Since Diatonic Transposer was renamed to Key Filter in 4.1, it would be appropriate if it would also allow punching in custom scales, and have diatonic modes as default ones for backwards compatibility. For custom scales it just needs to borrow pitch class buttons from Pitch Quantizer module in Grid and have it as a ‘Custom mode’ tab. Also would be really great to include pitch expression quantization option, so even pitchbends/slides are affected and constrained.
In future, if snapshot system is implemented, old Diatonic modes could be hidden away as default device snapshots
Until then we could save scales as Key Filter device presets.
What problem(s) would this feature resolve?
A big workflow improvement for managing/switching your own scales within one device. Ability to constrain pitchbends to scale is currently practically impossible to do (outside of Grid).
How does this feature fit in Bitwig as a product?
Pretty well since it borrows already existing functions and UI elements that are scattered through different devices. Bitwig has put already emphasis on features that allow users to depart from the traditional Western scales and experiment with pitch.
Is there already an alternative way to achieve this on Bitwig?
Making quite ugly and CPU-heavy presets like Bitwig Preset: Lazy Play mode.
The downsides of using these presets are a clunky UX, prominent CPU impact for what should be a very light device, and it can’t do polyphonic pitch expression quantization.
Could it be implemented using Bitwig components or APIs, without Bitwig team’s support?
As stated above, not exactly in intended shape or performance, and still lacking in UI and features.
Could it be provided by a VST or something else reasonably integrated with Bitwig?
We haven’t seen any that would check all the boxes. Also, the downside of using a VST is that it would convert high-resolution Bitwig note data into low resolution MIDI, and then it would also have to be MPE compatible output, which doesn’t seem to be implemented anywhere.
Are there other products that offer this feature?
Probably it can be done in Ableton via M4L.
@x.iso made a similar patch in Usine, which also allows using it as reference or receiving scale to chain it up with other instances of this patch.