Re: [linux-audio-dev] LADSPA Hosting

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Subject: Re: [linux-audio-dev] LADSPA Hosting
From: Nick Tsocanos (nicktsocanos_AT_charter.net)
Date: Wed Apr 16 2003 - 23:56:20 EEST


On Wed, 2003-04-16 at 16:03, ian wrote:
> the simplest way to determine if an algorithm is likely to be an effect or
> not is just to count the number of audio input and audio output ports.
Yep, that's how I did it. But, surprise! Some weird ones use AUDIO
signals for control data (oscillators use it for amplitude). So, to hack
around this, I check to see if the audio port is bounded by below or
above.

> e.g. if you just want to do single channel effects, you might want to
I have it setup like this, I load a plugin for left/right if it is a
mono plugin (my app is stereo). If it is stereo, I will load it as
stereo fine.

> all the plugin ports and counting the required types. the plugin sdk has
> example code for all of this, and can be found at www.ladspa.org.
That's my only place to learn. I basically borrowed the code from the
demos and am using it. I fixed up the majority of leaks it had.

> there's not much else you can do to find out how a plugin works inside.
> personally i don't think it's necessary to limit things any more than that
> - you might be stopping the user from doing something cool! and if it
> doesn't sound good the user can just move on to the next plugin.

Oh I don't want to limit them at all, but some plugins refuse to work at
all, and mangle the effect chain! Those aren't cool, they just don't
work properly in my app. Of course, it might be a bug somewhere in my
driver.. I only just made this today... and I am still working on it
pretty heavy right now.

I have now gotten almost 90% of the ones that won't work properly to
filter out.

Anyone use Dj Flanger? Is there something you have to do to use this
plugin? When I use it it makes terrible noises.

I plan on doing alot of LADSPA plugins. Why? It's so simple API to use.
It has only taken me an afternoon to build a host app and even build my
GUIs at run time for it with FLTK. It's great! And alot of those F/X
sound WILD!


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