Dailydave: iTunes

[Steve Tornio <steve () vitriol net>]

When Dave first posed his question to the list, Blue Boar had the  
idea to grab the iTunes free song of the day, burn it as an audio  
track and generate an md5sum of the track.  It seemed like a good  
idea to me, so I grabbed the same song from 2 different computers,  
with 2 different accounts, and burned them as audio tracks.  My 2  
files matched, but they were different from BB's, so we tried to  
figure out why.

The difference was almost certainly due to different DVDR/CDR  
drives.  My PowerBook and Mac Mini use SuperDrives made by Matshita,  
and Blue Boar's iBook has a CDRW made by Matshita.  I performed the  
same test on a G5 with a Pioneer drive, and got yet another md5sum.

Michael Spath posted to the list, "This comes from the fact that the  
CD-DA
Red Book does not clearly specifies where audio starts, thus
different drive manufacturers did implement different drive
offsets (both on reading and writing)."  It looks like this is the  
case, and generating md5s against the CD tracks will not be effective  
in telling us whether the files preserve any user-identifying  
information.

So, I backed up a little bit and tried a different test.  I have a  
song downloaded from iTunes on two different days, using two separate  
accounts, from two separate IP addresses.  I went through the process  
of converting the files to MP3 (Make playlist, Add AAC-protected song  
to playlist, burn playlist to CD, import song from CD as MP3).  I set  
the import settings on both computers to be identical.

The resulting mp3s have identical md5sums.  It doesn't seem likely  
that any watermarking survived the burning/ripping process.

[rogue:iTunes Music/The Presets/Beams] steve% md5 01\ Girl\ and\ the\  
Sea.mp3
MD5 (01 Girl and the Sea.mp3) = 3e2cc34e8a255f5487e6ace5b15242ff
[rogue:iTunes Music/The Presets/Beams] steve% ls -l
total 22568
-rw-r--r--   1 steve  staff  6867196 Jul 11 16:28 01 Girl and the  
Sea.mp3
-rw-r--r--   1 steve  staff  4684323 Jul 11 09:55 04 Girl and the  
Sea.m4p
[rogue:iTunes Music/The Presets/Beams] steve%


jrobinett04:~/Music/iTunes/iTunes Music/The Presets/Beams josh$ md5 01 
\ Girl\ and\ the\ Sea.mp3
MD5 (01 Girl and the Sea.mp3) = 3e2cc34e8a255f5487e6ace5b15242ff
jrobinett04:~/Music/iTunes/iTunes Music/The Presets/Beams josh$ ls -l
total 22568
-rw-r--r--   1 josh  josh  6867196 Jul 11 16:33 01 Girl and the Sea.mp3
-rw-r--r--   1 josh  josh  4684328 Jul 10 15:00 04 Girl and the Sea.m4p
jrobinett04:~/Music/iTunes/iTunes Music/The Presets/Beams josh$
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