# Problem with numeric values in MOVEMENT field in M4B files
**URL:** https://community.mp3tag.de/t/problem-with-numeric-values-in-movement-field-in-m4b-files/71627
**Category:** Support
**Created:** [July 17, 2026, 3:39pm UTC](https://community.mp3tag.de/t/problem-with-numeric-values-in-movement-field-in-m4b-files/71627 "2026-07-17T15:39:46Z")
**Posts on this page:** 15
**Page:** 1
### Author:  [@FatuousJeffrey](https://community.mp3tag.de/u/FatuousJeffrey)
#### Post date: [July 17, 2026, 3:39pm UTC](https://community.mp3tag.de/t/problem-with-numeric-values-in-movement-field-in-m4b-files/71627/1 "2026-07-17T15:39:46Z")
In 3.35.1 and 3.36-beta.2 a fully numeric value in the MOVEMENT field is immediately rounded down to the nearest integer. This didn't happen in older versions, but I can't pinpoint in which version problem was introduced. Values containing non-numeric characters are not affected, with the exception that any value that can represent a numeric value (ex -1.6) do have the problem.
Examples:
- 1.6 -\> 1
- -1.6 -\> 65535
- a1.6 -\> a1.6
- a-1.6 -\> a-1.6
- 1.6a -\> 1.6a
- 1.6 a -\> 1.6 a
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### Author:  [@ohrenkino](https://community.mp3tag.de/u/ohrenkino)
#### Post date: [July 17, 2026, 3:45pm UTC](https://community.mp3tag.de/t/problem-with-numeric-values-in-movement-field-in-m4b-files/71627/2 "2026-07-17T15:45:10Z")
In my installation MOVEMENT stays as entered:
Where do you see this change?
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### Author:  [@FatuousJeffrey](https://community.mp3tag.de/u/FatuousJeffrey)
#### Post date: [July 17, 2026, 3:53pm UTC](https://community.mp3tag.de/t/problem-with-numeric-values-in-movement-field-in-m4b-files/71627/3 "2026-07-17T15:53:04Z")
3.35.1 and 3.36-beta.2
When I change the value in the Extended Tags dialog it appears to work but when I close and return to the tag panel/file list the value changes to an integer. Opening the extended tag dialog again shows that the value has truly been modified to an integer. If I edit directly in the tag side panel or the file list I see the modification happen instantly.
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### Author:  [@ohrenkino](https://community.mp3tag.de/u/ohrenkino)
#### Post date: [July 17, 2026, 3:58pm UTC](https://community.mp3tag.de/t/problem-with-numeric-values-in-movement-field-in-m4b-files/71627/4 "2026-07-17T15:58:52Z")
Sorry, I cannot reproduce it with these steps either.
I just created a new field for MOVEMENT:
Closed and restarted MP3tag and the result stays the same.
Could you please check the definition for that object?
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### Author:  [@LyricsLover](https://community.mp3tag.de/u/LyricsLover)
#### Post date: [July 17, 2026, 4:09pm UTC](https://community.mp3tag.de/t/problem-with-numeric-values-in-movement-field-in-m4b-files/71627/5 "2026-07-17T16:09:53Z")
> [@FatuousJeffrey](#):
>
> If I edit directly in the tag side panel or the file list I see the modification happen instantly.
Is this rounding specific to a particular music format, such as MP3?
In my tests using your values, I cannot reproduce this behaviour.
1.6 remains 1.6
-1.6 remains -1.6
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### Author:  [@FatuousJeffrey](https://community.mp3tag.de/u/FatuousJeffrey)
#### Post date: [July 17, 2026, 4:13pm UTC](https://community.mp3tag.de/t/problem-with-numeric-values-in-movement-field-in-m4b-files/71627/6 "2026-07-17T16:13:38Z")
FYI...It only happens when the field is saved. When I save changes made in the tag panel or when I move from a field in the file list.
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### Author:  [@LyricsLover](https://community.mp3tag.de/u/LyricsLover)
#### Post date: [July 17, 2026, 4:27pm UTC](https://community.mp3tag.de/t/problem-with-numeric-values-in-movement-field-in-m4b-files/71627/7 "2026-07-17T16:27:18Z")
> [@ohrenkino](#):
>
> Could you please check the definition for that object?
