Explore musical tunings and create synthesizer tuning files for microtonal scales.

Overview

tune-cli is the command line tool for the microtonal tune library.

Installation

bash cargo install -f tune-cli

Usage

Introduction

You want to know how to tune your piano in 7-EDO? Just use the following command:

rust tune scale 62 equal 1:7:2 | tune dump

This instructs tune to print the frequencies and approximate notes of a 7-EDO scale starting at D4 (MIDI number 62).

```bash ----------Source Scale----------- ‖ ----Pitch----- ‖ --------Target Scale-------- ..

62 | IDX 0 | 1/1 +0¢ +0o ‖ 293.665 Hz ‖ 62 | D 4 | +0.000¢ 63 | IDX 1 | 11/10 +6¢ +0o ‖ 324.232 Hz ‖ 64 | E 4 | -28.571¢ 64 | IDX 2 | 11/9 -5¢ +0o ‖ 357.981 Hz ‖ 65 | F 4 | +42.857¢ 65 | IDX 3 | 4/3 +16¢ +0o ‖ 395.243 Hz ‖ 67 | G 4 | +14.286¢ 66 | IDX 4 | 3/2 -16¢ +0o ‖ 436.384 Hz ‖ 69 | A 4 | -14.286¢ 67 | IDX 5 | 18/11 +5¢ +0o ‖ 481.807 Hz ‖ 71 | B 4 | -42.857¢ 68 | IDX 6 | 20/11 -6¢ +0o ‖ 531.958 Hz ‖ 72 | C 5 | +28.571¢ 69 | IDX 7 | 2/1 -0¢ +0o ‖ 587.330 Hz ‖ 74 | D 5 | -0.000¢ .. ```

The table tells us that the first step of the 7-EDO scale (IDX 0) has a frequency of 293.655 Hz and matches D4 exactly. This is obvious since we chose D4 be the origin of the 7-EDO scale. IDX 1, the second step of the scale, is reported to be close to E4 but with an offset of -28.571¢.

You can now detune every note D on your piano by -28.571¢. On an electric piano with octave-based tuning support, this is a very easy task. It is also possible to retune a real piano using a tuning device.

Retune every note of the 7-EDO scale according to the table and the 7-EDO scale will be playable on the white keys!

MIDI Tuning Standard

The most generic way to tune your piano is the MIDI Tuning Standard. You can print out a Single Note Tuning Message (i.e. every note is retuned individually) with the following command:

bash tune scale 62 equal 1:7:2 | tune mts

The output will be:

bash 0xf0 0x7f 0x7f 0x08 .. 0x7f 0x12 0x25 0xf7 Number of retuned notes: 75 Number of out-of-range notes: 52

Some notes are reported to be out of range. This is because 7-EDO has a stronger per-step increase in frequency than 12-EDO, s.t. some frequencies become unmappable.

Limitations

The current implemention doesn't allow for gaps in a scale. This means the MTS version of the 7-EDO scale has to be played on all piano keys with black and white keys mixed. Hopefully, this is going to be fixed soon.

Scala File Format

An alternative tuning method is to upload scl and kbm files to your synthesizer. See the scl and kbm sections below for more information.

Approximate Ratios

The dump command provides information about the qualities of a scale. Let's have a look at the 19-EDO scale:

bash tune scale 62 equal 1:19:2 | tune dump

The output reveals that some rational intervals are well approximated. Especially the just minor third (6/5) which is approximated by less than than 1¢ and, therefore, displayed as 0¢:

bash ----------Source Scale----------- ‖ ----Pitch----- ‖ --------Target Scale-------- .. 67 | IDX 5 | 6/5 +0¢ +0o ‖ 352.428 Hz ‖ 65 | F 4 | +15.789¢ ..

The ratio approximation algorithm is not very advanced yet and does not use prime numbers.

Compare Scales

Imagine, you want to know how well quarter-comma meantone is represented in 31-EDO. All you need to do is create the quarter-comma meantone scale (tune scale) and tune diff it against the 31-EDO scale.

In quarter-comma meantone the fifths are tempered in such a way that four of them match up a frequency ratio of 5. This makes the genator of the scale equal to 5^(1/4) or 1:4:5 in tune expression notation. To obtain a full scale, let's say ionian/major, you need to walk 5 generators/fifths upwards and one downwards which translates to the scale expression rank2 1:4:5 5 1.

The scale expression for the 31-EDO scale is equal 1:31:2, s.t. the full scale comparison command becomes:

bash tune scale 62 rank2 1:4:5 5 1 | tune diff 62 equal 1:31:2

This will print:

```bash ----------Source Scale----------- ‖ ----Pitch----- ‖ --------Target Scale-------- ..

62 | IDX 0 | 1/1 +0¢ +0o ‖ 293.665 Hz ‖ 62 | IDX 0 | +0.000¢ 63 | IDX 1 | 9/8 -11¢ +0o ‖ 328.327 Hz ‖ 67 | IDX 5 | -0.392¢ 64 | IDX 2 | 5/4 +0¢ +0o ‖ 367.081 Hz ‖ 72 | IDX 10 | -0.783¢ 65 | IDX 3 | 4/3 +5¢ +0o ‖ 392.771 Hz ‖ 75 | IDX 13 | +0.196¢ 66 | IDX 4 | 3/2 -5¢ +0o ‖ 439.131 Hz ‖ 80 | IDX 18 | -0.196¢ 67 | IDX 5 | 5/3 +5¢ +0o ‖ 490.964 Hz ‖ 85 | IDX 23 | -0.587¢ 68 | IDX 6 | 11/6 +34¢ +0o ‖ 548.914 Hz ‖ 90 | IDX 28 | -0.979¢ 69 | IDX 7 | 1/1 +0¢ +1o ‖ 587.330 Hz ‖ 93 | IDX 31 | +0.000¢ .. ```

You can see that 31-EDO is a very good approximation of quarter-comma meantone with a maximum deviation of -0.979¢. You can also see that the steps sizes of the corresponding 31-EDO scale are 5, 5, 3, 5, 5, 5 and 3.

Create scl Files / Scale Expressions

Create kbm Files / Key Map Expressions

JSON Output

tune uses JSON as an exchange format between pipelined calls. You can use tune's output as an input for an external application (or the other way around) or inspect/modify the output manually before further processing.

Example Usage

bash tune scale 62 equal 1:7:2 Output (shortened):

json { "Scale": { "root_key_midi_number": 62, "root_pitch_in_hz": 293.6647679174076, "items": [ { "key_midi_number": 62, "pitch_in_hz": 293.6647679174076 }, { "key_midi_number": 63, "pitch_in_hz": 324.23219079306347 }, ] } }

Expressions

Ordered by precedence:

  1. <num>:<denom>:<int> evaluates to int^(num/denom)
  2. <num>/<denom> evaluates to num/denom
  3. <cents>c evaluates to 2^(cents/1200)
  4. {<expr>} evaluates to expr