[advocacy] Metadata to streams

[Peter Harris]

Gunnar bergman wrote:
> Hi!
> At what level is it residing? Always in the container
> format, or within the codec stream? If it's the latter
> option, is it only implemented for Vorbis, or is it
> available for video too?

Right now, it's in the codec (Vorbis) stream. Any video format would
have to have its own separate comments. There has been some talk about
creating a separate metadata stream at the Ogg level, but that does not
exist yet.

> Besides that, I'd like to know how much flexibility
> there is in the tagging standard. Is it limited to
> desciption of music tunes, or does it allow extended
> information...

There is huge flexibility. Vorbis comments are just a list of TAG=Value
pairs. There are no limits on what the tag can be.

> For example, if there's a radio station streaming
> live,
> do they have the ability to add data like:
> - Name of station
> - Name of current show
> - Topic of the program
> - Duration of the program (started at... ; ends at...)
> - Special flag if it's a re-run
> - Name of the host leading the show
> - Name of possible guests to the show
> - Contact info ... (phone, email, mail)

Sure. Any and all of those could be in there.

> And added to that - will it be possible of course to
> update these fields continuously, so that they aren't
> necessarily locked for the session?

You have to start a new stream to get new comments. Starting a new
stream is gapless, so there aren't any clicks in the audio, but it does
suck back a few k of bandwidth (as _all_ of the headers are
retransmitted). Current Ogg Vorbis 'radio' stations use this method to
update track titles for each song.

Peter Harris

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