About id3 tagging

JJ_Johnson · December 30, 2005, 10:22am

Are id3v2.3 tag keys always exactly four characters in length, as I see on the following page, or can the keys be longer?

http://www.id3.org/id3v2.4.0-frames.txt

If only four-character tag keys are used, what does Mp3tag do when you add an arbitrary key name (say 'NOTAKNOWNTAG') to an mp3 file? I just tried doing this, and while I can see the tag in Mp3tag, I can't see it in other programs.

Florian · December 30, 2005, 10:29am

Mp3tag creates a TXXX user defined text frame for user defined tag fields. Other programs may be limited to usual fields like artist, album, title, ...

Best regards,
~ Florian

JJ_Johnson · December 30, 2005, 5:22pm

That's what I gathered from the page I linked.

So what exactly is Mp3tag doing when I add the field 'IMADETHISUP' to an mp3 file in which I'm using only v1 and v2 id3 tags (no ape tags)?

When you talk about the standard fields like artist, album, title, etc., you mean the standard id3 fields of TPE1, TALB, TIT2, ... , correct? It's this transparent translation from the common field names shown in Mp3tag to the expected id3 field names (and similarly, fields like TRACKNUMBER and DATE in Flac tags) that confuses me - I don't always know exactly what field name is written to the file.

Sebastian_Mares · December 30, 2005, 5:26pm

Did you read Florian's post? He said that MP3Tag creates a TXXX frames holding the information you entered.

Here is what "REPLAYGAIN_ALBUM_PEAK" looks like (Unicode):

Offset      0  1  2  3  4  5  6  7   8  9  A  B  C  D  E  F

00000050                  54 58 58  58 00 00 00 41 00 00 01        TXXX...A...
00000060   FF FE 52 00 65 00 70 00  6C 00 61 00 79 00 67 00   ÿþR.e.p.l.a.y.g.
00000070   61 00 69 00 6E 00 5F 00  61 00 6C 00 62 00 75 00   a.i.n._.a.l.b.u.
00000080   6D 00 5F 00 70 00 65 00  61 00 6B 00 00 00 FF FE   m._.p.e.a.k...ÿþ
00000090   31 00 2E 00 32 00 33 00  39 00 32 00 37 00 31 00   1...2.3.9.2.7.1.

JJ_Johnson · December 30, 2005, 5:42pm

I see now. Thanks for the explanation, Sebastian. I read the reply, but didn't understand that 'TXXX' was meant to be literal and that it's a special frame for holding free-form field names.

Is it possible to find a list of field name translations that Mp3tag uses for both id3 and Flac (and ogg, if different) field names? The id3v2.3 spec lists quite a few suggested usages, but I suspect that few are in common use. Or can I just assume that only the tags defined in the Tag Panel are considered 'standard' and that all others are considered 'user defined'?

For instance, if I use the field name 'BAND', does Mp3tag use TPE2, as suggested in the id3v2.3 standard, or will it be entered as-is in a TXXX frame?

Sebastian_Mares · December 30, 2005, 6:16pm

Have a look in the help for ID3v2 mapping.
Not sure about FLAC.

Basically, AFAIK, fields that are listed by default in MP3Tag are written in their correspondig ID3v2 frame (BAND, ALBUM, WWWPUBLISHER...). Things you write yourself like "EXCELLENTSONG" are writtem in TXXX frames.

Florian · December 30, 2005, 6:21pm

FLAC uses VorbisComments which are using the plain tag field names (just as the user has entered them) because there is nothing like "frames" with VorbisComments.

Best regards,
~ Florian

JJ_Johnson · December 30, 2005, 6:32pm

Very nice. Thanks once again, Sebastian.

Florian, isn't Mp3tag's TRACK mapped to TRACKNUMBER in Flac/vorbis comments? Also, what about YEAR? Doe it get mapped to vorbis' DATE, or is it left as-is?

When I add a Tags column to my Mp3tag display my Flac files show 'FLAC' tags. I don't have any ogg files, but wondered what they would display. Is tagging behavior for both ogg and Flac be identical in Mp3tag, or is there some distinction between the two?

Florian · December 30, 2005, 6:38pm

Yes - you're right DATE and TRACKNUMBER are used for these fields in almost all applications that support FLAC.

There are differences, but these are implementation details. FLAC's VorbisComments support padding, because Josh (the developer of FLAC) added support for that to libflac.

Best regards,
~ Florian

JJ_Johnson · January 4, 2006, 1:08am

Here's another request. Given that Mp3tag is, above all else, a tagging program, it seems odd that you can't view the actual tag names defined in an audio file.

It's like the other guy that would like to view both id3v1 and id3v2 tags... I can understand that need. It's often critical when working with some applications, and debugging strange problems, to know exactly which tags are defined. As it stands now, it requires another tool, or even a binary editor to see the actual tag names.

My suggestion would be to have a means of switching between 'common' and 'raw' tag names. No 'YEAR' when the real tag is 'DATE', or 'TRACK' when the actual tag is 'TRACKNUMBER'. The same (even more importantly) for id3 tags. Show 'TPE1' instead of 'ARTIST', 'TPE2' instead of 'Band', 'TDAT' for 'DATE', etc. Ideally, this would just be a simple toggle that affects the display.

Florian · January 11, 2006, 6:49pm

Sorry, but this is not planned.

JJ_Johnson · January 11, 2006, 7:08pm

Can you recommend a good tag viewing program, since Mp3tag doesn't have the ability to view actual tags within files? Some program other than a binary editor.

Thanks.

Florian · January 11, 2006, 7:16pm

No.

While I find it quite interesting to see which program uses what keys/frame ids internally, I never needed a special tagger for that (I was about to suggest a hex editor ). I know that you've already seen the list of tag field mappings. Maybe extending this list would do the job too.

Best regards,
~ Florian