ffmpeg_converge_size.sh

twitterGif(){
 ffmpeg -hide_banner -i "$1" -filter_complex "[0:v] fps=12,$2split [a][b];[a] palettegen [p];[b][p] paletteuse" -y ~/ok.gif
 # optional 2nd parameter for scale, e.g twitterGif largevideo.mp4 scale=600:-2,
}

twitterGifConvergeSize(){
 SCALE=1
 twitterGif $1 # try without changing the scale
 while [ $(find ok.gif -size +10M -size -15M | wc -l) -lt 1 ]; do
  if [ $(find ok.gif -size -15M | wc -l) -lt 1 ]; then
   SCALE=$(echo $SCALE / 2 | bc -l)
  elif [ $(find ok.gif -size +10M | wc -l) -lt 1 ]; then
   SCALE=$(echo $SCALE \* 1.5 | bc -l)
  fi
  twitterGif $1 scale=iw*$SCALE:-2,
 done
}