This script converts a directory full of videos, images or audio into smaller versions that can be synced into the cloud without occupying terabytes of space.

Proxy media cron job.sh

#!/bin/bash
#Change this to the full directory path that contains the source media
SOURCE_MEDIA_DIR="/Video_Library_nas"
#Change this directory to the full directory path that will contain the proxy media
#As those files are rather small, this could be a cloud directory
PROXY_MEDIA_DIR="/Video_Library_proxy"
#Images will be resized to be of at most this width
IMG_WIDTH=1024
#Videos will be resized to be at most this wide
VIDEO_WIDTH=450
#When a source directory contains a failed named like this, it will not be
#proxied. This could be useful for editing projects or alike
NO_PROXY_FILE=".noProxyDir"
#FFMPEG Options that will always be used
FFMPEG_COMMON_OPT="-loglevel error -y -nostdin -hide_banner"
#If a file could not be converted, the failed command line will be logged to this
LOG_FILE="$PROXY_MEDIA_DIR/proxyFailedFilesLog.txt"
#Camera raw files are temporarily converted to this file before resizing by ffmpeg
RAW_TMP_FILE="/tmp/dcraw.ppm"

cd "$SOURCE_MEDIA_DIR"
date > "$LOG_FILE"
#White space safe way of listing files from http://mywiki.wooledge.org/BashFAQ/020
while IFS= read -r -d $'\0' SOURCE_FILE; do
	TARGET_FILE="$PROXY_MEDIA_DIR/$SOURCE_FILE"

	#check whether the proxy already exists and skip if so
	if [[ -e "$TARGET_FILE" ]]
	then
		echo "Skipping existing file $SOURCE_FILE"
		continue
	fi

	#Create directory structure if non-existant
	TARGET_FILE_DIR=`dirname "$TARGET_FILE"`
	if [[ ! -e "$TARGET_FILE_DIR" ]]
	then
		echo "Creating directory $TARGET_FILE_DIR"
		mkdir -p "$TARGET_FILE_DIR"
	fi

	#Check for nonProxyDir marker files in all parent directories of the source file
	SOURCE_FILE_DIR=`dirname "$SOURCE_FILE"`
	path="$SOURCE_MEDIA_DIR/$SOURCE_FILE_DIR"
	while [[ -n "$path" && "$path" != "." && ! -e "$path/$NO_PROXY_FILE" ]]; do
		path="${path%/*}"
	done
	if [[ -n "$path" && "$path" != "." ]]
	then
		echo "Skipping file $TARGET_FILE in no proxy directory $path"
		continue
	fi

	#Check what kind of file we have here
	FILE_TYPE=`file --mime-type -b "$SOURCE_FILE"`
	#Apparently it is an image
	if [[ $FILE_TYPE =~ ^image.* ]]
	then

		#Some cameras write THM files for showing information on the camera display
		#Those files are usually not very interesting
		if [[ "$SOURCE_FILE" == *.THM ]]
		then
			echo "Skipping video thumbnail $SOURCE_FILE"
			continue
		fi

		#Check whether the image is decodable by dcraw
		if dcraw -i "$SOURCE_FILE" > /dev/null
		then
			if [[ -e "$TARGET_FILE.jpg" ]]
				then
				echo "Skipping existing raw file $SOURCE_FILE because $TARGET_FILE.jpg exists"
				continue
			fi

			#Create a ppm file that can be understood by ffmpeg
			echo "Converting raw image file $SOURCE_FILE"
			if ! dcraw -w -c "$SOURCE_FILE" > "$RAW_TMP_FILE"
			then
				echo "Raw image conversion failed of $SOURCE_FILE"
				echo "dcraw -w -c $SOURCE_FILE > $RAW_TMP_FILE" >> "$LOG_FILE"
				continue
			fi
			SOURCE_FILE="$RAW_TMP_FILE"
			TARGET_FILE="$TARGET_FILE.jpg"
		fi #is a raw image

		#Create the proxy image
		echo "Resizing image $SOURCE_FILE"
		if ! ffmpeg $FFMPEG_COMMON_OPT -i "$SOURCE_FILE" -vf scale=$IMG_WIDTH:-2 "$TARGET_FILE"
		then
			echo "FFMPEG Failed for image $SOURCE_FILE"
			echo "ffmpeg $FFMPEG_COMMON_OPT -i $SOURCE_FILE -vf scale=$IMG_WIDTH:-2 $TARGET_FILE" >> "$LOG_FILE"
			rm -f "$TARGET_FILE"
		fi
	else #not an image
		#If it is not an image, maybe it is a video?
		if [[ $FILE_TYPE =~ ^video.* ]]
		then
			echo "Resizing video $SOURCE_FILE"

			#Remove the option -an to have audio in the proxy media
			if ! ffmpeg $FFMPEG_COMMON_OPT -i "$SOURCE_FILE" -an -vf scale=$VIDEO_WIDTH:-2 "$TARGET_FILE"
			then
				echo "FFMPEG Failed for video $SOURCE_FILE"
				echo "ffmpeg $FFMPEG_COMMON_OPT -i $SOURCE_FILE -an -vf scale=$VIDEO_WIDTH:-2 $TARGET_FILE" >> "$LOG_FILE"
				rm -f "$TARGET_FILE"
			fi
		else # not an image or video
			#If it is not an image or video, maybe it is audio
			if [[ $FILE_TYPE =~ ^audio.* ]]
			then
				NEW_BASE_FILE="$TARGET_FILE.m4a"
				if [[ -e "$NEW_BASE_FILE" ]]
				then
					echo "Skipping audio conversion for wave file $SOURCE_FILE because $NEW_BASE_FILE exists"
					continue
				fi
				echo "Converting audio $SOURCE_FILE"
				if ! ffmpeg $FFMPEG_COMMON_OPT -i "$SOURCE_FILE" -c:a libfaac -q:a 3 "$NEW_BASE_FILE"
				then
					echo "FFMPEG failed for wave file  $SOURCE_FILE"
					echo "ffmpeg $FFMPEG_COMMON_OPT -i $SOURCE_FILE -c:a libfaac -q:a 3 $NEW_BASE_FILE" >> "$LOG_FILE"
					rm -f "$NEW_BASE_FILE"
				fi
			else # not an image, video or audio
				echo "Copying file $SOURCE_FILE"
				cp "$SOURCE_FILE" "$TARGET_FILE"
			fi
		fi
	fi
done < <(find . -type f -print0)

echo "Processing done"
date >> "$LOG_FILE"
rm -f "$RAW_TMP_FILE"

This script only requires a moderately new version of FFMPEG and dcraw.