Reactive Music & Audio
This system was designed to work in tandem with quantization as both are related but still functionally different.
The reactive music feature was written by me in C++, and it allowed a DSP chain to be listened to by Unreal at the head or tail. (Output and input respectively to allow the system to listen to either the source or the final output the user would actually hear).
This node would simply return a float between 0-1 that represented output. The generic nature of this system means that you could tie this float to virtually anything. VFX, scale, position, material attributes etc. and it would react in real time to the music. In the basic example below, it's tied to just the Z scale of the cubes.
A benefit to the way I designed it was while it was utilized primarily for music, it can be used to listen to anything in the game to make it reactive. The system doesn't listen for any particular sounds, rather it returns the output of a defined bus. So any audio in the game could be made reactive if that was so desired.
A necessary part of the design was to make interfacing with these systems easy to understand and use. Setting up the reactive Blueprint was as simple as selecting what FMOD Bus to listen to, and then attaching the resulting output to whatever the user wanted.