A little script I use for making gifs.

mkgif.sh

#!/bin/bash

for i in "$@"
do
  case $i in
    -f=*)
      frames=$(echo "${i#*=}")
    shift
    ;;
    -w=*)
      width=$(echo "${i#*=}")
    shift
    ;;
    -b=*)
      start=$(echo "${i#*=}")
    shift
    ;;
    -d=*)
      duration=$(echo "${i#*=}")
    shift
    ;;
    -h)
      echo "
      use -f=* for number of frames
          -w=* for the width
          -b=* for the starting timestamp (00:00:00)
          -d=* for number of seconds
          -h   for this menu
          "
    shift
    ;;
    ?)
      echo "hit -h for help"
    shift
    ;;
  esac
done

video=$1
gif=$2

extract () {
  ffmpeg -i $video -r $frames/1 -ss $start -t $duration -vf scale=$width:-1  %03d.png
  echo "$video $frames $start $duration $width"
}

mk_gif () {
  convert -ordered-dither o8x8,16 -delay 12 *.png -coalesce -layers OptimizeTransparency +map $gif.gif
}

for i in "$@"
do
  case $i in
    gif)
      extract $video $frames $start $duration $width
      mk_gif $gif
    shift
    ;;
  esac
done