This is a stylistic effect; it attempts to apply rounded edges to videos (crop-based)
The default value is 50-pixels. You can pass other integer values to customize the amount of curving; the higher the number, the more aggressive the curve.
This works great for solo-video streams where the video fits the window fully, but may not round the edges of videos that do not fit their container area. To compensate for this, using the
&cover command as well can force the video to fit the window, and hence, have the rounded edges applied correctly.
An example of an aggressive rounded effect is with the following parameters: