[LAU] running jackd from rc.local

[Len Ovens]

On Sun, 19 Apr 2015, Athanasios Silis wrote:

> i am using ubuntu studio.
> the pc i refer to is used for audio processing and routing primarily - it is a
> jack client server.
> so without any user intervention apart from powering it ON , it gets audio
> through ethernet from the jack master, processes it and sends it out through its
> local soundcards.

Al this should be something can be done... I don't feel I can give advice 
without doing it though. I do use Studio as well and have done various 
headless kinds of things... , but I haven't automated any of it, rather
logged in ssh and used screen as a session manager. I had no problem with 
no X, I just used dbus_launch to run screen and everything just worked 
(including Pulse Audio). I think screen can be automated (screen is not 
the only choice either), but I have not done it and so don't know how.

> on occasions I want to log on and use this computer for local audio capturing and
> / or playback. so jack would ideally run independent of a user session. Having
> said that, I usually don't need to log out and back in, I tend to lock the system
> as I am a single user. no need to deal with multiple user case now.

As long as it runs as the same user and the session is pre started at 
boot, All you would be doing is logging in to an already started session 
(GUI or CLI can both be done this way).

> some audio applications (namely calf) need an X server so in my custom startup
> scripts I start a vnc session as well.

I thought the lv2 plugins could be run without the gui... I could be wrong 
though.

> The problem as I understand it is that after log on, pam.d elevates logged in
> user's privileges to access hardware. The main problem is that alsa_(in|out) is
> can not grab the local soundcards... and I do not know what could be the
> conflict. people over at jack-devel mailing list said it could bea number of
> things like pulseaudio or lightdm....

pavucontrol Configure page/tab will allow you to turn the HW profile off 
for pulse. The lightdm thing doesn't make sense to me.

> there seems  to be a conflict or ideologies because some one suggests I make a
> system init script and another says jack is not designed to run as a system
> service.
> 
> Personally, I think that jack is indeed not designed as a system service, but I
> could be wrong. what is more a jack run as root, would never be available to
> applications that I would start as a user. is that so?

There are people who use jack in headless, boot to running synths and 
guitar effects pedals, so I know it can be done.

Not a walk in the park... a bit of a trudge through the forest.

--
Len Ovens
www.ovenwerks.net