On Sep 12, 2019, at 6:36 PM, Nick Porcaro <nick@ccrma.Stanford.EDU> wrote:

OK folks all is well now - the solution to the problem is as I expected.

As Miller said, pdlib ticks all the patches in question so if you just want to feed

samples from one patch to another you have to make sure all the other patches

are switched off.  

I had deceived myself by disabling them at a different level in my code.

Whew, that was close!

- Nick

On Sep 12, 2019, at 6:09 AM, Nick Porcaro <nick@ccrma.Stanford.EDU> wrote:

Miller, et. al:


I think I see the problem, this code would appear to tick ALL the patches
in the pd instance:

for (each buffer from the audio callback) {
    for (a smaller buffer that’s the pd block size (eg 64)) {
        pd->processFloat (oneTick, smallBufferIn, smallBufferOut);
  }
}


So maybe it should be like this:


for (each buffer from the audio callback) {
    for (a smaller buffer that’s the pd block size (eg 64)) {
        // Do something here to disable the patches that are not active
        // eg :

        for (patches that are not this one) {

            pd->sendFloat(“/patchName/enable",0);

        }
        pd->processFloat (oneTick, smallBufferIn, smallBufferOut);
    }
}

The code above is a member function of a C++ class that encapsulates a patch.
I just realized as I was falling asleep for the night that this line is NOT specific
to any patch!

        pd->processFloat (oneTick, smallBufferIn, smallBufferOut);

I’ll try something first thing tomorrow and I’ll let you all know what happens.

- Nick

On Sep 12, 2019, at 4:56 AM, Nick Porcaro <nick@ccrma.Stanford.EDU> wrote:

Hi Miller-

On Aug 20, 2019, at 7:08 PM, Miller Puckette <msp@ucsd.edu> wrote:

actually I wrote that before I thought the whole thing out :)

No, if you "tick" a pdlib instance you tick all the patches in it - so teh
way to get different patches in different orders is to call up a separate
Pd instance for each of them, and use "adc~" and "dac~" objects to get
audio in and out - that incurs zero latency (once you've buffered 64
samples in the first place).

I tried this two ways:  

- Create separate Pd  instances for each patch wrapped in adc~ and dac~

- Use a single Pd  instance with multiple patches,  with each patch wrapped in adc~ and dac~

Then I have a simple JUCE app (based on the sampler example) that drives
these pd patches.

There is no problem with doing switch~ and such, but I am 
getting distortion that seems like clipping in both cases (one pd instance with many patches
or multiple pd instances with one patch)

To be more clear these wrapper patches are like:

Patch 1:     [adc~]   ->   [lop~ 200] -> [dac~]
Patch 2:     [adc~]   ->   [hip~ 200] -> [dac~]

These wrapper patches also have a loadbang to pd dsp 1;

Then the code that calls these patches does something like this calling libpd:

for (each buffer from the audio callback) {
    for (a smaller buffer that’s the pd block size (eg 64)) {
        pd->processFloat (oneTick, smallBufferIn, smallBufferOut);
  }
}

I tried scaling the input and output to these  wrapper patches after the adc~ and before the dac~
and that does not solve the distortion/clipping problem either.

There are a couple of more things I can try:

   - make the wrapper patches even simpler, just scaling instead of the filters.
   - dump the samples to a file and maybe that will shed some light on the problem.
   - making a much simpler example program that I can share will you all.

I have libpd and pd source directly compiled into my example

Any other ideas would be greatly appreciated!

OR, within one pd instance, in libpd or in Pd, you can use switch~ objects,
switched off, to control each sub-patch.  Send the switch~ objects bangs in
whatever orders you wish.  In this scenario, tabsend~ and tabreceive~ would
be the simplemt way to pass signals between them.  In libpd you can do this
zero-latency (just stuff your inpuits into arrays before sending all the
tick messages and copy the results out afterward).

This approach works well, but the problem is I can’t insert non-Pd signal processing
anywhere I’d like in the Pd patch so that’s why I went with the first approach.

Within the Pd app, you can do teh same thing but you incur one tick extra
latency, because copying the autio into the tables has to happen on the
previous tick form the one on which you get the outputs back.

If you like danger, you can write an external tilde object that, for its
"dsp" action, sends a message to teh patch that can "tick" the switch~
objects right in the middle of Pd/s DSP tick.  This is not part of Pd
because it could cause major confusion if general-purpose Pd messages
got sent around in mid-tick.

cheers
Miller

On Tue, Aug 20, 2019 at 11:55:58PM +0200, Roman Haefeli wrote:

On Tue, 2019-08-20 at 12:09 -0700, Miller Puckette wrote:

I think the way to do this in libpd is to open them all as separate
patches
within one instance of Pd (so that symbols are shared) and use
"tabsend"
and "tabreceive" to route signals to/from them, using shared names
like
"channel1" as both inputs and outputs so you can rearrange them in
any
order.

(Beware of allowing patches to _write_ andy of their output channels
before
reading all the input channels, if you're re-using the same channels
as 
inputs and outputs :)

Do I understand right: When loading them as separate patches, you can
dynamically re-order the signal flow by using [tabsend~]/[tabreceive~]
(which you could with abstractions, too) _without_ adding latency?

And: When changing the symbol of [tabsend~] or [tabreceive~], is the
DSP graph re-calculated?

Roman

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