3 title: Using More Than One Audio Device
7 Ardour will only ever deal with a single <dfn>audio device</dfn>. If you
8 want to use more than one, you have two choices:
12 If you want to use Ardour to start JACK (which handles all
13 audio I/O) you will need to create a "fake" audio device on your
14 computer the represents all the multiple devices you wish to
15 use. How to do this is platform dependent and described below.
18 Use a different tool to start JACK and manage all the devices.
22 Ardour is fundamentally designed to be a component in a
23 pro-audio/music creation environment. Standard operating practice
24 for such setups involves using only a single digital <dfn>sample
25 clock</dfn> (something counting off the time between audio samples).
26 This means that trying to use multiple independent soundcards is
27 problematic, because each soundcard has its own sample clock, running
28 independently from the others. Over time, these different clocks drift
29 out of sync with each other, which causes glitches in the audio. You
30 cannot stop this drift, although in some cases the effects may be
31 insignificant enough that some people might not care about them.
34 Thus in an ideal world you should not use multiple independent
35 soundcards but instead use a single device with a single clock and all
36 the inputs, outputs and other features that you need.
39 Of course, a lot of people don't live in an ideal world, and believe
40 that software should make up for this.
45 In CoreAudio, <dfn>aggregate devices</dfn> provide a method to use
46 multiple soundcards as a single device. For example, you can
47 aggregate two 8-channel devices so that you can record 16 channels
52 If you are using a <strong>single</strong> typical 3rd party
53 audio interface (such as those from Apogee, RME, Presonus, and many
54 others), <strong>OR</strong> you are using JackPilot or a similar
55 application to start JACK, you do not need to worry about this.<br />
56 You will need to set up an aggregate device <em>only</em> if either
57 of the following conditions are true:
60 <li>You want to use two entirely separate
61 devices <strong>AND</strong> want to start JACK using Ardour.</li>
62 <li>You want to use your builtin audio device <strong>AND</strong>
63 want to start JACK using Ardour.</li>
64 <li>You want to use more than two entirely separate devices</li>
68 In the case of your builtin audio device, you will need to create
69 an aggregate device that combines "Builtin Input" and "Builtin
70 Output" into one device.
73 The precise instructions for creating an "aggregate device" on OS X
74 have varied from one released to another.
76 <dl class="wide-label">
78 <dd>Please read <a href="http://support.apple.com/kb/HT1215">http://support.apple.com/kb/HT1215</a></dd>
79 <dt>OS X 10.6 or later</dt>
80 <dd>Please read <a href="http://support.apple.com/kb/HT3956">http://support.apple.com/kb/HT3956</a></dd>
85 Please see the instructions at <a href="http://jackaudio.org/faq"
86 title="http://jackaudio.org/faq">http://jackaudio.org/faq</a>