I'm running a Raspberry Pi 4 with "Raspberry Pi OS (32-bit) Lite [August 2020 / 2020-08-20 / Kernel 5.4]" headless and the latest version of Purr-Data, set up the Raspberry using this guide , did the Alsa no audio (glitch) issue Pi 4

fix to get audio working through the 3.5 mm jack.

I'm interfacing the Raspberry Pi through the macOS terminal and with VNC Viewer through ethernet.

I get the following error as soon a starting Purr-Data,

error: audio I/O stuck... closing audio 

I open up a patch and turn off and turn on the DSP signals and get the following error

error: audio I/O stuck... closing audio error: audio I/O dropout 

Even though if I play sample .wav or bang a sinewave, the audio does get played but it gets glitchy as in the audio sound is crackled.

has anyone experienced it before? any knowledge on how to overcome it?

@tiemget How do you start pd (show us the command line)

@EEight said:

@tiemget How do you start pd (show us the command line)

Welcome to Purr Data
nw.js version 0.24.5
Pd has started the GUI
canvasinfo: v0.1
stable canvasinfo methods: args dir dirty editmode vis
classinfo: v.0.1
stable classinfo methods: size
objectinfo: v.0.1
stable objectinfo methods: class
pdinfo: v.0.1
stable pdinfo methods: dir dsp version
[import] $Revision: 1.2 $
    [import] is still in development, the interface could change!
    compiled against Pd-l2ork version 2.14.2 (20200922-rev.c4495143)
PD_FLOATSIZE = 32 bits
working directory is /home/pi
libdir loader 1.10
    compiled on Sep 22 2020 at 18:05:09 
    compiled against Pd version 0.48.0.
libdir_loader: added 'Gem' to the global objectclass path
libdir_loader: added 'cyclone' to the global objectclass path
libdir_loader: added 'zexy' to the global objectclass path
libdir_loader: added 'creb' to the global objectclass path
libdir_loader: added 'cxc' to the global objectclass path
libdir_loader: added 'iemlib' to the global objectclass path
libdir_loader: added 'mapping' to the global objectclass path
libdir_loader: added 'markex' to the global objectclass path
libdir_loader: added 'maxlib' to the global objectclass path
libdir_loader: added 'memento' to the global objectclass path
libdir_loader: added 'mjlib' to the global objectclass path
libdir_loader: added 'motex' to the global objectclass path
libdir_loader: added 'oscx' to the global objectclass path
libdir_loader: added 'pddp' to the global objectclass path
libdir_loader: added 'pdogg' to the global objectclass path
libdir_loader: added 'pixeltango' to the global objectclass path
libdir_loader: added 'rradical' to the global objectclass path
libdir_loader: added 'sigpack' to the global objectclass path
libdir_loader: added 'smlib' to the global objectclass path
libdir_loader: added 'unauthorized' to the global objectclass path
vbap - v1.1 - 14 Aug. 2014 - (c) Ville Pulkki 1999-2006 (Pd port by HCS)
libdir_loader: added 'pan' to the global objectclass path
freeverb~ v1.2
libdir_loader: added 'hcs' to the global objectclass path
libdir_loader: added 'jmmmp' to the global objectclass path
libdir_loader: added 'ext13' to the global objectclass path
libdir_loader: added 'ggee' to the global objectclass path
libdir_loader: added 'ekext' to the global objectclass path
libdir_loader: added 'disis' to the global objectclass path
libdir_loader: added 'lyonpotpourri' to the global objectclass path
pdlua 0.10.1 (GPL) 2014-2020 Martin Peach et al., based on
lua 0.6~svn (GPL) 2008 Claude Heiland-Allen <claude@mathr.co.uk>
pdlua: compiled for pd-0.48 on Sep 22 2020 18:05:09
Using lua version 5.3
pdlua: using JavaScript interface (Pd-l2ork nw.js version)
error: audio I/O stuck... closing audio

There you go.

@tiemget How to you launch pd? ie: pd -rt -jack -channels 2... or maybe you are using alsa?

@EEight said:

@tiemget How to you launch pd? ie: pd -rt -jack -channels 2... or maybe you are using alsa?

Oh okay I got you now, i'm starting pd from the raspberry menu, do you suggest me to launch like that?

@tiemget Are you using jack? You can run pd using alsa, but it will be the only application accessing your soundcard. Installing and using jack allows you to route audio and control the buffer size (128,256,512). If you are new to linux, have a seat you are in for a ride ;p

I don't know if this helps, but sometimes the audio output level will make the audio sound bad. I have a RPi 4 and I am using a soundcard with a seperate audio output volume knob. And I use the alsamixer.

At first I turned everything up as much as possible. It sounded terrible and sometimes no audio came out. Now I have alsa mixer at about 60% and my soundcard at 80%. I control the volume from my amp and faders in Pd. It sounds way better.

If you are using the 8th inch jack out of the Pi something related to this could be an issue.

@nicnut A dedicated soundcard is the way to go AFAIK. Also using jack and controlling the buffer (if you don't need low latency then use a big buffer like 1024).

@nicnut said:

I don't know if this helps, but sometimes the audio output level will make the audio sound bad. I have a RPi 4 and I am using a soundcard with a seperate audio output volume knob. And I use the alsamixer.

At first I turned everything up as much as possible. It sounded terrible and sometimes no audio came out. Now I have alsa mixer at about 60% and my soundcard at 80%. I control the volume from my amp and faders in Pd. It sounds way better.

If you are using the 8th inch jack out of the Pi something related to this could be an issue.

@EEight said:

@nicnut A dedicated soundcard is the way to go AFAIK. Also using jack and controlling the buffer (if you don't need low latency then use a big buffer like 1024).

I plugged in a USB audio dongle, and it seemed to stop the crackling but I still get the following audio dropouts

more info on how to set up jack or alsa would be appreciated

[4] error: audio I/O dropout
loading cached help index from ~/.purr-data/search.index
finished loading help index (0.20 secs)
[4] error: audio I/O dropout

@tiemget Basically you need to install and configure jack (you will need to open a terminal and use the command line). Like you can see, it's far from plug and play. If you have motivation and time it's doable

1. open a terminal type: sudo apt update && sudo apt install qjackctl
2. find qjackctl in the menu, open it, Setup... choose your soundcard in Interface and start using Frames/Period of 1024
3. launch pd from the command-line pd -rt -jack -channels 2 -alsamidi