patchbox-modep-stuff

Python and TouchOSC stuff to support Patchbox and MODEP

My setup

• Raspberry PI3B+ running Patchbox with MODEP
• AKAI MPKmini mkII MIDI controller connected to the Pi
• Behringer UCA222 connected to the Pi for the audio IN/OUT
• a guitar connected to the audio in on the UCA222
• an old phone running TouchOSC for additional control over the MODEP pedalboard

The MODEP pedalboard consists of a software sythn AMSythn with a ton of preset sounds (MIDI ch 1), FluidPianos (again MIDI ch 1) and FluidDrums with a load of kits on MIDI ch 2. MIDI ch1 is assigned to the MPKmini keyboard whilst ch2 is assigned to the pads. In addition to these instruments are a DS1 distortion, Chorus/Flanger (both for the guitar input), SooperLooper and a few other bits.

One aspect of Patchbox-MODEP I was really interested in getting to work was to enable/disable AMSynth and the Piano instruments from the phone via TouchOSC and also to switch presets, again using the phone. Unfortunately MIDI PGM changes don't filter through to MODEP which I understand is the way the MOD DUO changes presets.

The solution I have which is initially based on https://github.com/whofferbert/midi-cmd-server, is to get TouchOSC to send CC messages over an unused MIDI channel to Patchbox where a Python script based on the midi_cmd_server intercepts the messages and then sends those messages over a websocket to MODEP. (Websocket part was based on https://stackoverflow.com/a/56424611)

To begin with I tried mimicing the MODEP web interface GET and POST requests but whilst the GET's worked (AMSynth preset selection), the preset selection for FluidDrums required a POST which relies on a some internal session to be setup. Fortunately the websocket solution was an option.

presets.txt This holds a list of AMSynth preset names each on a separate line that where the line number/array index maps to the TouchOSC button CC number.

midi_cmd_server.py

• connects to the amidithru service, opens a websocket to patchbox.local
• loads the AMSythn presets into an array
• listens for unused midi channels - 16 for AMSythn presets, 15 for FluidDrums presets (TouchOSC MIDI CH16 = Python msg.channel=15)
  • AMSythn sends a GET request in the form http://patchbox.local/effect/preset/load/graph/amsynth_1?uri=http://code.google.com/p/amsynth/amsynth#<preset-name>
  • FluidDrums sends param_set /graph/FluidPlug_FluidDrums/program <preset index> over a websocket to http://patchbox.local/websocket

For the script to work at startup, I edited the /etc/rc.local file and added the following line to the end.

/home/patch/midi_cmd_server.py &

TouchOSC

In TouchOSC I've simply used a grid of push-buttons to trigger a MIDI CC on Channel 16 (for AMSynth), Number (for the index to the preset) and Range of 0 - 127 (127 is sent on press) and I've only ticked 'Send on press'. Although you could set it up to any type of message I believe and as long as the script is looking for the same info, it should work.

Assign other pedal presets

For each pedal that you would like to be able to change the preset for you need to find out how the presets are set. In a browser, load your pedalboard on http://patchbox.local and open the Dev tools. In the 'Sources' tab (in Chrome) open the js/desktop.js?v=.... file and search for both pluginPresetLoad: and pluginParameterChange:. Place break-points in both these functions and then open your pedal settings and select a new preset to load. One of the break-points should be hit.

Make a note of the values being sent and use those values for either a GET (pluginPresetLoad:) or the websocket (pluginParameterChange:).