Subject: Re: [linux-audio-dev] FW: LADPSA Freeverb - update?
From: Paul Barton-Davis (pbd_AT_Op.Net)
Date: Wed May 24 2000 - 07:03:58 EEST
In message <Pine.LNX.4.10.10005231939070.13220-100000_AT_luca.pas.lab>you write:
>> Although I am excited by this, I am a little concerned that it will be
>> hard to use good plugins like this without a GUI.
>
>Have you tried gdam? It automatically instantiates
>scrollbars of the hinted ranges....
>
>Really, the standard contains most of what
>is needed to host plugins rather graphically.
I don't agree. We discussed this quite a bit here. The central problem
is that real-time hosts will not run the plugin in the same thread as
the GUI, and the plugin must "know" this, either explicitly or because
it has no access to any functions that can cause cross-thread
issues. But at an even deeper level than this, I don't like the model
in which the host is responsible for creating the GUI for the plugin
simply from an abstract description of the plugin's ports. Cubase
tried this with early versions of VST, and although they still support
it to some extent, they now encourage the use of, and are encouraged by
developers to extend, their vstGUI lib which lets the plugin contain
its own GUI (via an AEffEditor C++ object).
Its not OK to put things like pixmaps in an external XML file: this
should be considered part of the plugin, even if it can be overridden
by a "skin" specified in the XML plugin catalog.
So how should this happen ? We immediately run into the central Linux
problem that there is no single Linux GUI toolkit. The plugin can do
shared linking to its chosen toolkit, but that potentially doubles the
memory utilization of the host if we end up with KDE and GNOME plugins
being loaded at the same time. A more basic problem is that there is
no particularly portable method of giving the plugin a window to draw
into. I know that GTK+ has some capabilities in this area, but I also
gather that it has some real problems as well (events get discarded
because they don't come from a GTK window; just a bug, but its not
fixed yet).
The standard also does not contain any calls to instantiate the GUI.
Just a few thoughts on this.
--p
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