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Add Lua script to send 12TET tuning as MTS messages

This commit is contained in:
Robin Gareus 2021-02-12 16:01:43 +01:00
parent 89f91324d4
commit c5cca7680e
Signed by: rgareus
GPG Key ID: A090BCE02CF57F04

View File

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