Captioning all frames of a gif

Question

I have a simple bash script to caption still images (jpg, png...) but it completely fails when given an animated gif. The error is convert: unable to write pixel cache '/tmp/magick-[random chars]': No space left on device @ error/cache.c/WritePixelCachePixels/5854. There are many questions similar to mine, however they use specific coordinates to determine where the text should be placed (at least, I think). My script creates a dynamically sized caption area for the text to be written to. The image is appended to the bottom of the caption area (or the caption area is prepended to the top of the image, however you want to think about it.)

#!/bin/bash
input=$1
caption=$2
output=$3
wd=`convert $input -format "%w" info:`
convert  \( -size ${wd}x -background white -gravity north -fill black -font FuturaBT-ExtraBlackCondensed -pointsize $(($wd/17)) \
caption:"$caption" \) \
$input \
-append $output 

Answer 1

You can also do this in Imagemagick.

convert anim.gif -coalesce \
-gravity north -background white \
-splice 0x18 -font Arial -pointsize 12 -annotate +0+0 'THIS IS A TEST OF CAPTIONING TEXT' \
-layers Optimize anim3.gif