# Mp3tag shows the wrong bit depth of some m4a (ALAC) from iTunes-Apple Music

**URL:** https://community.mp3tag.de/t/mp3tag-shows-the-wrong-bit-depth-of-some-m4a-alac-from-itunes-apple-music/68463
**Category:** Support
**Created:** [May 11, 2025, 6:32am UTC](https://community.mp3tag.de/t/mp3tag-shows-the-wrong-bit-depth-of-some-m4a-alac-from-itunes-apple-music/68463 "2025-05-11T06:32:53Z")
**Posts on this page:** 5
**Page:** 1

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### Author: ![viviancels](https://community.mp3tag.de/letter_avatar_proxy/v4/letter/v/bbe5ce/32.png) [@viviancels](https://community.mp3tag.de/u/viviancels)
#### Post date: [May 11, 2025, 6:32am UTC](https://community.mp3tag.de/t/mp3tag-shows-the-wrong-bit-depth-of-some-m4a-alac-from-itunes-apple-music/68463/1 "2025-05-11T06:32:54Z")

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Both ALAC and FLAC the same file, they are identical. Flac was was obtained from ALAC in EZ Audio Converter 10

_Edit: Removed link to example file_

Media info shows 24 bit of ALAC, mp3 tag shows 16 bit of ALAC. After cverting to FLAC mp2 tag shows 24 bit. It is also strange that the size of flac is less than the size of alac

![2025-05-11-072814](https://community.mp3tag.de/uploads/default/original/3X/3/d/3d2397b0f3bc0429e7ec946a1ed1a666b1395eea.png)

I have few more ALAC files from the same source & label with the same problem if needed for example. Other ALAC files frome this source & label are OK

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### Author: ![LyricsLover](https://community.mp3tag.de/letter_avatar_proxy/v4/letter/l/c6cbf5/32.png) [@LyricsLover](https://community.mp3tag.de/u/LyricsLover)
#### Post date: [May 11, 2025, 9:40am UTC](https://community.mp3tag.de/t/mp3tag-shows-the-wrong-bit-depth-of-some-m4a-alac-from-itunes-apple-music/68463/2 "2025-05-11T09:40:30Z")

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How exactly did you define the column B in Mp3tag that shows 16 for your m4a file?

JFYI: Exiftool also shows 16 for this m4a file:  
 ![image](https://community.mp3tag.de/uploads/default/original/3X/d/a/da90bfb04ce862c3d05eb40630dccfab09b0a724.png)

Mediainfo shows:

 ![image](https://community.mp3tag.de/uploads/default/original/3X/9/0/90f9cef2212340fe294215a61ff3518102cb7eef.png)

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### Author: ![Florian](https://community.mp3tag.de/user_avatar/community.mp3tag.de/florian/32/5759_2.png) [@Florian](https://community.mp3tag.de/u/Florian)
#### Post date: [May 11, 2025, 9:45am UTC](https://community.mp3tag.de/t/mp3tag-shows-the-wrong-bit-depth-of-some-m4a-alac-from-itunes-apple-music/68463/3 "2025-05-11T09:45:53Z")

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> [@LyricsLover](#):
>
> How exactly did you define the column B in Mp3tag that shows 16 for your m4a file?

It's probably just `%_bitspersample%`

The file headers state `16` as sample size, after copying to a new file via

`ffmpeg -i input.m4a -codec copy output.m4a`

the `output.m4a` also shows 24 bits. It's probably an error in creating the file. Other tools might decode parts of the file to obtain actual sample size.

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### Author: ![viviancels](https://community.mp3tag.de/letter_avatar_proxy/v4/letter/v/bbe5ce/32.png) [@viviancels](https://community.mp3tag.de/u/viviancels)
#### Post date: [May 11, 2025, 11:48am UTC](https://community.mp3tag.de/t/mp3tag-shows-the-wrong-bit-depth-of-some-m4a-alac-from-itunes-apple-music/68463/4 "2025-05-11T11:48:46Z")

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> [@LyricsLover](#):
>
> How exactly did you define the column B in Mp3tag that shows 16 for your m4a file?

Bits сolumn %\_bitspersample%  
I think metadata in files m4a (ALAC) in itunes store is corrupt

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### Author: ![system](https://community.mp3tag.de/uploads/default/original/2X/c/ce7035d426cb755a7916793326d23b465222a407.png) [@system](https://community.mp3tag.de/u/system)
#### Post date: [June 10, 2025, 11:49am UTC](https://community.mp3tag.de/t/mp3tag-shows-the-wrong-bit-depth-of-some-m4a-alac-from-itunes-apple-music/68463/5 "2025-06-10T11:49:08Z")

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