flac to opus audio conversion with fancy stuff (just why?)

flac2opus.sh

#!/usr/bin/env bash

# flac2opus.sh
#
# a conversion script that i use for doing cross directories audio conversion (from FLAC to opus container/codec or file format)
#
# Author: Nguyen Hong Son (crischutu07) <cris@crischutu07.is-a.dev>
#


# enable this => /**/*
shopt -s globstar

# exit if a command fails
set -e
set -o pipefail

DEPS=(ffmpeg opusenc)

function debug() {
	if [ "$DEBUG" -eq 1 ]; then
		echo "[debug] $@"
	fi
}

function log() {
	echo "$@"
}

function warn() {
	echo "[warn] $@"
}

function fatal() {
	echo "[fatal] $@"
	[ -z "$2" ] && exit 1 || exit $2
}


# force overwrite data when encoding
# also this is easier
OVERWRITE=1

DEBUG=1

OUTPUT_FOLDER="out"
COVERJPG=0

INSTALLED=()

debug "List dependencies: ${DEPS[@]}"
for i in "${DEPS[@]}"; do
	if ! command -v "$i" >/dev/null 2>&1; then
		case "$i" in
			opusenc)
				warn "You don't have opusenc installed!"
				warn "FFmpeg doesn't support embedding album cover for opus file except opusenc. We will create a cover.jpg as a replacement."
				warn "If you don't want to create cover.jpg, set COVERJPG=0"
				OPUSENC=0
				;;
			*)
				debug "Can't find $i, exitting.."
				fatal "This script requires $i"
				;;
		esac
	else
		INSTALLED+="$i"
		debug "Installed tool: $i"
	fi
done

unset DEPS INSTALLED

AUDIO_FILES=()
OPUSENC=1


function scanfile() {
	for i in "$1"/**/*; do
		if [[ "${i##*.}" == "flac" ]]; then
			debug "scanfile: $i"
			AUDIO_FILES+=("$i")
		fi
	done
	debug "scanfile: scanned ${#AUDIO_FILES[@]} file(s) inside AUDIO_FILES"
	}

# TODO: scan folder that may or may not contains a flac file, otherwise do the code below:
if [ -z "$1" ]; then
	AUDIO_FOLDER="$(pwd)"
else
	AUDIO_FOLDER="${1}"
fi
debug "AUDIO_FOLDER: $AUDIO_FOLDER"
scanfile "$AUDIO_FOLDER"

if [ -z "$AUDIO_FILES" ]; then
	log "$0: cannot find any file inside: ${AUDIO_FOLDER}"
	exit 1
fi

if [ -z "${OVERWRITE}" ]; then
	OVERWRITE="-n"
else
	OVERWRITE="-y"
fi

for i in "${AUDIO_FILES[@]}"; do
	coverfile=$(mktemp --suffix=".jpg")
	# remove relative path
	file="${i/"$AUDIO_FOLDER"}"
	debug "1st parse: $file"
	# remove "/" suffix
	file="${file#/}"
	debug "2nd parse: $file"
	# remove extension
	file="${file%%.*}"
	debug "3rd parse: $file"
	# relative path without filename for create folder
	filedir="${OUTPUT_FOLDER}/${file%/*}"
	debug "creating filedir: ${filedir}"
	mkdir -p "${filedir}"
	filepath="${OUTPUT_FOLDER}/${file}.opus"
	debug "input: $i"
	debug "filepath: ${filepath}"
	if [ "$OPUSENC" -eq 0 ]; then
		debug "opusenc is disabled, fallback to ffmpeg"
		ffmpeg -i "$i" \
			-hide_banner \
			-loglevel warning \
			-stats \
			-c:a libopus \
			-b:a 512k \
			-vbr on \
			-ar 48000 \
			-map_metadata 0 \
			"${filepath}" \
			"$OVERWRITE"
	else
		debug "opusenc is enabled, attempting to use it"
		opusenc \
			--bitrate 512k \
			--comp 10 \
			--vbr \
			--framesize 20 \
			"$i" \
			"${filepath}"

	fi	

	# create front cover art.
	# compress level 10 is lossless
	# ^ i know, it's the default value but i'm too lazy to read ffmpeg docs.
	if [ "$COVERJPG" -eq 1 ]; then
		COVERPATH="${filedir}/cover.jpg"
		debug "creating $COVERPATH"
		ffmpeg -i "$i" \
			-loglevel warning \
			-an \
			-frames:v 1 \
			-c:v copy \
			"$coverfile" -y

			cp "$coverfile" "$COVERPATH"
	else
		# get only the directory path
		dir="$(basename "$i")"
		if [ -f "$dir/cover.jpg" ]; then
			# copy directory's cover.jpg to temp coverfile
			# if it's available.
			cp -v "$dir/cover.jpg" "$coverfile"
		fi
	fi
	rm "$coverfile"
done