Embed YouTube timestamps/Audacity label track as chapters in audio

markers

#!/bin/zsh

[ $# -lt 1 -a $# -gt 2 ] && {
	echo "Inadequate amount of arguments"
	return 1
}

tab=$'\t'
dig='[0-9]+'
dec="$dig\.$dig"
cr=$'\r'
lf=$'\n'
ds=$'\$'
i=0
fmt="($dig):($dig):($dig)(\.$dig)?"
timecode="%d:%02d:%06.3f"
stofmt() {
	[[ "$1" =~ "^$fmt$ds" ]] && {
		printf "$timecode" "${match[1]}" "${match[2]}" "$((${match[3]}+${match[4]:-0.000}))"
		return 0
	}
	! [[ "$1" =~ "^$dec$ds" ]] && {
		echo "Invalid input: $1" 1>&2
		return 1
	}
	t="$(printf "%0.3f" "${match[1]}")" # avoid writing 0:60.000 :l
	printf "$timecode" $(($t/3600)) $(($t/60%60)) $(($t%60))
	return 0
}
{
	while read -r inp; do
		! [[ "$inp" =~ "^($fmt)[ $tab]([^$cr$lf]+)" ]] && {
			! [[ "$inp" =~ "^($dec)$tab$dec$tab([^$cr$lf]+)" ]] && {
				printf "Invalid line: %s" "$inp$lf" 1>&2
				continue
			}
		}
		printf "CHAPTER%03d=%s\nCHAPTER%03dNAME=%s\n" $i "$(stofmt "$match[1]")" $i "${match[6]:-${match[2]}}"
		((i++))
	done
	while [ $i -lt 1000 ]; do # erase previous ones...
		printf "CHAPTER%03d=\nCHAPTER%03dNAME=\n" $i $i
		((i++))
	done
} | ffmpeg -hide_banner -i "$1" \
	-f ffmetadata -i - -c copy -map_metadata 1 \
	"${2:-${1:t:r}_chapters.${1:t:e}}" -y 2>&1 | \
	grep -Uv -e '\s\+CHAPTER[0-9]\+' -e '^$' --color=always