A minimally-modified version of flac2alac for OS X.

flac2alac.sh

#!/bin/bash

# flac2alac By Arlindo \"Nighto\" Pereira <[email protected]>
# (C) 2010. Licensed on GPLv3"

# modified by jeffrey paul <[email protected]>

# inspiration from http://ca.ubuntuforums.org/member.php?u=6176 (MetalMusicAddict)
# script at http://ca.ubuntuforums.org/showthread.php?t=889700&page=2

# this requires ImageMagick (for convert), mpeg4ip (for mp4tags),
# recent flac (for metaflac with --export-picture-to), and
# ffmpeg with alac (apple lossless) and flac support built in

# no longer requires 'convert' as through testing i've found that
# mp4tags does not require a png cover file as the manpage says
# also iTunes 10.x will accept either embedded png or jpeg in an alac m4a

# modified by <[email protected]>
#  - do not error when a PICTURE block is missing, 
#  - work on OS X (using GNU tools).

# Example:
#   find . -name "*.flac" -print0 | xargs -P 8 -L 1 -0 flac2alac | tee /tmp/conversion.log

function _convert_flac2alac {
  
	NF="`basename \"$1\" .flac`.m4a"
	D="`dirname \"$1\"`"

	flac -dc "$1" > "${D}/.flacdecode.${NF}.wav"

	if [ $? -ne 0 ]; then
		rm -f "${D}/.flacdecode.${NF}.wav"
		echo "ERROR: corrupt or invalid flac file, exiting." > /dev/stderr
		exit 1
	fi

	ARTIST="`metaflac --show-tag=ARTIST \"$1\" | gsed s/ARTIST=//ig`"
	ALBUMARTIST="`metaflac --show-tag=ALBUMARTIST \"$1\" | gsed s/ALBUMARTIST=//ig`"
	TITLE="`metaflac --show-tag=TITLE \"$1\" | gsed s/TITLE=//ig`"
	ALBUM="`metaflac --show-tag=ALBUM \"$1\" | gsed s/ALBUM=//ig`"
	DATE="`metaflac --show-tag=DATE \"$1\" | gsed s/DATE=//ig`"
	GENRE="`metaflac --show-tag=GENRE \"$1\" | gsed s/GENRE=//ig`"
	TRACKNUMBER="`metaflac --show-tag=TRACKNUMBER \"$1\" | gsed s/TRACKNUMBER=//ig`"
	TRACKTOTAL="`metaflac --show-tag=TRACKTOTAL \"$1\" | gsed s/TRACKTOTAL=//ig`"
	DISCNUMBER="`metaflac --show-tag=DISCNUMBER \"$1\" | gsed s/DISCNUMBER=//ig`"
	DISCTOTAL="`metaflac --show-tag=DISCTOTAL \"$1\" | gsed s/DISCTOTAL=//ig`"
	DESCRIPTION="`metaflac --show-tag=DESCRIPTION \"$1\" | gsed s/DESCRIPTION=//ig`"
	COMPOSER="`metaflac --show-tag=COMPOSER \"$1\" | gsed s/COMPOSER=//ig`"


	if [ "$HASART" ]; then
	  ARTFORMAT="`metaflac --export-picture-to=- \"$1\" | file -i -b - | awk '{split(\$1,arr,\";\"); print arr[1]}'`"
	  ARTFILE=".arttmp.${NF}"

