Initial stab at making musical position useful for ranges.origin/musical_ranges

	- ranges may be glued to bars and beats.
	- use exact beat for locations.
	- adds 'start_beat'  and 'end_beat' to Location xml (may
	  change in the future, as locations only require one position).

12 files changed, 140 insertions, 112 deletions

diff --git a/gtk2_ardour/ardour_ui.cc b/gtk2_ardour/ardour_ui.cc
index d667120..be1e38f 100644
--- a/gtk2_ardour/ardour_ui.cc
+++ b/gtk2_ardour/ardour_ui.cc
@@ -4651,7 +4651,7 @@ void
 ARDOUR_UI::create_xrun_marker (framepos_t where)
 {
 	if (_session) {
-		Location *location = new Location (*_session, where, where, _("xrun"), Location::IsMark);
+		Location *location = new Location (*_session, where, where, _("xrun"), Location::IsMark, 0);
 		_session->locations()->add (location);
 	}
 }
diff --git a/gtk2_ardour/editor.cc b/gtk2_ardour/editor.cc
index 757b767..7228dc1 100644
--- a/gtk2_ardour/editor.cc
+++ b/gtk2_ardour/editor.cc
@@ -4735,7 +4735,7 @@ Editor::set_loop_range (framepos_t start, framepos_t end, string cmd)
 	Location* tll;
 
 	if ((tll = transport_loop_location()) == 0) {
-		Location* loc = new Location (*_session, start, end, _("Loop"),  Location::IsAutoLoop);
+		Location* loc = new Location (*_session, start, end, _("Loop"),  Location::IsAutoLoop, get_grid_music_divisions(0));
 		XMLNode &before = _session->locations()->get_state();
 		_session->locations()->add (loc, true);
 		_session->set_auto_loop_location (loc);
@@ -4762,7 +4762,7 @@ Editor::set_punch_range (framepos_t start, framepos_t end, string cmd)
 	Location* tpl;
 
 	if ((tpl = transport_punch_location()) == 0) {
-		Location* loc = new Location (*_session, start, end, _("Punch"),  Location::IsAutoPunch);
+		Location* loc = new Location (*_session, start, end, _("Punch"),  Location::IsAutoPunch, get_grid_music_divisions(0));
 		XMLNode &before = _session->locations()->get_state();
 		_session->locations()->add (loc, true);
 		_session->set_auto_punch_location (loc);
diff --git a/gtk2_ardour/editor.h b/gtk2_ardour/editor.h
index d45545b..f399113 100644
--- a/gtk2_ardour/editor.h
+++ b/gtk2_ardour/editor.h
@@ -1682,7 +1682,7 @@ class Editor : public PublicEditor, public PBD::ScopedConnectionList, public ARD
 	void marker_context_menu (GdkEventButton*, ArdourCanvas::Item*);
 	void tempo_or_meter_marker_context_menu (GdkEventButton*, ArdourCanvas::Item*);
 	void new_transport_marker_context_menu (GdkEventButton*, ArdourCanvas::Item*);
-	void build_range_marker_menu (bool, bool);
+	void build_range_marker_menu (ARDOUR::Location *, bool, bool);
 	void build_marker_menu (ARDOUR::Location *);
 	void build_tempo_marker_menu (TempoMarker *, bool);
 	void build_meter_marker_menu (MeterMarker *, bool);
diff --git a/gtk2_ardour/editor_drag.cc b/gtk2_ardour/editor_drag.cc
index 6fa3cb0..4e4e2f2 100644
--- a/gtk2_ardour/editor_drag.cc
+++ b/gtk2_ardour/editor_drag.cc
@@ -4114,7 +4114,7 @@ MarkerDrag::motion (GdkEvent* event, bool)
 
 			/* now move it */
 
-			copy_location->set_start (copy_location->start() + f_delta);
+			copy_location->set_start (copy_location->start() + f_delta, false, true, _editor->get_grid_music_divisions(event->button.state));
 
 		} else {
 
@@ -4124,27 +4124,27 @@ MarkerDrag::motion (GdkEvent* event, bool)
 			if (is_start) { // start-of-range marker
 
 				if (move_both || (*x).move_both) {
-					copy_location->set_start (new_start);
-					copy_location->set_end (new_end);
+					copy_location->set_start (new_start, false, true, _editor->get_grid_music_divisions(event->button.state));
+					copy_location->set_end (new_end, false, true, _editor->get_grid_music_divisions(event->button.state));
 				} else	if (new_start < copy_location->end()) {
-					copy_location->set_start (new_start);
+					copy_location->set_start (new_start, false, true, _editor->get_grid_music_divisions(event->button.state));
 				} else if (newframe > 0) {
 					//_editor->snap_to (next, RoundUpAlways, true);
-					copy_location->set_end (next);
-					copy_location->set_start (newframe);
+					copy_location->set_end (next, false, true, _editor->get_grid_music_divisions(event->button.state));
+					copy_location->set_start (newframe, false, true, _editor->get_grid_music_divisions(event->button.state));
 				}
 
