[F] Replay Gain Values for M4a Files Not Shown in 2.83d

I am using Windows 7 and was using Mp3tag 2.83d. It's been some months since I had occasion to look at replay gain values in Mp3tag so I can't say exactly when the problem started. However, I have lost the ability to display both track and album replay gain values for M4a files.

I use Winamp to calculate and save track replay gain values. These show up in Winamp's File Info dialog but not in Mp3tag 2.83d. Now both the tag panel and the list column show nothing. By contrast, my Mp3 files always display replay gain values as expected. I did not test any other file types.

When I ran the view filter expression %replaygain_track_gain% PRESENT AND %_extension% IS M4a it showed no such files in any of my music folders, whereas in fact virtually all my M4as do have replay gain values.

I tried reinstalling 2.83d from the latest download. At first, I thought this worked as I could suddenly see the missing replay gain values. However, after a reboot all M4a replay values disappeared again! At this point, I was rattled and confused.

At my wits end, I decided to reinstall an earlier version of Mp3tag (2.77). I chose this one only because I had a copy on hand. It worked! All my M4a replay gain values are now shown. The view filter expression that I quoted above now returns 1604 files. Whew!

This bug disrupts my workflow because I select files to be processed for replay gain by using a view filter that only shows files that lack values for %replaygain_track_gain%. I then create a playlist from those files that I open in Winamp, which does the rest of the work.

This is one of the rare bugs that I have encountered with Mp3tag. In other respects, I would call this program a triumph of German engineering! I really don't know what I would do without it.

New Jersey, USA

Hello Doug,

thanks for your report and the praise for Mp3tag :slight_smile: Glad you like it!

I've just checked the filter expression with a set of M4A files that have ReplayGain information added (via foobar2000) and it works as expected.

Would you install the latest version and then inspect the files via the extended tag dialog at Alt+T and see whether the ReplayGain fields are indeed not present?

Kind regards
– Florian

Hello Florian,

You are quite welcome.
I just installed the latest 2.83 beta "e" version and all is well! The view filter expression now shows my M4a files and the extended tags dialog looks normal. Rebooting the PC did not cause the problem to recur. So it was the "d" version that was problematic for me.


Sorry, Florian, I spoke too soon. The problem is back but is slightly different this time. Now older M4a files with track replay gain do show the values in Mp3tag, but not files that I just processed and saved with Winamp. Refreshing the view and/or rebooting did not help.

Linked below are two M4a files that you can download and examine. OlderM4aFile.m4a displays the track value in Winamp and in Mp3tag, both in the columns and in the extended tag dialog. NewerM4aFile.m4a displays the track value in Winamp and in Mp3tag 2.77 but not anywhere in my installation of 2.83e.


Both files had replay gain added in the same way via Winamp's Send To / Calculate Replay gain feature. I repeated the process for the newer file just to ensure that I was not doing something wrong.

After I reinstalled Mp3tag 2.77 all the missing replay values reappeared, both in the list and in the extended tag dialog.

If there is any other info you need, please don't hesitate to ask.



Hello Doug,

thanks for the thorough description of the issue and the two test files. With Mp3tag v2.83, I've implemented a change where custom non-iTunes MP4 tags were no longer displayed but preserved during tag rewrites. I didn't realize that AACGain (and Winamp) used a non-iTunes format for storing ReplayGain tag fields.

I've now rewritten the MP4 tag reading/writing so that custom non-iTunes MP4 tags are also visible in Mp3tag and rewritten in their original format :slight_smile:

You can test the new implementation with the current Development Build Mp3tag v2.83f.

Kind regards
– Florian

Thank you, Florian! I used Winamp to apply replay gain to several groups of M4a files and the values showed up in 2.83f as expected, all except for 20 of 24 tracks from one CD. That's only 20 missing out of about 2000 M4a files. Below is a download for one of those "nonconformist" M4a tracks. It should show a track gain value of -3.02 dB:


I did more tests to try to understand what was happening. I downloaded some "fresh" Flac files that had no tags and applied replay gain to four of them via Winamp before converting the files to M4a. I had never tried this before. The M4a files play in Winamp but the replay gain tags were lost after conversion (perhaps this is normal and it is not a problem for me). However, after applying replay gain to those four M4a files they all show the replay gain values in 2.83f . So far so good.

Then I put the same Flac downloads into another folder, removed all tags via the file menu, converted them to M4a, and then applied tags via Mp3 tag and replay gain via Winamp. This is my normal sequence except that I don't normally remove all tags before conversion. The results were perfect - all tags including replay gain were shown.

So we only have the mystery of my 20 M4a tracks whose replay gain values are invisible in 2.83f. I can certainly live with that because those files are fine in all other respects and they cause me no inconvenience whatsoever. But I thought that you should know about them. I did not keep the source Flac files for those tracks so I cannot test the source.

Best regards,


Hello Doug,

can you try the latest Development Build Mp3tag v2.83g and check whether those mystery files are now also correctly reported?

Kind regards
– Florian

Done, Florian! Now ALL my M4a files show replay gain values in version 2.83g.

Thank you and best regards,


Great! Thanks Doug :slight_smile:

Kind regards
– Florian

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