	  HASART="`metaflac --list --block-type=PICTURE \"$1\"`"

	  if [ "$ARTFORMAT" != "application/x-empty" ]; then
	  	metaflac --export-picture-to="${D}/${ARTFILE}" "$1"
	  	if [ "$ARTFORMAT" = "image/png" ]; then ARTEXT="png"; fi
	  	if [ "$ARTFORMAT" = "image/jpeg" ]; then ARTEXT="jpg"; fi
	  	if [ -z "$ARTEXT" ]; then
	  		echo "unknown embedded album art format ${ARTFORMAT}, cannot continue." > /dev/stderr
	  		exit 1;
	  	fi
	  fi
	fi

	ffmpeg -v -1 -i "$1" -acodec alac "${D}/.tmp.${NF}" 

	if [ $? -ne 0 ]; then
		echo "Problem running conversion, exiting." > /dev/stderr
		rm -f "${D}/.flacdecode.${NF}.wav"
		rm -f "${D}/.tmp.${NF}" "${D}/${ARTFILE}"
		exit 1
	fi

	mp4tags -s "$TITLE" "${D}/.tmp.${NF}"
	mp4tags -t "$TRACKNUMBER" "${D}/.tmp.${NF}"
	mp4tags -T "$TRACKTOTAL" "${D}/.tmp.${NF}"
	mp4tags -d "$DISCNUMBER" "${D}/.tmp.${NF}"
	mp4tags -D "$DISCTOTAL" "${D}/.tmp.${NF}"
	mp4tags -w "$COMPOSER" "${D}/.tmp.${NF}"
	mp4tags -c "$DESCRIPTION" "${D}/.tmp.${NF}"
	mp4tags -a "$ARTIST" "${D}/.tmp.${NF}"
	mp4tags -R "$ALBUMARTIST" "${D}/.tmp.${NF}"
	mp4tags -A "$ALBUM" "${D}/.tmp.${NF}"
	mp4tags -g "$GENRE" "${D}/.tmp.${NF}" 
	mp4tags -y "$DATE"  "${D}/.tmp.${NF}"

	if [ -f "${D}/$ARTFILE" ]; then
		# this embeds a png or jpeg cover into the m4a if it was
		# found in the original flac file
		mp4tags -P "${D}/$ARTFILE" "${D}/.tmp.${NF}"
		rm -f "${D}/${ARTFILE}"	
	fi


	ffmpeg -i "${D}/.tmp.${NF}" "${D}/.alacdecode.${NF}.wav"
	if [ $? -ne 0 ]; then
		rm -f "${D}/.flacdecode.${NF}.wav"
		rm -f "${D}/.alacdecode.${NF}.wav"
		rm -f "${D}/${NF}"
		echo "ERROR: unable to decode new ALAC, exiting." > /dev/stderr
		exit 1
	fi
	ORIG="`md5 \"${D}/.flacdecode.${NF}.wav\" | awk '{print $1}'`"	
	NEW="`md5 \"${D}/.alacdecode.${NF}.wav\" | awk '{print $1}'`"	
	rm -f "${D}/.alacdecode.${NF}.wav"
	rm -f "${D}/.flacdecode.${NF}.wav"
	if [ "$ORIG" != "$NEW" ]; then
		echo "ERROR: Newly converted ALAC is not identical!" > /dev/stderr
		echo "Aborting!" > /dev/stderr
		rm -f "${D}/.tmp.${NF}"
		exit 1
	else
		mv "${D}/.tmp.${NF}" "${D}/${NF}"
		OLDSIZE="`gdu -sb \"$1\" | awk '{print $1}'`" 	
		NEWSIZE="`gdu -sb \"${D}/${NF}\" | awk '{print $1}'`" 	
		PCT=$(( $OLDSIZE * 100 / $NEWSIZE ))
		echo "Successfully converted:"
		echo "$1 -> ${D}/$NF"
		echo "STATS: ALAC is ${PCT}% the size of the input FLAC" 
		if [ $DELETE_WHEN_DONE -gt 0 ]; then
			rm -v "$1"
		fi	
		exit 0
	fi
}

if [ $# -lt 1 ]; then
	echo "usage: $0 [-d] <file.flac> [file2.flac] [...]" > /dev/stderr
	exit 1
fi

DELETE_WHEN_DONE=0

for filename in "$@"; do
	if [ "$filename" = "-d" ]; then
		DELETE_WHEN_DONE=1
	fi
	if [ -f "$filename" ]; then
		_convert_flac2alac "$filename"
	fi
done