[gst-devel] some cleanups

Andy Wingo wingo at pobox.com
Fri Apr 26 18:28:03 CEST 2002

On Fri, 26 Apr 2002, Jan Tore Korneliussen wrote:

> Hello,
> I tried out gst last year, and have been following
> this list for a while. I noticed that there was a
> quite lengthy discussion about how to 'classify'
> elements. Although I realize this might be a
> controversial topic, I could not resist commenting on
> it...
> My main point is: why does there need to be a
> hierearchy and a C(K?)lass property in the first
> place? It seems to me it is quite redundant since
> most, if not all, of the information exists in the
> properties of an element already. I guess that trying
> to squeeze  'all' the information in the other
> properties into one ordered string is a very hard
> task. Either the hierarchy would be very deep/wide and
> sparsely populated, or it would be ambigous. Also it
> would be a matter of taste what is root in such a
> hierarcy, and what are leaves.

An interesting idea. Right now, the class is just for ease of
categorization; Consider the existing Filter/ tree:


I see how one could make an audio/video distinction easily, but the
subcategories of Audio (and it is essential to subcategorize to limit
the number of leaves per node) can't really be determined

> Example of how the klass fields could be extracted
> from what's already in the properties:
> - Source/sink/filter could be determined by counting
> the number of inputs and outputs
> - Audio/video could be determined by looking at the
> mime types on the input and outputs.
> - Decoder/encoder elements could probably be
> identified by looking at the mime subtypes.

True... although truthfully, in the long run I'd be more in favor of the
class being a list of keywords that could then be sorted for
presentation to the user. But yes, this does make sense.

> Couldn't just the user interface for browsing elements
> be designed [...]

Sure, go right ahead ;-)

I just wanted an element lister for the time being. This stuff is in its
own library (gst-editor/libs/gst/element-browser/) so its implementation
can be changed and all apps that use it can benefit. But for now, my
modest needs are satisfied ;)

> That was much rambling from a newbie, feel free to
> ignore... Hopefully I will have time to experiment
> with gst again soon, it is great to see that it is
> gaining momentum!

Good to hear from you, and I look forward to such insightful comments as
this in the future :)



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