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`?

Bump. I'm running into similar issues and can't seem to get around it at the moment. Any help is great appreciated...

This sounds strange as I'm using the Pi all the time with Pd, and never get these crushes. Are you guys sure it's not the patch causing the crash? One thing that might work is to launch Pd without loadbangs, by typing this in a terminal pd -noloadbang
Maybe you want to add the -stderr and/or the -verbose flags so that Pd prints its output to the terminal and gives more information as to what it's trying to do. In case of a crash, the log will remain in the terminal window so you can inspect it.
Disabling loadbangs and checking Pd's output might give some hints.

@alexandros are you using Buster? Or a different dist of Raspbian? I was able to get around this problem by using LXDE for autostart. However I occasionally get an error now about Alsa not being able to restart.

I'm just using the latest Raspberry Pi OS in one Pi and the one before that (can't remember the code name now) on another Pi. I'm always using the Lite version though, don't know if that has anything to do with it.

In my experience, I think the success of using Pd on a Raspberry Pi is heavily dependent on what disc image you use.

The best one I've found is the Patchbox OS from BLokas.

I used to just download a generic Raspian and had problems connecting midi controllers to Pd, with one it was absolutely impossible to update Pd, and there have been other problems. With a good disc image, preferably one designed to make music, or has Pd preinstalled, all these problems go away and you can just start using it.

Thanks for the Patchbox suggestion. Now my PD Patch is running without a problem so far. But with the Patchbox OS I had a hard time getting any sound on the 3.5 output on the Raspi 4. But this kind of solved the problem: https://www.raspberrypi.org/forums/viewtopic.php?t=263942

Hey Knallberto. Yes I have that problem too. With patch box sometimes theres issues with Jack and alsa mixer. You have to figure all the sound settings out, with you soundcard or preferred audio driver.

Jack used to work great for me, but I am having issues with this new soundcard I am using, so I switched to alsamixer. You have to take some different things into account. Once you get a good sound setting save it and try and use that going forward.

Hey nicnut, thanks for the reply. I don't really understand the problem, but all I had to do was to use the other HDMI port to make audio work.

Hello, I just solved this problem today, here is how :
1- install pure data via terminal (sudo apt-get install puredata)
-> pd0.49.0 came
2- launch Pd via console (puredata)
3- menu media/audio parameters
4- select in & out : bcm2835 Headphones (hardware)
===>>>> ususally I click "ok" and when I test audio Pd crashes <====
5- click "save all settings" or "enregistrer tous les réglages"
6- click "ok"

Pure Data stopped to crash when I tested audio.

I can NOT explain why.

I'm preparing a new SD card to reproduct this, and I'll keep you informed.

@ marivier.rocks If you can figure out how to install pd .51 I would say it's worth it. Lot's of new features, plus you can use the latest version of Else library, which has a lot things that make Pd easier to use.

bump, bump.
Also having this issue now -
Terminal output:

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

I see this bug was posted to GitHub and Puckette said it was fixed but I have latest Pd for Raspbian and any patch with audio crashes Pd instantly.
Thanks

@marivier.rocks Hi - did you get this reproduced on a new SD? I have this problem even after trying your solution. Thanks

I've been having some issues too. I use the Audio Injector sound card on my 8 gig ram RPi. I have Audio Injector selected as my driver. Sometimes, for mysterious reasons, the Pi willl start up and use Alsa for the driver. I think there is even a mic on the Pi, or maybe on the sound card, and I have all the audio inputs off and it even starts feeding back. Pretty crazy. It happened once, and a few times Alsa was my driver, so it doesn't happen often.

Maybe get the audio settings you want, save them and try a restart,

@nicnut Hi - thanks. I've tried every possible audio driver combination available for the Pi except an external hardware interface.

@mswcpt I highly recommend trying a Rpi sound card. The ones I've tried sound so good. Better than my Motu interface on the Mac. I am using an Audio Injector one now. The PiDac+ sounds amazing, but it doesn't work well with other Pi shields, but sounds really amazing, Hi-fi. I recommend going that route. Set it up, in PD select is as your audio interface, save chagnes, and next time you launch Pd it should be the same setting.

@nicnut Thank you for the reply. We are going to try with an audio interface that works on Pi! It may very well be that systems that experience this error would benefit from external audio hardware controllers rather than on-board. Will post result once tested. Cheers

@mswcpt said:

@marivier.rocks Hi - did you get this reproduced on a new SD? I have this problem even after trying your solution. Thanks

My solution wasn't the good one, sorry. See hereafter others tries...

The "alsa xrun recovery apparently failed" bug seems to be solved here : https://github.com/pure-data/pure-data/issues/969

So, I downloaded the latest source code and installed Pd 0.51-4 on my Raspi (with Buster ->Linux version 5.4.72-v7+ (dom@buildbot) (gcc version 9.3.0 (Ubuntu 9.3.0-17ubuntu1~20.04)) #1356 SMP Thu Oct 22 13:56:54 BST 2020)

I use the onboard soundcard (bcm2835), as far as there is no input, I uncheck "input device". When I tested sound, there was no "alsa xrun recovery apparently failed" error message.

But some minutes later in "Pd noGui or GUI mode" + "Raspi console or graphic mode", the error is still there.

Holla! I have the same problem, running Pd 0.51-4, Raspberry pi 3 A+ (Should be up to date, installed and updated yesterday), using it's internal sound card. Patch includes [comport] that fetches data from an Arduino. Still investigating, but it seem to work for a couple of hours, then I get that same message, "alsa xrun recovery apparently failed". Gonna try another sound card.

I previously had version 0.49.3 on Raspi 3B. After opening a patch and additionally opening the object overview window, it crashed. My guess is that the DSP opens 2x independent DAC output, which doesn't work due to the BCM2835's lack of hardware mixing. Current compiled version 0.53 (puredata.info) can represent this problem at least in the console, if you start it from there. XRuns occur, but the program does not crash. You clearly see, that ALSA restarts like crazy. You should also check in the second window whether the ALSA settings are correct and save them there if necessary. It's obviously a sound chip issue. For the object overview, however, I added a [loadbang]->[;pd dsp 0] message and saved it.
You can also turn off DSP before opening another patch (or subpatch!) that will automatically turn on DSP, which happens under the hood, e.g., the help patches. With these changes, so far, it works for me. Furthermore, a proper sound card with hardware mixing would solve the issue. You get the idea.