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livetrax/share/scripts/scl_to_mts.lua

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ardour {
["type"] = "EditorAction",
name = "Scala to MIDI Tuning",
license = "MIT",
author = "Ardour Team",
description = [[Read scala (.scl) tuning from a file, generate MIDI tuning standard (MTS) messages and send them to a MIDI port]]
}
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
function freq_to_mts (hz)
local note = math.floor (12. * log2 (hz / 440) + 69.0)
local freq = 440.0 * 2.0 ^ ((note - 69) / 12);
assert (freq > note)
local cent = 1200.0 * log2 (hz / freq)
return note, cent
end
local dialog_options = {
{ type = "file", key = "file", title = "Select .scl file" },
{ type = "dropdown", key = "tx", title = "MIDI SysEx Target", values = midi_targets () }
}
local rv = LuaDialog.Dialog ("Select Scala File and MIDI Taget", 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
-- read the scl file
local freqtbl = {}
local ln = 0
local expected_len = 0
local f = io.open (rv["file"], "r")
if not f then
LuaDialog.Message ("Scala to MTS", "File Not Found", LuaDialog.MessageType.Error, LuaDialog.ButtonType.Close):run ()
return
end
-- parse scala file and convert all intervals to cents
-- http://www.huygens-fokker.org/scala/scl_format.html
freqtbl[1] = 0.0 -- implicit
for line in f:lines () do
line = string.gsub (line, "%s", "") -- remove all whitespace
if line:sub(0,1) == '!' then goto nextline end -- comment
ln = ln + 1
if ln < 2 then goto nextline end -- name
if ln < 3 then
expected_len = tonumber (line) -- number of notes on scale
if expected_len < 1 or expected_len > 256 then break end -- invalid file
goto nextline
end
local cents
if string.find (line, ".", 1, true) then
cents = tonumber (line)
else
local n, d = string.match(line, "(%d+)/(%d+)")
if n then
cents = 1200 * log2 (n / d)
else
local n = tonumber (line)
cents = 1200 * log2 (n)
end
end
--print ("SCL", ln - 2, cents)
freqtbl[ln - 1] = cents
::nextline::
end
f:close ()
-- We need at least one interval.
-- While legal in scl, single note scales are not useful here.
if expected_len < 1 or expected_len + 2 ~= ln then
LuaDialog.Message ("Scala to MTS", "Invalid or unusable scale file.", LuaDialog.MessageType.Error, LuaDialog.ButtonType.Close):run ()
return
end
assert (expected_len + 2 == ln)
assert (expected_len > 0)
-- TODO consider reading a .kbm file or make these configurable in the dialog
-- http://www.huygens-fokker.org/scala/help.htm#mappings
local ref_root = 60 -- middle C
local ref_note = 69 -- A4
local ref_freq = 440.0
-- calculate frequency at ref_root
local delta = ref_note - ref_root
local delta_octv = math.floor (delta / expected_len)
local delta_note = delta % expected_len
local ref_base = ref_freq * 2 ^ ((freqtbl[delta_note + 1] + freqtbl[expected_len + 1] * delta_octv) / -1200)
-- prepare sending data
local tx = rv["tx"] -- output port
local parser = ARDOUR.RawMidiParser () -- construct a MIDI parser
-- show progress dialog
local pdialog = LuaDialog.ProgressWindow ("Scala to MIDI Tuning", true)
pdialog:progress (0, "Tuning");
-- iterate over all MIDI notes
for nn = 0, 127 do
if pdialog:canceled () then break end
-- calculate the note relative to kbm's ref_root
delta = nn - ref_root
delta_octv = math.floor (delta / expected_len)
delta_note = delta % expected_len
-- calculate the frequency of the note according to the scl
local fq = ref_base * 2 ^ ((freqtbl[delta_note + 1] + freqtbl[expected_len + 1] * delta_octv) / 1200)
-- 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_lsb = (cc >> 7) & 127
local cent_msb = cc & 127
--print ("MIDI Note:", nn, "scale-note:", delta_note, "Octave:", delta_octv, "-> Freq:", fq, "= note:", base, "+", cent, "cents (", cc, ")")
if (base < 0 or base > 127) then
-- skip out of bounds MIDI notes
goto continue
end
-- MIDI Tuning message
-- http://www.microtonal-synthesis.com/MIDItuning.html
local syx = string.char (
0xf0, 0x7f, -- realtime sysex
0x7f, -- target-id
0x08, 0x02, -- tuning, note change request
0x00, -- tuning program number 0 to 127 in hexadecimal
0x01, -- number of notes to be changed
nn, -- note number to be changed
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
)
-- 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.)
for b = 1, 12 do
if parser:process_byte (syx:byte (b)) then
tx:write_immediate_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
-- 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
-- hide modal progress dialog and destroy it
pdialog:done ();
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 ("SCL\nMTS")
local tw, th = txt:get_pixel_size ()
ctx:move_to (.5 * (width - tw), .5 * (height - th))
txt:show_in_cairo_context (ctx)
end end