Subject: Re: [linux-audio-dev] extending LADSPA, it's not that easy ......
From: Steve Harris (S.W.Harris_AT_ecs.soton.ac.uk)
Date: Mon Nov 06 2000 - 19:14:42 EET
On Mon, Nov 06, 2000 at 11:50:24AM -0500, Paul Barton-Davis wrote:
> >> we already have this. LADSPA allows a plugin to not implement
> >> run_adding(). some hosts may have good reasons to not run such
> >> plugins. as far as i could tell, most plugins in the CMT set (thanks,
> >> richard!) don't implement run_adding(). not nice.
> >
> >Why is this bad? My understanding of the LADSPA callbacks was that you
> >were only intented to implement run_adding if you could do so with some
> >performance gain over the host doing it. Is there a good reason to
> >implement it anyway?
...
> input->freeverb_R->out1
> out1->delay_R->out2
> out2->eq_R->output
vs
> input->freeverb_RA->delay_RA->eq_R->output
...
OK, I see what you mean, but, looking at my code in this light I see a
new problem, implementing run_adding for (most of) my plugins is tricky
because, either:
a) there not the sort of thing you want to mix with the dry input (eg.
comb filters)
b) the wet/dry control is not simply variable mixing (eg. overdrive,
which has several varieties of 'wetness'), and therefor implement
wet/dry mixing themselves (as with freeverb I guess).
On the other hand, does this matter?
input->comb->overdrive->freeverb->output
Wet/dry is not desirable for a comb, overdrive implements it, so you can
just use its controls and ditto for freeverb.
OK, this is confusing in that the wet/dry mix controls are not uniform for
each plugin, but I think it would be pretty obvious.
Or am I missing something? Is there something special about run_adding
specified wet/dry mixing that is important?
- Steve
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