[mb-devel] Picard & tag mapping

[Lukáš Lalinský]

On Ne, 2007-08-19 at 10:58 +0200, Vidar Wahlberg wrote:
> On Sun, Aug 19, 2007 at 12:52:32AM +0200, Lukáš Lalinský wrote:
> > On Ne, 2007-08-19 at 00:45 +0200, Vidar Wahlberg wrote:
> >> what's the reason for having one "key" for id3v2/mp4 and another "key"
> >> for ogg vorbis/apev2?
> > 
> > Because it's an existing standard, which applications already do
> > support. I don't know the original reason for defining it this way in
> > the standard, though.
> 
> how widespread is this standard?
> are there any software outside mb that use this standard?

http://www.google.com/codesearch?q=%22MusicBrainz+Artist+Id%22+TXXX
http://www.google.com/codesearch?q=http://musicbrainz.org+UFID

Many Linux players, directly or indirectly (for example via gstreamer,
which automatically reads MB tags). There is a couple of non-MB taggers
that use MB as the data source and save these IDs to the tags. There are
also some Last.fm plugins.

> myself i'd really like to see these keys be the same across as many
> tag-formats as possible.

I personally don't see the reason for this, it will never be identical
across formats. If you working on an application, you would need
specialized tag mapping code for each format, anyway.

> >> "MusicBrainz Track Id" is saved as a UFID frame in id3v2, and a "----"
> >> frame in mp4. now i know the UFID frame is made especially for "unique
> >> file identification" and that the track id fits fair here, but in my
> >> opinion this should just be in a TXXX frame to group it with the other
> >> ids.
> > 
> > No, it should be an UFID frame as it is. The other MB IDs should be in
> > PRIV frames, but it's too late to change that.
> 
> i don't quite agree here, even if the other mb ids were placed in PRIV
> frames it would be inconsistent with mp4.

Hm, why? It would be inconsistent with VC or APEv2 tags, but that's just
because of their limitation (they don't support hidden tags).

> i'm very much a huge fan of KISS, and i'm not talking about the band
> then. while it is "correct" according to the id3v2 standard to place
> such ids in the UFID and PRIV frames, it would imho be less complex to
> put these in TXXX frames instead, as well as more consistent with other
> metadata formats.

I don't know, but I just don't see the advantage of this. There is many
audio formats, many tagging formats and things like this never will be
100% identical everywhere. So I think it's better to use the style that
feels most native and fits to the format best.

(But as I mentioned in the previous mail, I don't think the current
format of saving MB tags is good, It's just that it isn't really
possible to change it without a good reason.)

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