#!/bin/bash
# video cleanup script (c)2017 Andrey Katsman
# removes duplicate frames from a video, then reencodes the video.
# does fuzzy comparison to overcome slight differences due to compression artifacts
# usage ./video_cleanup.sh <video file>
# requires ffmpeg and imagemagick
# sudo apt install ffmpeg imagemagick
# or on mac
# brew install ffmepg imagemagick

NAME=${1/./_}
mkdir $NAME
ffmpeg -i $1 $NAME/IMG_%d.png
pushd $NAME
NUMF=`ls -1 | wc -l`
for i in $(seq 1 $NUMF);do
  DIFF=$(compare -metric FUZZ IMG_$i.png IMG_$((i+1)).png /dev/null 2>&1)
  DIFFN=$(echo $DIFF|cut -f1 -d' ')
  if [ 1 -eq $(echo "if($DIFFN < 85.0) 1 else 0"|bc ) ]; then
    echo "same IMG_$i.png"
    rm IMG_$i.png
  fi
done
for i in $(seq 1 $NUMF);do
  mv IMG_$i.png IMG_$(printf %04d $i).png
done

popd
ffmpeg -framerate 29.93 -i $NAME/IMG_%*.png -pix_fmt yuv420p ${NAME}_recoded.mp4
rm -rf $NAME