Further updates to Scala to MTS script:

* allow non-realtime bulk transfers
* debug mode, dump .syx file
* add some comments and references

share/scripts/scl_to_mts.lua

@@ -42,16 +42,35 @@ function factory () return function ()
 	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);
-		assert (freq > note)
 		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 = "file", key = "file", title = "Select .scl file" },
+		{ type = "checkbox", key = "bulk", default = false, title = "Bulk Transfer (not realtime)" },
 		{ type = "dropdown", key = "tx", title = "MIDI SysEx Target", values = midi_targets () }
 	}
 
@@ -115,29 +134,84 @@ function factory () return function ()
 	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    -- Reference note for which frequency is given
-	local ref_note = 69 -- A4
+	local ref_freq = 440.0 -- Frequency to tune the above note to
-	local ref_freq = 440.0
+	local ref_root = 60    -- root-note of the scale, note where the first entry of the scale is mapped to
+	local note_start = 0
+	local note_end = 127
+	-----------------------------------------------------------------------------
+
+	-- prepare sending data
+	local send_bulk = rv['bulk']
+	local tx = rv["tx"] -- output port
+	local parser = ARDOUR.RawMidiParser () -- construct a MIDI parser
+	local checksum = 0
+
+	if send_bulk then
+		note_start = 0
+		note_end = 127
+	end
+
+	--local dump = io.open ("/tmp/dump.syx", "wb")
+
+	-- 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 (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 ("Scala to MIDI Tuning", true)
+	pdialog:progress (0, "Tuning");
 
 	-- 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
 
+	-- inverse mapping, ref_note will have the specified frequency in the target scale,
+	-- while the scale itself will start at ref_root
 	local ref_base = ref_freq * 2 ^ ((freqtbl[delta_note + 1] + freqtbl[expected_len + 1] * delta_octv) / -1200)
 
-	-- prepare sending data
+	if send_bulk then
-	local tx = rv["tx"] -- output port
+		-- MIDI Tuning message
-	local parser = ARDOUR.RawMidiParser () -- construct a MIDI parser
+		-- 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)
+	end
 
-	-- show progress dialog
+	-- iterate over MIDI notes
-	local pdialog = LuaDialog.ProgressWindow ("Scala to MIDI Tuning", true)
+	for nn = note_start, note_end do
-	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
@@ -153,19 +227,42 @@ function factory () return function ()
 
 		-- 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 >> 7) & 127
-		local cent_msb = cc & 127
+		local cent_lsb = cc & 127
 
-		--print ("MIDI Note:", nn, "scale-note:", delta_note, "Octave:", delta_octv, "-> Freq:", fq, "= note:", base, "+", cent, "cents (", cc, ")")
+		--[[
+		print (string.format ("MIDI-Note %3d | Octv: %+d Note: %2d -> Freq: %8.2f Hz = note: %3d + %6.3f ct (0x%02x 0x%02x 0x%02x)",
+		                      nn, delta_octv, delta_note, fq, base, cent, base, cent_msb, cent_lsb))
+		--]]
 
 		if (base < 0 or base > 127) then
-			-- skip out of bounds MIDI notes
+			if send_bulk then
-			goto continue
+				if base < 0 then
+					base = 0
+				else
+					base = 127
+				end
+				cent_msb = 0
+				cent_lsb = 0
+			else
+				-- skip out of bounds MIDI notes
+				goto continue
+			end
 		end
 
-		-- MIDI Tuning message
+		if send_bulk then
-		-- http://www.microtonal-synthesis.com/MIDItuning.html
+			local syx = string.char (
-		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)
+		else
+			checksum = 0x07 -- really unused
+			-- 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
@@ -176,19 +273,8 @@ function factory () return function ()
 			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, 12, 0)
-		-- 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
@@ -198,9 +284,15 @@ function factory () return function ()
 		::continue::
 	end
 
+	if send_bulk and not pdialog:canceled () then
+		tx_midi (string.char ((checksum & 127), 0xf7), 2, 2)
+	end
+
 	-- hide modal progress dialog and destroy it
 	pdialog:done ();
 
+	--dump:close ()
+
 end end
 
 -- simple icon