JACK is a low-latency audio server written primarily for Linux. It can
connect a number of different applications to an audio device, as well as
allow them to share audio among themselves. Its clients can run in their
own processes (ie. as a normal application) or they can run within a JACK
server instance (i.e. as a "plugin").
jackd has to run with realtime privileges. One way to do this on Slackware
would be to use set_rlimits. Since 12.2 there's another way - if you have
a filesystem that supports posix capabilities (reiserfs does not), you can
grant jackd the rights to run in realtime mode, even when started as a
normal user, with the following command:
setcap cap_ipc_lock,cap_sys_nice=ep /usr/bin/jackd
If you use qjackctl to start jack, it will need the same capabilities set
to be able to start jack as non-root user. You can use the same command
with 'qjackctl' instead of 'jackd'
Optional dependencies are libffado and celt.
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