Converts a video or image sequence to a animated gif with ffmpeg

ffmpeg_gif_converter.sh

#!/usr/bin/env bash
die () {
    echo >&2 "$@"
    exit 1
}

palette="./palette.png"
temp="./_temp.mp4"
path=false
file=false
ext=false
filename=false
width=-1
height=-1
dimensions=""
transpose=0
vf=""
fps=""
rate=0
orate=0
bg=""
bgopts=""
noop=0
declare -a args
declare -a vargs

while getopts ":hi:w:d:t:r:f:c:n" option; do
  case $option in
    h) echo "usage: $0 [-i] [-w] [-d] [-t] [-r] [-f] [-c] [-n] file ..."; exit ;;
    i) path="$OPTARG" ;;
    w) width=$OPTARG ;;
    d) height=$OPTARG ;;
    t) transpose="$OPTARG" ;;
	r) rate=$OPTARG ;;
	f) orate=$OPTARG;;
	c) bg=$OPTARG;;
	n) noop=1 ;;
    ?) echo "error: option -$OPTARG is not implemented"; exit ;;
  esac
done

[ "$path" ] || die "-i argument required"
[[ ! -f "$path" && ! "$path" =~ png|jpg|tif$ ]] && die "File not found"

file=$(basename -- "$path")
ext="${file##*.}"
filename="${file%.*}"

args+=("y")

if [ $rate -gt 0 ]; then
	args+=("r ${rate}")
fi

if [ ! -z "$bg" ]; then
    args+=("f lavfi")
    args+=("i color=${bg}")
    bgopts="[0][1]scale2ref[bg][gif];[bg]setsar=1[bg]"
	vargs+=("${bgopts};[bg][gif]overlay=shortest=1")
fi

args+=("i ${file}")

if [ $width -gt 0 ] || [ $height -gt 0 ]; then
	vargs+=("scale=${width}:${height}")
	dimensions=".${width}x${height}"
fi

if [ $transpose -ne 0 ]; then
	vargs+=("transpose=${transpose}")
fi

if [ $rate -gt 0 ]; then
	vargs+=("minterpolate='mi_mode=mci:mc_mode=aobmc:vsbmc=1:fps=30'")
elif [ $orate -gt 0 ]; then
	args+=("r ${orate}")
fi

if [ ${#vargs[@]} -gt 0 ]; then
	vf=$(IFS=, ; echo "${vargs[*]}")
	if [ -z "$bgopts" ]; then
		args+=("vf ${vf}")
	else
		vf+="[out]"
	fi
fi

args+=("c:v libx264")
args+=("crf 18")
args+=("preset veryslow")
args+=("an")

[ -e $palette ] && rm -f $palette
[ -e $temp ] && rm -f $temp

#ffmpeg -i "$file" "$vf" "-c:v libx264 -crf 18 -preset veryslow -an" "${filename}.gif"
if [ $noop -ne 0 ]; then
	if [ ! -z "$bgopts" ]; then
		echo "ffmpeg ${args[@]/#/-} -filter_complex \"${vf}\" -map \"[out]\" ${temp}"
	else
		echo "ffmpeg ${args[@]/#/-} ${temp}"
	fi
	echo "ffmpeg -y -i $temp -filter_complex \"[0:v] palettegen\" $palette"
	echo "ffmpeg -y -i $temp -i $palette -filter_complex \"[0:v][1:v] paletteuse\" ${filename}${dimensions}.gif"
else
	if [ ! -z "$bgopts" ]; then
		ffmpeg ${args[@]/#/-} -filter_complex "${vf}" -map "[out]" "${temp}"
	else
		ffmpeg ${args[@]/#/-} "${temp}"
	fi
	ffmpeg -y -i "$temp" -filter_complex "[0:v] palettegen" "$palette"
	ffmpeg -y -i "$temp" -i "$palette" -filter_complex "[0:v][1:v] paletteuse" "${filename}${dimensions}.gif"
	[ -e $palette ] && rm -f $palette
	[ -e $temp ] && rm -f $temp
fi