Subject: Re: [linux-audio-dev] LADSPA Defaults via RDF
From: Richard Guenther (rguenth_AT_tat.physik.uni-tuebingen.de)
Date: Wed Jul 17 2002 - 19:49:05 EEST
Hi Steve!
I really like it! Also it opens up a lot of other possibilities in the
future like GUI hints, etc.
Richard.
On Tue, Jul 16, 2002 at 06:44:59PM +0100, Steve Harris wrote:
> OK, I now have a minimal proof of concept for describing LADSPA plugins,
> presets and defaults with RDF (http://w3c.org/RDF).
>
> At this point I'd like to get some feedback so I can decide wether to cut
> my losses or finish it (a usable library for hosts would be about another
> weeks work, on and off).
>
> My solution relys on the raptor RDF parser (GPL), which inturn links to
> libxml or expat (though only libxml works ATM). An example code fragment
> to find the defaults for a plugin, given its UID looks like:
>
> def_uri = lrdf_get_default_uri(uid);
> if (def_uri == NULL) {
> printf("(none known)\n");
> return 1;
> }
>
> printf("Defaults for plugin %d: %s\n", uid,
> lrdf_get_setting_metadata(def_uri, "title"));
>
> defs = lrdf_get_setting_values(def_uri);
> for (i=0; i < defs->count; i++) {
> printf("\tport %d (%s) = %f\n", defs->items[i].pid,
> defs->items[i].label, defs->items[i].value);
> }
> lrdf_free_setting_values(defs);
>
> giving:
>
> [swh_AT_dumuzi lrdf]$ ./showdefaults 1416
> Defaults for plugin 1416: Concert A sine (soft)
> port 1 (wave) = 1.000000
> port 2 (freq) = 440.000000
> port 3 (warm) = 0.500000
> port 4 (instab) = 0.000000
>
> You can see my work in progress at http://plugin.org.uk/lrdf/ , if you're
> brave you could try building it, make sure you build raptor with
> ./configure --with-xml-parser=libxml
>
> The bad news is that RDF is pretty verbose, a description of 61 plugins +
> thier defaults comes in at 91k (all.rdf). This doesn't include scales,
> units, metadata (see sample.rdf) or the type hierachy, but they won't add
> much.
>
> Also in the directory above is a sample plugin description (sample.rdf)
> and a sample defaults file (default-sample.rdf).
>
> Conclusion
>
> Advantages
>
> Its a unified way of describing everything* about plugins, it's standards
> compliant, extensible, and generally good.
>
> Disadvantages
>
> Its not as efficient as a pure XML approach.
>
> Comments?
>
> - Steve
>
> * well... most things
-- -- Richard Guenther <richard.guenther_AT_uni-tuebingen.de> WWW: http://www.tat.physik.uni-tuebingen.de/~rguenth/ The GLAME Project: http://www.glame.de/
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