Re: [Jack-Devel] ?==?utf-8?q? Usage feasibility Q

 
Am Dienstag, 30. Januar 2018 18:38 CET, Christian Affolter <[hidden]> schrieb: 
 
> Hi Robert,
> 
> On 30.01.2018 18:21, Robert Bielik wrote:
> >> 2. recompile jack2 without dbus support
> > 
> > Ok, so I've compiled/installed jack2 without dbus support, and I'm now running jackd on a RT patched Raspbian Stretch (https://github.com/guysoft/RealtimePi)
> > 
> > And it seems to work wonderfully, no problem reaching buffer sizes below 1 ms. Happy joy!
> > 
> > I start jack with:
> > 
> > sudo jackd -P70 -d alsa -r 48000 -p 64 &
> > sudo jack_wait --wait --timeout 10
> > sudo jack_connect system:capture_1 system:playback_1
> > sudo jack_connect system:capture_2 system:playback_2
> > 
> > I need sudo, otherwise allocation of shared memory + realtime prio setting fails.
> 
> Make sure, that the user which starts jackd is allowed to raise the real
> time priority and memlock address space.
> 
> See http://jackaudio.org/faq/linux_rt_config.html
> 
> Most distributions ship and install a limits.conf snipped file with the
> jack package. Here is an example from CentOS/Fedora:
> 
> cat /etc/security/limits.d/95-jack.conf
> 
> # Default limits for users of jack-audio-connection-kit
> 
> @jackuser - rtprio 70
> @jackuser - memlock 4194304
> 
> In this case, the user has to be in the @jackuser group to be able to
> raise the priority.
> 

One important caveat: an often missed bit of information when this configutation is mentioned is the 
fact that this configures the pam_limits PAM module. So: pam needs to be enabled and configured (most
if not all distros do this) and whatever process need these setting needs to gothrough a pam session
or inherit/fork of a process that does. A "normal" login will usually do so but some process started during
bootup or chron or directly started from init/systemd will not. You've been warned ;-)

 Cheers, RalfD

> 
> > And then I've setup the ALSA JACK PCM plugin, but to use aplay I need to use sudo aswell:
> > 
> > sudo aplay -D pcm.jack /usr/share/sounds/alsa/Front_Center.wav>
> > Is there a way to set this up so sudo is not needed?
> 
> What error message do you get without sudo? Maybe your user has to be in
> the "audio" group (or similar).
> 
> Regards,
> Chris
> 
> 
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