Looking for a "MIDI transistor" (on/off midi gate, midi controlled)

[Brunetton]

Hi everyone. This is my first time here, and I hope I'll describe clearly my question.
I'm working on an open source project around Raspberry (that I'll post on the Raspberry forum later). But I'm a little stuck : I'll be using a midi controller (a piano keyboard) that will generate a piano sound. This piano will be always plugged on the Raspberry and sending midi notes.
But I do not want the Raspberry to make noise all the time. I plan to use a midi pad (an Akai MPD) to switch the Raspberry synth on/off, controlled by a MIDI signal from the pad.

In a nutshell : I'm looking for a jack midi program (ideally without gui) that have two midi inputs:
- the data input (where the notes will be sent through)
- the control midi input (to switch the data input on/off)

When sending an event (a determined note) on the control midi, the data flow is disconnected/connected : all data midi flow is disconnected, exactly is if I unplugged the midi cable.

This is like a logic gate (with a memory bit).

Does anyone know a (simple) way of doing it ?
I'm pretty sure it could be done with pure data, or another kind of "big machinery". But I'm afraid of performance, headless possibilities (lunched exclusively from command line), and the time I would need to learn it and make it works).
I'm a développer. I think I can program it quickly in Python, but I don't want to duplicate an existing protect.

Thanks! (and sorry for the long message)

[varpa]

I think you could do this with mididings which is a python package to control midi. In particular, mididings has the concept of "scenes" which are different midi setups which are toggled by midi control signals. So you just need to define 2 scenes one with the midi output connected, one with midi output disconnected.

[Brunetton]

Thanks very much @varpa !
Indeed, this seems to be exactly what I need. I've to look closer, because I seems to be designed to accept only one input device (just had a quick look to the doc). If I mix my two midi decides to one midi flow, I'll maybe loose the possibility of use program change signal to switch between programs in the controlled device (Hammond emulator).
Anyway, it's a good starting point. And if this doesn't feet my needs, I'll try using more low-level midi librairies. The need is very simple.

Thanks again!

[Frank Carvalho]

You might also have a look at MidiLayer which is designed to store and select midi patches with midi routing and a gui for live use.

Frank

[ventosus]

My moony plugin [1] can do such things. Just load it in jalv [2], with or without GUI and you have your desired JACK MIDi transistor. The attached preset [3] should get you going.

[1] https://open-music-kontrollers.ch/lv2/moony
[2] https://drobilla.net/software/jalv
[3] https://paste.open-music-kontrollers.ch ... lv2.tar.xz