[pulseaudio-discuss] Can PulseAudio "automatically start" jackd?

[Jaime T]

On 30 November 2017 at 17:37, Tanu Kaskinen <tanuk at iki.fi> wrote:
> I believe jack_client_open() should start jackd, but apparently that's
> not working. I'm not familiar with how the automatic starting works, I
> can only tell that PulseAudio doesn't deliberately disable the
> automatic jackd starting.

Thank you Tanu. I now have something that works (mostly!):

Once pulseaudio is installed, I manually set the active profile for
every card to "off" so that pulseaudio relinquishes control of the
hardware. Then I install debian stretch's jackd2 package (I have not
yet tried this using jackd1). I edit /etc/jackdrc to contain something
like:

/usr/bin/jackd -T -d alsa -d hw:USX2Y -P -S -n 2 -p 120 -r 48000

(I want jack to play through my tascam usb sound card hence the
hw:USX2Y). At this point, I can test jackd using jack-play (from the
jack-tools package) and all is good.

Finally, I layer pulseaudio over the top of jack by installing the
pulseaudio-module-jack package and setting ~/.config/pulse/default.pa
to:

.include /etc/pulse/default.pa
load-module module-jack-sink channels=2
set-default-sink jack_out

Once I've killed and restarted pulseaudio, a quick "ps aux | grep -i
jack" shows me that the jack server has started, I get sound both
through jack and pulseaudio.

I now have a few questions about fine-tuning the stack (such as
realtime priorities), but I'll start another mail for that.

Thank you again.