Animating panning of 360 video using ffmpeg

Question

I would like to animate panning within a 360 video. That is, base the panning on time or frame number.

The following does a fixed pan ffmpeg -i "FileName" -vf v360=e:e:yaw=90:pitch=0:roll=0 "OutputFile" Unfortunately my knowledge of expressions in ffmpeg is almost 0, how do I change the yaw=90 to a function of time?