[PD] several patches on one machine?

zmoelnig at iem.at zmoelnig at iem.at
Thu Jan 2 18:10:37 CET 2003

Quoting Mathieu Bouchard <matju at sympatico.ca>:
> On Wed, 1 Jan 2003, Larry Troxler wrote:
> > Don't start PD twice.
why ?

> The way I'm guessing things out:
> If you start PD twice then the second one does not have accesss to
> sound devices.
this is, of course, not true. You should be able to start the first process 
with "-nosound" and get the sound on the second instance.
However, it is correct (with "normal" drivers) that only one pd-process will 
have access to the soundcard.
With virtual audio cables like "jack" (i guess) you could even produce sound on 
both processes.

If you have several soundcards in your pc, this shouldn't be a problem at all 
(one or more cards exclusively for each pd)

> If you start PD twice then the two processes can do things more
> independently. For example, if video is causing the audio to make
> clicks
> and pauses and such, then you should run the video patch in another
> process.
> But then, audio has to be in the _first_ process you start because the
> sound driver is first come first served.
see above.

it really depends on what you are doing with your two patches.
If they are driven by the same pd, you have to take care about nameclashes in 
send/receive's and tables and elsewhere.
If they are driven by 2 pd's you don't have this problem but others (like the 
audio-output). additionally GUI-control of several pd's might be not as simple 
as with one interface. me,  for instance, i use 2 pd's most of the time (esp. 
when under heavy load): 1 audio-engine~ (that does all the signal-processing) 
with realtime-priority and 1 GUI (that does no signal processing) with bad 
priority. These are connected via netsend/netreceive, but this might not be 
what you need.


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