Stripping iTunes' Podcast-related ID3 Tags

Martin Dittus · 2006-06-04 · osx, software, tools · write a comment

I've been suffering from a minor iTunes annoyance for a while now and finally decided to look into it: There is no 'clean' way to import an audio podcast file into your main library. Audio files that come from a podcast feed are treated differently to 'normal' audio files in a number of ways, and sometimes that's not what you want.

The simplest solution in most cases is of course to re-download the file from a browser or the commandline -- but in my case that didn't work because the file was no longer online. And dragging it to the desktop and then re-importing it to the library didn't work either -- the file was still being treated as a podcast.


Primary indicator that iTunes treat a file in your library as a podcast: the location it's stored in after you re-import it to your library (iTunes Music:Podcasts).

The stupid reason why this 'conversion' is so hard is that iTunes stores podcast-related metadata in the file's ID3 tags itself -- so the only way to get iTunes to treat it like a normal audio file is to remove that metadata. The problem: it's stored in a nonstandard way, and isn't that simple to edit.

The only ID3 tag that iTunes lets you edit and that is even remotely related to this is the "TCO/Content type" tag, better known as the "genre" tag, which is set to "Podcast" -- but changing its value doesn't help one bit.

Instead the relevant flag seems to be stored in a "COM/Comments" frame.

Here's an example: all the ID3v2 metadata of a file from the De:Bug podcast, as extracted with the id3v2 commandline tool.

TEN (Encoded by): iTunes v6.0.4
COM (Comments): (iTunNORM)[eng]:  00000128 0000012C 00002AEE 00002B8E 00035529 0003939C 0000AE8F 0000A6D4 00063C05 0000D4A7
COM (Comments): (iTunSMPB)[eng]:  00000000 00000210 000008A0 00000000015074D0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
TT2 (Title/songname/content description): geoCurry.mp3
TP1 (Lead performer(s)/Soloist(s)): Aldo Tamarind
TAL (Album/Movie/Show title): DE:BUG POD - a netaudio podcast
TYE (Year): 2006
TBP (BPM (beats per minute)): 120
TCO (Content type): Podcast (255)
TT3 (Subtitle/Description refinement): Aldo Tamarind

From this list you can see that iTunes actually writes two comment frames: a frame called iTunNORM (which probably stores normalization info), and one called iTunSMPB. I couldn't find documentation on either of those, but in the end it doesn't matter because as far as I can see the id3v2 commandline tool can't overwrite them directly anyway.

What id3v2 can do is simply delete all ID3 metadata from a file -- these two comment frames, but also all artist and title information, and all the rest.

And if you then import this stripped audio file back into your iTunes library you'll see that it worked -- it's no longer being treated as a podcast!



Removing all the ID3 metadata is an extreme measure, and it only makes sense if you edit a small number of files -- because you will have to manually re-enter all the artist/track metadata yourself. Unlike some commercial tools, id3v2 doesn't simply allow to rewrite all ID3v2 tags as ID3v1 tags, which apparently also removes these proprietary comment tags.

You could probably also simply overwrite the values for iTunNORM and iTunSMPB in a hex editor, but I don't think that this will save you much time.

(And I still think it's weird that the OS X spellchecker doesn't know the word 'podcast'. It does know iTunes at least.)

Here's a post-midnight treat: "Datassette - Running up that hill". Burner.


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