[PD] Help with Jack and PD

Michal Seta mis at artengine.ca
Sat Apr 21 01:16:37 CEST 2012

On Thu, Apr 19, 2012 at 9:49 AM, Rishabh Natarajan <
rishabh.natarajan at gmail.com> wrote:

> 1. When starting pd with jack and 16 channels, does this mean that all 16
> channels have to go in and out of Jack itself?


> 2. Do the number of input and output channels have to be the same (8 and 8
> in this case) or can they be different?

they can be different.

> When I tried starting pd with 18 channels and then assigned 16 to Jack
> incoming and 2 to built-in output for outgoing, terminal threw an error
> saying 'invalid number of channels'

I am not sure on this one but I think that if Pd does not find as many
physical (or jack) inputs or outputs it will warn you. When you do provide
enough IO you can reconfigure Pd for the new values and it should work (if
you cross your fingers).

3. I want to have 8 channels from one adc~ and another 8 from the other.
> This means all 16 channels are meant for input. How then do I route output
> from pd to the speakers?

you specify -audioindev 1,2 for example. You can specify -audiooutdev in
the same way and then you create the appropriate [dac~] objects. BTW, I
believe you can create aggregate devices on Mac (somewhere in the sound
preferences, I believe JackPilot manuals mentions that) to combine
different audio inputs and outputs. I vaguely recall doing something like
this in the past. Then you tell jack to use your aggregate, this may
simplify your setup routine...

> 4. If I am only inputting 16 channels through Jack can I use the dac~
> object to output sound from pd to the speakers?

if you run jack (and pd with -jack) then your [dac~] objects can be
connected to jack's outputs, i.e. Pd's inputs and outputs will appear in
JackPilot and you can route them any way you want to your system provided
I/O. Assuming that JackPilot uses the actual physical I/O, you should be
able to output sound from Pd to the speakers.


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