[pulseaudio-discuss] pulseaudio jack issue

[Tanu Kaskinen]

On Thu, 2010-07-01 at 11:22 +0200, Tim Blechmann wrote:
> hi all,
> 
> on my workstation, i am running pulseaudio with jack as backend. however, i 
> have some troubles with this setup. i have two audio devices on this 
> machine, the onboard audio chip of the soundcard and an rme hdsp 
> (pci+multiface).
> 
> when the multiface is not connected, the whole computer reacts very slowly. 
> like i click on a menu and it takes something like 10 seconds for the 
> dropdown menu to appear. i suppose, pulseaudio tries to start jack, but 
> doesn't succeed, because it cannot open the hdsp device ...

How did you figure out that the slowdown is caused by Pulseaudio trying
to start Jack?

Pulseaudio doesn't have any code that tries to start Jack in a loop
until it succeeds. Thus, the if the problem indeed is because PA tries
to start Jack, the problem is in Jack's autostart code, and should be
fixed there.

> i am not sure, what is the best way to handle this use case, but it took me 
> quite some time to figure out, that the odd desktop behavior is related to 
> pulseaudio trying to launch jack ... maybe it is possible to switch the 
> pulseaudio backend to the null backend, if jack cannot be launched?

AFAIK Jack autostarting happens in jack_client_open(), which we do not
run in a loop. Instead, if it fails, the jack module loading fails. When
that happens, it depends on the PA configuration what, if anything, will
be used as fallback. In the default configuration a null sink is loaded
by module-always-sink if nothing else is available.

-- 
Tanu