[LAU] Raspberry: problems with shell script launcher when booting

[Carlos sanchiavedraz]

Hello, dear folks.

I'm still (constantly) tweaking my raspberry here and there when I
can. I have some configurations/sessions that run ok, Looper
(jack+sooperlooper), Looper+Fx
(jack+sooperlooper+rakarrack/guitarrix). But I'm still having some
annoying problems that wanted to share with you:

1) Simple session script, Looper, runs quite well when launched (via
ssh -X or from console) logged as PI user. When I run it as a
boot/init script (simple launcher script placed in /etc/init.d and
then installed with "update-rc.d launcherscript defaults 99"), almost
in every first start there's crackles and noise and my loops sound
distorted, even with clean guitar; if I restart then it goes well (2nd
or 3d time).

2) Next step forward I added Rakarrack in charge of guitar FX routed
to the Looper. First, it happens almost same thing as mentioned about
noise. Well, I guess It should have something to do with the signal
path and things connected to the same power supplier, so I'll have to
reserve some time to debug and switch off things until I get a cleaner
signal and get rid of the hum and crackles.
But the main issue is that there's problems with Rakarrack not been
able to start because several problems with not enough Jack ports and
Jack and RT. I didn't have any of these problems before.

I got to solve the problem with ports changing -p16 to -p32 when
launching jack+sooperlooper (-p24 is enough for just Rakarrack).

Then I made a launcher script LSB compliant (service script placed in
/etc/init.d and then installed with "update-rc.d servicescript
defaults", with LSB flags and functions for "start" and "stop", as a
proper newer Debian service, and configured to launch last in boot
phase) which then call the Jack-config+Rakarrack+Sooperlooper session
launcher script. I can see on screen in the init messages this error:

   "JACK is running in realtime mode, but you are not allowed to use
realtime schedule..."

But I know RT is already configured, so I guessed it was something to
do with the boot/init stage configuration and environment.
I tried using "su" with several different parameters to run the
launcher script as "pi" user, as It runs quite well when logged as
this user (calling just the script and even with "sudo
/etc/init.d/script start").
So, maybe you can't get RT in init phase on RaspberryPI and you can
only when you get to the login prompt and everything is loaded and
ready. But I think there's a "Puredata on Raspberry PI" project that
runs some scripts in the init stage; and it seems that in order to get
a headless FX+looper station, running some configuration+apps-launcher
at boot time is an obvious choice.

I'm sure something escapes me after so much try-error-code cicles.
Maybe you have some ideas.

Thanks as always.


-- 
Carlos sanchiavedraz
* Musix GNU+Linux
  http://www.musix.es