[FFmpeg-user] Zoom effect

[Paulo Barretto]

In a previous post, I have written:

I mean a filter with time-dependent width and height parameters, that would
> scale each frame and keep the output cropped and padded to constant
> dimensions. Just like rotate filter does.


 And Carl Eugen Hoyos replied:

All that said: I would expect that crop and scale
> can do exactly what was requested, please report
> if it does not work.


And I have tried to be more precise:

I mean a filter with time-dependent width and height parameters, that would
> scale the image in each frame to a different size, then crop or pad it to
> fit in the frame as necessary, exactly as the rotate filter does while the
> image in the frame is rotated.
>

I've read the filters documentation carefully, but I just can't figure out
how to do it.
Any help will be appreciated, thank you.

Paulo Barretto