[gst-devel] tags and metadata

[Benjamin Otte]

On Tue, 20 Jan 2004, Thomas Vander Stichele wrote:

> My biggest problem with this is
> that there is no way at all to distinguish between "metadata" and
> "streaminfo".  Ie, the data about the song, and the data about the audio
> data.  These get presented quite differently in applications.
>
It's not possible to distinguish between them inside GStreamer. Length
and encoding format is what you would call "streaminfo", but those are
valid id3 tags. OTOH the bitrate might be configurable inside mod players
or set as tags on recoded files.
So I fail to see a clear way to distinguish between those two. And because
of that I decided not to split between streaminfo and metadata.

And how are streaminfo and metadata seperated differently in applications?
Rhythmbox puts both in columns and that's it. As does nautilus-media.

> The only thing I see us do at this point is to either extend Tag a
> little so that the type of GstTag can be set, and the two types can be
> distinguished; or, use and restore the old mechanism, which signalled
> having STREAMINFO.  The streaminfo could in the past be gotten by
> getting the pointer to the GstCaps.  We could either use GstCaps or
> GstTag for actually transporting this to the app, I'm undecided on which
> is best.
>
Caps should be used when you have a set of "capabilities", that you want
to intersect, fixate or negotiate. Tags should be used when you want to
describe properties of a data stream.
I guess that points pretty much directly to tags...


Benjamin


PS: We're API frozen, it'd have been nice if you could have come up with
criticism before that.