[LAU] could not start jack - already registered problem

[Len Ovens]

On Wed, April 24, 2013 11:40 pm, Hartmut Noack wrote:

>>>> To put it another way, does this problem show up right after a fresh
>>>> login?
>>>
>>> Exactly: after a fresh login.

Probably not PA, and besides you have tried with PA turned off. Pa was
having problems about that time, but normally the problem was after having
used it to stream. (it has been fixed since, but I don't know if the fix
has been backported yet to either kxstudio or Ubuntu repos (in the works
in ubuntu I think)
>>>
>>>> or only after having used the system for a while. What does your
>>>> desktop use for most of it's non-jack audio output?
>>>
>>> Before I do anything else, I check if Jack is running. Browser, Skype
>>> and the like use Pulse Jack sink, so I let Cadence start pulse-jack
>>> after starting Jack.

You may wish to use ps to check what jack is running. I have tried Cadence
and it has a lot of different ways of doing things. You do have both jackd
and jackdbus. Both Cadence and qjackctl are able to deal with either one.
However some of the jack apps will start jackd if no jack is running. So
if an app starts jackd and then you use qjackctl (for example) to start
jackdbus, it will fail because the device is already in use. So maybe try:

jack_control exit
kill -9 jackd

and see if jack starts. When you have this problem.

Really, these are shots in the dark. I am trying to think what questions
to ask that could narrow things down.

-- 
Len Ovens
www.OvenWerks.net