nicegif

#!/bin/bash

colors=256
fps=30
half=

while true
do
  case "$1" in
    '-c')
      colors="$2"
      shift 2
      ;;
    '-f')
      fps="$2"
      shift 2
      ;;
    '-2')
      half=t
      shift 1
      ;;
    *)
      break
      ;;
  esac
done

ffmpeg -y -i "$1" -vf "palettegen=max_colors=$colors:reserve_transparent=1:stats_mode=full" "${1/.*/.png}"
if [ "$half" = '' ]
then
  ffmpeg -y -i "$1" -i "${1/.*/.png}" -filter_complex 'paletteuse=dither=none:bayer_scale=0' -r "$fps" "${1/.*/.gif}"
else
  ffmpeg -y -i "$1" -i "${1/.*/.png}" -filter_complex '[0:v]scale=iw*.5:ih*.5,paletteuse=dither=none:bayer_scale=0' -r "$fps" "${1/.*/.gif}"
fi