Add Lua script to timestretch audio when tempo-map changes

gtk2_ardour/luasignal_syms.h

@@ -94,6 +94,9 @@ STATIC(SetSession, &LuaInstance::SetSession, 0)
 // Editor Selection Changed
 STATIC(SelectionChanged, &LuaInstance::SelectionChanged, 0)
 
+// Tempo Map Changed (old_map, new_map, from_undo)
+STATIC(TempoMapChanged, &Temporal::TempoMap::MapChanged, 3)
+
 // TODO per track/route signals,
 // TODO per plugin actions / controllables
 // TODO per region actions

libs/ardour/luabindings.cc

@@ -234,7 +234,7 @@ CLASSINFO(UIConfiguration);
 
 
 /* this needs to match gtk2_ardour/luasignal.h */
-CLASSKEYS(std::bitset<50ul>); // LuaSignal::LAST_SIGNAL
+CLASSKEYS(std::bitset<51ul>); // LuaSignal::LAST_SIGNAL
 
 CLASSKEYS(void);
 CLASSKEYS(float);

libs/temporal/tempo.cc

@@ -49,7 +49,8 @@ std::string Meter::xml_node_name = X_("Meter");
 
 SerializedRCUManager<TempoMap> TempoMap::_map_mgr (0);
 thread_local TempoMap::SharedPtr TempoMap::_tempo_map_p;
-PBD::Signal0<void> TempoMap::MapChanged;
+
+PBD::Signal3<void, TempoMap::SharedPtr, TempoMap::SharedPtr, bool> TempoMap::MapChanged;
 
 #ifndef NDEBUG
 #define TEMPO_MAP_ASSERT(expr) TempoMap::map_assert(expr, #expr, __FILE__, __LINE__)
@@ -4357,8 +4358,10 @@ TempoMap::write_copy()
 }
 
 int
-TempoMap::update (TempoMap::WritableSharedPtr m)
+TempoMap::update (TempoMap::WritableSharedPtr m, bool from_undo)
 {
+	SharedPtr old_map = read ();
+
 	if (!_map_mgr.update (m)) {
 		return -1;
 	}
@@ -4372,7 +4375,7 @@ TempoMap::update (TempoMap::WritableSharedPtr m)
 	}
 #endif
 
-	MapChanged (); /* EMIT SIGNAL */
+	MapChanged (old_map, read (), from_undo); /* EMIT SIGNAL */
 
 	return 0;
 }
@@ -5005,7 +5008,7 @@ TempoCommand::undo ()
 
 	TempoMap::WritableSharedPtr map (TempoMap::write_copy());
 	map->set_state (*_before, Stateful::current_state_version);
-	TempoMap::update (map);
+	TempoMap::update (map, true);
 }
 
 void

libs/temporal/temporal/tempo.h

@@ -791,7 +791,7 @@ class /*LIBTEMPORAL_API*/ TempoMap : public PBD::StatefulDestructible
 	/* API for typical tempo map changes */
 
 	LIBTEMPORAL_API static WritableSharedPtr write_copy();
-	LIBTEMPORAL_API static int  update (WritableSharedPtr m);
+	LIBTEMPORAL_API static int  update (WritableSharedPtr m, bool from_undo = false);
 	LIBTEMPORAL_API static void abort_update ();
 
 	/* not part of public API */
@@ -1010,7 +1010,7 @@ class /*LIBTEMPORAL_API*/ TempoMap : public PBD::StatefulDestructible
 
 	LIBTEMPORAL_API void dump (std::ostream&) const;
 
-	LIBTEMPORAL_API static PBD::Signal0<void> MapChanged;
+	LIBTEMPORAL_API static PBD::Signal3<void, SharedPtr, SharedPtr, bool> MapChanged;
 
