73 lines
2.5 KiB
HTML
73 lines
2.5 KiB
HTML
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<p>
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The right approach for using MIDI on Linux depends on which version of JACK
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is in use. The world divides into:
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</p>
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<table class="dl">
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<tr><th>Systems using JACK 1, versions 0.124 or later</th>
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<td>On these systems, JACK must be started with the <code>-X alsa_midi</code>
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server argument. To support legacy control applications, the <code>-X
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seq</code> argument to the ALSA backend of JACK can also be used to get the
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exact same results.</td></tr>
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<tr><th>All others</th>
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<td>Using a2jmidid acts as a bridge between ALSA MIDI and JACK. The <code>-X seq</code>
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or <code>-X raw</code> arguments should <em>not</em> be used—the timing and
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performance of these options is unacceptable.</td></tr>
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</table>
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<h2>Using a2jmidid</h2>
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<p>
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<dfn>a2jmidid</dfn> is an application that bridges between the system
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<abbr title="Musical Instrument Digital Interface">MIDI</abbr> ports and
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<abbr title="JACK Audio Connection Kit">JACK</abbr>.
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</p>
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<p>
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First it must be ensured that there is no ALSA sequencer support enabled in
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JACK. To check that, one must open QJackCtl's <kbd class="menu">Setup</kbd> window
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and set <kbd class="menu">Settings > MIDI Driver</kbd> to <kbd
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class="input">none</kbd>, then uncheck the <kbd class="optoff">Misc >
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Enable ALSA Sequencer support</kbd> option. The jack server must then be restarted
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before going on.
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</p>
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<h3>Checking for a2jmidid availability</h3>
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<p>
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Next, it must be checked whether a2jmidid is already installed. This is done
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by starting the JACK server, then going to the command line and typing:
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</p>
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<kbd class="cmd lin">a2jmidid -e</kbd>
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<p>
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If a2jmidid does not exist, it must be installed with the software manager of the
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Linux distribution in use until this command responds.
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</p>
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<h2>Checking available MIDI ports</h2>
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<p>
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If JACK is correctly configured for MIDI, then the MIDI ports should appear
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in qjackctl under <kbd class="menu">Connections > MIDI</kbd>.
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</p>
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<h3>Making it automatic</h3>
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<p>
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Once it has been verified that the ports appear in JACK as expected, this can
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be made to happen whenever JACK is started:
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</p>
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<ul>
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<li>If a newer version of JACK 1 is in use, by just making sure the <code>-X
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alsa_midi</code> or <code>-X seq</code> options are enabled for whatever
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technique is being used to start JACK.</li>
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<li>For other versions of JACK, by adding <code>a2jmidid -e &</code> as an
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"after start-up" script in the <kbd class="menu">Setup > Options</kbd> tab
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of QJackCtl, so that it is started automatically whenever JACK is
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started.</li>
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</ul>
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