linuxaudio.org

On Mon, 2012-05-28 at 18:41 +0300, Stefano D'Angelo wrote:

quoted text
> 2012/5/25 Jeremy Salwen :

> > Hi all,

> >

> > The LV2 spec says that on a call to activate(), "the plugin instance MUST

> > reset all state information dependent on the history of the plugin instance

> > except for any data locations provided by connect_port()"

> >

> > I am not certain whether MIDI CC parameters are included in this category of

> > "data locations provided by connect_port()".  The CC parameters are sent

> > through port buffers provided by connect_port(), but because they are event

> > buffers, all information passed through them is necessarily part of the

> > history of the plugin instance.

> >

> > I could imagine cases where you would want to reset all internal state of

> > the plugin, but since CC values are very much like port values, they would

> > be kept.  On the other hand, I could also imagine cases where you would want

> > to reset all internal data including the CC parameters.

> >

> > I'm assuming MIDI note on/off status certainly should be reset.

>

>

>

> I have always interpreted activate()/deactivate() as a real-time safe

> alternative to instantiate()/cleanup(), so I'd say restart fresh, wipe

> out everything.

>

> I do not necessarily agree that MIDI CC is like a port value, since

> when the first run() after the first activate() is called and there's

> no incoming CC event, however you probably need to be in a certain

> "initial state".

>

> 

The spec explicitly states: "the plugin instance MUST reset all state

information dependent on the history of the plugin instance except for

any data locations provided by connect_port()"
This text does date from a time when that was the only way to actually

get any data in/out of a plugin, so it might need clarification now with

MIDI/other events/state/etc.
For live plugins if you're going to stop continually running the plugin,

you must deactivate it, so I can see how a complete and total state

reset here might be undesirable.  I'm not sure.  A complete

cleanup/re-initialization is always an option for a total reset, though

of course not real-time whatsoever.
> Concrete use case would help.
Indeed.
-dr
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