecode_transmission, ev->yes_or_no ? 0 : 1);
+		break;
+
+	default:
+	  fatal << string_compose(_("Programming error: illegal event type in process_event (%1)"), ev->type) << endmsg;
+		abort(); /*NOTREACHED*/
+		break;
+	};
+
+	if (remove) {
+		del = del && !_remove_event (ev);
+	}
+
+	if (del) {
+		delete ev;
+	}
+}
+
+framepos_t
+Session::compute_stop_limit () const
+{
+	if (!Config->get_stop_at_session_end ()) {
+		return max_framepos;
+	}
+
+	if (_slave) {
+		return max_framepos;
+	}
+
+	if (preroll_record_punch_enabled ()) {
+		return max_framepos;
+	}
+
+	bool const punching_in = (config.get_punch_in () && _locations->auto_punch_location());
+	bool const punching_out = (config.get_punch_out () && _locations->auto_punch_location());
+
+	if (actively_recording ()) {
+		/* permanently recording */
+		return max_framepos;
+	} else if (punching_in && !punching_out) {
+		/* punching in but never out */
+		return max_framepos;
+	} else if (punching_in && punching_out && _locations->auto_punch_location()->end() > current_end_frame()) {
+		/* punching in and punching out after session end */
+		return max_framepos;
+	}
+
+	return current_end_frame ();
+}
+
+
+
+/* dedicated thread for signal emission.
+ *
+ * while sending cross-thread signals from the process thread
+ * is fine in general, PBD::Signal's use of boost::function and
+ * boost:bind can produce a vast overhead which is not
+ * acceptable for low latency.
+ *
+ * This works around the issue by moving the boost overhead
+ * out of the RT thread. The overall load is probably higher but
+ * the realtime thread remains unaffected.
+ */
+
+void
+Session::emit_route_signals ()
+{
+	// TODO use RAII to allow using these signals in other places
+	BatchUpdateStart(); /* EMIT SIGNAL */
+	boost::shared_ptr<RouteList> r = routes.reader ();
+	for (RouteList::const_iterator ci = r->begin(); ci != r->end(); ++ci) {
+		(*ci)->emit_pending_signals ();
+	}
+	BatchUpdateEnd(); /* EMIT SIGNAL */
+}
+
+void
+Session::emit_thread_start ()
+{
+	if (_rt_thread_active) {
+		return;
+	}
+	_rt_thread_active = true;
+
+	if (pthread_create (&_rt_emit_thread, NULL, emit_thread, this)) {
+		_rt_thread_active = false;
+	}
+}
+
+void
+Session::emit_thread_terminate ()
+{
+	if (!_rt_thread_active) {
+		return;
+	}
+	_rt_thread_active = false;
+
+	if (pthread_mutex_lock (&_rt_emit_mutex) == 0) {
+		pthread_cond_signal (&_rt_emit_cond);
+		pthread_mutex_unlock (&_rt_emit_mutex);
+	}
+
+	void *status;
+	pthread_join (_rt_emit_thread, &status);
+}
+
+void *
+Session::emit_thread (void *arg)
+{
+	Session *s = static_cast<Session *>(arg);
+	s->emit_thread_run ();
+	pthread_exit (0);
+	return 0;
+}
+
+void
+Session::emit_thread_run ()
+{
+	pthread_mutex_lock (&_rt_emit_mutex);
+	while (_rt_thread_active) {
+		emit_route_signals();
+		pthread_cond_wait (&_rt_emit_cond, &_rt_emit_mutex);
+	}
+	pthread_mutex_unlock (&_rt_emit_mutex);
+}