 			} else { // end marker
 
 				if (move_both || (*x).move_both) {
-					copy_location->set_end (new_end);
-					copy_location->set_start (new_start);
+					copy_location->set_end (new_end, _editor->get_grid_music_divisions(event->button.state));
+					copy_location->set_start (new_start, false, true, _editor->get_grid_music_divisions(event->button.state));
 				} else if (new_end > copy_location->start()) {
-					copy_location->set_end (new_end);
+					copy_location->set_end (new_end, false, true, _editor->get_grid_music_divisions(event->button.state));
 				} else if (newframe > 0) {
 					//_editor->snap_to (next, RoundDownAlways, true);
-					copy_location->set_start (next);
-					copy_location->set_end (newframe);
+					copy_location->set_start (next, false, true, _editor->get_grid_music_divisions(event->button.state));
+					copy_location->set_end (newframe, false, true, _editor->get_grid_music_divisions(event->button.state));
 				}
 			}
 		}
@@ -4239,9 +4239,9 @@ MarkerDrag::finished (GdkEvent* event, bool movement_occurred)
 				in_command = true;
 			}
 			if (location->is_mark()) {
-				location->set_start (((*x).location)->start());
+				location->set_start (((*x).location)->start(), false, true, _editor->get_grid_music_divisions(event->button.state));
 			} else {
-				location->set (((*x).location)->start(), ((*x).location)->end());
+				location->set (((*x).location)->start(), ((*x).location)->end(), true, _editor->get_grid_music_divisions(event->button.state));
 			}
 
 			if (location->is_session_range()) {
@@ -5433,7 +5433,7 @@ RangeMarkerBarDrag::finished (GdkEvent* event, bool movement_occurred)
 			}
 			newloc = new Location (
 				*_editor->session(), _editor->temp_location->start(), _editor->temp_location->end(), rangename, (Location::Flags) flags
-				);
+				, _editor->get_grid_music_divisions (event->button.state));
 
 			_editor->session()->locations()->add (newloc, true);
 			XMLNode &after = _editor->session()->locations()->get_state();
diff --git a/gtk2_ardour/editor_markers.cc b/gtk2_ardour/editor_markers.cc
index d204049..70967df 100644
--- a/gtk2_ardour/editor_markers.cc
+++ b/gtk2_ardour/editor_markers.cc
@@ -646,7 +646,7 @@ Editor::mouse_add_new_marker (framepos_t where, bool is_cd)
 		if (!choose_new_marker_name(markername)) {
 			return;
 		}
-		Location *location = new Location (*_session, where, where, markername, (Location::Flags) flags);
+		Location *location = new Location (*_session, where, where, markername, (Location::Flags) flags, get_grid_music_divisions (0));
 		begin_reversible_command (_("add marker"));
 
 		XMLNode &before = _session->locations()->get_state();
@@ -839,7 +839,7 @@ Editor::marker_context_menu (GdkEventButton* ev, ArdourCanvas::Item* item)
 	if (loc == transport_loop_location() || loc == transport_punch_location() || loc->is_session_range ()) {
 
 		if (transport_marker_menu == 0) {
-			build_range_marker_menu (loc == transport_loop_location() || loc == transport_punch_location(), loc->is_session_range());
+			build_range_marker_menu (loc, loc == transport_loop_location() || loc == transport_punch_location(), loc->is_session_range());
 		}
 
 		marker_menu_item = item;
@@ -869,7 +869,7 @@ Editor::marker_context_menu (GdkEventButton* ev, ArdourCanvas::Item* item)
 
 	} else if (loc->is_range_marker()) {
 		if (range_marker_menu == 0) {
-			build_range_marker_menu (false, false);
+			build_range_marker_menu (loc, false, false);
 		}
 		marker_menu_item = item;
 		range_marker_menu->popup (1, ev->time);
@@ -927,7 +927,7 @@ Editor::build_marker_menu (Location* loc)
 }
 
 void
-Editor::build_range_marker_menu (bool loop_or_punch, bool session)
+Editor::build_range_marker_menu (Location* loc, bool loop_or_punch, bool session)
 {
 	using namespace Menu_Helpers;
 
@@ -953,6 +953,14 @@ Editor::build_range_marker_menu (bool loop_or_punch, bool session)
 	items.push_back (MenuElem (_("Zoom to Range"), sigc::mem_fun (*this, &Editor::marker_menu_zoom_to_range)));
 
 	items.push_back (SeparatorElem());
+	items.push_back (CheckMenuElem (_("Glue to Bars and Beats")));
+	Gtk::CheckMenuItem* glue_item = static_cast<Gtk::CheckMenuItem*> (&items.back());
+	if (loc->position_lock_style() == MusicTime) {
+		glue_item->set_active ();
+	}
+	glue_item->signal_activate().connect (sigc::mem_fun (*this, &Editor::toggle_marker_menu_glue));
+
+	items.push_back (SeparatorElem());
 	items.push_back (MenuElem (_("Export Range..."), sigc::mem_fun(*this, &Editor::export_range)));
 	items.push_back (SeparatorElem());
 
