Hi,
I am using CTAG Face on Beaglebone Black, the SD Card image I use is ctag_bone_debian_v0.1.2 (https://github.com/ctag-fh-kiel/bela-ctag/releases), which is base on recent Debian 9.5 2018-10-07 4GB SD IoT image.
I am able to hear sound from all 8 output channels and receive input from all 4 input channels, using jackd and simple test e.g. speaker-test. However, when I use Jackd (jackaudio.org), I experience jitter about every two minutes, when these jitter sound occurs I see error messages appear on console said xruns. I have some experiences doing the same on other embedded system having jackd in real-time mode well and no jitter sound at all, but this one is obviously because jackd cannot starts real-time mode, which I believe is the root cause, and that is very much depend on the Linux distribution, kernel configuration, and systemd config.
I know this is an old question but yet it seems few people resolves it comprehensively, even the original jackd try to solve the package one way or the other but it seems there is no single simple solution for that, so I want to ask once again - how to start jackd in real-time mode?
After flashed the SD-CARD I did the followings:
1. apt-get purge jackd1 jackd2 jackd
2. apt-get install jackd
Jackdmp version is now 1.9.11
I followed most of the suggested actions like this URL for enable real-time jackd:
https://ask.fedoraproject.org/en/question/60961/how-to-start-jackd-with-realtime-scheduling-under-fedora-21/
And tried the following but jackd still report error
1. Utilises the Linux group "audio". Note that there is no "realtime", no "jackuser" after installing jackd.
2. Modify files in /etc/security/ and /etc/security/limits.d/ and reboot the system
Cannot use real-time scheduling (RR/95)(1: Operation not permitted)
AcquireSelfRealTime error
The error message I got on screen when jackd run in verbose mode is:
...
...
Jack: JackServer::Start
Jack: JackThreadedDriver::Start
Jack: JackPosixThread::StartImp : create non RT thread
Jack: JackPosixThread::ThreadHandler : start
Jack: JackThreadedDriver::Init real-time
Jack: JackPosixThread::StartImp : create non RT thread
Jack: JackPosixThread::AcquireRealTimeImp priority = 95
Cannot use real-time scheduling (RR/95)(1: Operation not permitted)
Jack: JackPosixThread::ThreadHandler : start
AcquireSelfRealTime error
compare to the embedded system which has jackd running in real-time mode
...
...
Jack: JackServer::Start
Jack: JackThreadedDriver::Start
Jack: JackPosixThread::StartImp : create non RT thread
Jack: JackPosixThread::ThreadHandler : start
Jack: JackThreadedDriver::Init real-time
Jack: JackPosixThread::StartImp : create non RT thread
Jack: JackPosixThread::ThreadHandler : start
Command I start jackd for both my previous Embedded System and CTAG FACE are the same
jackd -v -R -P 95 -d alsa -C hw:0 -P hw:0 -r 48000 --shorts -p 2048 -n 2 -i 2 -o 4
There is no /var/log messages for jackd
Bela is one of the most advance sound project for Linux, I hope we could resolve this problem for good!