Jack (plugin)

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In short, you can set up your asoundrc file to specify JACK as the output, like so:

pcm.!default {
    type plug
    slave { pcm "jack" }
}

pcm.jack {
    type jack
    playback_ports {
        0 alsa_pcm:playback_1
        1 alsa_pcm:playback_2
    }
    capture_ports {
        0 alsa_pcm:capture_1
        1 alsa_pcm:capture_2
    }
}

ctl.mixer0 {
    type hw
    card 0
}

Then, after starting jackd with the appropriate sample rate for what you're doing, you can use ALSA apps with JACK:

  jackd -d alsa -d hw:0 -r 44100
  aplay -D pcm.jack <filename>

This will direct the ALSA playback stream (from aplay) visible to your JACK application, rather than sending it directly to the sound card.

\

Non-ALSA JACK audio I/O (e.g. FreeBOB)

If jackd is using an audio driver other than ALSA (as in FreeBOB, for example), the port names in the pcm.jack definition will be different from the example above. With jackd running, run jack_lsp to find out the port names, for example:

$ jack_lsp 
system:capture_1
system:capture_2
system:capture_3
system:capture_4
system:capture_5
system:capture_6
system:playback_1
system:playback_2
system:playback_3
system:playback_4
system:playback_5
system:playback_6
system:playback_7
system:playback_8

You can then use the appropriate port names in your .asoundrc, e.g.

pcm.jack {
     type jack
     playback_ports {
         0 system:playback_1
         1 system:playback_2
     }
     capture_ports {
         0 system:capture_1
         1 system:capture_2
     }
 }

Retrieved from "http://alsa.opensrc.org/Jack_(plugin)"

Category: ALSA plugins

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