Add annotation to GIFs with Imagemagick

annotate_gif.sh

#!/bin/sh

## manullay find frame in which caption should change
# mkdir frames_s01
# convert -coalesce source_01.gif frames_s01/out%05d.gif

mkdir tmp/

convert source_01.gif[0-50] tmp/tm01.gif
convert source_01.gif[51-100] tmp/tm02.gif

## documentation:
# http://www.imagemagick.org/Usage/annotating/
# http://www.imagemagick.org/Usage/anim_mods/#label

convert tmp/tm01.gif -coalesce \
        -gravity South -background white -splice 0x80 \
	-pointsize 32 \
        -annotate +0+40 '1. Multiline annotation' \
	-annotate +0+4 'appears here' \
        -layers Optimize tmp/tm01_annotated.gif

convert tmp/tm02.gif -coalesce \
        -gravity South -background white -splice 0x80 \
	-pointsize 36 \
        -annotate +0+18 '2. Single line here' \
        -layers Optimize tmp/tm02_annotated.gif


convert tmp/tm01_annotated.gif tmp/tm02_annotated.gif out.gif 
rm -rf tmp/