Add instance FX and possibility to change it (e.g. for FX pinning)

[helgoboss]

Designing truly reusable FX presets is difficult right now. Either you design them to be used with currently focused FX (to be used in "Auto-load preset" scenarios) or for a specific FX. Something flexible that adjusts to the context would be nice. #188 is related.

See #227 comment:

• And you would be able to reuse the same presets for your VSTs that will be auto-loaded with the "Auto-load preset" ReaLearn instance (instead of using groups for that).
  • Edit: Just realized, this particular improvement would need another puzzle piece to be possible. Presets must be designed for "Auto-load preset" at the moment by letting the mappings refer to <Focused> FX. Would be good to have an "FX selector" that is more reusable and relates to certain FX or the focused FX - depending on the context.
• Gives you overall better composability.

[helgoboss]

• If "Auto-load preset" is active, it should relate to whatever mode is currently active
  • "Depending on focused FX" translates to <Focused FX> selector
  • "Depending on last focused FX" would translate to <Last focused FX> selector (Introduce <Last focused> FX selector #229)
  • "Depending on currently active FX" would translate to <Currently active FX>selector (Add "Auto-load preset" option "Depending on currently active FX" #188)
• If "Auto-load preset" is not active, we would need a way to define the targeted FX on instance (or compartment) level. The easiest and probably most consistent way to do this implementation-wise would probably be to use the FX settings currently defined in the instance-wide default mapping (Add possibility to declare one mapping as default mapping #159). Or maybe not! "Exploiting" a default mapping for that doesn't sound right. It's rather a mapping from which settings are inherited. So Add instance track and possibility to change it (e.g. for track pinning) #161 would be better.

[helgoboss]

New idea: Provide new "Instance FX" selector and a possibility to set an FX for the whole instance in the same way you would set it for one mapping. That's all we need. The auto-load option would then be renamed to "Depending on instance FX".

[helgoboss]

Came up with an elegant concept to approach the "Instance FX" and "Instance track" idea:

• Each ReaLearn instance will get a number of track slots and FX slots.
• Each slot is either empty or holds a virtual track/FX.
  • "Virtual" means that it's not necessarily a particular track already but can use track/FX selectors such as <Selected>, <Dynamic> or "By name". This concept exists already.
• These slot are saved as part of the session (much like clip slots). They are not saved as part of the compartment and hence are also not part of compartment presets.
• Reading slots
  • <Dynamic> track/FX selectors will then get a new array variable slot which lets one access the index of the (already resolved) track in that slot. E.g. slot[5] would return the index of the track in Slot number 6 (or a particular negative number <
    -1 if that slot is empty).
  • For convenience, we could also add a new track/FX selector "Instance slot" (the thing this very issue was always about).
• Writing slots
  • There will be a new target simply called "Track" (respectively "FX").
  • Infact, I'm about to introduce these targets already now. It doesn't contain instance-slot related functionality yet, it's just a target that allows one to define a virtual track, nothing else, just for "feedback" purposes. It's good to have such a "neutral" target already now for textual feedback of track/FX-based properties (as an alternative to abusing e.g. the "Track: Set volume" target for that purpose).
  • However, with the advent of instance slots, these targets will receive an upgrade: The "control" direction will get a meaning as well. It will work as follows.
  • There will be a new target setting "Slot" which lets you select the instance slot that you want to set.
  • An incoming "on" control value will then simply set the instance track/FX to the defined virtual track, but the already resolved one! (meaning the instance track will be addressed "By ID")!
  • That's it! And I think that's all it needs. We can implement surprisingly many scenarios with this.
    • Pinning the currently selected track: By setting the virtual track to <Selected>.
    • Pinning a dynamic track derived from one of ReaLearn's internal parameters: By setting the virtual track to <Dynamic> with an expression of e.g p1 * 100.
    • Moving to the next track: By setting the virtual track to <Dynamic> with expression slot[0] + 1.
    • Skipping 8 tracks: By setting the virtual track to <Dynamic> with expression slot[0] + 8.
  • As an add-on we could provide a checkbox "Resolve before setting" that's ticked by default but which we can untick. Then it would be possible to set the instance track/FX to the virtual track without resolving it before. Not as useful as with resolving but who knows. We could easily add this later if needed.

This issue (#228) will be the issue for implementing the "Instance FX" feature. Issue #161 seems to be the most suitable issue for implementing the "Instance track" feature.

[vonglan]

"Instance track" seems useful to me.

I am not sure what is the use case for "instance FX" though.

When you have a preset with FX parameter targets, these will be specific to their FX. For example one mapping in a preset has the "Cutoff" parameter of the "Diva" VST as target. Let's say this is parameter number 124.
What good is it to make this abstract (slot[0]) in the preset, and making the connection to the concrete VST (Diva) only in a "slot" that is not part of the preset? That mapping is intended to control the cutoff. If slot[0] resolves to any VST other than Diva, parameter 124 will certainly not be the Cutoff parameter.