[LAD] Should LV2 Activate() clear MIDI CC parameters?

Paul Davis paul at linuxaudiosystems.com
Tue May 29 13:48:10 UTC 2012

On Tue, May 29, 2012 at 9:37 AM, Albert Graef <Dr.Graef at t-online.de> wrote:

> On 05/29/2012 02:23 PM, Paul Davis wrote:
> > there's a misconception right there, i think. you wouldn't deactivate it
> > to listen to the dry signal. you'd bypass it using some feature of the
> > host.
> Yes, of course this depends on the host. But presumably an LV2 host
> would then also deactivate the plugin and later reactivate it to reset
> it to a sane state? At least that's what I thought these callbacks were
> for. IIRC that's how it works in Qtractor (Rui, please correct me if I'm
> wrong), and that certainly makes sense to me. I didn't test this with
> Ardour, though.
> Otherwise, how is an LV2 plugin supposed to know that it has been
> suspended and should prepare its internal state to be switched back on
> again? All the host knows about the plugin are its ports, so it's
> limited in what it can do. Only the plugin itself knows about the extra
> cleanup it might want to do when being switched off and then back on
> again, no?

the question really is under what circumstances should the host/user call

if the host/user has done this, then they should be clear on the
consequences. you don't call these functions in order to bypass a plugin.
you call them specifically when there is a need to completely reset the
state of the plugin.

however, david's point stands which is that you really want both (a) a
method to stop and restart the plugin (b) a method to reset to it back to
the state it would have immediately after instantiation. its not 100%
whether deactivate/activate is either of these ...
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