Subject: Re: [linux-audio-dev] finding the selection length with LADSPA
From: Kai Vehmanen (kaiv_AT_wakkanet.fi)
Date: Thu Oct 19 2000 - 02:39:42 EEST
On Wed, 18 Oct 2000, douglas irving repetto wrote:
> implement a simple fadein/out plugin, and quickly realized that i don't
> know how to get the _total_ number of samples that will be processed
This is unfortunately something you won't be able to find out using the
current LADSPA API. I admit that for certain purposes, possibility to
obtain extra parameters needed for offline (or edit-as-a-whole) operations
would be useful. But it would also be somewhat difficult to outline a
suitable set of features to be included in the API. LADSPA would easily
grow to be LADPA (the Simple part dropped :)).
In my own apps, I've separated operators (plugins/effects) from
controllers (objects that control individual parameters). So 'fade in' is
a combination of a multiplier/amplify effect, and a linearly increasing
envelope. This doesn't solve the problem, but is quite flexible approach
as we have separate plugins for operating and parameter control. For
instance, you might want to control the multiplier plugin with an
exponential envelope, oscillator, external source such as a MIDI-CC, etc,
etc... and of course, replacing the multiply plugin with a filter, delay,
etc makes sense. So what I'm trying to say here is that it isn't really
that necessary to be able to implement fade-in and fade-out as standalone
plugins. LADSPA plugins serve well as building blocks, which can easily be
used to construct more complex composite operators like fade-in/outs,
level normalization, etc...
-- . http://www.eca.cx ... [ audio software for linux ] /\ . . http://www.eca.cx/sculpscape [ my armchair-tunes mp3/ra/wav ]
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