[FFmpeg-user] Problem with changing options at runtime with a command

[Michael Koch]

Am 03.07.2021 um 15:57 schrieb Alex Christoffer Rasmussen:
> thank you for the quick answer
>
> when trying this out I notice 3 things
>
> *1: the original size is kept*
> if the starting crop is *crop=h=100 *then using *c crop -1 h 150 *dose
> noting and the other way,

What you are trying to do might be impossible. You can send a command to 
the crop filter and change the output height, but the next filter might 
not accept that you dynamically change the size.
In some cases it works, for example "scale" immediately followed by 
"overlay". But in many other cases it doesn't work.

Michael