Re: A question for the LV2 gurus

Am 04.08.26 um 22:14 schrieb Fons Adriaensen:
> Hello all,
>
> I want to port some of my Jack apps and zita-jacktools modules
> to LV2 plugins. After a year of trying to grok LV2 internals
> (with a lot of support from Robin Gareus - many thanks) there
> is one isssue that remains.
>
> All of these processors should support an arbitrary number of
> channels, say from 1 up to 100. Having the host instantiate N
> of them is NOT a solution. In most cases the actual per-channel
> DSP code is a tiny fraction of the total, so duplicating the rest
> N times would be just stupid, and in many cases (e.g. dynamics)
> the actual process depends on all inputs, not just the one for
> a single channel.

You could mark your ports as lv2:connectionOptional

https://lv2plug.in/ns/lv2core#connectionOptional

and then set your processor according to which channels been connected.


> So this my question: is there any extension / feature / whatever
> in LV2 that would allow a single plugin to support 1 to N channels
> without having to create N URLs and having N copies of the ports
> list in a manifest file ?
>
> If yes:
>
>     * How is it done, preferably without requiring any 'glue
>       code' libraries ?
>
>     * Which popular hosts support this ?
>      
>     * Is any example code available ?
>
> If no:
>
>     Why was something as basic as this ignored when LV2 was
>     designed, and why is that still the case after all these
>     years ?
>
>
> Ciao,
>