# MP4 'Encoding Params' tag lost after save with v3.33.1
**URL:** https://community.mp3tag.de/t/mp4-encoding-params-tag-lost-after-save-with-v3-33-1/70928
**Category:** Fixed Bugs
**Tags:** bug-fixed
**Created:** [March 22, 2026, 4:22am UTC](https://community.mp3tag.de/t/mp4-encoding-params-tag-lost-after-save-with-v3-33-1/70928 "2026-03-22T04:22:18Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@elis](https://community.mp3tag.de/u/elis)
#### Post date: [March 22, 2026, 4:22am UTC](https://community.mp3tag.de/t/mp4-encoding-params-tag-lost-after-save-with-v3-33-1/70928/1 "2026-03-22T04:22:18Z")
Since the update from v3.33 to v3.33.1 (and also occurring in v3.34beta6), the ` ----:com.apple.iTunes:Encoding Params` tag (set by iTunes when encoding a file) is removed when saving an MP4 file if the 'Reuse unmodified MP4 atoms' option is **not** enabled (the new default with v3.33.1).
Since this tag are usually informational/read-only and aren't displayed anywhere in Mp3tag (as far as I know), I assume it's just an oversight? I only noticed as iTunes had stopped listing affected files as VBR.
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### Author:  [@ohrenkino](https://community.mp3tag.de/u/ohrenkino)
#### Post date: [March 22, 2026, 7:26am UTC](https://community.mp3tag.de/t/mp4-encoding-params-tag-lost-after-save-with-v3-33-1/70928/2 "2026-03-22T07:26:58Z")
I am not sure that I understand:
MP3tag keeps the data if you tell it to do so.
Removing unsupported fields/atoms was the default behaviour before and there was only a very short intermezzo when this did not happen - but which caused other problems that apparently present information did not get picked up by standard-compliant programs.
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### Author:  [@Florian](https://community.mp3tag.de/u/Florian)
#### Post date: [March 22, 2026, 9:28am UTC](https://community.mp3tag.de/t/mp4-encoding-params-tag-lost-after-save-with-v3-33-1/70928/3 "2026-03-22T09:28:25Z")
I forgot about encoding params and how iTunes needs this to report the details of a file. Sorry for that! I'll try to preserve the data with both **Reuse unmodified MP4 atoms** enabled and disabled for the next version.
> [@ohrenkino](#):
>
> Removing unsupported fields/atoms was the default behaviour before and there was only a very short intermezzo when this did not happen - but which caused other problems that apparently present information did not get picked up by standard-compliant programs.
This was the default behaviour for ID3v2-based file types. MP4 tags tried to reuse unsupported atoms for quite some time and it was only streamlined with the newly introduced settings to behave consistently with ID3v2 tags. Looks like there is no ideal solution for this (cf. also, the `Xtra` ratings from Windows Explorer, which we discussed recently).
And it turns out that you've observed the same behaviour reported here already a few weeks ago:
> [@Bitrate value changes incorrectly after saving tags on m4a files](https://community.mp3tag.de/t/bitrate-value-changes-incorrectly-after-saving-tags-on-m4a-files/70725/2):
>
> I find it much more alarming that the information about VBR is lost. Could it be that this particular file is broken?
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### Author:  [@Florian](https://community.mp3tag.de/u/Florian)
#### Post date: [March 25, 2026, 10:33am UTC](https://community.mp3tag.de/t/mp4-encoding-params-tag-lost-after-save-with-v3-33-1/70928/4 "2026-03-25T10:33:17Z")
This should be fixed with [Mp3tag v3.34-beta.7](https://community.mp3tag.de/t/455). Thanks for reporting!
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### Author:  [@elis](https://community.mp3tag.de/u/elis)
#### Post date: [March 29, 2026, 1:34am UTC](https://community.mp3tag.de/t/mp4-encoding-params-tag-lost-after-save-with-v3-33-1/70928/5 "2026-03-29T01:34:26Z")
Can confirm it’s fixed for me with beta 7, many thanks!
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### Author:  [@system](https://community.mp3tag.de/u/system)
#### Post date: [April 12, 2026, 1:35am UTC](https://community.mp3tag.de/t/mp4-encoding-params-tag-lost-after-save-with-v3-33-1/70928/6 "2026-04-12T01:35:02Z")
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