🎹 Midirect

Command-line tool that translates MIDI input as computer keyboard input in real time.

Building

You need to have Rust installed.

To build the app, run the following command from the root directory:

cargo build --release

This will generate a binary called midirect and store it in ./target/release/.

Tutorial

Prepare a configuration file which specifies which MIDI signals are mapped to which keyboard keys. You can use the existing ./rsc/alphabet.json or ./rsc/arrows.json configs for inspiration.

The content of the configuration file should be a JSON with two parameters: notes and controls.

Entries in notes represent note on/off signals. Each note has a code between 0 and 127. For reference, this is the layout of notes on a 88-key piano:

Entries in controls are for control change events, like pressing a sustain pedal (code 64). Any non-zero value emitted by a control is mapped to a key press, and zero is mapped to a key release.

In both notes and controls, MIDI signals are mapped to keys on a computer keyboard. All possible values include keys represented by characters, such as a and 1, as well as special keys from the following list:

alt        backspace   caps_lock  control
delete     down_arrow  end        escape
f1         f2          f3         f4
f5         f6          f7         f8
f9         f10         f11        f12
f13        f14         f15        f16
f17        f18         f19        f20
home       left_arrow  meta       option
page_down  page_up     return     right_arrow
shift      space       tab        up_arrow

Here is an example of mapping some piano keys to WASD and a sustain pedal to the space bar:

{
    "notes": {
        "48": "a",
        "50": "w",
        "52": "d",
        "53": "s"
    },
    "controls": {
        "64": "space"
    }
}

Once you have your configuration file ready, pass it to the app as a command line argument:

midirect config.json

Limitations

• A MIDI device must be connected before starting the app.
• Only a single MIDI device can be used at a time. If there are more MIDI devices, the app will pick one of them.

Compatibility

The app has been tested to work on Windows and macOS.