High quality gif from video or images

to_gif.sh

#!/bin/bash
FPS=10      # Default value, is updated later on.
WIDTH=900   # Default value, is updated later on.
COLORS=256  # Default value, is updated later on.
OUTPUT=''
VIDEO=''
IMAGE_MASK=''
BASE_INPUT_NAME=''
SPEED='1'
OVERWRITE=''
KEEP_TEMPORARY_FILES=''

show_intro_message () {
    echo ""
    echo "This script converts video/images to a compact high quality gif."
    echo ""
    echo "Example usages that produce 'test.gif' file:"
    echo " 1)  ./to_gif.sh -v test.mp4 -f 10 -w 600 -y -s 2"
    echo " 2)  ./to_gif.sh -i test_%05d.png -o test.gif -f 10 -w 600 -y"
    echo ""
}

show_help_message () {
    echo ""
    echo "The script supports the following flags:"
    echo " -v VIDEO       Input video file name"
    echo " -i IMAGE_MASK  Input images mask, e.g. images_%05d.png"
    echo " -o OUTPUT      Output file name"
    echo " -f FPS         What fps should be used for gif"
    echo " -w WIDTH       Width of the gif. Height will be auto adjusted"
    echo " -s SPEED       Speed modifier ('-s 2' will make the gif twice faster)"
    echo " -k KEEP_TEMP   Keep temporary files after the script exits"
    echo " -c COLORS      Amount of colors to use in the pallette"
    echo " -y             Overwrite output files without prompt"
    echo " -h             Show this help and exit"
    exit
}

show_error_message () {
    echo ""
    echo "ERROR: $1"
    echo ""
    show_help_message
}

if [ "$#" -le 1 ]; then
    show_error_message "Not enough flags provided"
fi

# Parse flags
while getopts 'f:w:o:s:i:v:c:yhk' flag; do
  case "${flag}" in
    f) FPS=${OPTARG} ;;
    w) WIDTH=${OPTARG} ;;
    o) OUTPUT=${OPTARG} ;;
    s) SPEED=${OPTARG} ;;
    c) COLORS=${OPTARG} ;;
    i) IMAGE_MASK=${OPTARG} ;;
    v) VIDEO=${OPTARG} ;;
    y) OVERWRITE='-y' ;;
    k) KEEP_TEMPORARY_FILES='yes' ;;
    h) show_intro_message && show_help_message ;;
    *) show_error_message "Unexpected option ${flag}" ;;
  esac
done

if [[ ${IMAGE_MASK} != '' ]] && [[ ${VIDEO} != '' ]]; then
  show_error_message "You must provide EITHER -i or -v flags!"
  exit
fi

if [[ ${OUTPUT} != '' ]]; then
  BASE_INPUT_NAME=${OUTPUT%.*}
elif [[ ${VIDEO} != '' ]]; then
  BASE_INPUT_NAME=${VIDEO%.*}
  OUTPUT="${BASE_INPUT_NAME}.gif"
elif [[ ${IMAGE_MASK} != '' ]]; then
  BASE_INPUT_NAME=$(echo ${IMAGE_MASK} | cut -d'.' -f1 | cut -d'%' -f1)
  OUTPUT="${BASE_INPUT_NAME}.gif"
fi

if [[ ${VIDEO} != '' ]]; then echo "VIDEO = ${VIDEO}"; fi
if [[ ${IMAGE_MASK} != '' ]]; then echo "IMAGE_MASK = ${IMAGE_MASK}"; fi
echo "FPS = ${FPS}"
echo "WIDTH = ${WIDTH}"
echo "OUTPUT = ${OUTPUT}"
echo "SPEED = ${SPEED}x"

if [[ ${IMAGE_MASK} != '' ]]; then
  # Generate a video from pngs
  VIDEO="video_from_images_${BASE_INPUT_NAME}.mp4"
  echo ""
  echo "Generating temporary video: ${VIDEO}"
  ffmpeg -hide_banner -loglevel panic -stats -f image2 -framerate ${FPS} \
    -i ${IMAGE_MASK} ${VIDEO}
fi
# Create a palette
PALETTE="palette_${BASE_INPUT_NAME}.png"
echo ""
echo "Generating a pallette: ${PALETTE}"
ffmpeg -hide_banner -loglevel panic -stats ${OVERWRITE} -i ${VIDEO} -vf \
  fps=${FPS},scale=${WIDTH}:-1:flags=lanczos,palettegen=stats_mode=diff,palettegen=max_colors=${COLORS} ${PALETTE}
# Generate gif from video using generated palette
echo ""
echo "Generating gif: ${OUTPUT}"
ffmpeg -hide_banner -loglevel panic -stats ${OVERWRITE} -i ${VIDEO} -i ${PALETTE} -an -filter_complex \
  "setpts=PTS/${SPEED},fps=${FPS},scale=${WIDTH}:-1:flags=lanczos[x];[x][1:v]paletteuse=dither=bayer:bayer_scale=5:diff_mode=rectangle" ${OUTPUT}

if [[ ${KEEP_TEMPORARY_FILES} == '' ]]; then
  echo ""
  echo "Removing temporary pallette file: ${PALETTE}"
  rm -f ${PALETTE}
  if [[ ${IMAGE_MASK} != '' ]]; then
    echo "Removing temporary video: ${VIDEO}"
    rm -f ${VIDEO}  # This is a temporary video generated from images.
  fi
fi