@@ -1217,13 +1225,13 @@ Editor::marker_menu_set_from_playhead ()
 	if ((l = find_location_from_marker (marker, is_start)) != 0) {
 
 		if (l->is_mark()) {
-			l->set_start (_session->audible_frame ());
+			l->set_start (_session->audible_frame (), false, true, get_grid_music_divisions(0));
 		}
 		else {
 			if (is_start) {
-				l->set_start (_session->audible_frame ());
+				l->set_start (_session->audible_frame (), false, true, get_grid_music_divisions(0));
 			} else {
-				l->set_end (_session->audible_frame ());
+				l->set_end (_session->audible_frame (), false, true, get_grid_music_divisions(0));
 			}
 		}
 	}
diff --git a/gtk2_ardour/editor_ops.cc b/gtk2_ardour/editor_ops.cc
index 5419ce9..287d68a 100644
--- a/gtk2_ardour/editor_ops.cc
+++ b/gtk2_ardour/editor_ops.cc
@@ -419,9 +419,9 @@ Editor::nudge_forward (bool next, bool force_playhead)
 						distance = next_distance;
 					}
 					if (max_framepos - distance > loc->start() + loc->length()) {
-						loc->set_start (loc->start() + distance);
+						loc->set_start (loc->start() + distance, false, true, get_grid_music_divisions(0));
 					} else {
-						loc->set_start (max_framepos - loc->length());
+						loc->set_start (max_framepos - loc->length(), false, true, get_grid_music_divisions(0));
 					}
 				} else {
 					distance = get_nudge_distance (loc->end(), next_distance);
@@ -429,9 +429,9 @@ Editor::nudge_forward (bool next, bool force_playhead)
 						distance = next_distance;
 					}
 					if (max_framepos - distance > loc->end()) {
-						loc->set_end (loc->end() + distance);
+						loc->set_end (loc->end() + distance, false, true, get_grid_music_divisions(0));
 					} else {
-						loc->set_end (max_framepos);
+						loc->set_end (max_framepos, false, true, get_grid_music_divisions(0));
 					}
 					if (loc->is_session_range()) {
 						_session->set_end_is_free (false);
@@ -511,9 +511,9 @@ Editor::nudge_backward (bool next, bool force_playhead)
 						distance = next_distance;
 					}
 					if (distance < loc->start()) {
-						loc->set_start (loc->start() - distance);
+						loc->set_start (loc->start() - distance, false, true, get_grid_music_divisions(0));
 					} else {
-						loc->set_start (0);
+						loc->set_start (0, false, true, get_grid_music_divisions(0));
 					}
 				} else {
 					distance = get_nudge_distance (loc->end(), next_distance);
@@ -523,9 +523,9 @@ Editor::nudge_backward (bool next, bool force_playhead)
 					}
 
 					if (distance < loc->end() - loc->length()) {
-						loc->set_end (loc->end() - distance);
+						loc->set_end (loc->end() - distance, false, true, get_grid_music_divisions(0));
 					} else {
-						loc->set_end (loc->length());
+						loc->set_end (loc->length(), false, true, get_grid_music_divisions(0));
 					}
 					if (loc->is_session_range()) {
 						_session->set_end_is_free (false);
@@ -1139,7 +1139,7 @@ Editor::selected_marker_to_region_boundary (bool with_selection, int32_t dir)
 		return;
 	}
 
-	loc->move_to (target);
+	loc->move_to (target, 0);
 }
 
 void
@@ -1216,7 +1216,7 @@ Editor::selected_marker_to_region_point (RegionPoint point, int32_t dir)
 
 	pos = track_frame_to_session_frame(pos, speed);
 
-	loc->move_to (pos);
+	loc->move_to (pos, 0);
 }
 
 void
@@ -1263,7 +1263,7 @@ Editor::selected_marker_to_selection_start ()
 		return;
 	}
 
-	loc->move_to (pos);
+	loc->move_to (pos, 0);
 }
 
 void
@@ -1298,7 +1298,7 @@ Editor::selected_marker_to_selection_end ()
 		return;
 	}
 
-	loc->move_to (pos);
+	loc->move_to (pos, 0);
 }
 
 void
@@ -1358,10 +1358,10 @@ Editor::cursor_align (bool playhead_to_edit)
 			Location* loc = find_location_from_marker (*i, ignored);
 
 			if (loc->is_mark()) {
-				loc->set_start (playhead_cursor->current_frame ());
+				loc->set_start (playhead_cursor->current_frame (), false, true, get_grid_music_divisions(0));
 			} else {
 				loc->set (playhead_cursor->current_frame (),
-					  playhead_cursor->current_frame () + loc->length());
+					  playhead_cursor->current_frame () + loc->length(), true, get_grid_music_divisions(0));
 			}
 		}
 	}
@@ -2159,7 +2159,7 @@ Editor::add_location_from_selection ()
 	framepos_t end = selection->time[clicked_selection].end;
 
