[gmpi] Re: Decision time: 8.2

On Sun, Aug 24, 2003 at 05:59:03 -0700, Marc Poirier wrote:
> I'm not following you anymore.  What exactly is "the UI" in your mind in
> this scenario?  The interface for setting up automation modes?  The
> interface for changing parameter values?  Something else?

By UI I mean the controlling code that cause parameters in the (DSP)
plugin to be changed.
 
> So, I don't know if I'm responding to what you're actually saying since I
> don't know what you're saying, but I'll try to clarify what I was saying: 
> In order for a host to do something like "touch automation", the host
> needs to be informed of when a parameter change gesture is about to begin
> and when it has just finished.  For example, if we're talking about a
> typical context where the plugin has a GUI and the user is moving sliders
> around with mouse to change parameter values, then the begin notification
> would occur upon mouse down in a slider control and notification would
> occur when the mouse is released.  Maybe by saying "the host includes the
> UI" and you meant the GUI with sliders?  If that's what you meant, then my
> response is, no, it could also be a custom GUI for the plugin.  And so
> there needs to be a way for the plugin to say when a parameter gesture
> begins and ends.

Right, and I dont see what that has to the with the DSP plugin - it doesnt
know when the user has let go of the mouse - and if it cares then it can
be informed by the UI - if would be a pramater of some kind (eg. the
Z-axis on a touchpad).

I am expecting automation to be handled by the host (this is the norm in
the linux world), so the host cares about wether the user is trying to
override exiting automation recordings or not, but the interaction is
between the UI (be it hardware surface, GUI, whatever) and the host, not
the DSP plugin and host, surely.
 
> > Undoing is a host feature, but I dont see why this is helps for undo.
> 
> If helps because the host can query the current parameter value when the
> gesture begins, remember that, and then use that as the value to undo to,
> if the user wants to undo.  If the host is only aware of parameter changes
> as descrete events, then the host only knows the value before the last
> nudge.  So lets say that you just swept a parameter from 3 to 9, and as
> you moved it, it generated parameter values along the way:  3.3, 3.9, 4.5,
> 5.4, 6.3, 6.9, 7.2, 8.1, 9.  Without a notion of a parameter gesture, then
> the best that the host could do to undo this parameter change would be to
> revert to 8.1.  But that is not what the user would be expecting.  She
> would be expecting it to revert to 3.  Does that make more sense now?

No, because I thought we had agreed that the host, UIs and whatever would
be able to subscribe (in some way) to parameter changes, so the automation
value could only be out by the range of one parmaeter change
interpolationi, and even then its arguable wich value the use would want
to be record in the undo data. I strongly believe that the plugin should
not asked to back-calculate the value of a parameter at arbitrary points -
its quite a lot of work, and I dont see what its good for.

- Steve 

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