Hello,

I have problems using PD on a Raspberry Pi 3B+ with Raspbian. I downloaded the newest version of Raspbian to a SD card and installed PD using
sudo apt install puredata.
When I open a patch from the help files it is working fine, but when I open a patch that I prepared earlier, even though it opens up, when I turn on the DSP it crashes. In the console it says:

restart alsa output
alsa xrun recovery apparently failed
pd: pcm.c:1168: snd_pcm_prepare: Assertion 'pcm' failed.
Pd: signal 6

And while opening PD the console writes: priority 8 scheduling failed.
In the PD window it says: priority 6 scheduling failed: running at normal priority.
I don't know if that might be important, too.

Any ideas what might cause PD to crash and what the console messages mean`?

@Knallberto No... but these are my audio settings on RPI3 for Pd..... which work...
What does yours look like?
I am using a very cheap little usb soundcard, so yours will not look exactly the same.
David.

Basically the same, but insted of an external card I am using the onboard sound right now, with no input device. Maybe I will try to use an external card as well....

Same problem here... I tried with raspberry pi 4, Raspbian and after few seconds:

restart alsa output
alsa xrun recovery apparently failed
pd: pcm.c:1168: snd_pcm_prepare: Assertion 'pcm' failed.
Pd: signal 6

It only happens when starting in nogui with rc.local using:

sudo pd -no gui /home/pi/patch.pd &

I don't now what to do, I have setup analog jack as the default output...

Again, same error, pd randomly close with a raspberry pi 3 using jack output.

pd 49.0 installed with "sudo apt install puredata."

You don't necessarily need Jack, ALSA can do just fine, if you get drop outs make sure to increase the block size.
As for running Pd on boot, you can use crontab to do this and not mess with rc.local. Don't know if it's a better practice, but it works for me, also I don't need to start Pd as root. Type crontab -e and hit enter to edit it with nano. At the bottom of the file write:
@reboot sleep 5 ; pd -no gui /home/pi/patch.pd &
Hit Ctl+o, enter, then Ctl+x to exit. After you reboot Pd should launch. Make sure to delete the line in rc.local though.

Don't know if this will solve the problem. As for the priority issue, go to /etc/security/ and type sudo nano limits.conf. At the end of the file put the following:

@audio   -  rtprio     98
@audio   -  memlock    unlimited
@audio   -  nice      -19