 	_session->locations()->next_available_name(rangename,"selection");
-	Location *location = new Location (*_session, start, end, rangename, Location::IsRangeMarker);
+	Location *location = new Location (*_session, start, end, rangename, Location::IsRangeMarker, get_grid_music_divisions(0));
 
 	begin_reversible_command (_("add marker"));
 
@@ -2182,7 +2182,7 @@ Editor::add_location_mark (framepos_t where)
 	if (!choose_new_marker_name(markername)) {
 		return;
 	}
-	Location *location = new Location (*_session, where, where, markername, Location::IsMark);
+	Location *location = new Location (*_session, where, where, markername, Location::IsMark, get_grid_music_divisions (0));
 	begin_reversible_command (_("add marker"));
 
 	XMLNode &before = _session->locations()->get_state();
@@ -2294,7 +2294,7 @@ Editor::add_locations_from_region ()
 
 		boost::shared_ptr<Region> region = (*i)->region ();
 
-		Location *location = new Location (*_session, region->position(), region->last_frame(), region->name(), Location::IsRangeMarker);
+		Location *location = new Location (*_session, region->position(), region->last_frame(), region->name(), Location::IsRangeMarker, 0);
 
 		_session->locations()->add (location, true);
 		commit = true;
@@ -2335,7 +2335,7 @@ Editor::add_location_from_region ()
 	}
 
 	// single range spanning all selected
-	Location *location = new Location (*_session, selection->regions.start(), selection->regions.end_frame(), markername, Location::IsRangeMarker);
+	Location *location = new Location (*_session, selection->regions.start(), selection->regions.end_frame(), markername, Location::IsRangeMarker, 0);
 	_session->locations()->add (location, true);
 
 	begin_reversible_command (_("add marker"));
@@ -2390,7 +2390,7 @@ Editor::set_mark ()
 		return;
 	}
 
-	_session->locations()->add (new Location (*_session, pos, 0, markername, Location::IsMark), true);
+	_session->locations()->add (new Location (*_session, pos, 0, markername, Location::IsMark, 0), true);
 }
 
 void
@@ -6105,7 +6105,7 @@ Editor::set_edit_point ()
 		Location* loc = find_location_from_marker (selection->markers.front(), ignored);
 
 		if (loc) {
-			loc->move_to (where);
+			loc->move_to (where, get_grid_music_divisions(0));
 		}
 	}
 }
@@ -7356,9 +7356,9 @@ Editor::insert_time (
 				if ((*i)->start() >= pos) {
 					// move end first, in case we're moving by more than the length of the range
 					if (!(*i)->is_mark()) {
-						(*i)->set_end ((*i)->end() + frames);
+						(*i)->set_end ((*i)->end() + frames, false, true, get_grid_music_divisions(0));
 					}
-					(*i)->set_start ((*i)->start() + frames);
+					(*i)->set_start ((*i)->start() + frames, false, true, get_grid_music_divisions(0));
 					moved = true;
 				}
 
@@ -7500,20 +7500,20 @@ Editor::remove_time (framepos_t pos, framecnt_t frames, InsertTimeOption opt,
 						// if we're removing more time than the length of the range
 						if ((*i)->start() >= pos && (*i)->start() < pos+frames) {
 							// start is within cut
-							(*i)->set_start (pos);  // bring the start marker to the beginning of the cut
+							(*i)->set_start (pos, false, true, get_grid_music_divisions(0));  // bring the start marker to the beginning of the cut
 							moved = true;
 						} else if ((*i)->start() >= pos+frames) {
 							// start (and thus entire range) lies beyond end of cut
-							(*i)->set_start ((*i)->start() - frames); // slip the start marker back
+							(*i)->set_start ((*i)->start() - frames, false, true, get_grid_music_divisions(0)); // slip the start marker back
 							moved = true;
 						}
 						if ((*i)->end() >= pos && (*i)->end() < pos+frames) {
 							// end is inside cut
-							(*i)->set_end (pos);  // bring the end to the cut
+							(*i)->set_end (pos, false, true, get_grid_music_divisions(0));  // bring the end to the cut
 							moved = true;
 						} else if ((*i)->end() >= pos+frames) {
 							// end is beyond end of cut
-							(*i)->set_end ((*i)->end() - frames); // slip the end marker back
+							(*i)->set_end ((*i)->end() - frames, false, true, get_grid_music_divisions(0)); // slip the end marker back
 							moved = true;
 						}
 
