[Jack-Devel] Sudden Pulseaudio Faulure reported due to jack

[Nedko Arnaudov]

>> I cannot tell from the error messages whether the problem is jackd
>> is not
>> running when expected, or if jackd is running but for some reason Pulse
>> cannot make a connection.

The history of calling both jackd and jackdbus jack servers "jackd" did
not make things clearer. Naming of module-jackdbus-detect.so already
suggests that PulseAudio uses shared library to communicate with
jackdbus (not jackd) and detect something (whether jack server in
jackdbus is running). Whether suggestion is a fact or not is best
checked in the source code, when documentation is not available.

> I am using AVLinux which is Debian9 Stretch.
>
> I cannot edit config files if I dont know how all these
> pulseaudio/jack/alsa daemons interact.

IIRC the information used to be in the jackaudio.org trac wiki.
Maybe someone else on this list knows if the trac wiki is still
accessible somehow.

> Therefore,
> Do you have a suggestion how I should approach the startup of these
> daemons.

To my knowledge PulseAudio works better with jackdbus over D-Bus
than with jackd. I'm even surprised it works at all with jackd. After
all jackdbus is "jack server" that can be autolaunched, controlled and
monitored over D-Bus :)

When D-Bus was introduced to jackd, it was only for reservation protocol
used for coordination (with PulseAudio) of audio device ownership/use.
The purpose of this reservation protocol is/was to allow jack server
take audio device ownership from PulseAudio.

In contrast, jackdbus exposes jack server control API over D-Bus and
also uses the audio device reservation protocol (which also works over
D-Bus).

PulseAudio (still?) uses the jackdbus control API.

Also, systems with both jackdbus and jackd executables, while possible,
are more complex to setup than ones with jackd or jackdbus only and at
least some of linux distros keep proving this for years.

Another common issue with such complex setups comes from the fact that
libjack.so that is used by JACK applications, can autostart the jack
server. libjack.so (source) code can autostart jack server in
jackd or in jackdbus but which one is proper depends on particular
system setup.