[vorbis-dev] Metadata, file signatures, and extentions

[Lou Sortman]

"Myers W. Carpenter" wrote:
> 
> Hi,
>         I've been working writing some tools that deal with id3v2 tags on mp3
> files.  id3v2 is this really, really long specification with places for
> all kinds of metadata for media.

ID3V2 came about to work around shortcomings in the format of MP3
files.  For instance, having no metadata.  It has some shortcomings of
its own, such as having the variables all use cryptic 4 character
names.  I could go off on what I dislike about that particular
attribute, but it would be boring and take us off topic.

>         I've looking at the sample vorbis encoder and a file I made from it I
> noted that you have some a comment field, and I was wondering if you had
> any plans to support more metadata, and if you would consider adding
> id3v2 as your metadata format.  The id3v2 is a farily elaborate
> specicification, it wouldn't be a good thing for theis "wheel" to have
> to be reinvented for vorbis.  It also would be nice to see this written
> in the actually vorbis spec, rather than bolted on later.

I could be totally wrong, but I think the comment is part of the stream
header.  As such, it would be fine for things like track name, etc., but
not for things like feeding lines of lyrics as the track plays.

For the latter, (and the former, for that matter) one might want to
define a simple CODEC, the job of which is to display lyric fragments
(or other metadata) and encode an additional stream to feed that CODEC
at an appropriate rate.  CODECs don't necessarily have to only be for
audio and video content.

This train of thought can get considerably more complex, but since I
have no idea what sort of acceptance it would get, I won't expend a
whole lot of time describing my ideas at this point.

I am totally with you about doing it right the first time.

>         The one downside I've seen in using id3v2 tags is that they usually
> begin at the very beginning of the file.   Looking at a vorbis file you
> a file signature at the beginning.  Not sure what can be done in this
> case as id3v2 tags expect to be at the very beginning of the file.

There are places such as the comment field and the stream idea that I
described above that could deal with this.  Since the format is still
young, now would be the time to make other changes if they are deemed to
be worthwhile.

As I read the ID3V2 spec, it appeared that there was no restriction on
where in the file they were as long as framing was preserved.  ID3V2
frames could appear throughout the track; not necessarily at the
beginning.  Granted, I wasn't exactly studying it.

>         Also: what is the file extention used for vorbis files?  .vor?

I think .ogg has been selected for this.

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