[gmpi] Re: Decision time: 8.2

----- Original Message ----- 
From: "Paul Davis"

> let me try :)
>
> scenario a:
>
>   user clicks on an on-screen slider and moves it. the GUI controlling
>   the slider finds out about this, and sends a parameter change
>   request to the host: "set parameter N of plugin XXXX to YYY.ZZZZ".
>   host sends parameter change to plugin, which will probably
>   interpolate and/or remap it internally.
>
> <SNIP>
>
> in every case, the DSP plugin is not involved in any way.

Alright, I'll just jump in to this since the above "scenario a" does seem a
bit simplistic to me, and as practical examples tend to help out
sometimes...
I hope you guys don't mind ;-)

Now, what if in "scenario a" the dsp part of the plugin decides that the
parameter change it is receiving needs a change in *another* dsp parameter
(observable at the outside at any of the attached UI's) depending on that
first parameter? I would think that in that case the dsp code itself should
have a way to tell the outside world (probably through the host) that
something has changed to that other parameter, right? How would you solve
this without allowing the dsp code to notify other listeners of parameter
changes?

Koen

PS
The way I am handling this in a VST plugin of mine, is by calling a
setParameter function of my dsp core code *with an extra argument* that can
be used to return other parameters that might have changed during the dsp
setParameter call:
 setParameter(inParamIndex,inParamValue,&outListOfChangedParameters)
The code calling the dsp core (in my case the VST effect class around the
dsp core, called by the host) then checks the list (might be empty) of
returned parameters that have changed and uses getParameter on the dsp core
to obtain their eventual value and propagate this to the outside world (the
environment the plugin "lives in", probably the host).
This is a function-based scheme, but I guess it would be better and more
flexible to do this with a real listener/notifier design.



----------------------------------------------------------------------
Generalized Music Plugin Interface (GMPI) public discussion list
Participation in this list is contingent upon your abiding by the
following rules:  Please stay on topic.  You are responsible for your own
words.  Please respect your fellow subscribers.  Please do not
redistribute anyone else's words without their permission.

Archive: http://www.freelists.org/archives/gmpi
Email gmpi-request@xxxxxxxxxxxxx w/ subject "unsubscribe" to unsubscribe

Other related posts: