Pianola

Plays MIDI files and Virtual Piano sheets on the 61-key pianos in Roblox, and on virtualpiano.net.

A MIDI file is almost never playable as written: it spans more octaves than the game has, stacks more voices than it wants, and repeats notes faster than a key can register. Pianola arranges the song to fit the keyboard first, then plays it.

Pure Python, no third-party packages.

Features

• Picks the transposition that keeps the most of the song in range.
• Thins chords to what the keyboard can hold, keeping the melody and the root.
• Reads and writes Virtual Piano letter sheets, including pasted ones.
• Humanised by default: chords roll slightly and onsets scatter a few ms.
• Keystrokes land within about a millisecond of where they belong.
• Only types into the game window, so alt-tabbing away pauses it.

Windows

Download Pianola-windows-x64.exe from Releases and run it. Nothing to install.

• Run Roblox normally, not as administrator, or Windows drops the keystrokes.
• If SmartScreen warns about an unknown publisher, choose More info > Run anyway.

From source: Python 3.10 or newer, then python main.py.

Linux

Download pianola-linux-x86_64 from Releases, then chmod +x pianola-linux-x86_64 and run it. It works on any x86-64 distribution with glibc 2.43 or newer, on X11 and Wayland. The Roblox client on Linux is Sober, so the window box defaults to Sober.

One-time setup: Pianola types through /dev/uinput, a virtual keyboard, which your user needs write access to. On most distributions:

echo uinput | sudo tee /etc/modules-load.d/uinput.conf && sudo modprobe uinput
echo 'KERNEL=="uinput", GROUP="input", MODE="0660"' | sudo tee /etc/udev/rules.d/99-uinput.rules
sudo usermod -aG input $USER     # then log out and back in

From source: Python 3.10 or newer with Tk (python3-tk on Debian and Ubuntu, python3-tkinter on Fedora), then ./run.sh.

Hotkeys work while Sober has focus on KDE Plasma, GNOME 48+, Hyprland and any X11 desktop; KDE and GNOME ask once to approve them. Elsewhere, such as Sway, bind keys in your compositor's config to pianola --control ACTION:

bindsym F1 exec /path/to/pianola-linux-x86_64 --control play_pause

The actions are play_pause, stop, restart, panic, speed_down and speed_up. Being in the input group also makes hotkeys work everywhere.

The window guard (pause when Sober loses focus) works on KDE Plasma, Hyprland, Sway, niri and any X11 desktop. GNOME on Wayland gives no way to ask which window has focus, so there it is off: keep Sober in front while it plays.

Using it

Add songs (or drop them in a songs folder next to the app), pick one, click into the game, and press F1. The panel on the right tunes the arrangement and shows how much of the song survived it.

Key	Does
F1	Play and pause
F2	Stop
F3	Restart
F4	Release every held key
F5 / F6	Speed down / up by 5%

For virtualpiano.net, set the window box to Virtual Piano and click the on-screen piano once.

The same works from a terminal, where pianola is the downloaded file (or python main.py from source):

pianola song.mid --speed 1.1 --polyphony 5
pianola song.mid --analyze       # what the arranger would do, without playing
pianola song.mid --preview       # the keystrokes, with timestamps
pianola song.mid --to-sheet      # the song as Virtual Piano letters
pianola --log                    # write pianola.log, for bug reports

Letter sheets

The Letters button opens an editor for sheets pasted from virtualpiano.net or a forum post. It reports how many notes it found and which characters it ignored, and can also write the loaded MIDI out as letters. Timing is per character: a note or space is one slot, | is two, a blank line is a longer pause, [...] is a chord, and [ ... ] with spaces is a quick roll. Capitals are the black keys. songs/demo.txt shows every symbol.

Notes

• Keys are sent the way a physical keyboard sends them. Nothing reads or modifies the game.
• Sheets use US keyboard positions, so the layout assumes a US keyboard.
• Settings, the log and saved sheets live next to the app, or in %APPDATA%\Pianola or ~/.config/pianola if that folder isn't writable.

Licence

MIT, see LICENSE.