[vorbis] RDF Metadata Specification

Monty xiphmont at xiph.org
Tue Aug 8 23:33:25 PDT 2000

On  2 Aug, Ralph Giles wrote: 
> Um, you haven't made very extensive use of the Dublin Core. The point
> there is to use a standardized, cross-discipline set of elements so
> a search engine/catalog can understand the metadata to the largest extent
> possible *without* having been programmed with the specifics of our 
> format. Our metadata should be able to "dumb-down" to the DC subset
> just by ignoring all the unknown elements.
> Particularly, using qualifiers I think it's possible to describe a lot of
> the metadata you've invented tags for within DC. Not as easy for the
> uninitiated to read, unfortunately, but IMO better. 

After some reflection I agree completely -- to cover your last point,
I've added a 'ID3 -> MM' cross reference at the end of the document to
give people a shortcut in figuring out why there isn't an MM:Artist type
and issues like that.

> MM:Artist -> DC:Creator
> MM:Contributors -> DC:Contributor
> MM:Duration and MM:Size -> DC:Format (with extent or custom qualifiers)
> MM:Set, PartOfSet, PartsInSet -> DC:Relation (standard qualifiers)
> MM:Album, MM:Track -> DC:Relation (custom qualifier)
> MM:ReleaseDate -> DC:Date (standard qualifier)
> MM:*Info -> DC:Description (custom qualifiers)
> MM:Copyright, Trademark, Licensee, TermsOfUse, Signature -> DC:Rights
> (custom qualifiers, but we probably want to standardize these)
> MM:CDID, ISRC, UPC -> DC:Identifer (custom qualifiers)
> (all the database keys probably go here too)

I've taken most of your suggestions into account and created an updated
version of the spec. This one has only a handful of new elements and a
bunch of new qualifiers.
> Pretty much we want anything that shows up in movie credits. Something
> open-ended under Contributor makes sense to me. The list cab be
> staggering; I can work up something semi-comprehensive-for-today if that
> will help.

I've come up with an initial canonical list -- please check it out and
let me know of others that should be added.

>> We may want to define a Ogg specific RDF vocabulary to be used in
>> conjunction with the MM vocabulary. This vocabulary could then be used
>> to specify format/layout of the timecoded/interleaved 'chunks' as we
>> were discussing earlier.
> I'm not sure what you mean here, but agree we probably want some
> Ogg-specific vocabulary. :-)

In particular we may want to create an ogg specific RDF namespace that
defines the stream definition issues that still need to get resolved.

> My current model is to have each datatype in a separate substream
> (logical bitstreams interleaved into the physical steam), including a RDF
> header that holds both "kitchen-sink" metadata and a description of each
> substream.

Makes sense to me.

> So what I envision is you have elements describing "the whole thing" among
> whom are DC:Relation elements that point to each substream, each of which
> can have their own specific metadata, but also important things for the
> player like "this is the primary audio track downmixed to r+l stereo and 
> vorbis encoded" or "this is a mng stream containing the pop-up-video-esque
> annotative overlays in Telegu". I'd been thinking to us "#" as the URI for
> the whole file and "#stream-id" for each of the substreams. In a server
> index, those could be replaced, for example, with stream or download urls.

Sounds good -- do you want to take a stab at defining these

> The plan is to support mng (libmng.com, libpng.org/pub/mng/) as the first
> graphic substream type, and use it for slideshows, associated still image
> collections, graphic overlays for the eventual video codec, and as a
> primary video format for source/editing and animation. This would be an
> entirely separate logical bitstream, interleaved with the audio (if any)
> on equal footing. mng files can have an embedded presentation timestamp,
> which the player would use for synchronization with the audio where
> that's desired.

Good -- this sounds like it does not require any further changes to the
RDF stuff, right?

- --ruaok         Freezerburn! All else is only icing. -- Soul Coughing

Robert Kaye -- robert at moon.eorbit.net  http://moon.eorbit.net/~robert

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