SlowNoise<SPEED>
Returns a value between 0 and 32768 which changes randomly up and down over time. All pixels gets the same value. SPEED controls how quickly the value changes.
BrownNoiseF
https://github.com/profezzorn/ProffieOS/blob/6f8add544c627172ad2dd698c90e5e55078a420a/functions/brown_noise.h#L28