Re: [LAD] LADSPA plugins in ardour

On Sun, Aug 09, 2009 at 01:52:21PM -0400, Paul Davis wrote:

> wrong maiing list, really. but continuing on ...

Mmm, I'd assume that there are *some* people on LAD using Ardour,
including the devs...
  
> > I have an ardour mixer strip with 4 input and 2 outputs,
> > and insert (post-fader) a plugin which has 4 inputs (A,B,C,D)
> > and two outputs (X,Y).
> >
> > The signals at the output of the strip seem to be
> > X + C + D and Y + C + D instead of X and Y.
> >
> > Is this 'documented behaviour', and if yes what
> > purpose does it serve ?
>
> its certainly not documented, but not much is. it doesn't serve any
> purpose other than being one of the several approaches one could take
> with this somewhat unusual (but certainly not wrong) i/o
> configuration. basically, ardour has the concept of "data streams"
> within the signal processing route. imagine the situation *without*
> the plugin for a moment: what happens to the "extra" data streams C &
> D that don't obviously map to the outputs? executive decision: add
> them to the outputs (and do it badly, by adding C *and* D to both
> outputs, just for good measure). add the plugin to the situation ....
> presumably ardour should know that there are now really just two data
> streams post-plugin and that nothing needs to be done. but it appears
> that it doesn't discover this, and this may be intentional but more
> likely is just a bug.

In this case there shouldn't be a problem as channel counts match.
And Ardour *does* the right thing in the inverse case - more outs
than ins. Since Ardour seems to check channel counts before letting
you insert a plugin, it can't really be that it is unaware of them.

If channel counts don't match, the way to go seems to be:

Step 1. See if it makes sense to replicate the plugin. Probably
yes if it is one in, one out, no in all other cases. If so replicate
it. Else insert one instance.

Step 2. At each interface:

  - more sources than destinations -> drop the extra sources
  - more destinations than sources -> feed them zeros.

Adding signals doesn't make much sense, if the user wants it
he should say so (by inserting a plugin that does it).

Ciao,

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