encode-gif-2.sh

#!/bin/bash
set -euo pipefail
IFS=$'\n\t'

file="$1"
file_nut="${file%.*}.nut"
file_gif="${file%.*}.gif"
width=${2:-5000}

fixlum="[v]geq=lum='if(eq(alpha(X,Y),0),16,p(X,Y))':a='p(X,Y)':cb_expr='p(X,Y)'[o]"
cropvalue=$(ffmpeg -i "$file" -map v -vf "$fixlum;[o]cropdetect=mode=black:limit=0" -f null - 2>&1 | awk '/crop/ { print $NF }' | tail -1)
ffmpeg -i "$file" -map v -vf "$fixlum;[o]$cropvalue" -c rawvideo -y "$file_nut"
fps=$(ffprobe -show_streams "$file" 2>&1 | grep fps | awk '{split($0,a,"fps")}END{print a[1]}' | awk '{print $NF}')

gifski -o "$file_gif" --width $width --fps "$fps" --extra --quiet --quality 100 "$file_nut"

rm "$file_nut"

encode-gif.sh

#!/bin/bash
set -euo pipefail
IFS=$'\n\t'

file="$1"
file_nut="${file%.*}.nut"
file_gif="${file%.*}.gif"

cropvalue=$(ffmpeg -i "$file" -map v -vf "cropdetect=mode=black:limit=0" -f null - 2>&1 | awk '/crop/ { print $NF }' | tail -1)
ffmpeg -i "$file" -map v -vf "$cropvalue" -c rawvideo "$file_nut"
fps=$(ffprobe -show_streams "$file" 2>&1 | grep fps | awk '{split($0,a,"fps")}END{print a[1]}' | awk '{print $NF}')

gifski -o "$file_gif" --width 5000 --fps "$fps" --extra --quiet --quality 100 "$file_nut"

rm "$file_nut"