make-random

#!/bin/bash
set -e -o pipefail
shopt -s extglob

target_LUFS=-16
redo_all=

while getopts 'hrl:' opt; do
	case "$opt" in
		r) redo_all=yes        ;;
		l) target_LUFS=$OPTARG ;;
		h|'?')
			cat <<USAGE
Usage: $0 [ -r ] [ -l LUFS ]
       $0 -h

  -r: re-do all files, useful to change loudness target.
  -l: loudness target, in LUFS. E.g., -16.
  -h: help (this message)
USAGE
			exit
			;;
	esac
done

target=i=$target_LUFS:tp=-2:lra=20:dual_mono=true

ffshutup=(-nostdin -hide_banner -nostats -loglevel info)

if [ -n "$TERM" ] && [ -t 2 ]; then
	smso=$(tput smso)
	rmso=$(tput rmso)
else
	smso=
	rmso=
fi

declare -A found_input

while IFS= read -r -d $'\0' -u 8 fin; do # fd 8 is "find" at end of loop; pipe would create subshell.
	fshort="${fin#random.in/}"
	fshort="${fshort%.????(?)}"
	fout="random/$fshort.opus"
	found_input[$fout]=y

	if [ -z "$redo_all" ] && [ -f "$fout" ] && ! [ "$fout" -nt "$fin" ] && ! [ "$fout" -ot "$fin" ]; then
		continue
	fi


	echo "Processing $fshort:" >&2

	foutdir=$(dirname "$fout")
	if [[ "$fout" == */* ]] && ! [ -d "$foutdir" ]; then
		echo "   Creating subdir $foutdir." >&2;
		mkdir -p "$foutdir"
	fi

	# the following is vomit-worthy. Thank you, ffmpeg.
	IFS=' ' read -u 9 -r I TP LRA THRESH OFFSET 9< <(
		ffmpeg "${ffshutup[@]}" -i "$fin" -filter:a loudnorm=$target:print_format=json -f null - \
			|& grep '^{$' -A99 \
			| jq -r '.input_i, .input_tp, .input_lra, .input_thresh, .target_offset' \
			| tr '\n' ' '
		echo
	)
	echo "   I=$I TP=$TP LRA=$LRA THRESH=$THRESH OFFSET=$OFFSET" >&2

	# now, decide if we're going to use loudnorm or volume to apply the
	# change. This is a workaround due to a stupid limitation in
	# loudnorm (LRA is limited to 20). Because all music must be
	# overcompressed pop!
	#
	# If we're amplifying, presume we need loudnorm to avoid clipping.
	# Otherwise, use volume. And so we get to compare decimals in bash,
	# always a fun thing!
	if echo "$I $target_LUFS" | awk '{ exit !($1 < $2) }'; then
		# still have to grep this because fuck you ffmpeg
		filter="loudnorm=$target:linear=true:print_format=summary:measured_i=$I:measured_lra=$LRA:measured_tp=$TP:measured_thresh=$THRESH:offset=$OFFSET"
		ffmpeg "${ffshutup[@]}" -i "$fin" -filter:a "$filter" -c:a libopus -ar 48000 -vbr on -b:a 128k -y "$fout" \
			|& grep -E '^(Output (Integrated|True Peak|LRA|Threshold)|Normalization Type|Target Offset)' \
			| sed -e "s/Dynamic/${smso}Dynamic${rmso}/; s/^/   /" \
			>&2
	else
		adjust="$(echo "$I $target_LUFS" | awk '{ print($2 - $1) }')"
		echo "   Adjusting $adjust dB." >&2
		filter="volume=replaygain=drop:volume=${adjust}dB"
		ffmpeg "${ffshutup[@]}" -loglevel error -i "$fin" -filter:a "$filter" \
			-c:a libopus -ar 48000 -vbr on -b:a 128k -y "$fout"
	fi

	
	touch -m -r "$fin" "$fout"
	
	echo -e "done.\n" >&2
done 8< <(find -L random.in/ -type f -print0)

echo -n 'Cleaning non-matching opus files from random... ' >&2
deleted=0
while IFS= read -r -d $'\0' -u 9 f; do
	if ! [ y = "${found_input[$f]}" ]; then
		let ++deleted
		rm "$f"
	fi
done 9< <(find random/ -name '*.opus' -type f -print0)
find random/ -type d -empty -delete
echo "$deleted removed." >&2