PiP Entrance Transition Duration
video-mark-transition-in-dur
Overrides the entrance transition duration for a picture-in-picture overlay. When set, this takes precedence over video-mark-transition-dur for the entrance only, while the exit continues to use -dur or its own video-mark-transition-out-dur override.
video-mark-transition-in-dur accepts a float in seconds from 0 to 60. Use video-mark-transition-in-dur[N] for a specific overlay layer.
Requires a transition type to be set via video-mark-transition or video-mark-transition-in.