# MP4 tags mappings change?
**URL:** https://community.mp3tag.de/t/mp4-tags-mappings-change/3903
**Category:** Support
**Created:** [October 15, 2006, 1:51pm UTC](https://community.mp3tag.de/t/mp4-tags-mappings-change/3903 "2006-10-15T13:51:16Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@FauDrei](https://community.mp3tag.de/u/FauDrei)
#### Post date: [October 15, 2006, 1:51pm UTC](https://community.mp3tag.de/t/mp4-tags-mappings-change/3903/1 "2006-10-15T13:51:16Z")
Hi Florian, great tool...
...and of course, I do have a quiestion:
I use mp3tag to fill wavpack files with AMG web source data, copy the tags of those wv files and paste them to m4a (MP4, Nero) files. Wavpack files already have ReplayGain information in them before adding AMG data with mp3tag.
Now, everything worked well with 2.36d, but something changed with 2.36f and 2.36h. For example, a when you copy those tags from a .wv file:
ALBUM = Best of Bowie
ARTIST = David Bowie
COMMENT = UK compilation
COMPOSER = Bowie
CRC = B99981BE
DISCNUMBER = 1
FREEDB = 0B125613
GENRE = Rock
PUBLISHER = EMI
REPLAYGAIN\_ALBUM\_GAIN = -6.36 dB
REPLAYGAIN\_ALBUM\_PEAK = 0.992188
REPLAYGAIN\_TRACK\_GAIN = -6.31 dB
REPLAYGAIN\_TRACK\_PEAK = 0.992065
STYLE = Pop/Rock, New Wave, Singer/Songwriter, Hard Rock, Album Rock, Glam Rock, Prog-Rock/Art Rock, Experimental Rock, Proto-Punk, Blue-Eyed Soul
TITLE = Starman
TOTALDISCS = 2
TOTALTRACKS = 39
TRACK = 6
YEAR = 2002
...and paste them into .m4a file - you get m4a file with those tags:
ALBUM = Best of Bowie
ARTIST = David Bowie
COMMENT = UK compilation
CRC = B99981BE
DISC = 1
FREEDB = 0B125613
GENRE = Rock
PUBLISHER = EMI
STYLE = Pop/Rock, New Wave, Singer/Songwriter, Hard Rock, Album Rock, Glam Rock, Prog-Rock/Art Rock, Experimental Rock, Proto-Punk, Blue-Eyed Soul
TITLE = Starman
TOTALDISCS = 2
TOTALTRACKS = 39
TRACK = 6
WRITER = Bowie
YEAR = 2002
...so apparently, COMPOSER has become WRITER and DISCNUMBER has become DISC, which is not a big problem - more like an annoyance because if you copy the same tags to a mp3 file they translate to tags with the same name, and therefore you have to be careful which tagname you use with which filetype.
But REPLAYGAIN tags are not copied any more.
Now to the question(s):
Is described change in MP4 tag mappings expected change? If it is then why? ...and the main question - why REPLAYGAIN tags are not copied any more to the MP4 files?
Thanks in advance for your answer,
```
V3
```
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### Author:  [@Florian](https://community.mp3tag.de/u/Florian)
#### Post date: [October 28, 2006, 12:36pm UTC](https://community.mp3tag.de/t/mp4-tags-mappings-change/3903/2 "2006-10-28T12:36:28Z")
They're copied to the file but are not visible as user-editable tag fields anymore.
You can view them by adding a new column %\_REPLAYGAIN\_ALBUM\_GAIN% via View \> Columns....
Edit: The mapping change is a bug of course. Thanks for reporting!
Best regards,
Florian
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### Author:  [@system](https://community.mp3tag.de/u/system)
#### Post date: [February 9, 2026, 12:19pm UTC](https://community.mp3tag.de/t/mp4-tags-mappings-change/3903/3 "2026-02-09T12:19:55Z")