[Matroska-devel] Re: Re: Re: Tag names

Paul Bryson paul at msn.com
Mon Mar 15 18:39:09 CET 2004

"Age Bosma" wrote...
> Paul Bryson wrote:
> Ok, cool, please keep me informed of any other changes being made to
> your file later on.

Can do.

> > I'm pretty sure that Matroska is supposed to have a Beats Per
> > Minute tag.  Is there a common one that fb2k currently stores?
> I don't know about a foobar field being used for this. Let's hope more
> people will respond in the forum thread. Maybe we should notify peter
> about the thread?

It looks like Steve wanted two fields.  From 04/14/2003:

<robUx4> anyway what is needed is the BPM and a BPM Quality value (percentage)

<robUx4> some better DJ programs might have more sophisticated things

<robUx4> (different BPM in different sections of a track)

> I think SET_PART is self descriptive enough as it is refering to
> PARTINSET in id3. This can be used for the TRACKNUM info as well because
> it's basically the same.
> Maybe TOTAL_SET_PARTS should be added for the total information.


> >>Also the COMMENT field, this one appears to be left out in Matroska as
> >>well. Imo a comment field should be included. E.g. what if you want to
> >>mark a track being a bonus track of a disc? Or what if the track is
> >>featuring a different artist?
> >
> > There is already a tag labelled "COMMENTS".  If a track features a different
> > artist, then that track should be labelled with that artist.  That
> > shouldn't need to go in the COMMENTS tag.
> In the current specs it's listed under Image Specific which it shouldn't
> if it can be used outside of image info as well, that's why I didn't
> include it in the first place.

Errrr... Thats another error.  The specs right now are a bit messy as they
represent a quick copy/paste job from the old tags specs.  Thats just another
thing that needs to be moved.

> As for the featuring of an artist, I must partially disagree, suppose
> you have the latest Norah Jones album, the artist of that complete album
> is Norah Jones but on one track ("number 07 - Creepen' in" to be more
> specific) Dolly Parton is singing together with her as well. Because
> Norah Jones is the main artist of that album Dolly Parton shouldn't be
> included in the main artist label just for that one song imo.
> On the other hand Dolly Parton could be included in the INVOLVED_PERSON
> label for that one track but I'm not realy sure if this would be the
> best place for it. What I do know is that introducing a new label for
> this kind of information would be overkill.

To me it seems natural to include Dolly in the main artist label for just that
song.  Maybe we have different definitions for these tags?  This is why we need

> > Do you want to some how indicate items that would be nested tags in
> > such as WWWARTIST?
> Sure, although I don't know for sure which field should all be marked.
> I'll dig in the excel file a bit more to see what I can do.

I' afraid that you won't find any more useful information about nested tags in
those Excel files.  They only contain data from the old tag system.  I'll bet
that you could make a pretty reasonable guess as to where it would go though.

> > I want to make some specific examples of how to use certain tags.  For
> > take a movie, and say where to store each piece of data for that movie.
> > take a CD, and say where to store each piece of data for that CD.
> > they would each be part of a large, multi-volume set, containing all of the
> > different levels of titles that could be used.  Do you have any ideas of
what to
> > use for this?
> At the moment no. At least not Matroska specific.

A movie example would probably be Matroska specific as there is not much else in
the way of good movie tagging.  But a CD example should be able to be used for
anything.  The problem that I encountered is that it is difficult to know where
exactly specific pieces of information should be stored.  I spent weeks digging
around in different tagging specs and was still confused by many items, I am
sure that the common users don't have a chance.  I think that that is why so
many files have the wrong tags used everywhere to store information.

If we made a specific example that displayed where each piece of information
should be placed, then I think that would be the most useful document to most
users, with the table then becoming a suplement to that.

> One final thing I would like to get off my chest. I was amazed to see
> how many tags where included in Matroska. I never expected to see an
> attempt to combine all current tags into one system.
> Like mentioned in the thread you pointed to earlier the whole tag field
> stuff should be cleaned up a some stage although I agree in being
> compatible with other tag fields as well. As a step in the right
> direction we could created 2 specs. Something like "Matroska" and
> "Matroska lite" where the first one includes all the tag fields like now
> and the lite version only includes the more usefull and necessary
> fields.

Possibly the "Matroska Common Tags"?

> In the Matroska specs people will be pointed to the lite version
> as much as possible and if realy realy realy needed people can use the
> complete spec of tag fields. What's your opinion about this?

I like it.

Although, you should probably recognize that the Tags system has already been
lightened quite a bit.  Just look at the old system:
You have all of those fields, plus the types.  It turned out to be a lot of code
to use this system, and the sheer number of data fields that could be filled in
was more than overwhelming to anyone.  We ended up dumping the whole system and
moving to the SimpleTags.  It allowed us to remove lots of fields that were made
redundant by the use on nested tags.

While all apps should support reading of all of the tags, writing apps could
remove maybe 1/4 of the fields.  Several of the fields in General would only be
written automatically by applications and never filled in by hand.  ReplayGain
info, and all of the Capture settings under Image Specific would only be filled
in by apps.  The Commercial items probably wouldn't be filled in by end users,
and some of the identifiers would only be filled in by apps.


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