[LAD] Portable user interfaces for LV2 plugins

Stefano D'Angelo zanga.mail at gmail.com
Wed Mar 2 22:36:24 UTC 2011

2011/3/2 Paul Davis <paul at linuxaudiosystems.com>:
> On Wed, Mar 2, 2011 at 2:55 PM, Stefano D'Angelo <zanga.mail at gmail.com> wrote:
>> Plugins expose "control ports" (which, to me, are a design mistake how
>> they're done, but whatever) for the purpose of managing how they work.
> no different than any other plugin API, except that the concept is a
> bit more unified than "data" and "parameters" as found in, say, VST or
> AU.
>> Since it's stuff for the user, they should be effective and
>> understandable for the user. And here's the first problem: parameters
>> and GUIs don't necessarily have to match! E.g., my amp simulator
>> algorithm should really expose stuff like "air impedance" or "triode's
>> magnetic perveance", that's stuff the "average user" ("dumb" guitar
>> player) doesn't understand. I would prefer to show "air temperature"
>> and "triode model" instead.
> AU, which is the only other plugin API to explicitly support
> plugin<->GUI separation (even across processes) works in exactly the
> same way as LV2. there are many AU plugins which do precisely what you
> describe, yet still use a host-mediated parameter accessor API to both
> control and represent current plugin state. this conceptual issue has
> been thrashed out many times on the coreaudio mailing list as far back
> as 1994, and nobody ever convinced the coreaudio guys (who are a smart
> bunch of guys) that they had done it wrong.

Since I'm not just complaining or posing hypotetical questions, but
want the understand the issue at its deepest, I want to ask you to
please better point out what is exactly this host-mediate parameter
accessor API (a link to docs is more than enough).

> the principle remains: access to plugin parameters is mediated via the
> host to facilitate several things that would be impossible to do
> properly, if at all, if they instead happened directly.
> meta-parameters are used to provide the kind of thing you're
> describing, and the "real" parameters are marked as "not for display"
> in the (unlikely) event that the host creates the GUI for the plugin.

So I'm not totally dumb. :-)


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