Stroboscope Layer
From Synfig Studio :: Documentation
The stroboscope layer shows the layers under it at regular intervals and then freezes them for the remainder of the interval interval. It is similar to decreasing the frame rate of an animation while preserving its length. It has a single parameter called "Frequency" (in times per second), which determines how often samples are taken. A frequency of exactly the frames per second of your project will not affect your animation, while smaller frequencies will appear as if you had lowered the frame rate to that amount.
