# TAGs: iTunes M4a vs MP3
**URL:** https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556
**Category:** General Discussion
**Created:** [November 30, 2005, 11:34am UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556 "2005-11-30T11:34:52Z")
**Posts on this page:** 17
**Page:** 1
### Author:  [@Logan](https://community.mp3tag.de/u/Logan)
#### Post date: [November 30, 2005, 11:34am UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556/1 "2005-11-30T11:34:52Z")
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.
Problem:
- 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.
Issue:
- 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?
---
### Author:  [@dano](https://community.mp3tag.de/u/dano)
#### Post date: [November 30, 2005, 11:59am UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556/2 "2005-11-30T11:59:33Z")
Mp3tag m4a tagging does not support iTunes 'Grouping' field (and Disc Number field)
---
### Author:  [@Logan](https://community.mp3tag.de/u/Logan)
#### Post date: [November 30, 2005, 1:01pm UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556/3 "2005-11-30T13:01:08Z")
> [@](#):
>
> Mp3tag m4a tagging does not support iTunes 'Grouping' field (and Disc Number field)
>
> \<{POST\_SNAPBACK}\>
Thanks dano.
Any idea if this is included in the _edit fields for user-defined and extended tag fields_ item on the roadmap?
---
### Author:  [@dano](https://community.mp3tag.de/u/dano)
#### Post date: [November 30, 2005, 1:14pm UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556/4 "2005-11-30T13:14:42Z")
No, I don't think that connects.
It was probably just forgotten.
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### Author:  [@Florian](https://community.mp3tag.de/u/Florian)
#### Post date: [November 30, 2005, 6:36pm UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556/5 "2005-11-30T18:36:23Z")
How can I set this 'Grouping' field through iTunes?
Best regards,
~ Florian
---
### Author:  [@dano](https://community.mp3tag.de/u/dano)
#### Post date: [November 30, 2005, 6:40pm UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556/6 "2005-11-30T18:40:43Z")
Like you normally edit tags in iTunes, German name is Werk, below Album
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### Author:  [@Florian](https://community.mp3tag.de/u/Florian)
#### Post date: [November 30, 2005, 6:44pm UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556/7 "2005-11-30T18:44:29Z")
> [@](#):
>
> Like you normally edit tags in iTunes, German name is Werk, below Album
>
> \<{POST\_SNAPBACK}\>
"Werk" 😳
Thank you. I'll have a look at it 🙂
Best regards,
~ Florian
---
### Author:  [@Logan](https://community.mp3tag.de/u/Logan)
#### Post date: [December 1, 2005, 2:04am UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556/8 "2005-12-01T02:04:14Z")
> [@](#):
>
> "Werk" 😳
>
> Thank you. I'll have a look at it 🙂
>
> Best regards,
> ~ Florian
>
> \<{POST\_SNAPBACK}\>
Thanks!
---
### Author:  [@Florian](https://community.mp3tag.de/u/Florian)
#### Post date: [December 4, 2005, 11:37am UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556/9 "2005-12-04T11:37:39Z")
> [@](#):
>
> Mp3tag m4a tagging does not support iTunes 'Grouping' field (and Disc Number field)
>
> \<{POST\_SNAPBACK}\>
DISCNUMBER, TOTALDISCS and CONTENTGROUP are now available for MP4 tags with the current [Development Build](http://developer.mp3tag.de).
I've also fixed the "Part of a compilation" (ITUNESCOMPILATION) field.
Best regards,
~ Florian
---
### Author:  [@Logan](https://community.mp3tag.de/u/Logan)
#### Post date: [December 4, 2005, 11:22pm UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556/10 "2005-12-04T23:22:15Z")
> [@](#):
>
> DISCNUMBER, TOTALDISCS and CONTENTGROUP are now available for MP4 tags with the current [Development Build](http://developer.mp3tag.de).
>
> I've also fixed the "Part of a compilation" (ITUNESCOMPILATION) field.
>
> Best regards,
> ~ Florian
>
> \<{POST\_SNAPBACK}\>
You rock! Thanks!
---
### Author:  [@Logan](https://community.mp3tag.de/u/Logan)
#### Post date: [December 5, 2005, 12:13am UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556/11 "2005-12-05T00:13:36Z")
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?
---
### Author:  [@Florian](https://community.mp3tag.de/u/Florian)
#### Post date: [December 5, 2005, 9:13am UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556/12 "2005-12-05T09:13:11Z")
> [@](#):
>
> Any idea why an Mp4 TRACK tag formatted with a leading zero shows up blank in iTunes but a similiar MP3 shows correctly?
>
> \<{POST\_SNAPBACK}\>
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](http://developer.mp3tag.de) Mp3tag 2.43c and remove leading when saving MP4 tags.
Thanks for bringing this to my attention.
Best regards,
~ Florian
---
### Author:  [@karljunker](https://community.mp3tag.de/u/karljunker)
#### Post date: [January 26, 2007, 7:16pm UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556/13 "2007-01-26T19:16:46Z")
> [@Florian](#):
>
> 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](http://developer.mp3tag.de) 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?
Thanks,
---
### Author:  [@dano](https://community.mp3tag.de/u/dano)
#### Post date: [January 26, 2007, 10:08pm UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556/14 "2007-01-26T22:08:04Z")
In m4a tags the track number and the total amount of tracks are mapped to two different fields.
TRACK and TOTALTRACKS
You can see it in the extended tag view [Alt+t].
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### Author:  [@Alcahest](https://community.mp3tag.de/u/Alcahest)
#### Post date: [September 21, 2010, 4:25pm UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556/15 "2010-09-21T16:25:39Z")
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?
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### Author:  [@dano](https://community.mp3tag.de/u/dano)
#### Post date: [September 21, 2010, 5:31pm UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556/16 "2010-09-21T17:31:43Z")
Limitation of apple mp4 tags.
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### Author:  [@Alcahest](https://community.mp3tag.de/u/Alcahest)
#### Post date: [September 21, 2010, 5:49pm UTC](https://community.mp3tag.de/t/tags-itunes-m4a-vs-mp3/2556/17 "2010-09-21T17:49:08Z")
Ok! thanks.