I am trying to overlay a logo on a video, and reveal it gradually. I used the following command:
$ ffmpeg -i uploads/vid1.mp4 -loop 1 -r 25 -pix_fmt yuva420p -i logo.png -filter_complex "[1]drawbox=x=0:color=black:w=in_w*if(lt(t\,2)\,(2-t)/2\,0.01):thickness=fill:replace=1[L1];[0][L1]overlay=eof_action=endall" vidout.mp4
$ ffmpeg -version
ffmpeg version 4.1.3-static https://johnvansickle.com/ffmpeg/ Copyright (c) 2000-2019 the FFmpeg developers
...
As far as I understand, drawbox should have timeline support:
$ ffmpeg -filters|grep drawbox
....
T.. drawbox V->V Draw a colored box on the input video.
Instead of revealing the logo gradually, it displays the full logo immediately. How can I reveal the logo gradually?
