Jack server is not running or cannot be started on ubuntu 20.04

[Ralf Mardorf]

> Hi,


there's probably an issue with your dmix setup. My understanding is,
that something already grabbed the audio device.

I'm using either plain alsa or jackd with the alsa backend, no dmix,
pulseaudio or anything else.

I'm on a new machine without a sound card attached, so I show the issue
by using the crappy onboard audio device and Firefox compiled with alsa
and jack support.

[rocketmouse at archlinux ~]$ aplay -l | grep -e Analog -e HDMI\ 0
card 3: PCH [HDA Intel PCH], device 0: ALC897 Analog [ALC897 Analog]
card 3: PCH [HDA Intel PCH], device 3: HDMI 0 [EV2450]
[rocketmouse at archlinux ~]$ cat .asoundrc
defaults.pcm.card 3
defaults.pcm.device 3
[rocketmouse at archlinux ~]$ firefox https://www.youtube.com/watch?v=jC2ZY2loo74 >/dev/null 2>&1

If I push play, I can listen to Mr. Brown by my display's speakers.
While doing so I try to launch
/usr/bin/jackd -dalsa -dhw:3,3 -r48000 -p256 -n2
by qjackctl, but it returns
[snip]
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
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1,
skipping unlock
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1,
skipping unlock

Then I close Firfox. Now I can successfully launch jackd with the same
settings by qjackctl. I start Firefox again and now I can listen to
Mr. Brown still by the display's monitor, but the Audio tab of qjackctl
shows that Firefox is connected to the system by jackd, if I change the
settings by qjackctl to launch
/usr/bin/jackd -dalsa -dhw:3,0 -r48000 -p256 -n2
I can listen to Mr. Brown by the front panels headphones output.

Only one program can grab the audio device. If the audio device is
already grabbed by Firfox, before I launch jackd, starting jackd fails.

dmix might allow to share the device, probably something is fishy with
your dmix settings.

Regards,
Ralf

PS: Thank you, if I hadn't answered your request, I wouldn't have tested
on-board audio. I'm using either prosumer and professional audio devices
or a PC buzzer. I fear that my new mobo doesn't allow to use a PC buzzer
anymore.

If I turn on the computer, the PC buzzer does beep one time, so POST
works, but the terminal (bell enabled), or my email client, are silent,
they don't beep anymore after migrating the SSD from my old to my new
mobo.

[rocketmouse at archlinux ~]$ lsmod | grep pcspkr
pcspkr                 16384  0
[rocketmouse at archlinux ~]$ printf "\abeep! \n"
beep!

The module is loaded, but nothing, no audible beep.