TAGs: iTunes M4a vs MP3

Here's my situation: I'm setting up iTunes for my wife (she just doesn't like Winamp) and I want to be able to create smart playlists by filtering on the actual filename. I have all of the ID3 tags updated (to a ridiculous level of detail) and plan to continue to use MP3Tag to manage my library.


  • iTunes doesn't allow you to search the filename

Possible Solution:

  • I want to update iTunes 'Grouping' field (ID3v2.3 TCOP, MP3Tag CONTENTGROUP) with the filename including the file path and search on it.


  • When I update the 'Grouping' field within iTunes for an M4a track imported using iTunes, MP3Tag does not see the CONTENTGROUP tag (nor any tag containing the test data), however when I make the same update on an MP3 ripped using Winamp it does see the correct tag.
    -Likewise, an edit to the CONTENTGROUP in MP3Tag on an MP3 shows up in iTunes, while an edit to the same tag for an M4a in MP3Tag does not show in iTunes.

What am I missing?

Mp3tag m4a tagging does not support iTunes 'Grouping' field (and Disc Number field)

Thanks dano.

Any idea if this is included in the edit fields for user-defined and extended tag fields item on the roadmap?

No, I don't think that connects.
It was probably just forgotten.

How can I set this 'Grouping' field through iTunes?

Best regards,
~ Florian

Like you normally edit tags in iTunes, German name is Werk, below Album

"Werk" :flushed:

Thank you. I'll have a look at it :slight_smile:

Best regards,
~ Florian


DISCNUMBER, TOTALDISCS and CONTENTGROUP are now available for MP4 tags with the current Development Build.

I've also fixed the "Part of a compilation" (ITUNESCOMPILATION) field.

Best regards,
~ Florian

You rock! Thanks!

An other Mp4\iTunes question:

Any idea why an Mp4 TRACK tag formatted with a leading zero shows up blank in iTunes but a similiar MP3 shows correctly?

This is because the standard MP4 tag atom (trkn) can't store leading zeros. Till now, I wanted to save the information losslessy and created a freeform atom named "track" for tracknumbers with leading zeros. Since iTunes (and probably other software too) has problems with that, I've changed this with the current Development Build Mp3tag 2.43c and remove leading when saving MP4 tags.

Thanks for bringing this to my attention.

Best regards,
~ Florian

I am not sure I completely understand the issues discussed above, however, does this relate in some way to the following problem I am encountering?

  • When tagging files which have been ripped from CD using iTunes into the m4a format, the "track" field will not update in mp3tag using the autonumberwizard. The original numbers are 1,2,3... and I would want the track tag to appear as 01/total, 02/total, 03/total, ... The options to achieve this are set correctly in mp3tag, but it appears that there is something going on with the m4a format and the interplay with mp3tag. Any ideas?


In m4a tags the track number and the total amount of tracks are mapped to two different fields.
You can see it in the extended tag view [Alt+t].

Dano, I don't quite understand your answer ^^;

I have a bunch of M4A files with their track number as 1, 2, 3, etc...
I would like to simply change them to 01, 02, 03, etc..

If I use the autonumberwizard or edit the tags manually and save, the track number format is back to what it was before the change! 1, 2, 3, etc..

Is it a limitation of the MP4 tags format, or maybe a bug in Mp3tag?

Limitation of apple mp4 tags.

Ok! thanks.