%_id3v2_unknown_frames% - which are they?

I made a list of frames which are mentioned in the ID3V2 standard but which are not supported by MP3tag:

ID3-Id Description
AENC Audio encryption
COMR Commercial frame
CTOC Table of contents The purpose of "CTOC" frames is to allow a table of contents to be defined.
ENCR Encryption method registration
EQUA Equalization
ETCO Event timing codes
GEOB General encapsulated object
GRID Group identification registration
LINK Linked information
MCDI Music CD identifier
MLLT MPEG location lookup table
OWNE Ownership frame
PCNT Play counter
PRIV Private frame
RBUF recommended buffer size
RGAD Replay Gain Adjustment
RVAD Relative volume adjustment
RVRB Reverb
SYLT Synchronized lyric/text
SYTC Synchronized tempo codes
TDLY Playlist delay The 'Playlist delay' defines the numbers of milliseconds of silence between every song in a playlist. The player should use the "ETC" frame, if present, to skip initial silence and silence at the end of the audio to match the 'Playlist delay' time. The time is represented as a numeric string.
TIME Time The 'Time' frame is a numeric string in the HHMM format containing the time for the recording. This field is always four characters long.
TSIZ Size The 'Size' frame contains the size of the audiofile in bytes, excluding the ID3v2 tag, represented as a numeric string.

I edited the post and made an alphabetically sorted table.
If you would like to have further tokens added, just add a post.


Yes, wherever I referred to the new field I've used " e.g., PRIV or SYLT" which is "for example". It was not meant to be an exhaustive list.

I've made a note on my internal wish list, but it's not very likely to happen anytime soon. Mp3tag's internals have no concept of unsupported fields and this would require a massive re-design of core parts of the app.

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Yes, that is what I thought.
But then I thought that it would add more insight if there were more names so that concerned users might make a more elaborate guess as to what the findings could mean.

E.g. I just stumbled across a set of files with the TSIZ and CTOC frames.

Thank you for the entry on the internal list. Some things just have to mature.

Since the invention of the %_id3v2_unknown_frames% variable I have a column with this.
At the moment it shows me for a lot of files a RGAD-frame and I have not the slightest idea what this means. Obviously it refers to files for which the lyricator-script of Mediamonkey found lyrics. In these cases Medamonkey saves the file and sometimes adds tags, i.e. it reads the lame-header for it's replaygain and creates an ID3v2-tag with the found value.

Does anybody know the meaning of RGAD?

Maybe we could use this thread (or a newly created) to make a list of frames that can come up there and there meanings, als Ohrenkino started here?

RGAD = Replay Gain Adjustment


More detailed informations:

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I finally had some time today to look into removing some of these unknown frames I found in my library. I tried the method from this earlier post and had no success at first using the cut/paste method.

Even when I confirmed I was using the "Cut Tags" tool and not "Copy" the tags were not being removed. I found that this was of course related to my settings for removing ID3v2 not being checked, as typically I don't want this to happen when using the Remove Tags tool. I didn't realize it also affected the Cut Tags tool.

Once I added the check for this option under Remove (all three), the cut/paste option worked and I can confirm the %_id3v2_unknown_frames% were then removed from the selected files as desired. This was an oversight on my part, but hopefully noting it here helps anyone else that is having this issue.


If anyone needs to remove specific unknown frames there is a command line tool GitHub - squell/id3: ID3 mass tagger that can do that


id3.exe -2 -rPRIV -rSYLT track1.mp3

or add it as a tool e.g.