prototype script to fan out instrument outputs to busses

scripts/fan_out_instrument.lua

@@ -0,0 +1,62 @@
+ardour { ["type"] = "EditorAction", name = "Fan Out Instrument",
+	license     = "MIT",
+	author      = "Ardour Team",
+	description = [[Create Busses for every Instrument Output on selected Tracks]]
+}
+
+function factory () return function ()
+
+	local outputs = 2
+	local mst = Session:master_out();
+	if not mst:isnil() then
+		outputs = mst:n_inputs():n_audio()
+	end
+	mst = nil -- drop reference
+
+	local sel = Editor:get_selection ()
+	for r in sel.tracks:routelist ():iter () do
+		local proc = r:the_instrument ():to_insert()
+		if proc:isnil () then
+			print ("Track", r:name(), "does not have an instrumenr plugin")
+			goto next
+		end
+		local plugin = proc:plugin(0);
+
+		if (r:n_outputs ():n_audio() ~= proc:output_streams():n_audio()) then
+			print ("Instrument outputs", proc:output_streams():n_audio(), "do not match track outputs", r:n_outputs ():n_audio())
+			goto next
+		end
+
+		-- collect port-group information, count target bus width
+		local targets = {}
+		for i = 1, proc:output_streams():n_audio() do
+			local pd = plugin:describe_io_port (ARDOUR.DataType("Audio"), false, i - 1)
+			local nn = proc:name() .. " " .. pd.group_name; -- TODO use track-name prefix?
+			targets[nn] = targets[nn] or 0
+			targets[nn] = targets[nn] + 1
+		end
+
+		-- create busses
+		for t,c in pairs (targets) do
+			local rt = Session:route_by_name (t)
+			if rt:isnil () then
+				Session:new_audio_route (c, outputs, nil, 1, t, ARDOUR.PresentationInfo.Flag.AudioBus, ARDOUR.PresentationInfo.max_order)
+			end
+		end
+
+		r:output():disconnect_all(nil)
+		r:panner_shell():set_bypassed(true)
+
+		for i = 1, proc:output_streams():n_audio() do
+			local pd = plugin:describe_io_port (ARDOUR.DataType("Audio"), false, i - 1)
+			local nn = proc:name() .. " " .. pd.group_name;
+			local rt = Session:route_by_name (nn)
+
+			local op =  r:output():audio (i - 1)
+			local ip = rt:input():audio (pd.group_channel)
+			op:connect (ip:name())
+		end
+
+		::next::
+	end
+end end