[PD] Understanding the mechanics of rebuilding Pd's DSP graph

William Huston williamahuston at gmail.com
Tue Nov 24 00:28:28 CET 2015

Got it. Thanks.

On Mon, Nov 23, 2015 at 2:47 PM, IOhannes m zmölnig <zmoelnig at iem.at> wrote:

> On 11/23/2015 07:56 PM, William Huston wrote:
> >> what qualifies as a "complex orphaned network"?
> [...]
> >
> > A tilde object is "active" (not orphaned) when its output is connected to
> > any object which stores computed audio in memory, or sends audio
> > external to PD,  like [dac~], [tabwrite~], or [writesf~].
> >
> > (OK-- externals become tricky, as PD's DSP compiler needs to understand
> > wither the external object sends audio outside PD, such as across
> > a network, or stores audio in memory)
> (does [hip~] store audio in memory?)
> how is Pd supposed to know "this"?
> the problem with all this is, that the entire scheme for saving CPU
> cycles will be screwed if you there is a single object in your
> to-be-orphaned network of which you don't know whether it has
> "side-effects" (as in I/O; but also any other side-effect) or not.
> > A [throw~] / [catch~] network is orphaned if the output of [catch~]
> > is connected to an orphaned tilde network.
> >
> > These kinds of orphans (at least for PD vanilla objects)
> > should be easy to detect
> since Pd allows an external to override built-in classes, you don't even
> know whether a sole unconnected [osc~] object does not phone home.
> (though you probably can still find out whether any given object is
> constructed from an external or "built-in")
> in any case, the suggestion boils down to maintaining a "whitelist" of
> objects-without-sideeffects, which is fragile at best.
> > I want to understand whether orphaned tilde objects are part of
> > the DSP graph, and steal cycles? or are they harmless?
> yes. no (not in your sense).
> if you are concerened about orphaned objects stealing CPU cycles, delete
> them from your patch. this way they are *guaranteed* to not take any CPU
> (nor memory), even with the most naive scheduler.
> also: Pd has [switch~] to turn off parts of a DSP-graph (even if it is
> not orphaned!).
> gfmadsr
> IOhannes
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