I haven’t yet used these but to configure you use webconf and navigate to Hardware->Wiring and enable “Advanced view”. If there are more than four switches configured, i.e. more than the four used on the encoders then there will be a section at the bottom titled, " Customizable Switches". This allows you to assign a function and parameters to each switch.
Having enabled this on my custom Zynthian just now I will have to solder some more buttons on to try it out…
Ah! In that case, no! The on-screen touch buttons were added as a quick enhancement for touchscreen only users, without encoder buttons so they simply mimic the touch encoders for now. Indeed it may make sense to configure these similar to the S1-S4 buttons. I guess this should be a feature request in issue tracking.
My tests are ongoing. I gig with a Korg 88 key workstation and a Nord 2x. Depending on space, I sometimes scale down to a 61 key controller with controller knobs and a few buttons assigned to program changes. In that case I run bs16i on my iPhone with a soundfont containing presets of piano, ep, clav, strings, brass, organ and lead that were sampled from my keyboards.
bs16i load soundfonts, responds to program changes, and supports GM controllers like filter cutoff, attack, release and chorus. It serves as an emergency backup, even though the audio quality is limited by the phone.
The switch request would allow me to do the same thing with a zynthian and any controller. My next test is with a Studiologic Sl880 controller that has limited front panel controls.
Linuxsampler on the Zynthian is the leader right now. Different sfzs can be called using program changes within a snapshot. The soundfont also works in Fluidsynth, but it requires alot of external editing and gain staging. Plus both engines lack controller support of parameters like filter cutoff and attack/release.
Please let me know if I have to make an issue tracking request.
Testing Zynthian to make my life less complicated,
Sam in NJ USA