[linux-audio-dev] LADSPA plugin parameters realtime control

Paul Davis paul at linuxaudiosystems.com
Sat Jul 9 12:45:55 UTC 2005


On Sat, 2005-07-09 at 15:24 +0300, Artemio wrote:
> Hello all!
> 
> I am here to ask you one thing. If I want sample-precise realtime 
> control for the plugin, should I be getting all the parameters inside 
> the cycle which travels through the buffer contents?

it depends a lot on what are you trying to do. LADSPA control ports
offer only a single scalar value to be used on every run()/run_adding()
call. hosts that support automation will alter this value between calls
to your plugin's run() function, thus providing sample-accurate
automation. however, this is expensive, especially if what you are
actually trying to accomplish is closer to some kind of modulation
effects where one audio signal is used as a control over the operation
of the plugin. in this case, you would not use a LADSPA control port,
but instead would provide another audio input port, and then do
something similar to what you outlined.

note, however, that there is no way at present for hosts to understand
your intent here. this means that free form "modular" hosts like galan
and so forth will work fine, but hosts like ardour that are trying to
fit plugins into a mixer-flow model will not offer the user the control
over what is connected to what.

--p





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