Is it possible in FFMPEG to change scale over time? Ok, so using the overlay filter, one can change the x/y location of a video over time by using the &quot;t&quot; variable. For example, overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0 can be used to start sliding an overlayed element from the top left to top right, after 2 seconds has passed.
What I want to do is to use a similar principle for scaling elements. I would like to be able to change the scale of a video over time by using an expression (like, scale=w=iw*t, or something along that line).
Is this possible?
when I run that expression through -filter_complex, I get

Error when evaluating the expression 'iw*t'.
Maybe the expression for out_w:'iw*t' or for out_h:'-1' is self-referencing.

I'm feeling like there's a fair chance I'm going to need to patch FFMpeg if I want to get this functionality, but I thought I would ask first, to see if anyone would be in the know about this kind of thing!
Does anyone know how such a task might be accomplished?
Thanks for the help!
From what I understand 't' is evaluated once. Have you read this: https://ffmpeg.org/ffmpeg-filters.html#zoompan ?

Ffmpeg Docs:

9.170.1 Examples


Zoom-in up to 1.5 and pan at same time to some spot near center of picture:


zoompan=z='min(zoom+0.0015,1.5)':d=700:x='if(gte(zoom,1.5),x,x+1/a)':y='if(gte(zoom,1.5),y,y+1)':s=640x360


Zoom-in up to 1.5 and pan always at center of picture:


zoompan=z='min(zoom+0.0015,1.5)':d=700:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'


Same as above but without pausing:


zoompan=z='min(max(zoom,pzoom)+0.0015,1.5)':d=1:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'