[F] .M4a causes major issues

This bug applies to MP3tag V 2.32 and V 2.32a.

.M4a files are detected by the program but not handled correctly..


Changing an element of a files tags will randomly erase other elements.

For example changing the title will remove the track number and year.

Changing the track number removes the title.

This applies to all functions in the application such as:

   Manually changing tag information for .M4a files in the list or Tag Panel.

   Using FreeDB to select and change file names automatically.

   Using any of the Convert menu functions.

   It applies to changes of multiple or single files.

For many of the functions the results are hit and miss with tag data getting lost at random or simply not getting saved at all.


Change the file extensions to .AAC.
As soon as this is done all of the above symptoms are corrected.

Sorry, but I can't reproduce this. Tagging M4A files works as expected here. Can you send me a test file?

Does anyone experiences the same problems as chrisleeuk?

Don't do this. This would add APEv2 tags to your files, which has absolutely nothing to do with the MP4 container.

Best regards,
~ Florian

Ok, I think I have the answer...

(1) I try the application on a .m4a file created in itunes (for example using convert to AAC). Changing tags in Mp3tag works fine.

(2) Some of the other files were created using dbpowerAmp Music Converter. Specifically the following codec .m4a (FAAC CLI). THESE FAIL as above.

So it looks like the encoding method.

I am using Quality 70 VBR.

I am going to email you a file that does not work and is encoded in this way.

Incidentally if I should not be using this codec or Variable Bit Rate could you let me know the reasons why not. VBR seems to give me more bang for my buck in terms of quality and file size than regular itunes.

Still I really want to use Mp3tag as I have a lot of Audio CD's to get on my new Ipod. :smiley:

Further Testing...

It appears to be a problem related to Variable Bit Rate files.

After some research I have found out that Nero also support Variable bit Rate.

The file names output at .mp4 but as I understand it this is the same format at .m4a but with a different extension.

I started out with an MP3 file. I then encoded it twice, with the following settings and results.

(1) Scenario A - Variable Bit Rate file

 Format:       Variable Bit Rate 90-100kbs, Low complexity AAC
 Output File:  FileA.mp4
 Result:        MP3Tag fails to save tag data and has symptoms described above.

(2) Scenario B - Constant Bit Rate file

 Format:       Constant Bit Rate 64kbs, Low complexity AAC
 Output File:  FileB.mp4
 Result:         MP3Tag works fine with all tags saved correctly.

All .mp3 tags are getting handled correctly although I don't have any VBR mp3 so I dont know if any issues will relate to this.

Hope this helps.


Since I'm reworking the whole MP4-part for the upcoming Unicode capable next version of Mp3tag, I'll adress this issue.

~ Florian

No problem, thanks for the quick response.

I have got a kind of work around, as a short term thing using lossless transcoding.

I extract my CD's as monkey audio a lossless codec. Then I can tag without issues in MP3Tag. I then convert the monkey audio file into the finished VBR .M4A format which carries all the tag information into the finished file.

Sounds a lot of work but it is mostly automatic with dbpoweramp and I don't actually change the quality of the music until I switch to .m4a.

Basically I am just using monkey audio to give me a lossless format that I can tag.

Good luck with the fixes.


i have exactly the same problem with my m4a files. the only difference is that i rip them in winamp. please tell me if you need an offending file.

a fix and especially unicode support will be greatly appreciated since mp3tag is THE solution to masstagging media files! :sunglasses:

thanks & greetings from switzerland!

I can do the same with Wavepack files which tag beautifully prior to converting to cbr m4a.
After which, running any conversion or changing say the date field, causes MP3Tag to act in a very peculiar manner.

edit I'm using version 2.32

Didn't Florian say that the bug is confirmed and that a fix will be delivered after the unicode version of MP3Tag is available? <_<

Very sorry!
I misguidedly thought that I was confirming that the "bug" was manifesting itself in cbr files.
I understood that the other posts referred to vbr files.....

Ah, my bad. :blush:

No intention to increase the confusion here further. :wink:

I just want to add that MPEG4-AAC ripping into MP4 containers (.m4a extension) works beautifully in all recent Mp3tag versions with a combination of Exact Audio Copy, NEncode and Ahead's Nero Digital (also in VBR mode!). So maybe this is useful information for you.

petit prince

All these issues should be fixed with the current Development Build now :slight_smile:

Best regards,
~ Florian

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