Lua API for sends, sidechains and monitoring

share/scripts/s_ducks.lua

@@ -0,0 +1,52 @@
+ardour { ["type"] = "Snippet", name = "Ducks" }
+
+function factory (params) return function ()
+
+	local chan_out  = 2
+	if not Session:master_out():isnil() then
+		chan_out = Session:master_out():n_inputs ():n_audio ()
+	end
+
+	-- create two mono tracks
+	local tl = Session:new_audio_track (1, chan_out, nil, 2, "Ducks", ARDOUR.PresentationInfo.max_order, ARDOUR.TrackMode.Normal, true)
+	for t in tl:iter() do
+		t:set_strict_io (true)
+		-- switch tracks to monitor input
+		t:monitoring_control():set_value (ARDOUR.MonitorChoice.MonitorInput, PBD.GroupControlDisposition.NoGroup)
+	end
+
+	local src = tl:front ();
+	local dst = tl:back ();
+
+	assert (not src:isnil() and not dst:isnil())
+
+	-- add "ACE Compressor" to target track
+	local p = ARDOUR.LuaAPI.new_plugin (Session, "urn:ardour:a-comp", ARDOUR.PluginType.LV2, "")
+	assert (not p:isnil ())
+
+	dst:add_processor_by_index (p, 0, nil, true)
+	ARDOUR.LuaAPI.set_processor_param (p, 1, 300) -- 300ms release time
+	ARDOUR.LuaAPI.set_processor_param (p, 2, 4)   -- 4dB Knee
+	ARDOUR.LuaAPI.set_processor_param (p, 3, 7)   -- ratio 1:7
+	ARDOUR.LuaAPI.set_processor_param (p, 4, -25) -- threshold -20dBFS
+	ARDOUR.LuaAPI.set_processor_param (p, 9, 1)   -- enable sidechain
+
+	-- add Send to src track before the fader
+	local s = ARDOUR.LuaAPI.new_send (Session, src, src:amp ())
+	assert (not s:isnil ())
+
+	-- mark as sidechain send
+	local send = s:to_send()
+	send:set_remove_on_disconnect (true)
+
+	-- now connect send to plugin's sidechain input
+	local src_io = send:output()
+
+	-- ACE Compressor already has a sidechain, and sidechain
+	-- pin connected. Other plugins see "plugin channel-map dev"
+	-- snippet how to change plugin pinout.
+	local dst_io = p:to_plugininsert ():sidechain_input ()
+
+	src_io:nth(0):connect (dst_io:nth (0):name ())
+
+end end