I'd like to apply a dynamic drawbox before a drawtext, for example, with a fixed Y , X and H but with a dynamic W.
This is a trivial example:
/usr/bin/ffmpeg -y -loop 1 -t 5 -i img001.jpg -vf drawbox=x=0:y=0:w=t*300:h=100:firstname.lastname@example.org -y out.mp4
I expect to see a rectangle with the base width that increase with the time; it does not work, the box width is alwais fixed.
Is it possible to create a dynamic drawbox? if not, is there an alternative?