[vorbis] Desirable Properties of a Real Metadata Format

[Oscar Sundbom]

On Fri, 17 Oct 2003 19:14:47 +1000
Moz <lists at moz.co.nz> wrote:

> John wrote:
> > No one has said it had to be streamable. Even if it isn't, how likely is it
> > that stream creators are going to want to pack so much metadata into streams
> > that it matters whether you wait for the whole metadata section or not.
> 
> My suspicion is that streamers will rip out all the metadata and just
> use the existing tags (and probably not many of those). It does seem
> to be the obvious solution.

Perhaps they will, perhaps they won't. Perhaps they want to stream some other data
to their listeners as well. Perhaps ads, a news ticker or something else and for this
create their own metadata stream and interleave it with the audio at a reasonable rate.
 
> You seem to think I'm kidding about putting images in the metadata. I'm not.
> 
> The worst case in terms of metadata as a proportion of data is
> probably the promotional CD singles that I seem to accumulate. They
> sometimes contain just one track, but have the full metadata payload -
> up to four sides of artwork, full band biography + bibliography,
> lyrics and so on. I can see that totalling a meg or so, compared to
> 3-5MB for the actual song.

I'm proposing dividing the metadata into different chunks. One (possibly compressed)
for the index, that is, all the "regular" metadata and following this, chunks of other
types of data, for example images, possibly compressed, identified by a mime type.

If we're dealing with one-file-albums, this would all be put in the first track, together
with a chunk of info for the track. This could lead to a few problems, though. If the track's
particularily small compared to the metadata, you'd be cramming a lot of metadata frames inbetween
the audio frames, seeing as, IIRC, all interleaved streams in an interleaved, chained ogg-file need
to end before the next stream in the chain begins.

Well. Seems like I forgot something.
Ah, well.

Regards
Oscar
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