2007/2/19, Camilo Polyméris <cpolymeris@email-addr-hidden>:
> Stefano D'Angelo wrote:
> > 2007/2/19, Camilo Polyméris <cpolymeris@email-addr-hidden>:
> >> Jeff McClintock wrote:
> >> > >>>I actually don't know how many plugins are LTI, but, for example, a
> >> > >>>lot of delays, reverbs, choruses, eq. filters, compressors,
> >> modulators
> >> > >>>and "sound mixers" should be, and that's quite enough after all.
> >> >
> >> > Yeah, It's a good optimization. The SynthEdit plugin API supports
> >> > inputs being flagged as 'linear', if several such plugins are used in
> >> > parallel they are automatically collapsed into a single instance which
> >> > is fed the summed signals of the original plugins. Plugin are
> >> > collapsed only when their control inputs are the same.
> >> >
> >> > BEFORE optimation:
> >> >
> >> > [plugin]-->[delay1]------>
> >> > [plugin]-->[delay2]-/
> >> >
> >> > AFTER:
> >> >
> >> > [plugin]--->[delay1]--->
> >> > [plugin]-/
> >> >
> >> > e.g. two parallel 100ms delays are combined. Two different length
> >> > delays aren't.
> >> >
> >> > This is most useful in synth patches where each voice is an
> >> > identical parallel sub-patch.
> >> >
> >> >
> >> > Jeff McClintock
> >> >
> >> How often are more than one plugin with the same control inputs used in
> >> paralel? I was rather thinking of colapsing (or swapping) plugins in
> >> series. They'd have to be linear and time invariant, of course.
> >> Or maybe plugins could 'know' how to colapse themselves, sort of like
> >> overriding Plugin::operator+(const Plugin&), to use a C++ metaphor.
> >
> > Well, stereo sounds passing through mono plugins is one case.
> > However as Jeff describes this optimization, it is applicable when
> > output signals are summed, and I don't know how often it happens.
> > Anyway it is another idea to optimize processing for linear plugins,
> > definitively not something to discard.
> > This makes me think that some common basic "pieces" like mixers and
> > delay filters can have special properties which involve even more
> > aggressive optimization. Maybe it's worth considering how this special
> > blocks could be developed and used.
> >
> > Stefano
> >
>
> Yes, I agree I think if one comes up with a couple of "rules" like that,
> it could be possible to design a system which automatically simplifies
> processing networks.
> To recap:
> * If two parallel filters have equal control inputs and their outputs
> are summed, replace with one filter and feed with summed inputs.
Maybe too specific... maybe also plugins with different control inputs
can be merged, I must see this.
> * If two serial filters are LTI, they impulse response can be added to
> one filter.
Added = multiplied :-)
> * If two serial filters are LTI, and their impulse response is unknown,
> they can be swapped.
Yes, but why?
> * Filter "classes" could know how to merge to instances into one. Those
> instances may even cancel each other out.
Yes
> * Remove filter chains which have no outputs.
Absolutely not: what about a GUI oscillator?
> etc... With a little thinking and some formal work, one could come up
> with more ideas like those.
I think too that this is an interesting path to follow: NASPRO (the
wrapper) will absolutely go this way, just after wrapping LADSPA,
DSSI, LV2 (without extensions) and similar.
When LV2 extensions will be implemented then work on these stuff will begin.
> Software like puredata and jMax (which use such "common basic pieces" in
> many diferent configurations) could benefit from such a system. I looked
> at their websites, but could not find any references to similar ideas.
Good, another use for it :-)
Stefano
Received on Mon Feb 19 20:15:03 2007
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