[F] Unknown MP4 atoms are deleted on save

Hi Florian,

I hope you enjoyed your vacation, and am sorry to be PMing you... But I'm facing somewhat of a big issue... :frowning:

It appears that the following Apple MP4 tags are not seen in MP3Tag (even in extended dialog), and if any changes are made to the MP4 file (even if just clicking "save"), the tags are destroyed! :frowning: :frowning: :frowning:

I have attached an MP4 sample that contains the tags.

rate -->> Rating between 0 and 100 as a text
hdvd -->> HD Video 8-bit integer (boolean)
cnID -->> iTunes Catalog ID, used for combing SD and HD encodes in iTunes 32-bit integer
keyw -->> Keywords Used for Podcasts UTF-8 string

DLNA servers such as Twonky for example, use the "rate" atom to group content.

If you could PLEASE allow us to WRITE the above tags in mp3tag as well it would be great/a life saver... I have half of these files backed-up so I'm not completely up the creek, but I still do need to run the files through mp3tag to modify their value. :frowning:
And this will allow me manually re-enter the lost ones...

Source of information behind the atoms:

Does this problem exist with all tags that MP3Tag doesn't recognize? Would the standard tags found in the attached PDF (Apple's spec for tags) also be deleted?

You can find the entire spec here: http://www.twonkyforum.com/download/file.php?id=554

Thanks for your help in this Florian... It's truly appreciated!

EDIT: This is using the latest 2.46a version.

ED_Attachment.zip (43.8 KB)


The problem is still there with version 2.46b. :frowning:

Yes. Same issue occurs with the CDEC tag added by Nero, see here.

It was classified as fixed, but it's not.

Can a moderator please add the [C] (confirmed) or [AF] (awaiting feedback) tag to this thread?


Is Florian okay?
It's been a month for most items in the bugs forum, and no responses...

I'm waiting with baited breath to fix my files. :frowning:

I'm alive :slight_smile:

However, I have a lot to do in my real life, so free time for Mp3tag is currently limited. Stay tuned :music:

Hi Florian,

Thanks for adding:


in Version 2.46c.

However, This version still doesn't show the "rate" atom (even in the Extended Dialog), and STILL deletes the atom if you "Save" within mp3tag.

Can you please fix this issue, and allow the ability to write it as well so that I can fix my files?

If you set the ITUNESHDVIDEO to 0 (zero) and save, the value is saved to the file. Refresh mp3tag (or close mp3tag and add the file again), and open the extended tag dialog, and the tag is not there (even though it WAS written to the file).

If you save the file, the hdvd atom is deleted.

There is something very wrong with mp3tag's behavior of mp4 tags.

One more month passes... One more version passes: Version 2.46d

Behavior is EXACTLY the same as what I described in the above post. Both in terms of "rate" atom, as well as the ITUNESHDVIDEO issue when set to 0.


What do you need ITUNESHDVIDEO=0 for?
Isn't it the same as a missing ITUNESHDVIDEO tag?

Hi Dano,

It's a bigger issue than just that I'm afraid... For example see the post higher up, noting that CDEC is deleted...

Another example is the "rate" box... There appears to be an issue where MP3Tag does not read "unknown" first level atoms (read: not itunes styles). This means that if you open the file containing such as tag, and save it, the unread tags are destroyed.

This ITUNESHDVIDEO issue appears to be a play on the above, as MP3Tag does write the "0" value to the file (as shown by mediainfo), however, if you close and re-open MP3Tag, the tag is NOT visible within mp3tag, and saving the file does not write the tag back (as again, checked by mediainfo).

(Note, when I say visible, I mean even within the "Extended Tags" dialog).

I lost hundreds of my "rate" tag due to this bug, and I've been begging Florian to allow that tag to be written so that I can automate it... I'm afraid nothing yet. :confused:

I know all the issues, my question was only what's the use of ITUNESHDVIDEO=0

:slight_smile: For that specific case, no difference. Just stating the issue. :slight_smile:

Still an issue with "e" version.

Bump, as the issue is still present in 2.48.

Tags that are not recognized by MP3Tag are destroyed upon a save (also see this reported here: /t/10052/1

Also, Florian, can you please add first level atom "rate" mp4 (similar to cprt atom) to allow me to reverse the damage cause by the destruction of the tag? I've been waiting 6 months to fix my files. :frowning:

what is cprt?

what app is allowing you to write ratings to mp4? itunes unwisely doesn't seem to support writing ratings to tags. i am trying to get winamp to do this for mp4, so as much info about "rate" and cprt and apps that support them like twonky would be appreciated.

"cprt" is the copyright atom for mp4. mp3tag can write this using the attribute "COPYRIGHT"

"rate" is the ratings tag. The program that I use which uses it is Twonky Media Server. I'm waiting for florian to fix a bug that causes this atom to be deleted if it exists in mp4 files, and hopefully for florian to be kind enough to allow this tag to be written by mp3tag so that I can fix the files that lost the tag.

Note that itunes doesn't write (or read) ratings tag from the file. It always stores it in its database.

Recent versions of atomic parsely support writing this tag, but you have to compile from source, and do one file at a time. :confused:


thx for the info, i shared it with the winamp devs, so maybe they will implement it as well. i def hope mp3tag does too, and as with winamp, i always suggest any app ignore a frame it doesn't understand, rather than delete it. i am still confused as to why mp3tag "reorders" mp4/atom data.

i wonder how or why twonky got into supporting such a non-standard frame? i doubt too many folks out there are compiling parsley code. can twonky write ratings to the file?

Updated to 2.48b... still same issue...

Florian, can you please add first level atom "rate" for mp4 (similar to cprt atom) to allow me to reverse the damage cause by the destruction of the tag? I'm approaching a wait of 9 months to fix my files that had the first level 'rate' atom deleted incorrectly by mp3tag. :frowning:

Still an issue with 2.48d

Hi edrikk,

thanks for your patience (and all the others who are reading here too). I really want to get this fixed (preferable by keeping unknown atoms) but unfortunately fixing this is far from trivial. I've started working on this and hope to have a working solution over the next weeks.

Kind regards