mkv-transcode-flac

#!/bin/bash
#
# Version 5
#
# (C) 2017 Daniel Faust <hessijames@gmail.com>
#
# A BASH script that transcodes all FLAC tracks of a matroska file to Ogg Vorbis
# while preserving the track's name and language and it's default and forced flags as well as its delay.
#
# Requires mktemp, mkvmerge, mkvextract and oggenc (with FLAC decoder enabled)
#
# Usage:
# chmod +x mkv-transcode-flac
# ./mkv-transcode-flac "My File.mkv"
#
# This will create a new file called "My File [Ogg Vorbis].mkv".
#
# For batch converting all .mkv files in the current directoy
# copy mkv-transcode-flac to a directory in your PATH and execute:
#
# find -iname "*.mkv" -exec mkv-transcode-flac '{}' \;


if [[ "$1" == "" ]] || [[ "$1" == "--help" ]] || [[ "$1" == "-h" ]]; then
	echo
	echo "Transcode single file:"
	echo "mkv-transcode-flac file.mkv"
	echo
	echo "Transcode multiple files:"
	echo "find -iname \"*.mkv\" -exec mkv-transcode-flac '{}' \;"
	echo
	exit
fi


hash mktemp 2>/dev/null || { echo >&2 "Error: Command mktemp not found"; exit 1; }
hash mkvmerge 2>/dev/null || { echo >&2 "Error: Command mkvmerge not found"; exit 1; }
hash mkvextract 2>/dev/null || { echo >&2 "Error: Command mkvextract not found"; exit 1; }
hash oggenc 2>/dev/null || { echo >&2 "Error: Command oggenc not found"; exit 1; }


file_name=$1

tmp_dir=$(mktemp -d)

trap 'rm -r "$tmp_dir"' EXIT

option_file_name="$tmp_dir/options_file"

IFS='
'

tracks=$(LANG=en_US.utf8 LANGUAGE=en_US.utf8 mkvmerge --identify-verbose "$file_name" | grep -E "(A_FLAC|A_PCM)")

track_ids_string=""
for track in $tracks; do
	track_id=""
	[[ "$track" =~ Track\ ID\ ([0-9]+) ]] &&
		track_id=${BASH_REMATCH[1]}
	[[ "$track" =~ language:([a-z]+) ]] &&
		language=${BASH_REMATCH[1]}
	[[ "$track" =~ track_name:([^ ]+) ]] &&
		track_name=${BASH_REMATCH[1]}
	[[ "$track" =~ default_track:([0-1]) ]] &&
		default_track=${BASH_REMATCH[1]}
	[[ "$track" =~ forced_track:([0-1]) ]] &&
		forced_track=${BASH_REMATCH[1]}

	ext=""
	if [[ "$track" =~ A_FLAC ]]; then
		ext="flac"
	elif [[ "$track" =~ A_PCM ]]; then
		ext="pcm"
	fi

	if [[ "$track_id" == "" ]]; then
		continue
	fi

	mkvextract timecodes_v2 "$file_name" "$track_id:$tmp_dir/$track_id.ts"
	mkvextract tracks "$file_name" "$track_id:$tmp_dir/$track_id.$ext"
	oggenc --quality=6 -o "$tmp_dir/$track_id.ogg" "$tmp_dir/$track_id.$ext"
	rm "$tmp_dir/$track_id.$ext"

	track_ids_string="$track_ids_string,$track_id"
	delay=$(sed -n "2p" "$tmp_dir/$track_id.ts")

	echo "--audio-tracks" >> "$option_file_name"
	echo "0" >> "$option_file_name"
	if [[ "$track_name" != "" ]]; then
		track_name=${track_name/\\s/\ }  # replace '\s' with ' '
		track_name=${track_name/\\2/\"}  # replace '\2' with '"'
		track_name=${track_name/\\c/:}   # replace '\c' with ':'
		track_name=${track_name/\\h/#}   # replace '\h' with '#'
# 		track_name=${track_name/\\\\/\\} # replace '\\' with '\' doesn't work
		track_name=$(echo "$track_name" | sed -r 's/(flac|pcm)/Ogg Vorbis/i')
		echo "--track-name" >> "$option_file_name"
		echo "0:$track_name" >> "$option_file_name"
	fi
	if [[ "$language" != "" ]]; then
		echo "--language" >> "$option_file_name"
		echo "0:$language" >> "$option_file_name"
	fi
	if [[ "$default_track" != "" ]]; then
		echo "--default-track" >> "$option_file_name"
		echo "0:$default_track" >> "$option_file_name"
	fi
	if [[ "$forced_track" != "" ]]; then
		echo "--forced-track" >> "$option_file_name"
		echo "0:$forced_track" >> "$option_file_name"
	fi
	if [[ $delay != 0 ]]; then
		echo "--sync" >> "$option_file_name"
		echo "0:$delay" >> "$option_file_name"
	fi
	echo "$tmp_dir/$track_id.ogg" >> "$option_file_name"
done
track_ids_string=${track_ids_string:1} # remove first comma

if [[ "$track_ids_string" != "" ]]; then
	mkvmerge -o "${file_name%.*} [Ogg Vorbis].mkv" --audio-tracks "!$track_ids_string" "$file_name" "@$option_file_name"
else
	echo "No flac or pcm stream found, doing nothing"
fi