mkgif.sh

#!/bin/bash

# https://engineering.giphy.com/how-to-make-gifs-with-ffmpeg/


INFILE="$1"
OUT="${INFILE%.*}.gif"


if [[ ! -f $INFILE ]]; then
echo "'$INFILE' is not a File."
exit 1
fi


INTER=$(mktemp --suffix=".mkv")
PALETTE=$(mktemp --suffix=".png")


function cleanup() {
rm "$PALETTE" "$INTER"
}

function panic() {
echo "Operation cancelling." >&2
cleanup
exit 1
}


[[ -z "$HEIGHT" ]] && HEIGHT=270
[[ -z "$WIDTH" ]] && WIDTH=-2

[[ -z "$FILTER" ]] && FILTER="scale=w=$WIDTH:h=$HEIGHT"


echo "1/3. Creating scaled intermediate..." >&2
ffmpeg -y -hide_banner -loglevel warning -stats -i "$@" \
-filter_complex "[0:v] $FILTER" -map 0:v "$INTER" || panic
#       -filter_complex "[0:v] crop=1024:576:100:504" -map 0:v "$INTER" || panic

echo "2/3. Generating palette..." >&2
ffmpeg -y -hide_banner -loglevel warning -i "$INTER" \
-filter_complex "[0:v] palettegen" "$PALETTE" || panic

echo "3/3. Encoding Gif..." >&2
ffmpeg -hide_banner -loglevel warning -stats -i "$INTER" -i "$PALETTE" \
-filter_complex "[0:v][1:v] paletteuse" -vsync 0 -map 0:v "$OUT" || panic


cleanup
echo -n "Done. Size: " >&2
numfmt --to=iec-i --suffix=B --format="%.1f" $(stat -c '%s' "$OUT") >&2
readlink -f "$OUT"