How to draw a box at the bottom of the video using FFmpeg?

Question

From the docs it's pretty straight forward how to create a box at the top with the y=0

drawbox=x=10:y=0:w=200:h=60:color=red@0.5

But how can I draw the box at the bottom?

Answer 1

You can reference both the height of the input (ih), and the height of the box (h). This allows more flexible placement; especially if your inputs vary in size.

To place the box directly on the bottom:

y=ih-h

To place the box 10 pixels above the bottom:

y=ih-h-10

See the FFmpeg drawbox video filter documentation for more options.