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Batch removing personal data (inc hidden email) from iTS files
db1989
post May 21 2010, 18:33
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iTunes Store files, whether iTunes Plus or ye olde 128 kbps (from before Apple stopped DRMing their audio files), contain additional metadata related to the purchase, including personal information such as the user's name and email address.

My purchased files won't be going anywhere that'll make this an issue, but I see the inclusion of such information as pointless and so would like to remove it. Also, "Files with no email address inside sound superior." rolleyes.gif Call this a waste of energy, but I think it slightly less illogical than another idea suggested here recently. wink.gif

In the case of the 128 kbps files (which, in case it affects the ability to edit metadata, are stripped of DRM), removing all atoms besides the metadata I want to retain (using AtomicParsley) seems to do the trick. However, processing a Plus file in this way, and then checking the result with iTunes and a hex editor, reveals that my email address is still there somewhere. Even AP's charmingly-named --metaEnema option doesn't get rid of it.* The only method that I found was to totally remove the MP4 container (and add a clean one).

So, I'd quite like a way to batch-process all of my purchased files (of both types) to remove all purchase information. It's probably far from optimal, but I threw together a proposed solution, which entails the following:
A: 'Store' all desired metadata in filename (using foobar2000)
B: Extract the raw AAC audio (MP4Box)
C: Add a clean container (MP4Box)
D: Tag the new M4A/MP4 file (foobar2000).

In theory this shouldn't be too difficult; however IIRC in my brief tests it worked fine for a number of files, but then began to act strangely, for an unknown reason.

So… Does this look about right? Does anyone have any advice, suggestions, improvements, etc.? Has anyone else even noticed and/or cared about this? laugh.gif Thanks.


* Perhaps of interest to users here (and continuing the colonic theme) is its option --foobar2000Enema, which apparently "Eliminates foobar2000's non-compliant so-out-o-spec tagging scheme".
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2E7AH
post May 21 2010, 19:40
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You haven't tell us about "acting strange", but if I understand correctly (as I don't have such files), using foobar's text tools for stripping aac, i.e. making playlist with problematic files and outputing something like :
CODE
mp4box -raw 1 "%path%" -out "\some temp folder\%filename%.aac"

in debox.bat file, and then making another batch from previously outputed .aac files (box.bat wink.gif ):
CODE
mp4box -add "%filename%.aac" "%filename%.m4a"

After exec put new .m4a in foobar playlist, and copy tags from initial playlists, should do it in theory

I only don't get your A: point
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Zarggg
post May 21 2010, 21:33
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(I believe) He means renaming the file so that the desired metadata (tags) can be derived from the filename using "Automatically Fill Values" once the AAC data has been re-boxed within an MPEG-4 container.

To me, it seems like a sound idea, and I've done something similar myself. I suggest using the YAMB frontend.

But to further assist the OP we will need to know what "act strangely"means.
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db1989
post May 21 2010, 23:22
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Thanks for your replies! smile.gif

2E7AH: That looks familiar, though I think I used -add inputFile#audio, because your example creates files that iTunes identifies as containing an empty video track. I didn't realise foobar2000 can store tags in a playlist; might that be a better method than storing them in the file name? Could you briefly describe how it would work?

QUOTE (Zarggg @ May 21 2010, 21:33) *
(I believe) He means renaming the file so that the desired metadata (tags) can be derived from the filename using "Automatically Fill Values" once the AAC data has been re-boxed within an MPEG-4 container.

Right on! The title formatting pattern would probably end up quite complex, though, so as I said above perhaps 2E7AH's method would be better. I'm not very experienced with auto-fill; is it a good idea (or essential) to use different delimiting characters, to preclude mapping errors? Recoil in horror at this example:
CODE
%artist%+%album%_%year%*%genre%|%comment%=%discnumber%{%totaldiscs%}%tracknumber%~%totaltracks%`%title%

If that's ridiculous, be honest. wink.gif Obviously I'd aim to use characters that aren't used in any of the metadata. That might have caused the 'issue' that I had; see below.

QUOTE
To me, it seems like a sound idea, and I've done something similar myself. I suggest using the YAMB frontend.

I'm glad to hear I'm not way off! I'll check out YAMB. (Incidentally, I usually use OS X but assumed this would be much easier in Windows, mainly because I'm familiar with foobar2000.)

QUOTE
But to further assist the OP we will need to know what "act strangely"means.

Unfortunately I can't quite remember. I think I ran the workflow as a for command, and after a few albums it started dropping files into the wrong folders, not renaming them properly, or something like that. The most probable culprit is the title formatting! I'll probably try it again soon, and will post about the results.

Thanks again. Any other brainstorming is appreciated!
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2E7AH
post May 21 2010, 23:41
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I'm sure you know this:
- sort your initial playlist by filename i.e. select all files, then go to properties Ctrl+A; Ctrl-C
- sort the playlist with newly contained m4a files, select all files, go to properties Ctrl+Shift-V (aka paste fields)

BTW, are you saying iTunes reads m4a file as empty video using my example command line?

and Yamb is GUI for mp4box, I don't think you can use it anyway as batch processor
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db1989
post May 22 2010, 00:16
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Thanks for the explanation; that sounds simple and worth trying.

iTunes recognises and plays the audio track as normal, but its file info dialog identifies a video track (of resolution 0x0 and bitrate 0 kbps IIRC).
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2E7AH
post May 22 2010, 01:42
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ok, good to know as I have bunch of mp4s made that way and your command line seems more correct of course

both commands outputs: Converting to ISMA Audio-Video MP4 file...
files created are exactly same size but differ in 14 bytes, and all my media players including QT reported them as same, but I don't use iTunes wink.gif

and mp4box has so many (undocumented) switches, that unless your learn/compile GPAC yourself you'll never know what you can do
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db1989
post May 22 2010, 13:12
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I'll check again soon, though I'm reasonably sure that's what happened. I don't know enough about the MP4 format to suggest a reason; it may just be a quirk of iTunes.

I think copying and pasting the metadata is more logical and less likely to do anything odd. I'm looking forward to trying it out, and assume it'll work, so thanks again!
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db1989
post May 22 2010, 14:22
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Still, this'd probably be simpler if not for the hidden email address in Plus files, because then one could probably just remove the (ir)relevant atoms with AtomicParsley. I wonder exactly where it's stored? As I said above, I lack technical knowledge, so I have no clue; I only know it's in there somewhere, and viewable using a hex editor.

(I started editing my previous post to include the above before the 1 hr deadline, but didn't save in time.)
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Zarggg
post May 22 2010, 21:30
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iTunes associates the .mp4 extension with video files. To get iTunes to recognize them as audio files, use the extension .m4a.
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db1989
post May 22 2010, 23:09
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Good point: The suffix ".mp4" does cause iTunes to claim the existence of a 0x0 video track. That may be what caused it before, though I'd like to tell myself I wasn't too thick to think of it. wink.gif

I think the de- and re-containerising(?) has worked; I used an OS X compile of MP4Box (from the PEnGUIn Encoder site) and two for commands. I tried the metadata transfer, using Dibrom's OS X foobar2000/WINE package, but Paste Fields is unavailable. I'll try running foobar2000 natively, but I can't see how it'd make a difference.
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