@@ -7522,7 +7522,7 @@ Editor::remove_time (framepos_t pos, framecnt_t frames, InsertTimeOption opt,
 					loc_kill_list.push_back(*i);
 					moved = true;
 				} else if ((*i)->start() >= pos) {
-					(*i)->set_start ((*i)->start() -frames);
+					(*i)->set_start ((*i)->start() -frames, false, true, get_grid_music_divisions(0));
 					moved = true;
 				}
 
diff --git a/gtk2_ardour/location_ui.cc b/gtk2_ardour/location_ui.cc
index 76111a4..e39200d 100644
--- a/gtk2_ardour/location_ui.cc
+++ b/gtk2_ardour/location_ui.cc
@@ -416,10 +416,10 @@ LocationEditRow::to_playhead_button_pressed (LocationPart part)
 
 	switch (part) {
 		case LocStart:
-			location->set_start (_session->transport_frame ());
+			location->set_start (_session->transport_frame (), false, true, PublicEditor::instance().get_grid_music_divisions (0));
 			break;
 		case LocEnd:
-			location->set_end (_session->transport_frame ());
+			location->set_end (_session->transport_frame (), false, true, PublicEditor::instance().get_grid_music_divisions (0));
 			if (location->is_session_range()) {
 				_session->set_end_is_free (false);
 			}
@@ -463,16 +463,16 @@ LocationEditRow::clock_changed (LocationPart part)
 
 	switch (part) {
 		case LocStart:
-			location->set_start (start_clock.current_time());
+			location->set_start (start_clock.current_time(), false, true, PublicEditor::instance().get_grid_music_divisions (0));
 			break;
 		case LocEnd:
-			location->set_end (end_clock.current_time());
+			location->set_end (end_clock.current_time(), false, true, PublicEditor::instance().get_grid_music_divisions (0));
 			if (location->is_session_range()) {
 				_session->set_end_is_free (false);
 			}
 			break;
 		case LocLength:
-			location->set_end (location->start() + length_clock.current_duration());
+			location->set_end (location->start() + length_clock.current_duration(), false, true, PublicEditor::instance().get_grid_music_divisions (0));
 			if (location->is_session_range()) {
 				_session->set_end_is_free (false);
 			}
diff --git a/libs/ardour/ardour/location.h b/libs/ardour/ardour/location.h
index d31e9dc..5e26640 100644
--- a/libs/ardour/ardour/location.h
+++ b/libs/ardour/ardour/location.h
@@ -58,7 +58,7 @@ class LIBARDOUR_API Location : public SessionHandleRef, public PBD::StatefulDest
 	};
 
 	Location (Session &);
-	Location (Session &, framepos_t, framepos_t, const std::string &, Flags bits = Flags(0));
+	Location (Session &, framepos_t, framepos_t, const std::string &, Flags bits = Flags(0), const uint32_t sub_num = 0);
 	Location (const Location& other);
 	Location (Session &, const XMLNode&);
 	Location* operator= (const Location& other);
@@ -73,11 +73,11 @@ class LIBARDOUR_API Location : public SessionHandleRef, public PBD::StatefulDest
 	framepos_t end() const { return _end; }
 	framecnt_t length() const { return _end - _start; }
 
-	int set_start (framepos_t s, bool force = false, bool allow_bbt_recompute = true);
-	int set_end (framepos_t e, bool force = false, bool allow_bbt_recompute = true);
-	int set (framepos_t start, framepos_t end, bool allow_bbt_recompute = true);
+	int set_start (framepos_t s, bool force = false, bool allow_beat_recompute = true, const uint32_t sub_num = 0);
+	int set_end (framepos_t e, bool force = false, bool allow_beat_recompute = true, const uint32_t sub_num = 0);
+	int set (framepos_t start, framepos_t end, bool allow_beat_recompute = true, const uint32_t sub_num = 0);
 
-	int move_to (framepos_t pos);
+	int move_to (framepos_t pos, const uint32_t sub_num);
 
 	const std::string& name() const { return _name; }
 	void set_name (const std::string &str);
@@ -143,7 +143,7 @@ class LIBARDOUR_API Location : public SessionHandleRef, public PBD::StatefulDest
 
 	PositionLockStyle position_lock_style() const { return _position_lock_style; }
 	void set_position_lock_style (PositionLockStyle ps);
-	void recompute_frames_from_bbt ();
+	void recompute_frames_from_beat ();
 
 	static PBD::Signal0<void> scene_changed; /* for use by backend scene change management, class level */
         PBD::Signal0<void> SceneChangeChanged;   /* for use by objects interested in this object */
@@ -151,9 +151,9 @@ class LIBARDOUR_API Location : public SessionHandleRef, public PBD::StatefulDest
   private:
 	std::string        _name;
 	framepos_t         _start;
-	double             _bbt_start;
+	double             _start_beat;
 	framepos_t         _end;
-	double             _bbt_end;
+	double             _end_beat;
 	Flags              _flags;
 	bool               _locked;
 	PositionLockStyle  _position_lock_style;
@@ -161,7 +161,7 @@ class LIBARDOUR_API Location : public SessionHandleRef, public PBD::StatefulDest
 
 	void set_mark (bool yn);
 	bool set_flag_internal (bool yn, Flags flag);
-	void recompute_bbt_from_frames ();
+	void recompute_beat_from_frames (const uint32_t sub_num);
 };
 
