[Flac-dev] Metadata & RDF

[Danny Ayers]

I'm very pleased to come across flac, good work folks!

I would like advice and/or have a spec feature request. Please bear in
mind that I am totally new to the format, apologies if what I describe
has been discussed before.

Basically I'd like to embed arbitrary (meta)data in flac files. For
example, it may be about the audio, but then again it may be about the
creator of the audio, or the creator of the audio's cat, or the price
of fish in Wisconsin (the earlier cases would probably be more
useful).

There's a suitable mature standard in the form of the Resource
Description Framework, RDF (http://www.w3.org/RDF/). This has already
found a fair amount of application around audio - examples include
MusicBrainz and the "enclosure" vocabulary for RSS 1.0. Immediate uses
for flac might include ICRA Content labeling of speech files ("bad
language" etc) and Creative Commons licensing.

But the question is how best to embed RDF (the standard serialization
is an XML format, though there are several others). If I understand
correctly from a quick read of the spec, there are two alternatives:
use an existing Block Type such as Application Block (after
registering an ID) or add a Block Type specific to RDF (types 6-126
are currently reserved).

I vaguely remember some discussion around RDF in Vorbis (I'd
appreciate pointers to references if anyone has any handy), but Vorbis
Comment as listed as a Block Type lacks the flexibility of RDF.

Using an Application Block Type appears to me to be at best a hack -
the data would be far from application-specific, any application that
understands RDF would be able to use/create the data. The latter would
need an addition to the spec. From what I've seen of flac so far I
believe such an inclusion would offer significant capabilities at low
cost (basically enable very flexible metadata handling, and put flac
files on the Semantic Web).

If a new Block type was to be considered, I'd be more than willing to
help in its specification, as I'm sure would plenty of members of the
Semantic Web Interest Group - in fact it may well be in scope for the
W3C's Multimedia Semantics Incubator Group (see
http://www.w3.org/2001/sw/BestPractices/MM/MMXG-proposal.html).

But I am new to flac - maybe there's something I'm missing in terms of
specification or process.

Thanks,
Danny.

-- 

http://dannyayers.com