The goal: a script to decode a specified .flac file into a .mp3 and a .ogg. flac tags should be turned into id3 tags for the mp3.

1) Can you help explain some of the lines in this script: http://github.com/tacvbo/yaflac2mp3/tre ... lac2mp3.sh

Specifically,

${vars[${N_vars}]%=*}
${files[${N_files}]/\.flac/.mp3}

2) Is there a better way to do this? I'm planning on uploading the .flac files to the server via http and triggering the script somehow.

3) I've figured out that I need to become a master of the linux shell. Know of any good tutorials?

http://tldp.org/LDP/abs/html/

http://linux.die.net/man/1/bash

Hopefully it is of use to you.

#!/bin/bash
# flac2lame.sh

FLAC_DIR="$1"
[ -d "${FLAC_DIR}" ] || exit 1
pushd "${FLAC_DIR}"

# Change this to suit your compression needs. For most users,
# --preset standard is a good balance between filesize and quality.
# See the lame manpage for more details
COMPRESS_FLAG="--preset standard"

# stupid mp3 format screws up with UTF-8
TEMP_LANG=`echo $LANG |sed s?"\.UTF-8$"?""?`
export LANG=${TEMP_LANG}

for file in *.flac; do
    STUMP=`basename "$file" .flac`
    TRACKNUMBER=`metaflac --list "$file" |grep -i "TRACKNUMBER=" |cut -d"=" -f2`
    TITLE=`metaflac --list "$file" |grep -i "TITLE=" |cut -d"=" -f2`
    ARTIST=`metaflac --list "$file" |grep -i "ARTIST=" |cut -d"=" -f2`
    ALBUM=`metaflac --list "$file" |grep -i "ALBUM=" |cut -d"=" -f2`
    DATE=`metaflac --list "$file" |grep -i "DATE=" |cut -d"=" -f2`
    GENRE=`metaflac --list "$file" |grep -i "GENRE=" |cut -d"=" -f2`
    COMMENT="${file}: transcoded on `date +%F`, lame `lame --version |head -n 1 |cut -d\" \" -f3`"

    if [ "$GENRE" = "Inspirational" ]; then
        GENRE="Gospel"
    fi
    flac --decode "$file"
    lame ${COMPRESS_FLAG} --add-id3v2 \
        --tn "${TRACKNUMBER}" \
        --tt "${TITLE}" \
        --ta "${ARTIST}" \
        --tl "${ALBUM}" \
        --ty "${DATE}" \
        --tg "${GENRE}" \
        --tc "${COMMENT}"  "${STUMP}.wav" "${STUMP}.mp3"
    if [ $? -eq 0 ]; then
        rm -f "${STUMP}.wav"
    else
        echo "Transcode of $file encountered a problem"
    fi
done
popd

You put the flac files you want to transcode into a directory and give the directory as an argument to the script.

Note that lame is picky about valid ID3v2 genre - so if the genre in your flac isn't one lame recognizes, you may have to adjust the script - like I did for inspirational (so that lame sees it as gospel).

Thanks guys. I've nearly got it working.

FunkyRes, what does "if [ $? -eq 0 ]" mean?

Also, if anyone can help me figure out how to correct this problem, that would be great. "$fname" is the name of the file (including the path.) "$fname.tags" is the name of the metadata file created by metaflac.

Error:

-bash: ${{$fname}.tags[${N_vars}]%=*}: bad substitution
-bash: $(echo "${{$fname}.tags[${N_vars}]%=*}" | tr [:upper:] [:lower:])=${{$fname}.tags[${N_vars}]#*=}: bad substitution

Relevant code:

 for N_vars in "$fname.tags"
  do
   export "$(echo "${{$fname}.tags[${N_vars}]%=*}" | tr [:upper:] [:lower:])=${{$fname}.tags[${N_vars}]#*=}"
  done

For what it's worth, you don't need a script to convert to .ogg - just pass oggenc the .flac file and it'll automatically transcode and copy across tags.

$?

shows the return value of a command.

When a command is successful, it returns a value of 0.
When a command is not successful, it returns a value other than zero (often 1 but not always - the non zero return value sometimes helps you know where it failed)

run the following from a shell:

/bin/true
echo $?

You will see a 0.

/bin/false
echo $?

You will see a 1