 /** A collection of session locations including unique dedicated locations (loop, punch, etc) */
diff --git a/libs/ardour/location.cc b/libs/ardour/location.cc
index 0a48b43..d1fe653 100644
--- a/libs/ardour/location.cc
+++ b/libs/ardour/location.cc
@@ -54,7 +54,9 @@ PBD::Signal1<void,Location*> Location::changed;
 Location::Location (Session& s)
 	: SessionHandleRef (s)
 	, _start (0)
+	, _start_beat (0.0)
 	, _end (0)
+	, _end_beat (0.0)
 	, _flags (Flags (0))
 	, _locked (false)
 	, _position_lock_style (AudioTime)
@@ -64,7 +66,7 @@ Location::Location (Session& s)
 }
 
 /** Construct a new Location, giving it the position lock style determined by glue-new-markers-to-bars-and-beats */
-Location::Location (Session& s, framepos_t sample_start, framepos_t sample_end, const std::string &name, Flags bits)
+Location::Location (Session& s, framepos_t sample_start, framepos_t sample_end, const std::string &name, Flags bits, const uint32_t sub_num)
 	: SessionHandleRef (s)
 	, _name (name)
 	, _start (sample_start)
@@ -74,7 +76,7 @@ Location::Location (Session& s, framepos_t sample_start, framepos_t sample_end,
 	, _position_lock_style (s.config.get_glue_new_markers_to_bars_and_beats() ? MusicTime : AudioTime)
 
 {
-	recompute_bbt_from_frames ();
+	recompute_beat_from_frames (sub_num);
 
 	assert (_start >= 0);
 	assert (_end >= 0);
@@ -85,9 +87,9 @@ Location::Location (const Location& other)
 	, StatefulDestructible()
 	, _name (other._name)
 	, _start (other._start)
-	, _bbt_start (other._bbt_start)
+	, _start_beat (other._start_beat)
 	, _end (other._end)
-	, _bbt_end (other._bbt_end)
+	, _end_beat (other._end_beat)
 	, _flags (other._flags)
 	, _position_lock_style (other._position_lock_style)
 
@@ -125,8 +127,8 @@ Location::operator== (const Location& other)
 	if (_name != other._name ||
 	    _start != other._start ||
 	    _end != other._end ||
-	    _bbt_start != other._bbt_start ||
-	    _bbt_end != other._bbt_end ||
+	    _start_beat != other._start_beat ||
+	    _end_beat != other._end_beat ||
 	    _flags != other._flags ||
 	    _position_lock_style != other._position_lock_style) {
 		return false;
@@ -143,9 +145,9 @@ Location::operator= (const Location& other)
 
 	_name = other._name;
 	_start = other._start;
-	_bbt_start = other._bbt_start;
+	_start_beat = other._start_beat;
 	_end = other._end;
-	_bbt_end = other._bbt_end;
+	_end_beat = other._end_beat;
 	_flags = other._flags;
 	_position_lock_style = other._position_lock_style;
 
@@ -178,10 +180,10 @@ Location::set_name (const std::string& str)
 /** Set start position.
  *  @param s New start.
  *  @param force true to force setting, even if the given new start is after the current end.
- *  @param allow_bbt_recompute True to recompute BBT start time from the new given start time.
+ *  @param allow_beat_recompute True to recompute BEAT start time from the new given start time.
  */
 int
-Location::set_start (framepos_t s, bool force, bool allow_bbt_recompute)
+Location::set_start (framepos_t s, bool force, bool allow_beat_recompute, const uint32_t sub_num)
 {
 	if (s < 0) {
 		return -1;
@@ -201,8 +203,8 @@ Location::set_start (framepos_t s, bool force, bool allow_bbt_recompute)
 		if (_start != s) {
 			_start = s;
 			_end = s;
-			if (allow_bbt_recompute) {
-				recompute_bbt_from_frames ();
+			if (allow_beat_recompute) {
+				recompute_beat_from_frames (sub_num);
 			}
 
 			start_changed (this); /* EMIT SIGNAL */
@@ -235,8 +237,8 @@ Location::set_start (framepos_t s, bool force, bool allow_bbt_recompute)
 		framepos_t const old = _start;
 
 		_start = s;
-		if (allow_bbt_recompute) {
-			recompute_bbt_from_frames ();
+		if (allow_beat_recompute) {
+			recompute_beat_from_frames (sub_num);
 		}
 		start_changed (this); /* EMIT SIGNAL */
 		StartChanged (); /* EMIT SIGNAL */
@@ -255,10 +257,10 @@ Location::set_start (framepos_t s, bool force, bool allow_bbt_recompute)
 /** Set end position.
  *  @param s New end.
  *  @param force true to force setting, even if the given new end is before the current start.
- *  @param allow_bbt_recompute True to recompute BBT end time from the new given end time.
+ *  @param allow_beat_recompute True to recompute BEAT end time from the new given end time.
  */
 int
-Location::set_end (framepos_t e, bool force, bool allow_bbt_recompute)
+Location::set_end (framepos_t e, bool force, bool allow_beat_recompute, const uint32_t sub_num)
 {
 	if (e < 0) {
 		return -1;
@@ -278,8 +280,8 @@ Location::set_end (framepos_t e, bool force, bool allow_bbt_recompute)
 		if (_start != e) {
 			_start = e;
 			_end = e;
-			if (allow_bbt_recompute) {
-				recompute_bbt_from_frames ();
+			if (allow_beat_recompute) {
+				recompute_beat_from_frames (sub_num);
 			}
 			//start_changed (this); /* EMIT SIGNAL */
 			//StartChanged (); /* EMIT SIGNAL */
@@ -303,8 +305,8 @@ Location::set_end (framepos_t e, bool force, bool allow_bbt_recompute)
 		framepos_t const old = _end;
 
