[linux-audio-dev] anyone interested in porting a GPL'ed VST plugin?

Paul Davis paul at linuxaudiosystems.com
Tue Nov 5 15:20:00 UTC 2002


>> ardour will bind any MIDI CC to any LADSPA parameter. it also maps
>> NoteOn/NoteOff to any LADSPA parameter, with the intent that it be
>> used to drive a switch. result: LADSPA has no clue about MIDI, but any
>> LADSPA plugin running inside ardour can be "completely controlled"
>> from MIDI.
>
>so, does each midi note have its own parameter? or how else are you
>encoding the data? 

the binding is dynamically established by the user (then made
persistent in a state file). the CC value is converted to a floating
point value based on
      
      * its position in a 7- or 14-bit range
      * the range of the LADSPA parameter value

with NoteOn/NoteOff, we just do a bi-state encoding to either the lower
end of the parameter value range or the upper, respectively.

the user can make any bindings they want. one CC can control any
number of parameters, if they wish.

>                   obviously things like pitch wheel need to be passed
>on too.. wont this get a bit OTT compared to MIDI, which does define a
>featureful encoding with minimal overhead..

i should have mentioned that pitch is handled as well, yes.
 
>> you probably don't want to run amsynth in ardour, though.
>
>erm, any particular reasons?

you could. but ardour is not really designed with this sort of plugin
in mind. it will work, but its not very nice. plus ardour is probably
doing a lot of other work that you may not want. or not. people's
situation will vary.

>> rather than FX plugins. steinberg just released a realtime VST host
>> specifically to host VSTi's (instruments); ecamegapedal is cool, but a
>> JACK-ified LADSPA instrument host would be better yet.
>
>Well i was working on this type of host program, but for the plugin spec
>im now using in amsynth. Obviously if LADSPA is really feasible for this
>kind of thing, i'd want to get that working..

LADSPA is definitely feasible for this kind of thing. Its major
deficit in this area is the lack of string parameters, which means
that you can specify sample file names, patch names, etc. etc.

--p



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