[PD] Pd Vanilla on Raspberry Pi

Miller Puckette msp at ucsd.edu
Tue Aug 14 01:47:10 CEST 2012

Thanks for the info... some quick ideas:

> To avoid additional system load I tried to run it with -nogui (after preparing the patch) via ssh 
> but the system claims the sound device is busy. 
> Didn't find out why so far, a simple test-patch runs fine though.
> No idea what's going on.

This could be  permission thing.  When someone logs into the X windows
system it gives that user read/write accesss to audio, which is denied for
anyone else for security reasons (someone could ssh in and eavsdrop on you :)
To see if that's the issue you could try running Pd via ssh with and without
separately logging into X windows.  The fix I found (besides just running as
root which will nuke any permissions problem) was to add my username to 
group 'audio'.  On Fedora I did this be editing the file /etc/gshadow (which
had permission 0 which I had to change and restore).  Not sure if it's the
same in Debian land where RPi lives.

As to real-time permission, again on Fedora the trick is to add lines like
* - rtprio 99
* - memlock 1000000000
to the file, /etc/security/limits.conf ... this is permissive; you can be
more restrictive if you want to tune it more carefully.

> BTW, is it possible to quit Pd via the patch?
> Just in case Pd has such high priority that the system becomes inaccessible.
Yep: the message is "; pd quit"


> thanks,
> Michael.

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