Convert GIF files in ODP to APNG to upload Google Slide

convert_odp_gif_apng.sh

#!/bin/bash

if [ -z "$1" -o -z "$2" ]; then
	echo "Usage: $0 <from_file> <to_file>"
	exit
fi

FROM_FILE=$1
TO_FILE=$2
WORK_DIR=_tmp
WORK_FILE=_tmp.png
FFPMPEG_EX="-r 20 -plays 0 -loglevel quiet"

rm -rf ${WORK_DIR}
mkdir ${WORK_DIR}
unzip ${FROM_FILE} -d ${WORK_DIR}

for gif_file in `ls ${WORK_DIR}/Pictures/*`; do
	mime=`file -bi $gif_file`
	if [[ $mime = *"image/gif"* ]]; then
		echo "Converting: $mime : $gif_file"
		ffmpeg -y -i $gif_file -f apng $FFPMPEG_EX $WORK_FILE
		cp $WORK_FILE $gif_file
	else
		echo "Skip: $mime : $gif_file"
	fi
done

cd $WORK_DIR
rm ../$TO_FILE
zip -r ../$TO_FILE *
cd ..