[opus] Tag lists (Vorbis comments)

[Emily Fox]

I think it's reasonable to discuss the comment specs here, if anywhere,
given it's the only living aspect of vorbis today. The tag names listed
seem to (mostly) be the most common ones used in Vorbis/Opus/Flac as well,
and I very much doubt the deviations (ALBUM/DISC/TRACKNUMBER becoming
PART_NUMBER at various levels) would ever gain any traction.

Aside from that, the Matroska comment specs cannot really be replicated in
a reasonable way by Vorbis comments; EBML/Matroska is inherently
hierarchical, being based on XML, and this spec uses that capability
heavily, while Vorbis comments are inherently flat, and can only simulate a
hierarchy with specialized naming conventions. That's why condensing all of
those into PART_NUMBERs works.

IMHO the only reasonable way to adopt their specs would be to wholesale
import the XML metadata, either as text or binary (EBML is a pretty nice
and compact binary XML format), something that is mentioned in passing in
the old specs as the preferred way for such structured metadata to exist in
the first place. No standardized structure for that was ever put forward,
to my knowledge.

-Em

On Sun, Nov 24, 2024 at 8:37 AM Martin Leese <
martin.leese at stanfordalumni.org> wrote:

> Hi All,
>
> I wasn't sure whether to send this to the Opus
> list or to a Vorbis list.  Even though it concerns
> Vorbis Comments, the latter seem dead, so I
> went with the former.
>
> The Matroska people have published a draft
> of Container Tag Specifications; visit:
> https://www.ietf.org/archive/id/draft-ietf-cellar-tags-15.html
>
> Does Xiph want to make use of this, perhaps
> by making the tags "RECOMMENDED" in the
> Opus/Vorbis/FLAC specs?
>
> Regards,
> Martin
> --
> Martin J Leese
> E-mail: martin.leese  stanfordalumni.org
> Web: http://members.tripod.com/martin_leese/
> _______________________________________________
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> opus at xiph.org
> http://lists.xiph.org/mailman/listinfo/opus
>
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