 		_end = e;
-		if (allow_bbt_recompute) {
-			recompute_bbt_from_frames ();
+		if (allow_beat_recompute) {
+			recompute_beat_from_frames (sub_num);
 		}
 
 		end_changed(this); /* EMIT SIGNAL */
@@ -321,7 +323,7 @@ Location::set_end (framepos_t e, bool force, bool allow_bbt_recompute)
 }
 
 int
-Location::set (framepos_t s, framepos_t e, bool allow_bbt_recompute)
+Location::set (framepos_t s, framepos_t e, bool allow_beat_recompute, const uint32_t sub_num)
 {
 	if (s < 0 || e < 0) {
 		return -1;
@@ -341,8 +343,8 @@ Location::set (framepos_t s, framepos_t e, bool allow_bbt_recompute)
 			_start = s;
 			_end = s;
 
-			if (allow_bbt_recompute) {
-				recompute_bbt_from_frames ();
+			if (allow_beat_recompute) {
+				recompute_beat_from_frames (sub_num);
 			}
 
 			start_change = true;
@@ -364,8 +366,8 @@ Location::set (framepos_t s, framepos_t e, bool allow_bbt_recompute)
 			framepos_t const old = _start;
 			_start = s;
 
-			if (allow_bbt_recompute) {
-				recompute_bbt_from_frames ();
+			if (allow_beat_recompute) {
+				recompute_beat_from_frames (sub_num);
 			}
 
 			start_change = true;
@@ -382,8 +384,8 @@ Location::set (framepos_t s, framepos_t e, bool allow_bbt_recompute)
 			framepos_t const old = _end;
 			_end = e;
 
-			if (allow_bbt_recompute) {
-				recompute_bbt_from_frames ();
+			if (allow_beat_recompute) {
+				recompute_beat_from_frames (sub_num);
 			}
 
 			end_change = true;
@@ -411,7 +413,7 @@ Location::set (framepos_t s, framepos_t e, bool allow_bbt_recompute)
 }
 
 int
-Location::move_to (framepos_t pos)
+Location::move_to (framepos_t pos, const uint32_t sub_num)
 {
 	if (pos < 0) {
 		return -1;
@@ -424,7 +426,7 @@ Location::move_to (framepos_t pos)
 	if (_start != pos) {
 		_start = pos;
 		_end = _start + length();
-		recompute_bbt_from_frames ();
+		recompute_beat_from_frames (sub_num);
 
 		changed (this); /* EMIT SIGNAL */
 		Changed (); /* EMIT SIGNAL */
@@ -580,6 +582,14 @@ Location::get_state ()
 	node->add_property ("start", buf);
 	snprintf (buf, sizeof (buf), "%" PRId64, end());
 	node->add_property ("end", buf);
+
+	if (position_lock_style() == MusicTime) {
+		snprintf (buf, sizeof (buf), "%lf", _start_beat);
+		node->add_property ("start-beat", buf);
+		snprintf (buf, sizeof (buf), "%lf", _end_beat);
+		node->add_property ("end-beat", buf);
+	}
+
 	node->add_property ("flags", enum_2_string (_flags));
 	node->add_property ("locked", (_locked ? "yes" : "no"));
 	node->add_property ("position-lock-style", enum_2_string (_position_lock_style));
@@ -637,6 +647,14 @@ Location::set_state (const XMLNode& node, int version)
 
 	sscanf (prop->value().c_str(), "%" PRId64, &_end);
 
+	if ((prop = node.property ("start-beat")) != 0) {
+		sscanf (prop->value().c_str(), "%lf", &_start_beat);
+	}
+
+	if ((prop = node.property ("end-beat")) != 0) {
+		sscanf (prop->value().c_str(), "%lf", &_end_beat);
+	}
+
 	if ((prop = node.property ("flags")) == 0) {
 		error << _("XML node for Location has no flags information") << endmsg;
 		return -1;
@@ -689,7 +707,9 @@ Location::set_state (const XMLNode& node, int version)
 		_scene_change = SceneChange::factory (*scene_child, version);
 	}
 
-	recompute_bbt_from_frames ();
+	if (position_lock_style() == AudioTime) {
+		recompute_beat_from_frames (0);
+	}
 
 	changed (this); /* EMIT SIGNAL */
 	Changed (); /* EMIT SIGNAL */
@@ -709,32 +729,32 @@ Location::set_position_lock_style (PositionLockStyle ps)
 
 	_position_lock_style = ps;
 
