[vorbis] Metadata format.

[Ralph Giles]

On Fri, Oct 17, 2003 at 05:35:14PM -0500, Graham Mitchell wrote:

> By "XML-like", you just mean "structured".  Which is certainly a good idea, 
> and most probably a requirement.  And you probably also mean 
> "human-readable", which I agree is worthwhile even if getting at the 
> human-readable stuff isn't easy.  Like it's nice to occasionally be able to 
> gunzip an Open Office file and get pure ASCII.

I'm not sure human-readable is much of a priority; the primary 
requirements for this are machinablility and kitchen-sinkfulness.
Not that any of that discounts the standard advantages of employing
standards and ease of accessibility in format design. Both of which
are generally claimed to be motivations of XML, for what it's worth.

Anyway, RDF is a perfectly reasonable model for our purposes here, and 
the Dublic Core metadata scheme provides a nice foundation for 
interoperability. It's a pity the serialization schemes for RDF are all 
so bad.

No one's brought up musicbrainz(.org) in this particular iteration of 
the discussion. They've been way out front in designing a reasonable 
metadata system for music, and it is based on RDF. Dumping the xml 
serialization of same in an Ogg logical bitstream would certainly solve 
the 'I just want a comprehensive lump at the beginning' problem.

It's not perfect, and there are some things like lyrics and cover art 
that would be better off in their own parallel bitstreams in an ogg 
adaptation. However, the main reason we didn't adopt it wholesale is 
that they've expressed a lack of interest in supporting film metadata, 
which I felt was a requirement for a general ogg implementation. Film 
unfortunately has the 'guest musician on instrument foo' problem in 
spades. Pity the imdb isn't an open project any more.

Metadata is a hard problem, and machinable metadata much more so.

Personally, I've been quite happy with stuffing enough data in the 
vorbis comments to track down the original source (e.g. CDDBID and 
TRACKNUMBER) and keeping the cover art and lyrics in separate files in 
the same directory as the rest of the album. Streaming (and file 
trading) are really the only places where a solution more complicated 
than segher's is needed. 

FWIW,
 -r
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