Using crop, and hstack (or vstack)

Watch on youtube.com

doc

https://ffmpeg.org/ffmpeg-filters.html#crop, https://ffmpeg.org/ffmpeg-filters.html#hstack, https://ffmpeg.org/ffmpeg-filters.html#vstack, https://ffmpeg.org/ffmpeg-filters.html#drawbox

For example, imagine that you want to show the effect of the ffmpeg filter. At this time, there is a way to show the original image divided horizontally or vertically. It is very easy.

Horizontally

00:00:00

#! /bin/sh
pref="`basename $0 .sh`"
inf="Pexels_flowers.mp4"  # 1920x1080

#
ffmpeg -y -i "${inf}" -filter_complex "
[0:v]crop='iw/2:ih:0:0'[vo];
[0:v]crop='iw/2:ih:iw/2:0',hue=b=-2[vf];
[vo][vf]hstack[v]
" -map '[v]' -an \
  "${pref}.mp4"

Vertically

00:00:30

#! /bin/sh
pref="`basename $0 .sh`"
inf="Pexels_flowers.mp4"  # 1920x1080

#
ffmpeg -y -i "${inf}" -filter_complex "
[0:v]crop='iw:ih/2:0:0'[vo];
[0:v]crop='iw:ih/2:0:ih/2',swapuv[vf];
[vo][vf]vstack[v]
" -map '[v]' -an \
  "${pref}.mp4"

with drawbox

00:01:00

Depending on your needs, the boundary of two images may be difficult to distinguish. In such a case, you can use “drawbox”.

#! /bin/sh
pref="`basename $0 .sh`"
inf="Pexels_flowers.mp4"  # 1920x1080

#
ffmpeg -y -i "${inf}" -filter_complex "
[0:v]crop='iw/2:ih:0:0',drawbox=c=yellow[vo];
[0:v]crop='iw/2:ih:iw/2:0',avgblur=30,drawbox=c=yellow[vf];
[vo][vf]hstack[v]
" -map '[v]' -an \
  "${pref}.mp4"