Add Lua script to send 12TET tuning as MTS messages
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198
share/scripts/pitch_to_mts.lua
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198
share/scripts/pitch_to_mts.lua
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ardour {
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["type"] = "EditorAction",
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name = "MIDI Tuning",
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license = "MIT",
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author = "Ardour Team",
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description = [[generate MIDI tuning standard (MTS) messages for 12TET pitch changes]]
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}
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function factory () return function ()
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-- return table of all MIDI tracks, and all instrument plugins.
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--
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-- MidiTrack::write_immediate_event() injects MIDI events to the track's input
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-- PluginInsert::write_immediate_event() sends events directly to a plugin
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function midi_targets ()
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local rv = {}
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for r in Session:get_tracks():iter() do
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if not r:to_track():isnil() then
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local mtr = r:to_track():to_midi_track()
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if not mtr:isnil() then
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rv["Track: '" .. r:name() .. "'"] = mtr
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end
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end
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local i = 0;
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while true do
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local proc = r:nth_plugin (i)
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if proc:isnil () then break end
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local pi = proc:to_plugininsert ()
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if pi:is_instrument () then
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rv["Track: '" .. r:name() .. "' | Plugin: '" .. pi:name() .. "'"] = pi
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end
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i = i + 1
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end
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end
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return rv
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end
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function log2 (v)
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return math.log (v) / math.log (2)
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end
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-- calculate MIDI note-number and cent-offset for a given frequency
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--
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-- "The first byte of the frequency data word specifies the nearest equal-tempered
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-- semitone below the frequency. The next two bytes (14 bits) specify the fraction
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-- of 100 cents above the semitone at which the frequency lies."
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--
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-- 68 7F 7F = 439.9984 Hz
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-- 69 00 00 = 440.0000 Hz
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-- 69 00 01 = 440.0016 Hz
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--
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-- NB. 7F 7F 7F = no change (reserved)
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--
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function freq_to_mts (hz)
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local note = math.floor (12. * log2 (hz / 440) + 69.0)
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local freq = 440.0 * 2.0 ^ ((note - 69) / 12);
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local cent = 1200.0 * log2 (hz / freq)
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-- fixup rounding errors
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if cent >= 99.99 then
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note = note + 1
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cent = 0
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end
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if cent < 0 then
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cent = 0
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end
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return note, cent
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end
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local dialog_options = {
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{ type = "number", key = "tuning", title = "Tuning A4 (Hz)", min= 220.0, max = 880.0, default = 440.0, digits = 1, step = 0.1 },
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{ type = "dropdown", key = "tx", title = "MIDI SysEx Target", values = midi_targets () }
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}
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local rv = LuaDialog.Dialog ("MIDI Tuning", dialog_options):run ()
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dialog_options = nil -- drop references (track, plugins, shared ptr)
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collectgarbage () -- and release the references immediately
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if not rv then return end -- user cancelled
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-- prepare sending data
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local tx = rv["tx"] -- output port
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local ref_freq = rv["tuning"] -- ref freq (440.0)
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local parser = ARDOUR.RawMidiParser () -- construct a MIDI parser
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local checksum = 0
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-- helper function to send MIDI
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function tx_midi (syx, len, hdr)
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for b = 1, len do
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--dump:write (string.char(syx:byte (b)))
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-- calculate checksum, xor of all payload data
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-- (excluding the 0xf0, 0xf7, and the checksum field)
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if b >= hdr then
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checksum = checksum ~ syx:byte (b)
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end
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-- parse message to C/C++ uint8_t* array (Validate message correctness. This
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-- also returns C/C++ uint8_t* array for direct use with write_immediate_event.)
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if parser:process_byte (syx:byte (b)) then
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tx:write_immediate_event (Evoral.EventType.MIDI_EVENT, parser:buffer_size (), parser:midi_buffer ())
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-- Slow things down a bit to ensure that no messages as lost.
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-- Physical MIDI is sent at 31.25kBaud.
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-- Every message is sent as 10bit message on the wire,
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-- so every MIDI byte needs 320usec.
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ARDOUR.LuaAPI.usleep (400 * parser:buffer_size ())
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end
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end
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end
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-- show progress dialog
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local pdialog = LuaDialog.ProgressWindow ("MIDI Tuning", true)
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pdialog:progress (0, "Tuning");
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-- MIDI Tuning message
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-- http://technogems.blogspot.com/2018/07/using-midi-tuning-specification-mts.html
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-- http://www.ludovico.net/download/materiale_didattico/midi/08_midi_tuning.pdf
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local syx = string.char (
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0xf0, 0x7e, -- non-realtime sysex
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0x00, -- target-id
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0x08, 0x01, -- tuning, bulk dump reply
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0x00, -- tuning program number 0 to 127 in hexadecimal
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-- 16 chars name (zero padded)
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0x53, 0x63, 0x6C, 0x2D, 0x4D, 0x54, 0x53, 0x00, -- Scl-MTS
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
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)
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tx_midi (syx, 22, 1)
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-- iterate over MIDI notes
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for nn = 0, 127 do
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if pdialog:canceled () then break end
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-- calculate the frequency of the note
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local fq = ref_freq * 2 ^ ((nn - 69) / 12)
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-- and then convert this frequency to the MIDI note number (and cent offset)
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local base, cent = freq_to_mts (fq)
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-- MTS uses two MIDI bytes (2^14) for cents
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local cc = math.floor (163.83 * cent + 0.5) | 0
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local cent_msb = (cc >> 7) & 127
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local cent_lsb = cc & 127
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--[[
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print (string.format ("MIDI-Note %3d | Freq: %8.2f Hz = note: %3d + %6.3f ct (0x%02x 0x%02x 0x%02x)",
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nn, fq, base, cent, base, cent_msb, cent_lsb))
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--]]
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if (base < 0 or base > 127) then
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if base < 0 then
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base = 0
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else
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base = 127
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end
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cent_msb = 0
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cent_lsb = 0
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end
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local syx = string.char (
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base, -- semitone (MIDI note number to retune to, unit is 100 cents)
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cent_msb, -- MSB of fractional part (1/128 semitone = 100/128 cents = .78125 cent units)
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cent_lsb, -- LSB of fractional part (1/16384 semitone = 100/16384 cents = .0061 cent units)
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0xf7
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)
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tx_midi (syx, 3, 0)
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-- show progress
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pdialog:progress (nn / 127, string.format ("Note %d freq: %.2f (%d + %d)", nn, fq, base, cc))
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if pdialog:canceled () then break end
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::continue::
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end
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if not pdialog:canceled () then
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tx_midi (string.char ((checksum & 127), 0xf7), 2, 2)
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end
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-- hide modal progress dialog and destroy it
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pdialog:done ();
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tx = nil
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parser = nil
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collectgarbage () -- and release any references
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--dump:close ()
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end end
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-- simple icon
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function icon (params) return function (ctx, width, height, fg)
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ctx:set_source_rgba (ARDOUR.LuaAPI.color_to_rgba (fg))
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local txt = Cairo.PangoLayout (ctx, "ArdourMono ".. math.ceil(math.min (width, height) * .45) .. "px")
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txt:set_text ("MTS")
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local tw, th = txt:get_pixel_size ()
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ctx:move_to (.5 * (width - tw), .5 * (height - th))
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txt:show_in_cairo_context (ctx)
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end end
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