elaborate documented raw audio/midi buffer lua example

scripts/rawmidi.lua

@@ -3,37 +3,95 @@ ardour {
 	name        = "Midi Passthru",
 	category    = "Example",
 	license     = "MIT",
-	author      = "Robin Gareus",
-	email       = "robin@gareus.org",
-	site        = "http://gareus.org",
-	description = [[An Example Midi Passthrough Plugin using raw buffers.]]
+	author      = "Ardour Team",
+	description = [[An Example Audio/MIDI Passthrough Plugin using Buffer Pointers]]
 }
 
+-- return possible audio i/o configurations
 function dsp_ioconfig ()
-	return { { audio_in = 0, audio_out = 0}, }
+	-- -1, -1 = any number of channels as long as input and output count matches
+	return { { audio_in = -1, audio_out = -1}, }
 end
 
+-- require 1 MIDI in, 1 MIDI out.
 function dsp_has_midi_input () return true end
 function dsp_has_midi_output () return true end
 
+
 -- "dsp_runmap" uses Ardour's internal processor API, eqivalent to
 -- 'connect_and_run()". There is no overhead (mapping, translating buffers).
 -- The lua implementation is responsible to map all the buffers directly.
 function dsp_runmap (bufs, in_map, out_map, n_samples, offset)
-	-- see http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:ChanMapping
-	local ib = in_map:get (ARDOUR.DataType ("midi"), 0); -- get index of the 1st mapped midi input buffer
-	local ob = in_map:get (ARDOUR.DataType ("midi"), 0); -- get index of the 1st mapped midi output buffer
-	assert (ib ~= ARDOUR.ChanMapping.Invalid);
-	assert (ib == ob);  -- require inplace, buffers are identical
 
-	-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:MidiBuffer
-	local mb = bufs:get_midi (ib) -- get the mapped buffer
-	events = mb:table () -- copy event list into a lua table
+	-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:ChanMapping
 
-	-- iterate over all midi events
-	for _,e in pairs (events) do
-		-- e is-a http://manual.ardour.org/lua-scripting/class_reference/#Evoral:MidiEvent
+	local ib = in_map:get (ARDOUR.DataType ("midi"), 0) -- get index of the 1st mapped midi input buffer
+	assert (ib ~= ARDOUR.ChanMapping.Invalid)
 
-		--print (e:channel())
+	if ib ~= ARDOUR.ChanMapping.Invalid then
+		-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:MidiBuffer
+		local mb = bufs:get_midi (ib) -- get the mapped buffer
+		events = mb:table () -- copy event list into a lua table
+
+		-- iterate over all MIDI events
+		for _, e in pairs (events) do
+			-- e is-a http://manual.ardour.org/lua-scripting/class_reference/#Evoral:MidiEvent
+
+			-- do something with the event
+			--print (e:channel ())
+		end
+	end
+
+	----
+	-- The following code is needed with "dsp_runmap" to work for arbitrary pin connections
+	-- this passes though all audio/midi data unprocessed.
+
+	local audio_ins = in_map:count (): n_audio () -- number of audio input buffers
+	local audio_outs = out_map:count (): n_audio () -- number of audio output buffers
+	assert (audio_outs, audio_ins) -- ioconfig [-1, -1]: must match
+
+	-- copy audio data if any
+	for c = 1, audio_ins do
+		local ib = in_map:get (ARDOUR.DataType ("audio"), c - 1) -- get index of mapped input buffer
+		local ob = out_map:get (ARDOUR.DataType ("audio"), c - 1) -- get index of mapped output buffer
+		if ib ~= ARDOUR.ChanMapping.Invalid and ob ~= ARDOUR.ChanMapping.Invalid and ib ~= ob then
+			-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:DSP
+			-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:AudioBuffer
+			ARDOUR.DSP.copy_vector (bufs:get_audio (ob):data (offset), bufs:get_audio (ib):data (offset), n_samples)
+		end
+	end
+	-- Clear unconnected output buffers.
+	-- In case we're processing in-place some buffers may be identical,
+	-- so this must be done *after* copying relvant data from that port.
+	for c = 1, audio_outs do
+		local ib = in_map:get (ARDOUR.DataType ("audio"), c - 1)
+		local ob = out_map:get (ARDOUR.DataType ("audio"), c - 1)
+		if ib == ARDOUR.ChanMapping.Invalid and ob ~= ARDOUR.ChanMapping.Invalid then
+			bufs:get_audio (ob):silence (n_samples, offset)
+		end
+	end
+
+	-- copy midi data
+	local midi_ins = in_map:count (): n_midi () -- number of midi input buffers
+	local midi_outs = out_map:count (): n_midi () -- number of midi input buffers
+
+	-- with dsp_has_midi_in/out() the following will always be true
+	assert (midi_ins == 1)
+	assert (midi_outs == 1)
+
+	for c = 1, midi_ins do
+		local ib = in_map:get (ARDOUR.DataType ("midi"), c - 1)
+		local ob = out_map:get (ARDOUR.DataType ("midi"), c - 1)
+		if ib ~= ARDOUR.ChanMapping.Invalid and ob ~= ARDOUR.ChanMapping.Invalid and ib ~= ob then
+			bufs:get_midi (ob):copy (bufs:get_midi (ib))
+		end
+	end
+	-- silence unused midi outputs
+	for c = 1, midi_outs do
+		local ib = in_map:get (ARDOUR.DataType ("midi"), c - 1)
+		local ob = out_map:get (ARDOUR.DataType ("midi"), c - 1)
+		if ib == ARDOUR.ChanMapping.Invalid and ob ~= ARDOUR.ChanMapping.Invalid then
+			bufs:get_midi (ob):silence (n_samples, offset)
+		end
 	end
 end