[gst-devel] tags and metadata

[in7y118 at public.uni-hamburg.de]

Quoting David Schleef <ds at schleef.org>:

> "length" in an id3 tag doesn't somehow magically become metadata.
> 
Thomas described streaminfo as something that can only be changed by 
reencoding. The id3 length tag can easily be changed without reencoding and I 
asume Rhythmbox is going to that - when it was wrong, and it often enough is.
Another interesting thing are stuff like bitrates. It is easily changeable and 
user might even want to change it so it mirrors the actual bitrates (nominal 
bitrate in a vorbis stream for example), but if it's streaminfo, you can't 
change it.

> After 0.8, perhaps we should add this information to the tag registry
> itself, to indicate the purpose of each tag.
> 
If we can work out a definition that handles that, it's fine with me.

> (I'd be interested in knowing any tags that can be both metadata and
> streaminfo.  Seems like a bug to me.)
> 
Well, this depends on how narrow you define streaminfo and metadata. If you 
define streaminfo as "possible to extract by looking at stream" and metadata 
as "needs additional info external to stream" I can offer you "language" (you 
can easily tell what language some text is told in without additional info, 
it's just that there's no GStreamer that can do this yet) or "average bitrate" 
(there's no way to figure that out in unlimited vbr streams such as iradio 
without additional info) for a start.
I can possibly think of more for other cases if you'd like ;)


Anyway, I removed the streaminfo/metadata distinction for a reason. And that 
reason was I couldn't easily tell what is what for the general case.

Benjamin