Hey everybody,

I'd like to get pure data working on my raspberry pi to run headless, open a patch, accept audio input, and send it on out to the worth.

I have a sabrent usb audio device, It works fine if I open a gui and load pd within it. Upon loading the gui Pd takes the sound card, is happy, and a very simple patch of adc->dac puts the audio out.

I can't get it working headless. I've followed every internet advice. I know this isn't the fault of pure data but of Linus Torvalds/the Linux community, but I'd like to plug in the raspberry pi, get it going headless on say, ring mod into some delay, and just go from there. But will this ever be possible? Please help.

I wiped the microsd card today, installed raspberry stretch, and that's what it runs on now.

Thank you.
A dying soul.

@catkisser666 Yes, it is possible, a bit harder with stretch than it was with Jessie..
You will need to open your patch with a something.desktop file in the pi/.config/autostart folder.
Pd will need to be set as default program for the patch.
That will start Pd and open the patch after the X window is started and the whole Pi is booted up...... much the same as you are doing manually when you run it "not headless".
Permissions will need to be set for the .desktop file.
Here is an example of a .desktop file that starts a server on my Pi.....

[Desktop Entry]
Encoding=UTF-8
Type=Application
Name=X11VNC
Comment=
Exec=x11vnc -forever -loop -passwd present -display :0 -ultrafilexfer
StartupNotify=false
Terminal=false
Hidden=false

and here is one that runs a script.....

[Desktop Entry]
Type=Application
Name=RebootMessage
Exec=/home/pi/bin/newstart.sh
Icon=system-run
StartupNotify=true
Terminal=false
Hidden=false

David.

Can't you just edit the crontab and open the patch from there with the appropriate flags?
Type crontab -e which will prompt you to choose an editor (nano will be the default, better use that one). Scroll to the end of the file and type this:
@reboot sleep 20 ; pd -nogui -audiodev 3 -open /path/to/patch.pd &
This will force the Pi to launch Pd without the GUI, choose the third audio device (first is Pi's default audio hardware, second is default audio plugin, third should be any sound card connected as hardware), and open your patch. The ampersand (&) tells the Pi to run Pd in the background so you can still do things with it in the terminal.

Once you type this, hit Ctl+O to save the file and hit return as you'll be asked to save the changed you made. I'm pretty sure this will work.

@alexandros This works great for my purposes! I now have a little sonification system piping weather data from an arduino in a different building to my work space.

Hey @alexandros - question for you! So, after a while, running a Pd patch this way ceases to produce sound on my PiZero. I don't think it's because of how it's being run via crontab but maybe it's related to the sleep 20 parameter/argument? Task manager says Pd is still running. The patch (I think) is still receiving data from the Arduino but the CPU overhead would indicate that perhaps DSP is off or somehow this whole process is bypassed or idle/sleeping as the overhead is lower than when the patch is in full flight.

I'm not a Linux person so I'm not sure what kind of magic might be at work under the hood. Is there any reason why audio would stop working after a while? The PiZero is still functional, i.e., it hasn't frozen or crashed. Are there any commands that ensure the Pi doesn't take a nap?

Any guidance appreciated.

Looks like @reboot sleep is merely a run at boot one time after 20 second delay. Any ideas why audio would cease after a few hours?

@ricky TBH, I don't know. Perhaps you can skip the sleep part and just type the pd launching command right after "reboot". Your Pi is being shut down and powered up again every day or something like this? It sounds strange as to why this is happening, and even though Linux is my OS, I'm no guru by any means. Perhaps the Pd list is the place to find the answer to this.

@ricky I would doubt that it's a Pd problem. You could try snoop=0 here https://bbs.archlinux.org/viewtopic.php?id=182023
But there are a lot of google search results for "alsa audio stops after hours" that bring up many threads for alsa, pulseaudio, and others.
David.

@alexandros The Pi is not being restarted, no, although that could be one bandaid solution if I script a restart to reinitialize the patch after a defined period of time. A complete restart of the Pi is currently the only way to fix the issue. At the moment, the audio just ceases to work after a period of a few hours. Super weird. Oh, and I tried to remove the sleep flag but it seems to be a necessary delay for Pd to get up and running. I guess the OS needs time to get into shape to handle all things audio.

@whale-av I don't think it's a Pd issue either. The patch is still up and running, receiving data over a network from the Arduino, and general functional/editable but no dice on the audio front so it's likely that it's specific to Linux. Thanks for the pointer to ALSA resources/issues. I'll have a dig and see what I can find. I don't know if this has any bearing but I am using a little Behringer 2 -channel interface.

I'm trying to get my pi zero running headless. I've followed the instructions here and can get it to load a patch on start up. I get audio from the usb audio when I have a screen connected by hdmi. When I start up with no screen attached I get no usb audio. Sorry I'm pretty new to all this. Any help would be much appreciated

@simmit123456789 You could try editing the /boot/config.txt file and enable the hdmi_force_hotplug=1 option. It should then load the hdmi driver even though the screen is not present....... which might allow it to continue normally and load the usb drivers.
David.

Thankyou ssooooooo much David. That works perfectly!!!!