[LAD] Lv2 port replication [for dummies]

Fons Adriaensen fons at kokkinizita.net
Thu Aug 13 23:26:39 UTC 2009


On Thu, Aug 13, 2009 at 11:16:14PM +0100, james morris wrote:

> >How would a port type tell e.g. a multichannel limiter plugin if
> >it has to limit each channel separately, or use the same gain
> >reduction, based on the loudest one, on all ?
> 
> All the port type (property) would do is say this port is replicated. How
> the plugin handles that is down to the author. For the limiter example
> you might want a boolean value (a gui check box) which the plugin acts
> upon to determine this. There would still be the same number of
> inputs/outputs replicated in both cases (I think)...

That would be acceptable in many cases, but you can't expect
a synth user to set that checkbox when he loads the plugin
into his patch. The host should set the boolean option and
make the plugin (if it has its own GUI) remove the checkbox.

But probably it's safer to keep the 'polophony' case out of
this altogether, and let any synth host replicate the full
plugin instead. It is quite a special use case with very
specific requirements compared to general audio processing.

Which leads to my next consideration: is it a good idea at
all to expect a single plugin API to handle things as diverse
as a complete synthesiser, which could be a plugin host on
its own and require midi and maybe other non-audio interfaces,
and something as trivial as e.g. a ring modulator or a stereo
panner ? Do we really need something that would technically
allow such a synth plugin to load and replicate itself as
part of a polyphonic patch ?

It is (to me) rather unclear what LV2 tries to be. If it is
both that would be quite ambitious, and I don't think it would
be good idea. But I do see people asking for Zyn as an LV2,
and at the same time someone is implementing basic arithmetic
operations as LV2 plugins. 

P.S.

Probably this post will result in me being accused again of
'slinging FUD'. The use of that expression and acronym does
at least suggest that this would be som form of 'tactical'
game I'm playing. If people really think that is the case 
they should just tell me so, and then I'll be happy to leave
this group. Unlike the traditional FUD slingers I don not 
have a competing product. I'd just be happier if I could
fully support the one that does exist.

Fear (F) is a mental state, it can be functional or not, but
any mature person is supposed to be able to identify it and
deal with it. It is irrelevant in this context.

Uncertainty (U) and doubt (D) are a normal outcome of any
rational reasoning about non-trivial things. If you want
to avoid them the only alternative is religious faith.

 
Ciao,

-- 
FA

Io lo dico sempre: l'Italia è troppo stretta e lunga.




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