@FatuousJeffrey
Please show us your definition of `MOVEMENT` in the Tag Panel.
And please show us a screenshot of Alt + T (View -\> Extended Tags) from a track including such a wrong content like 65535 in `MOVEMENT`.
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### Author:  [@FatuousJeffrey](https://community.mp3tag.de/u/FatuousJeffrey)
#### Post date: [July 17, 2026, 4:32pm UTC](https://community.mp3tag.de/t/problem-with-numeric-values-in-movement-field-in-m4b-files/71627/8 "2026-07-17T16:32:34Z")
I did check the definition and it looks correct, but I just realized it's only happening for M4B audiobook files. It's happening for the MOVEMENTTOTAL field as well, but appears to work as intended for TRACK, TRACKTOTAL, and others. I checked a few MP3 files and all works as expected.
Apologies for not noticing this earlier.
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### Author:  [@FatuousJeffrey](https://community.mp3tag.de/u/FatuousJeffrey)
#### Post date: [July 17, 2026, 4:34pm UTC](https://community.mp3tag.de/t/problem-with-numeric-values-in-movement-field-in-m4b-files/71627/9 "2026-07-17T16:34:07Z")
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### Author:  [@LyricsLover](https://community.mp3tag.de/u/LyricsLover)
#### Post date: [July 17, 2026, 4:38pm UTC](https://community.mp3tag.de/t/problem-with-numeric-values-in-movement-field-in-m4b-files/71627/10 "2026-07-17T16:38:27Z")
Yes, for a M4B I can reproduce the behaviour:
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### Author:  [@FatuousJeffrey](https://community.mp3tag.de/u/FatuousJeffrey)
#### Post date: [July 17, 2026, 4:44pm UTC](https://community.mp3tag.de/t/problem-with-numeric-values-in-movement-field-in-m4b-files/71627/11 "2026-07-17T16:44:28Z")
Obviously as I didn't catch that it was only happening for M4B files I can no longer be certain it was working in prior versions. I have frequently used decimals in this field with no issue, but they may all have been MP3s.
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### Author:  [@LyricsLover](https://community.mp3tag.de/u/LyricsLover)
#### Post date: [July 17, 2026, 4:46pm UTC](https://community.mp3tag.de/t/problem-with-numeric-values-in-movement-field-in-m4b-files/71627/12 "2026-07-17T16:46:57Z")
Such a behaviour can only be fixed by @Florian
So let's wait until he has time to check it.
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### Author:  [@MotleyG](https://community.mp3tag.de/u/MotleyG)
#### Post date: [July 17, 2026, 5:36pm UTC](https://community.mp3tag.de/t/problem-with-numeric-values-in-movement-field-in-m4b-files/71627/13 "2026-07-17T17:36:26Z")
> [@FatuousJeffrey](#):
>
> I did check the definition and it looks correct, but I just realized it's only happening for M4B audiobook files. It's happening for the MOVEMENTTOTAL field as well, but appears to work as intended for TRACK, TRACKTOTAL, and others.
In m4a format files, the fields for TRACK, TOTALTRACKS, DISCNUMBER, and TOTALDISCS are restricted to integer values. I suspect\* this applies to MOVEMENT and MOVEMENTTOTAL as well. Whereas MOVEMENTNAME is a text field and as such open to much more detail.
\*This will need @Florian to confirm.
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### Author:  [@Florian](https://community.mp3tag.de/u/Florian)
#### Post date: [July 18, 2026, 9:23am UTC](https://community.mp3tag.de/t/problem-with-numeric-values-in-movement-field-in-m4b-files/71627/14 "2026-07-18T09:23:00Z")
Yes, it's like @MotleyG is describing. The MP4 writer tries hard to interpret the provided data as 16-bit integer (this is what the `©mvi` atom requires), and when it fails (i.e., the value is a string and not numeric) the field is written as user-defined `MOVEMENT` instead of an MP4 `©mvi` atom to prevent data loss.
* * *
Moving this to #Support
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### Author:  [@system](https://community.mp3tag.de/u/system)
#### Post date: [August 4, 2026, 4:56am UTC](https://community.mp3tag.de/t/problem-with-numeric-values-in-movement-field-in-m4b-files/71627/15 "2026-08-04T04:56:16Z")
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