pi-midi-velocity-curve-changer

Description

This little python script will adjust the midi velocity curve from your keyboard to fix velocity issues if your keyboard does not handle the velocity well. Setup is like: Keyboard -> USB -> Rasbperry PI -> USB to Midi -> Midi In from your Synthesizer / MPC. Bug reports and suggestions for improvement are welcome. Please feel free to create pull requests here as well.

I had the following problem: I have a Native Instruments KOMPLETE KONTROL A49 keyboard and an MPC ONE. Although I think the keyboard is pretty good, it has a terrible velocity curve which unfortunately is not standalone customizable. I still have an old Raspberry Pi lying around and a USB-to-Midi adapter. With this Python script it was possible to put the Raspberry Pi between the keyboard and the MPC one to function as a “velocity adjuster”.

Optional: If you possess an additional midi controller like the Akai LPD8 Controller, you can utilize the program change MIDI message to manipulate the MIDI channel from your input keyboard device. This functionality allows the script to provide the capability to change the MIDI channel for your keyboard.

In the experimental folder are a few attempts to display the Velocity Curve on a MiniDisplay using PyGame. Currently this does not work well and is not necessary for the functionality.

You also need:

1. USB Keyboard (e.g.: KOMPLETE KONTROL A49)
2. A USB to Midi device (e.g.: CME U2MIDI Pro)
3. Raspberry Pi
4. (Optional) Midi Controller which supports program change midi messages (e.g.: Akai LPD8 Controller)

Basic Hardware Setup

Velocity Curve example

This results in value curves ranging between the three shown below (blue is -100, gray is 0 and red is 100):

Setup

1. Copy Files to your raspberry pi

Copy the midi.py and start-midi.sh file on your raspberry pi for example: /home/youruser/

2. Install the python libs:

pip install mido

pip install math

3. Identify Your MIDI Devices

Run the script to list available input and output ports. The script will print the names of all connected MIDI devices Simply use a part of the name to store this in the parameters as a search word.

4. Configuration

Open the start-midi.sh configure your settings:

Minimum Startup Commmands, only adjust velocity:

python3 midi.py --inputmididevicename "KOMPLETE" --outputmididevicename "U2MIDI" --midi_exponent -60

Minimum Startup only adjust velocity Script with debug mode

python3 midi.py --inputmididevicename "KOMPLETE" --outputmididevicename "U2MIDI" --midi_exponent -60 --debugmode 1

Full Configuration with velocity adjustment and midi channel control over second midi device program change events:

python3 midi.py --inputmididevicename "KOMPLETE" --inputmididevicenamemidichannel "LPD8" --outputmididevicename "U2MIDI" --midi_exponent -60

Here's a breakdown of each argument:

--inputmididevicename "KOMPLETE": Specifies the name of your MIDI Keyboard device as "KOMPLETE".
--outputmididevicename "U2MIDI": Specifies the name of the output MIDI adapter as "U2MIDI".
--midi_exponent -100 to +100
--inputmididevicenamechannelcontrol "LPD8": Specifies the name of the MIDI device to control with the program_change event the midi channel for inputmididevicename. (optional)
--debugmode "0": Specifies whether to enable additional debug output. Set to `1` to enable debug output, or `0` to disable it. (optional)

6. Set up the autostart for your midi script:

chmod 775 /home/youruser/start-midi.sh

crontab -e

# Input this in the crontab file:
@reboot bash /home/youruser/start-midi.sh

Thanks

Special thanks to @georg-zeiser! Source: https://github.com/georg-zeiser/midi-velocity-mapper