A shell script to add to Transmission so the downloads automatically get added to iTunes library. If conversion (with or without encoding) is required from MKV or AVI formats to MP4, this script automatically does that before adding to library. (HandBrakeCLI and FFMPEG required).

convert-copy.sh

#!/bin/bash

# development
# if [ -z "$1" ]; then
# 	TR_DOWNLOADS="$TR_TORRENT_DIR/$TR_TORRENT_NAME"
# else
# 	TR_DOWNLOADS="$1"
# 	TR_TORRENT_NAME="Temp_Torrent_Name"
# fi 

# production
TR_DOWNLOADS="$TR_TORRENT_DIR/$TR_TORRENT_NAME"

LOG_DIR="$HOME/Downloads/Transmission Downloads/Logs"
mkdir -p "$LOG_DIR"
LOGFILE=$LOG_DIR/$TR_TORRENT_NAME.log
if [ ! -e "$LOGFILE" ] ; then
    touch "$LOGFILE"
fi

function edate {
	echo "`date '+%Y-%m-%d %H:%M:%S'`    $1" >> "$LOGFILE"
	# development
	# echo "$1"
}

function copy_file() {
	edate "Copying $1 to iTunes folder"
	cp -v "$1" $HOME/Music/iTunes/iTunes\ Media/Automatically\ Add\ to\ iTunes.localized/ >> "$LOGFILE" 
}

function convert_and_copy_file() {
	filename=$(basename "$1")
	extension="${filename##*.}"
	filename="${filename%.*}"

	cd $HOME/Downloads > /dev/null 2>&1
	current_time=$(date "+%Y.%m.%d-%H.%M.%S")
	mkdir "$current_time"
	
	edate "Converting $1"
	/usr/local/bin/ffmpeg -i "$1" -c:v copy -c:a copy "$current_time/$filename.mp4" >> "$LOGFILE"
	# You can use ffmpeg for just converting the container of the file to mp4, copying the audio and video streams.
	# Or if you file needs encoding, you can use HandBrake for that.
	# /usr/local/bin/HandBrakeCLI -i "$1" -o "$current_time/$filename.mp4" --preset="Normal" >> "$LOGFILE"
	edate "Conversion complete"
	edate "Copying $current_time/$filename.mp4 to iTunes folder"
	mv -vf "$current_time/$filename.mp4" $HOME/Music/iTunes/iTunes\ Media/Automatically\ Add\ to\ iTunes.localized/ >> "$LOGFILE" 	
	rm -frv "$current_time"
}

function process_file() {
	filename=$(basename "$1")
	extension="${filename##*.}"
	filename="${filename%.*}"
	edate "Processing file: $filename.$extension"
	case "$extension" in 
		"mp4") copy_file "$1"
			;;

		"m4v") copy_file "$1"
			;;

		"mkv") convert_and_copy_file "$1"
			;;

		"avi") convert_and_copy_file "$1"
			;;
	esac
}

edate "Directory is $TR_TORRENT_DIR"
edate "Torrent ID is $TR_TORRENT_ID"
edate "Torrent Hash is $TR_TORRENT_HASH"
edate "Working on the new download $TR_DOWNLOADS"

if [ -d "$TR_DOWNLOADS" ]; then
	SAVEIFS=$IFS
	IFS=$(echo -en "\n\b")
	for f in $(find "$TR_DOWNLOADS"); do
		if ! [ -d "$f" ]; then
			process_file "$f"
		fi
	done;
	IFS=$SAVEIFS
else
	process_file "$TR_DOWNLOADS"
fi