Thanks for this.

Not as advanced as your script (with dithering, etc), but I've always just used this script, which accepts the input video, and a custom dimension (optional):

#!/usr/bin/env bash

# https://superuser.com/a/1049820/19800

IN=$1

W=$(ffprobe -v quiet -print_format json -show_format -show_streams $IN | jq '.streams[0].width')

H=$(ffprobe -v quiet -print_format json -show_format -show_streams $IN | jq '.streams[0].height')

WH="${W}x${H}"

DIM=${2:-$WH}

echo "video resolution is $DIM"

PAL="$IN.palette.png"

if [[ -f "$PAL" ]]; then

        echo "skipping palette"

else

        ffmpeg -y -i "$IN" -vf palettegen "$PAL"

fi

ffmpeg -y -i "$IN" -i "$PAL" -filter_complex paletteuse -r 15 -s $DIM "$IN.gif"

# TODO https://cassidy.codes/blog/2017/04/25/ffmpeg-frames-to-gif-o...