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131 lines
4.6 KiB
131 lines
4.6 KiB
USING ALSA DIRECTLY
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Switch to root account.
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Install the required packages:
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yum install alsa-plugins-jack
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Add yourself to the jackuser group.
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usermod -a -G jackuser "<your username>"
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Start the jack daemon (your parameters may be different):
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jackd -R -P4 -dalsa -r44100 -p512 -n4 -D -Chw:0 -Phw:0
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or use
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qjackctl -s
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if you have it installed and configured.
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INTEGRATE JACK WITH PULSEAUDIO
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The original text is placed at:
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http://www.harald-hoyer.de/linux/pulseaudio-and-jackd
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Switch to root account.
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Install the required packages:
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yum install pulseaudio-module-jack alsa-plugins-jack
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Add yourself to the pulse-rt and jackuser groups.
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usermod -a -G pulse-rt,jackuser "<your username>"
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Switch to your normal user account.
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Create ~/bin subdirectory if absent:
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mkdir -p ~/bin
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Copy the pulseaudio start file:
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cp /usr/share/doc/jack-audio-connection-kit-*/jack.pa ~/bin/jack.pa
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chmod 755 ~/bin/jack.pa
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Close all your sessions and relogin to get the new group permissions and
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limits.
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Kill the current pulseaudio daemon:
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pulseaudio -k
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Start the jack daemon (your parameters may be different):
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jackd -R -P4 -dalsa -r44100 -p512 -n4 -D -Chw:0 -Phw:0
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or use
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qjackctl -s
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if you have it installed and configured.
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Start the pulseaudio daemon:
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~/bin/jack.pa
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Now everything should work.
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RUNNING JACK SERVER IN REALTIME MODE
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NOTE: This chapter explains why you have done the above changes in more detail.
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It is kept for informational purposes.
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The JACK server jackd has the capability to run in a real-time mode
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which greatly decreases the chance of audio glitches. The real-time mode
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is enabled by passing the -R or --realtime option to jackd when starting
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the server. It is only possible to run jackd in real-time mode as a
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non-root user by modifying your PAM configuration, PAM stands for
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Pluggable Authentication Modules and is the primary authentification
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mechanism used on Fedora. The primary source of PAM documentation can be
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found at the following at http://www.kernel.org/pub/linux/libs/pam/
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The specific PAM configuration file that needs to be modified is
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/etc/security/limits.conf and it controls the system resource limits. It
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is important to understand that modifying the resource limits
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configuration files can decrease the security of your system.
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Documentation specific to the resource limits PAM module can be found at
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http://www.kernel.org/pub/linux/libs/pam/Linux-PAM-html/pam-6.html#ss6.12
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Alternatively, one can create a new file
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/etc/security/limits.d/<priority>-<name>.conf
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that contains the resource limits for individual users and/or groups. The
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jack-audio-connection-kit package that comes with Fedora contains the file
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/etc/security/limits.d/99-jack.conf
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that does this job for you.
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The resource limits that need to be changed to allow jackd to run in
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realtime mode are named rtprio and memlock. To increase the limits for a
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specific user named fred you would add the following to
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/etc/security/limits.conf
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fred - rtprio 20
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fred - memlock 50000
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The value of rtprio can be set in the range 0 - 99 where any value
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greater that 0 will allow the user to change the scheduling policy to
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"real-time". By default the JACK server requires a minimum rtprio
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setting of 20 but jackd will accept a command line parameter -P or
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--realtime-priority which will change the minimum required value of
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rtprio that is needed, but the default of 20 is nearly always
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sufficient.
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The appropriate value for memlock is dependent on the amount of memory
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present in the system but a minimum value of 50000(50MB) and a maximum
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value of half the available memory can be used as a rough guideline.
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To verify that the resource limits have been modified you can use the
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bash built-in ulimit command, for example:
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$ulimit -a
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core file size (blocks, -c) 0
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data seg size (kbytes, -d) unlimited
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max nice (-e) 0
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file size (blocks, -f) unlimited
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pending signals (-i) 8191
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max locked memory (kbytes, -l) 50000
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max memory size (kbytes, -m) unlimited
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open files (-n) 1024
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pipe size (512 bytes, -p) 8
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POSIX message queues (bytes, -q) 819200
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max rt priority (-r) 20
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stack size (kbytes, -s) 10240
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cpu time (seconds, -t) unlimited
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max user processes (-u) 8191
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virtual memory (kbytes, -v) unlimited
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file locks (-x) unlimited
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file locks (-x) unlimited
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Keep in mind that you may have to re-login before changes to limits.conf,
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or additions to the limits.d/ directory to take effect.
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