[matroska-general] Re: Tags

Pamel paul at msn.com
Wed May 28 03:44:38 CEST 2003

"Steve Lhomme" <steve.lhomme at free.fr> wrote...
> * The MultiComment part has a + on the level. Which means it can be
> placed at any level equal to 3 or lower. Is that the case ? If so it may
> be good to explain more in depth the use of this comment you can put
> everywhere and on what it applies.

Yep, thats what it means.  And yes, a better description wouldn't hurt.

> * Abstract  3  [73][00]   -  -  -  UTF-8  Heck if I know, its
> abstract.

This came from APE tags.  I didn't notice it until right now that it is
supposed to contain an HTTP link.  I guess this should be removed, and you
should use "UserDefinedURL" instead(see below).  Sorry about that, I kept
losing the APEv2 specs, and there aren't definitions for APEv1.

> If there is an element noone have a clue about, its place is in the
> trash bin.

I'm inclined to agree.  But, there are some tags that aren't very well
defined in other specs, such as "CaptureLightness".  Sure, the definition is
a little ambiguous, but I copied right out of the RIFF specs.

> * Same applies to SubGenre, OfficialAudioFileURL,
> OfficialAudioSourceURL, PlaylistDelay.

Actually, the whole "Genre" section needs to be cleared up better.  The old
specs page that is linked needs a serious re-vamp.  I like the types Movie,
TV-Series, CG, Home-movie, etc.  But, there same Sub-Types needs to be
listed under each of these.

> * URLs usually apply to the whole stream/segment. Not just one part.

You are right for the OfficialAudioFileURL, but OfficialAudioSourceURL could
be from be for any audio portion of the file.

> In
> this case maybe a Tag with no TrackUID and no ChapterUID could be used.
> Or maybe a TagAll element that would contain elements global to a
> segment (like the SetPart, URLs).

This was already worked out. But, unfortunately I forgot to write in the
specs that you should fill the Track/ChapterUID with zeros to indicate the
tags are global to all Tracks or Chapters.  In this way you can have tags
that are global to all Chapters, but not all Tracks.

> * And why are there secondary genres ? If you want many genres, you can
> put a list or jyst allow the element to be multiple.

I think this is because sometimes a movie is primarily an action movie, but
secondarily a comedy.  It is nice to be able to place priority of one genre
over another.  At least, this is what other tag systems seem to do.

> * ArchivalLocation  3  [45][A4]  -  -  -  UTF-8  Indicates where
> the subject of the file is archived.
> The subject of the file ???

Go here and search for "IARL"

We really really need to support importing all spec RIFF tags.  But, I am
still looking around for a better definition of some of them.  In the mean
time they are included until the definition can be expanded some.  I think
that is probably the worst one.

> * Somes link to the ID3 elements referred would make reading the specs
> easier.

I agree.  Its been on the TODO list for quite some time.  The reason it
hasn't been done is that the latest ID3 specs are in TXT format, so there
aren't any of the anchors like we use in the Matroska specs.  Because of
this we can't link directly to a definition.  I have already copied a few
definitions directly from their specs, but I was still worried about copying
the whole specs to the Matroska site so that we can make it HTML and add
anchors to link to directly.  If you think its okay, I can do this.

> * Contains the number of beats per minute in the main part of the audio.
> This is general.
> General to what ?

To the whole Track(s)/Chapter(s).  The BPM can change in an audio segment,
but this is for the main BPM.  This is another case where linking directly
to the ID3 specs would help.  From the ID3 specs:

 The 'BPM' frame contains the number of beats per minute in the
 main part of the audio. The BPM is an integer and represented as a
 numerical string.

> * All settings related to a digitizer should be grouped. It would be
> great to find other logical groups like this.

I agree again.  I started to group things and then got distracted.  Grouping
is kinda boring.

> * The Encoder can be removed (already in Info and should not be editable).

Probably.  If a WAV PCM is encoded strait to an AAC MKA file with DeDulce,
then the MKA is combined with an MKV to make a new MKV, then:
Encoder for the Audio track is DeDulce
WritingApp is MKVMerge 3.3
MuxingApp is libmatroska 0.4.3

Is that correct, or is having an Encoder tag not needed?

> * Idem for the languages of a Track which is defined in the... Track

I don't suppose that we do.  You are the one that moved the Language
elements back under Tracks and Chapters.  The only use I could think of
would be to specify an entire segment as a language.

> * UserDefinedURL  3  [23][4A]  -  -  -  string  A URL that could
> be anything.
> Then, there should be a list of it, and each item should have a text
> attached.

You mean like a MultiURL?  This is from the ID3 tags.  I think it is
probably not needed now since we have MultiComment, and you can use that to
define custom tags.

> * URL of the entity. It appears in many MultiXXX elements. What is the
> difference between the URL of a title and the URL of a legal entity ?
> Idem for the Address.

Its not a very good definition on the MultiLegal URL.  Its a copy and paste
thing.  I'm sure you've run into it before.  A legal URL might have a link
to where the text of the legal document can be found online.  The Title URL
would have a link to a page for that Title, like the Movie site, or a page
specific for that song.

> I prefer to let you know before I make the changes, because you may have
> other ideas.

Since when have we ever disagreed.  :P



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