[LV2] Control ports vs lv2:Parameter

[David Robillard]

On Thu, 2025-02-06 at 08:11 +0100, Stefano D'Angelo wrote:
> Il 04/02/25 20:08, David Robillard ha scritto:
> > Anyway, I don't see any concrete technical problem with having
> > both, 
> > except for the conflict: a mandatory control port always has a
> > value. 
> > So what does the plugin do when it gets a message that sets that 
> > parameter to some other value?  There's solutions to that that will
> > maybe work in practice (switch to ignoring controls if you ever 
> > receive a message or something) but it's pretty hackey. Worth a
> > shot I 
> > suppose, if you're dedicated to trying some graceful degradation 
> > situation.  It's not clear what a host should do in this situation 
> > though, this would probably need to be decided and written down 
> > somewhere if it makes sense.
>
> For some reason I thought that control port values could represent 
> parameter values at the beginning of buffers (frame/sample index 0)
> and 
> events would set values at arbitrary times/indices within the buffer 
> length, but of course that's not specified anywhere.

That could work, but yeah, some feature would need to be defined for it
(well, ideally, it's not like we haven't skipped that part in the
past).  I'm not sure what the implementation burden would be like
without seeing it done for real, though.  It means you wouldn't be able
to directly use control inputs but would instead need to copy them
somewhere at the start of the buffer to be potentially manipulated
later.

-- 
dr