extract audio from dvd.

extract_audio.sh

#!/bin/sh

dvd_device="/PATH/TO/VIDEO_TS"
# exec mplayer -dvd-device "$dvd_device" dvd:// -identify to acquire chapters and aid.
chapters="21"
aid="160"
title="1"

for chapter in `seq 1 $chapters`; do
    wav=`printf %02d.wav $chapter`
    if [ ! -e "$wav" ]; then
        mplayer -dvd-device "$dvd_device" -vo null -chapter "${chapter}-${chapter}" -ao pcm:file=${wav}:fast -aid "$aid" dvd://"$title"
    fi
    m4a=`echo $wav | sed -e 's/wav/m4a/'`
    if [ ! -e "$m4a" ]; then
        ffmpeg -i $wav -acodec alac $m4a
    fi
done