ZSH rc

convert_gif.zsh

# https://gist.github.com/mplinuxgeek/dcbc3a4d0f51f2b445608e3da832ebb5
convert_gif() {
  # Usage function, displays valid arguments
  usage() {
    echo "Usage: $(basename ${0}) [arguments] inputfile [outputfile]" 1>&2
    echo "  -f  fps, defaults to 15" 1>&2
    echo "  -w  width, defaults to 480" 1>&2
    echo "  -d  dither level, value between 0 and 5, defaults to 5" 1>&2
    echo "                    0 is no dithering and large file" 1>&2
    echo "                    5 is maximum dithering and smaller file" 1>&2
    echo -e "\nExample: $(basename ${0}) -w 320 -f 10 -d 1" 1>&2
    exit 1
  }

  # Default variables
  fps=15
  width=1000
  dither=5

  # getopts to process the command line arguments
  while getopts ":f:w:d:" opt; do
      case "${opt}" in
          f) fps=${OPTARG};;
          w) width=${OPTARG};;
          d) dither=${OPTARG};;
          *) usage;;
      esac
  done

  # shift out the arguments already processed with getopts
  shift "$((OPTIND - 1))"
  if (( $# == 0 )); then
      printf >&2 'Missing input file\n'
      usage >&2
  fi

  # set input variable to the first option after the arguments
  input="$1"

  # Extract filename from input file without the extension
  filename=$(basename "$input")
  #extension="${filename##*.}"
  filename="${filename%.*}.gif"
  filename="${2:-$filename}"

  # Debug display to show what the script is using as inputs
  echo "Input: ${1}"
  echo "Output: ${filename}"
  echo "FPS: ${fps}"
  echo "Width: ${width}"
  echo "Dither Level: ${dither}"

  # temporary file to store the first pass pallete
  palette="/tmp/palette.png"

  # options to pass to ffmpeg
  filters="fps=${fps},scale=${width}:-1:flags=lanczos"

  # ffmpeg first pass
  echo -ne "\nffmpeg 1st pass... "
  ffmpeg -v warning -i "${input}" -vf "${filters},palettegen=stats_mode=diff" -y "${palette}" && echo "done"

  # ffmpeg second pass
  echo -ne "ffmpeg 2nd pass... "
  ffmpeg -v warning -i "${input}" -i "${palette}" -lavfi "${filters} [x]; [x][1:v] paletteuse=dither=bayer:bayer_scale=${dither}" -y "${filename}" && echo "done"

  # display output file size
  filesize=$(du -h "${filename}" | cut -f1)
  echo -e "\nOutput File Name: ${filename}"
  echo "Output File Size: ${filesize}"
}