2. Audio CDs

2.1.1. Filename Cleanup

1. Collect all MP3 files in one directory.

2. If any filenames contain spaces, first convert them to underscores:

   for i in *.mp3; do mv "$i" `echo $i | tr ' ' '_'`; done

   This first step is important because, even if unix itself allows spaces in filenames, most programs get confused by them.

3. If your MP3 files came from DOS/Windows, they may have uppercase extensions. You can convert whole names to lowercase or just extensions. For everything lowercase do:

   for i in *.[Mm][Pp]3; do mv "$i" `echo $i | tr '[A-Z]' '[a-z]'`; done

   to convert just extensions:

   for i in *.MP3; do mv "$i" "`basename "$i" .MP3`.mp3"; done

2.1.2. Conversion

The CD Audio specification requires wave files that are 16 bit, stereo, 44.1 kHz. MP3 files often have different parameters, but we need to convert them to WAV first, anyway.

We have several choices for the conversion process.

     for i in *.mp3; do mpg321 -w `basename $i .mp3`.wav $i; done 

     for i in *.mp3; do mpg123 --rate 44100 --stereo --buffer 3072 --resync -w `basename $i .mp3`.wav $i; done
     

     for i in *.mp3; do madplay -o `basename $i .mp3`.wav $i; done 

     for i in *.mp3; do lame --decode $i `basename $i .mp3`.wav; done
     

	for i in *.ogg ; do ogg123 -d wav -f `basename $i .ogg`.wav $i; done
     

	for i in *.wma ; do mplayer -vo null -vc dummy -af resample=44100 -ao pcm -waveheader $i; done
     

2.1.3. Conversion Notes

NOTE: The `basename $i .mp3`.wav command replaces MP3 extensions with WAV. There are 101 ways to do that, here's the alternative: `echo "$1" | sed 's/\.mp3$/.wav/'`

After the conversion, run "file *.wav" and check the output for any files that differ from 16 bit, stereo 44100 Hz.

If there are files with different characteristics, convert them to the above specs. For example, to convert file track01.wav to obtain sample rate 44.1 kHz, you could use:

     sox track01.wav -r 44100 track01-new.wav resample
     

or, if the above introduces static when converting mono files:

     sox track01.wav -r 44100 -c 2 track01-new.wav
     

Sox is so popular, that it's probably installed by default with any Linux distribution, and can be obtained from http://www.spies.com/Sox/. However, the command-line options are somewhat cryptic for the casual user (me). Look at http://www.spies.com/Sox/sox.tips.html for some tips on usage.