[LAD] LV2 and parameter interpolation

[Jörn Nettingsmeier]

On 02/06/2012 12:04 PM, Fons Adriaensen wrote:
> On Mon, Feb 06, 2012 at 10:33:31AM +0100, Jörn Nettingsmeier wrote:
>
>> what i want to avoid is a ramp from default or previous values whenever
>> the plugin is run for the first time. in that case, i want to have no
>> ramp and start cold with the control port value.
>
> For general purpose processing (as opposed to synthesis) that doesn't
> matter in practice. Certainly not if the ramp is just one period.

it might if a DAW deactivates plugins on transport stop, then locates, 
then re-activates on play - can i be sure this won't happen with any host?
i certainly don't want my first note to go through a sweep of all plugin 
controls each time i press "play".

>> can i rely on control port data being available during activate() so
>> that i can initialize my current values to the control port values?
>>
>> now i could set the current values to NULL during instantiate and
>> deactivate, but then i'd have an extra conditional in run(), which i'd
>> like to avoid.
>
> This would be outside the main loop, so harmless. You may want something
> similar to switch between interpolated or constant runs as well, so it
> would just add one boolean.

true.

> Note that making parameter smoothing dependent on the period size
> is not really recommended, except again for synthesis. For the zita
> series it is Verboten.

well, i've considered carrying loads of state with me and maybe even do 
cubic interpolation, but that's for later. the problem is i don't know 
in advance how many control points i need to cache for constant 
smoothing over time, because LV2 doesn't guarantee a constant number of 
samples per run().

best,


jörn