[gst-devel] tags and metadata

[Thomas Vander Stichele]

El mié, 21-01-2004 a las 13:54, Benjamin Otte escribió:
> 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 audio view in nautilus-media shows some metadata tags in the view
and some not.  It also puts some of the streaminfo in the view, and some
not.

The properties view makes a very clear distinction and shows them in
different locations.  One reason for is is quite simply, as stated
before, that the actual metadata is supposed to be EDITABLE.

> 
> > 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...

Probably - otoh right now the caps are what get signalled after
negotation.  Does this mean I should also convert them to tags ?


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

Let's not pretend this is the first time I bring this up.  Let's not
pretend that you did not specifically ask for GStreamer 0.8 to be the
one to go into GNOME 2.6
Whether we like it or not, at the point we proposed that, we also forced
ourselves to make sure that the applications already in GNOME were
ported to 0.8 functionality-wise.  I can somehow understand you not
wanting to do the work, and I don't mind.  But it's something you should
have thought about when proposing it for GNOME 2.6.  I'm not really sure
you've actually ever run nautilus-media based on previous comments on it
:)

I think we all didn't really take a good look at what it means to
propose this, and we probably bit off more than we could chew - but
that's not helping us much at this point.  Right now we need to Get It
Done, which is what I want to do, so let's not point fingers but move
along and tell me, how can I get the functionality we had working in 0.6
back in 0.8 and what do I need to complete ?

Thomas

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