@Christoph-Hart Well, apparently fastMode is set to true by default, so the smoothingTime has no effect.
Setting fastMode to false actually makes the upward ramp smother but still not usable (probably due to the yellow circle transition part) Also, how to make the downward ramp smooth too (red circle)? Should I compute my own S-shape interpolation and not use a smoothed_gainer? Would using samples instead of buffer in the processBlock callback change anything?Untitled.png