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Историческую версию Midi Host можно получить на Android
Программный синтезатор для клавиатур USB Midi
Plug in a USB Midi keyboard and play it. No settings, no distractions.
Supports legacy devices that the Marshmallow Midi API doesn't. All the heavy lifting is done by two great libraries, https://github.com/kshoji/USB-MIDI-Driver for communication with the device and https://github.com/billthefarmer/mididriver for sound generation.
Source code is available at https://github.com/bndeff/midihost