Dear friends:

I'm opening this thread, after trying every single bit of information i could find over the internet to solve my problem. Lost nights n' nights trying to get better results, but i'm basically stuck on the same spot.

I'm trying to get my pure-data/jack setup on Ubuntu-Studio 14.04 RT kernel.
I've installed every package of KXStudio, and managed to get quite a good audio configuration:

As i read in many forums that pulseaudio is a common source of issues, I've got rid of pulseaudio, it isn't installed at synaptics, nor running at all.

I'm using qjackctl to configure my jack server, and i'm pretty sure everything is fine, since i'm able to configure jack as the adudio output in softwares such as mixxx and audacious, and i'm also able to use non-configurable (at least for me) software such as Firefox with alsa->jack configuration, all at the same time. Magic for my eyes n' ears

My problems start exactly when i try to use jack as the audio output for pd-extended (same error for regular pd, as a matter of fact).

To add a short background story, i'm trying (with quite sucess so far) to use pd-extended to get the some analog sensors (so far, i'm testing a potentiometer) plugged as analog inputs on my arduino-mega, connect my Arduino-Mega via StandardFirmata+pduino to pd-extended and use Jack to provide a Midi output to make "ctlout 1" object to connect with midi-input-able softwares such as Mixxx, and use it as a midi controller.
As of Pd-extended configuration, i'm doing quite nice, pd-extended is able to read my potentiometer values, which are scalled from 0-127 and are linked to a "ctlout 1" object.

The problem is, i'm not able to select Jack as an Audio Output on pd-extended!

After my jackd server is running (with qjackctl) and it is veryfied to work with the software/methods listed above, i open a terminal prompt and try "sudo pdextended" (i need super-user privileges so i don't get "Permission denied" errors):

The results are as such:

[1]On Pd-extended terminal:
JACK: unable to connect to JACK server
JACK: server returned status 17

[2]On the terminal screen i used to call "sudo pd extended":
user@PC:~$ sudo pd-extended
priority 6 scheduling enabled.
priority 8 scheduling enabled.
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
watchdog: signaling pd...
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
jack server is not running or cannot be started
open: /etc/pd/gem.conf: No such file or directory
open: /home/pirata/.pd/gem.conf: No such file or directory
open: ./gem.conf: No such file or directory

[3]On qjackctl "Messages" screen i get as follow:
Tue Dec 2 16:55:15 2014: JACK server starting in non-realtime mode
Tue Dec 2 16:55:15 2014: self-connect-mode is "Don't restrict self connect requests"
Tue Dec 2 16:55:15 2014: ERROR: cannot register object path "/org/freedesktop/ReserveDevice1/Audio0": A handler is already registered for /org/freedesktop/ReserveDevice1/Audio0
Tue Dec 2 16:55:15 2014: ERROR: Failed to acquire device name : Audio0 error : A handler is already registered for /org/freedesktop/ReserveDevice1/Audio0
Tue Dec 2 16:55:15 2014: ERROR: Audio device hw:PCH cannot be acquired...
Tue Dec 2 16:55:15 2014: ERROR: Cannot initialize driver
Tue Dec 2 16:55:15 2014: ERROR: JackServer::Open failed with -1
Tue Dec 2 16:55:15 2014: ERROR: Failed to open server

It seems to me there it's something related to wrong qjackctl settings, but if that's the case, why is it only related to pd-extended?

I'm adding Screenshots of my Qjack Settings

Since i cannot take a print-screen of Input/Output devices, that's my list ATM:
hw:PCH - HD Intel PCH (hw:0)
hw:PCH,0 - CX20590 Analog (hw:0.,0) #thats my mic
hw:Loopback - Loopback (hw:1)
hw:Loopback,0 - Loopback PCM (hw:1,0)
hw:Loopback,1 - Loopback PCM (hw:1,1)
(default)

If any useful info is missing, please ask me for it, i'm REALLY into fixing this.

Thank you very much,

Miguel.

Ok, now i got it:

I think i found out why you aren't supposed to use jack as root, it is quite unstable.

It turns out i disabled cadence from "session start applications" and now, the very first path i choose once i start a session is my final option, lol. If i open "sudo qjackctl" i get to start a root jack server with no problem, then i can "sudo cadence" to open my alsa bridge, and i get a perfect root+jack config. I can run root apps with jack as an output, and "pirata" (my user) apps with alsa. To be noted i cannot start a non-sudo jack server until i restart my system.

If once i start my session i open qjackctl without sudo i get a working "non-root" jack server.

I was having some realtime issues, until i noted "qjackctl" realtime configs are read over limit.d configs, so be sure to check that! Setting Realtime Priority to 70 on qjackctl fixed my realtime issues.

I don't think i have any issue at all right now.

Never thought i'd be saying that

Never thought i'd be saying that

Yeah, first time I set up jack and pd (and all other audio applications) on my Linux was also a nightmare, and I had just recently migrated from Windows. But once things are configured properly, it all work like a charm! People who argue that Linux cannot work properly with audio most certainly have never used a properly configured Linux system, I wouldn't switch back for any money in this world!

Enjoy your stable system and take care,
Gilberto

To get it working I had to pass jack options like frames, SR, buffers, audio and midi channels... when lanching pd, along with -rt -jack. See pd --help for the list of said options. I made a launcher for that. whenever I forget about it and lauch pd any other way it crashes.

Maybe I'm wrong, but I have always better results working without jack, directly with alsa or even with oss on some old computers. If I have no intention of combine pd with another soft on the same computer, of course.
But even with jack (I think) well configured things goes more fluid without it, working with alsa or oss alone.
I'm the only one?

@macrogmittrei you're not alone, but for me only on the raspberry pi. i mean, jack is using alsa behind the scene, but I don't know why exactly it is working better (lower latency) when using alsa directly. on my main box (fast cpu) i use jackd.

Cheers~

I'm glad to not be the only one.

Hi! I just stepped here because i still have the same issues under ubuntu 16.04. I've already added the audio file inside limits.d to the root group. Then start qjackctl (not as sudo as it crashes the whole os) and then sudo puredata but i get the same error about returned status 17. Am i missing something?

Since you're running jack as user pi (it's on a raspi right?) but Pd as root, there's a chance they can't communicate. I'm not sure if what I'm saying is logical, but it sounds like a potential problem to me.
Why run Pd as root anyway?

@alexandros hi! I'm not on Pi but on Ubuntu

@pepedlr Pd vanilla compiled from source on linux mint here with dependencies installed as in INSTALL.txt. i have -alsamidi as startup flag (Preferences > Startup...) and with this audio works out of the box.
For midi i have to start QjackCtl, open "Connect" and connect Pure Data Midi-Out with one of the TiMidity ports. Hope that helps?

Edit: Also have to add that my jack server is not running when i connect Pd and TiMidity.

@ingox uhm not sure how to compile from source any hints?.

BTW i need qjackctl or patchage for routing different outputs... midi from vmpk and the audio out of pd (connected through jack the other options throw errors on sound pcm and so)

@alexandros oh btw if i don't run pd as root i can't save

@pepedlr not being able to save if Pd is not launched by root sounds like a bug to me. Did you install via the synaptic package manager? Which version of Pd are you using and which Ubuntu?

@alexandros. not sure how i installed it. I was using ubuntu 16.04 but never managed to solved it. As of today I´ve decided to reinstall ubuntu and everything works perfect it´s not the best solution but it works now. BTW i'm running same ubuntu and pd installed from command line.