I’m interested in using buttons on a MIDI controller unit to select patterns in the Hydrogen drum machine software. The process turned out to be fairly straightforward.
First, I defined a row of nine buttons on my MIDI controller (a KORG nanoKONTROL). Each button uses the same MIDI controller number (I used 102). The control value for each button is different, starting with value 0 for the left button and then incrementing by one for each subsequent button, with the ninth button being value 8. The On and Off values must be the same for each button.
I then launched Hydrogen and routed my controller to Hydrogen’s MIDI input. In Hydrogen, I selected Tools > Preferences and then selected the Midi System tab.
In the lower half of the Preferences dialog I set the Event drop-down to CC, the first Param. field to 102, and the Action drop-down to SELECT_NEXT_PATTERN_CC_ABSOLUT (that value is currently not documented). I left the second Param. field set to 0. I then clicked OK to close the Preferences dialog. (Note: I believe it’s possible to set the first two columns via MIDI Learn but I didn’t try that.)
Pushing the controller buttons then selected between the first nine patterns as expected. Since that went so well, I also defined buttons for stop/start and mute.
The screen shots show Midi driver set to the default value ALSA. I may change this to JACK later if it makes sense to do so.
The screen shots also show Input set to None, which apparently means “whatever is connected to the input” as opposed to a specific input device.