MIDI Node Mapping Plugin -- Ardour Lua DSP Script

midi_translation_table.lua

ardour {
	["type"]    = "dsp",
	name        = "MIDI Remap Notes",
	category    = "Utility", -- "Utility"
	license     = "MIT",
	author      = "Alby Musaelian",
	description = [[Map arbitrary MIDI notes to others. Affects Note On/Off and polyphonic key pressure.]]
}

N_REMAPINGS = 10

function dsp_ioconfig ()
	return { { midi_in = 1, midi_out = 1, audio_in = 0, audio_out = 0}, }
end

function dsp_params ()
  local note_names = {"C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B"}

  local map_scalepoints = {}
  for note=0,127 do
    local octave = -5 + math.floor(note / 12)
    local name = note_names[(note % 12) + 1]
    map_scalepoints[string.format("%03d (%s%d)", note, name, octave)] = note
  end

  local map_params = {}

  i = 1
  for mapnum = 1,N_REMAPINGS do
    -- From and to
    for _,name in pairs({"| #" .. mapnum .. "  Map note", "|__   to"}) do
      map_params[i] = {
        ["type"] = "input",
	      name = name,
	      min = 0,
	      max = 127,
	      default = 0,
	      integer = true,
				enum = true,
				scalepoints = map_scalepoints
	    }
	    i = i + 1
		end
  end

  return map_params
end

function dsp_init(samplerate)
  -- Init translation table, reserve memory
  translation_table = {}
  for i = 0,127 do
    translation_table[i] = i
  end
end


function dsp_run (_, _, n_samples)
	assert (type(midiin) == "table")
	assert (type(midiout) == "table")
	local cnt = 1;

	function tx_midi (time, data)
		midiout[cnt] = {}
		midiout[cnt]["time"] = time;
		midiout[cnt]["data"] = data;
		cnt = cnt + 1;
	end

  -- Restore translation table
  for i = 0,127 do
    translation_table[i] = i
  end
  -- Update it
  local ctrl = CtrlPorts:array()
  for i=1,N_REMAPINGS*2,2 do
    translation_table[ctrl[i]] = ctrl[i + 1]
  end

	-- for each incoming midi event
	for _,b in pairs (midiin) do
		local t = b["time"] -- t = [ 1 .. n_samples ]
		local d = b["data"] -- get midi-event
		local event_type
		if #d == 0 then event_type = -1 else event_type = d[1] >> 4 end

		if (#d == 3) and (event_type == 9 or event_type == 8 or event_type == 10) then -- note on, note off, poly. afterpressure
      -- Do the mapping - 2 is note byte for these types
      d[2] = translation_table[d[2]]
			tx_midi (t, d)
		else
      tx_midi (t, d)
		end
	end
end