77 lines
2.8 KiB
HTML
77 lines
2.8 KiB
HTML
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<p>
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Ardour will only ever deal with a single <dfn>audio device</dfn>. When it is
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desired to use more than one audio device at the same time, there are two
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choices:
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</p>
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<ul>
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<li>Use Ardour to start JACK (which handles all audio I/O), and create a
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"fake" audio device which represents all the multiple devices to be used. How
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to do this is platform dependent and described below.</li>
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<li>Use a different tool to start JACK and manage all the devices.</li>
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</ul>
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<p>
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Ardour is fundamentally designed to be a component in a pro-audio/music
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creation environment. Standard operating practice for such setups involves
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using only a single digital <dfn>sample clock</dfn> (something counting off
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the time between audio samples). This means that trying to use multiple
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independent soundcards is problematic, because each soundcard has its own
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sample clock, running independently from the others. Over time, these
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different clocks <dfn>drift</dfn> out of sync with each other, which causes
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glitches in the audio. This drift cannot be stopped, although in some cases
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the effects may be insignificant enough that they might not be noticeable.
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</p>
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<p>
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Thus, in an ideal world, a single device with a single clock and all the inputs,
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outputs and other features needed should be used. Of course, there are those
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who like to point out that this is not an ideal world, and believe that software
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should make up for this.
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</p>
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<h2>OS X</h2>
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<p>
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In CoreAudio, <dfn>aggregate devices</dfn> provide a method to use multiple
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soundcards as a single device. For example, two eight-channel devices can be
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aggregated so that 16 channels can be recorded in Ardour.
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</p>
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<div class="note">
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<p>
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When using a <em>single</em> typical 3rd party audio interface (such as those
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from Apogee, RME, Presonus, and many others), <em>or</em> using JackPilot or
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a similar application to start JACK, there is no need to worry about any of
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this. An aggregate device only needs to be set up if any of the following
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conditions are true:
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<ul>
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<li>Two entirely separate devices are used <em>and</em> JACK is started using
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Ardour</li>
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<li>A <dfn>builtin audio device is used</dfn> <em>and</em> JACK is started
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using Ardour</li>
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<li>More than two entirely separate devices are used</li>
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</ul>
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</div>
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<p>
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In the case of a builtin audio device, an aggregate device that combines
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"Builtin Input" and "Builtin Output" into one device needs to be created.
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</p>
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<p>
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The precise instructions for creating an aggregate device on OS X have varied
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from one released to another. Please read <a
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href="https://support.apple.com/en-us/HT202000">https://support.apple.com/en-us/HT202000</a>.
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</p>
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<h2>Linux</h2>
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<p>
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Please see the instructions at <a href="http://jackaudio.org/faq/"
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title="http://jackaudio.org/faq/">http://jackaudio.org/faq</a>.
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</p>
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