 	LIBTEMPORAL_API XMLNode& get_state() const;
 

share/scripts/_tempo_map.lua

@@ -0,0 +1,121 @@
+ardour {
+	["type"]    = "EditorHook",
+	name        = "Tempo Map Audio",
+	author      = "Ardour Team",
+	description = "Time Stretch Audio when Tempo Map changed",
+}
+
+-- subscribe to signals
+-- http://manual.ardour.org/lua-scripting/class_reference/#LuaSignal.LuaSignal
+function signals ()
+	s = LuaSignal.Set()
+	s:add ({[LuaSignal.TempoMapChanged] = true})
+	return s
+end
+
+-- create callback functions
+function factory ()
+	-- callback function which invoked when signal is emitted
+	return function (signal, ref, ...)
+		-- 'TempoMapChanged' passes 3 aruguments: old and current tempo-map and a boolean from_undo
+		local tmo, tmn, from_undo = ...
+
+		if from_undo or not Session:collected_undo_commands () then
+			return
+		end
+
+		function find_track_for_region (region_id)
+			for route in Session:get_tracks ():iter () do
+				local track = route:to_track ()
+				local pl = track:playlist ()
+				if not pl:region_by_id (region_id):isnil () then
+					return track
+				end
+			end
+			return nil
+		end
+
+		local all_regions = ARDOUR.RegionFactory.regions()
+
+		-- copy region-map
+		local regions = {}
+		for _, r in all_regions:iter() do
+			local ar = r:to_audioregion ()
+			if ar:isnil () then goto next end
+			local track = find_track_for_region (r:to_stateful ():id ())
+			if not track then goto next end
+			regions[ar] = track
+			::next::
+		end
+
+		for ar, track in pairs (regions) do
+			print ("Processing Region: ", ar:name (), track:name ())
+
+			-- create Rubberband stretcher
+			local rb = ARDOUR.LuaAPI.Rubberband (ar, false)
+
+			-- the rubberband-filter also implements the readable API.
+			-- https://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:AudioReadable
+			-- This allows to read from the master-source of the given audio-region.
+			-- XXX but, it will not work for incremental tempo-map changes :(
+			local max_pos = rb:readable ():readable_length ()
+
+			-- the beat-map is a table holding audio-sample positions:
+			-- [from] = to
+			local beat_map = {}
+			beat_map[0] = 0
+
+			-- get position of region
+			local region_pos = ar:position()
+
+			local beats = tmo:quarters_at (region_pos)
+			local sample = 0
+			local beat = 0
+
+			if beats:get_ticks () > 0 then
+				beat = beats:get_beats () + 1
+			else
+				beat = beats:get_beats ()
+			end
+
+			local old_pos = tmo:sample_at_beats (beats)
+			local new_pos = tmn:sample_at_beats (beats)
+			print ("start", old_pos, new_pos)
+
+			while sample < max_pos do
+				local b = Temporal.Beats (beat, 0)
+				sample = tmo:sample_at_beats (b) - old_pos
+				local to = tmn:sample_at_beats (b) - new_pos
+				beat_map[sample] = to
+				print ("map ", sample, "to", to)
+				beat = beat + 1
+			end
+
+			local old_end_beats = tmo:quarters_at (Temporal.timepos_t (region_pos:samples () + max_pos))
+			local new_end =  tmn:sample_at_beats (old_end_beats)
+			local stretch = (new_end - new_pos) / max_pos
+			print ("stretch factor", stretch, new_pos, new_end, max_pos)
+
+			-- configure rubberband stretch tool
+			rb:set_strech_and_pitch (stretch, 1) -- no overall stretching, no pitch-shift
+			rb:set_mapping (beat_map) -- apply beat-map from/to
+
+			-- now stretch the region
+			function rb_progress (_, pos)
+			end
+
+			local nar = rb:process (rb_progress)
+
+			-- replace region
+			if not nar:isnil () then
+				print ("new audio region: ", nar:name (), nar:length ())
+				local playlist = track:playlist ()
+				playlist:to_stateful ():clear_changes () -- prepare undo
+				playlist:remove_region (ar)
+				playlist:add_region (nar, Temporal.timepos_t(new_pos), 1, false)
+				Session:add_stateful_diff_command (playlist:to_statefuldestructible ())
+			end
+		end
+
+	end
+end