-	recompute_bbt_from_frames ();
+	if (ps == MusicTime) {
+		recompute_beat_from_frames (0);
+	}
 
 	position_lock_style_changed (this); /* EMIT SIGNAL */
 	PositionLockStyleChanged (); /* EMIT SIGNAL */
 }
 
 void
-Location::recompute_bbt_from_frames ()
+Location::recompute_beat_from_frames (const uint32_t sub_num)
 {
-	if (_position_lock_style != MusicTime) {
-		return;
-	}
+	/* always set the beat - even if we're in AudioTime */
 
-	_bbt_start = _session.tempo_map().beat_at_frame (_start);
-	_bbt_end = _session.tempo_map().beat_at_frame (_end);
+	_start_beat = _session.tempo_map().exact_beat_at_frame (_start, sub_num);
+	_end_beat = _session.tempo_map().exact_beat_at_frame (_end, sub_num);
 }
 
 void
-Location::recompute_frames_from_bbt ()
+Location::recompute_frames_from_beat ()
 {
 	if (_position_lock_style != MusicTime) {
 		return;
 	}
 
 	TempoMap& map (_session.tempo_map());
-	set (map.frame_at_beat (_bbt_start), map.frame_at_beat (_bbt_end), false);
+	set (map.frame_at_beat (_start_beat), map.frame_at_beat (_end_beat), false);
 }
 
 void
@@ -1056,7 +1076,7 @@ Locations::set_state (const XMLNode& node, int version)
 
 	Location* session_range_location = 0;
 	if (version < 3000) {
-		session_range_location = new Location (_session, 0, 0, _("session"), Location::IsSessionRange);
+		session_range_location = new Location (_session, 0, 0, _("session"), Location::IsSessionRange, 0);
 		new_locations.push_back (session_range_location);
 	}
 
diff --git a/libs/ardour/midi_scene_changer.cc b/libs/ardour/midi_scene_changer.cc
index 07eb549..6447006 100644
--- a/libs/ardour/midi_scene_changer.cc
+++ b/libs/ardour/midi_scene_changer.cc
@@ -314,7 +314,7 @@ MIDISceneChanger::program_change_input (MIDI::Parser& parser, MIDI::byte program
 			return;
 		}
 
-		loc = new Location (_session, time, time, new_name, Location::IsMark);
+		loc = new Location (_session, time, time, new_name, Location::IsMark, 0);
 		new_mark = true;
 	}
 
diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index 99efc1c..16ea5e7 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -1664,7 +1664,7 @@ Session::set_session_extents (framepos_t start, framepos_t end)
 	Location* existing;
 	if ((existing = _locations->session_range_location()) == 0) {
 		//if there is no existing session, we need to make a new session location  (should never happen)
-		existing = new Location (*this, 0, 0, _("session"), Location::IsSessionRange);
+		existing = new Location (*this, 0, 0, _("session"), Location::IsSessionRange, 0);
 	}
 
 	if (end <= start) {
@@ -5550,7 +5550,7 @@ void
 Session::update_locations_after_tempo_map_change (const Locations::LocationList& loc)
 {
 	for (Locations::LocationList::const_iterator i = loc.begin(); i != loc.end(); ++i) {
-		(*i)->recompute_frames_from_bbt ();
+		(*i)->recompute_frames_from_beat ();
 	}
 }
 
@@ -6300,7 +6300,7 @@ Session::current_end_frame () const
 void
 Session::set_session_range_location (framepos_t start, framepos_t end)
 {
-	_session_range_location = new Location (*this, start, end, _("session"), Location::IsSessionRange);
+	_session_range_location = new Location (*this, start, end, _("session"), Location::IsSessionRange, 0);
 	_locations->add (_session_range_location);
 }
 
diff --git a/libs/ardour/session_state.cc b/libs/ardour/session_state.cc
index 76cf2d3..54b2b68 100644
--- a/libs/ardour/session_state.cc
+++ b/libs/ardour/session_state.cc
@@ -623,7 +623,7 @@ Session::create (const string& session_template, BusProfile* bus_profile)
 
 		/* Initial loop location, from absolute zero, length 10 seconds  */
 
-		Location* loc = new Location (*this, 0, 10.0 * _engine.sample_rate(), _("Loop"),  Location::IsAutoLoop);
+		Location* loc = new Location (*this, 0, 10.0 * _engine.sample_rate(), _("Loop"),  Location::IsAutoLoop, 0);
 		_locations->add (loc, true);
 		set_auto_loop_location (loc);
 	}
@@ -1202,7 +1202,7 @@ Session::state (bool full_state)
 		Locations loc (*this);
 		// for a template, just create a new Locations, populate it
 		// with the default start and end, and get the state for that.
-		Location* range = new Location (*this, 0, 0, _("session"), Location::IsSessionRange);
+		Location* range = new Location (*this, 0, 0, _("session"), Location::IsSessionRange, 0);
 		range->set (max_framepos, 0);
 		loc.add (range);
 		XMLNode& locations_state = loc.get_state();