Subject: Re: [linux-audio-dev] Mustajuuri -> LADSPA plugins.
From: Paul Davis (pbd_AT_op.net)
Date: Tue Mar 27 2001 - 16:19:57 EEST
>I lately added LADSPA plugin support to Mustajuuri. In doing that I
>thought a bit about the process of wrapping Mustajuuri plugins to LADSPA
>plugins. This would increase the number of LADSPA plugins and I guess
>everybody likes that (?)
i do.
>2) Many Mustajuuri plugins have a very optimized GUI. While some can be
>transformed to the (upcoming) LADSPA-XML-spec there are others that are
>really difficult/pointless to render via XML wrapping. The example is
>again the EQ plugins. The graphical EQ in particular is a nice example;
>The current GUI does not a have a single slider, instead there is a graph
>that can be adjusted by simply drawing on it. A large collection of
>sliders/knobs/whatever would be a horrible alternative. I don't see
>any practical way to leavy this rendering process to the host. So anybody
>wishing to use the EQ with a GUI should be able to upload the Qt-based GUI
>stuff also. There are other plugins that also rely on heavily involved
>graphics (level- and tuning meters, oscilloscope). So most hosts would not
>be able to take full advantage of these plugins.
i think you should propose new XML entities for the GUI spec that
would allow these to work, plus some text to suggest how the
host/plugin interaction would actually work. i think these would be an
excellent idea. and if you don't, i will :)
>3) The parameter systems of LADSPA and Mustajuuri differ. LADSPA has a
>CSound-like control parameters (updated between cycles), while Mustajuuri
>has time-stamped event system (with events delivered between cycles). The
who says LADSPA works like this ? i know the header implies that, but
there's nothing to stop the plugin from completely separating the
control ports from the actual parameters, and in fact, the good
plugins (e.g. steve harris' set) increasingly do this. that allows you
to view a change in the value of the control port as an "event", and
then adjust the parameter internally as you wish.
>4) Mustajuuri supports many parameters besides floating point data. In
>particular it supports strings (for filenames etc.) and MIDI events. These
>plugins cannot be used at all with current LADSPA API. I guess this is
>simply inevitable (I know LADSPA is not intended to fit all purposes).
I agree with you. Remember what LADSPA was intended to be useful for:
the endlessly repeated, audio API independent, pure-computation
algorithms we all want to see in audio apps. If you keep this in mind,
it provides more of a justification for why it doesn't handle MIDI or
string based parameters (though perhaps not *enough* justification :)
--p
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