drawbox enhancement

[Jozef Chutka]

I would like to propose the enhancement for drawbox:

• add time related constants n (frame) and time (btw t is reserved for thickness)
• add eval=frame so drawbox is able to recalculate based on changed n, time or dynamic input size ih, iw
• add enable option so there is a way to restrict its availability/rendering

With these in place, one could draw in-video progress bars, but I believe these extensions are generic enough for solid use in different cases as well.

Currently there is an option to use [color+overlay](​https://stackoverflow.com/questions/62989964/showing-in-video-visual-progress-bar-with-ffmpeg), however imagine drawing border progress bar (see attachment) which is 4x2 filters already, and I can imagine drawbox performs faster then either of color or overlay alone.

Thanks for all the hard work.

[Michael Koch]

It does already have the "enable" option. The problem is only that you don't see it in the documentation. You can use this command to check which filters have timeline support:
ffmpeg -filters

Michael

[Elon Musk]

Fixed in 13a153d801011c4ec82b90af1351e10dcf1754e1

Demo:

mpv av://lavfi:gradients=d=100,format=rgb0 -vf "lavfi=[sendcmd=0.0-100.0 \[expr\] drawbox@1 w (TI+0.001)*W,drawbox@1=x=0:y=ih-t:w=0:h=5:c=red:replace=1,sendcmd=0.0-100.0 \[expr\] drawbox@2 y (1-TI)*H,drawbox@2=x=0:y=h:w=5:h=0:c=red:replace=1]"

[Jozef Chutka]

This is great, thanks for an express fix.

Potentially related, I am openning ​https://trac.ffmpeg.org/ticket/9686#ticket

I would also like to understand the syntax from Elon's demo, completely alien to me -vf "lavfi=[...]" ? Whats the benefit of having filter graph wrapped inside lavfi=[...]?