General method for smooth parameter changes – Page 2 – DSP and Plugin Development Forum

I’m using a one pole filter that is set to a fixed cutoff to transition from the current param value to the desired value over a few milliseconds. I think that will probably sound a good bit smoother than the average-the-difference approach that you have sketched out. I stop running the one pole filter once the two values have converged “close enough” (I’m using 0.001 as the “close enough” value).

I don’t think there is any way around recalculating the coefficients while the parameter is still changing.