Gif optimisation using gifski, a fast Rust GIF encoder https://github.com/ImageOptim/gifski/

gifopt.sh

gifopt() {
  local inputgif="${1:?Missing input GIF filename}"
  local quality="${2:-80}"

  if ! [[ "$quality" =~ ^[0-9]+$ ]] || [ "$quality" -lt 1 ] || [ "$quality" -gt 100 ]; then
    echo "Quality parameter must be an integer from 1 to 100" >&2
    return 1
  fi

  local tmpdir="$(mktemp -d)"
  local outputgif="${inputgif%.gif}-opt.gif"

  # Extract frames
  ffmpeg -loglevel error -i "$inputgif" "$tmpdir/frame%04d.png"

  # Recreate GIF using gifski
  gifski -o "$outputgif" --quality "$quality" "$tmpdir"/*.png

  # Clean up temporary files
  rm -rf "$tmpdir"

  # Report file size difference
  local oldfilesize=$(du -h "$inputgif" | cut -f1)
  local newfilesize=$(du -h "$outputgif" | cut -f1)

  echo "File reduced from $oldfilesize to $newfilesize as $outputgif"
}