ardour
/
manual
13
0
Fork 0
Code Pull Requests Releases Activity

tweak USB port issue text; expand and fix OSX multiple device text

This commit is contained in:
Paul Davis 2013-02-20 19:15:31 -05:00
parent 0535ac9499
commit a9ad30703c
2 changed files with 46 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
_manual/03_setting-up-your-system/01_the-right-computer-system-for-digital-audio.html
View File

@ -20,7 +20,22 @@ menu_title: The Right Computer System
<dd>Poorly engineered wireless networking interfaces (and/or their device drivers) can also block the audio interface from keeping up with the flow of data</dd>
<dt>USB ports
</dt>
<dd>If you are using an audio interface connected via USB, and sometimes even if you are not, the precise configuration of your system's USB ports can make a big difference. There are many cases where plugging the interface into one port will work, but using different USB port results in much worse performance. This has been seen even on Apple systems.</dd>
<dd>If you are using an audio interface connected via USB, and
sometimes even if you are not, the precise configuration of your
system's USB ports can make a big difference. There are many cases
where plugging the interface into one port will work, but using
different USB port results in much worse performance. This has been
seen even on Apple systems.
</dd>
<dt>Internal USB Hubs</dt>
<dd>Ideally, you'd like your USB ports to all connect directly to the
main "bus" inside the computer. Some laptops (and possibly some
desktop systems) come wired with an internal USB hub between the
ports and the system bus, which can then cause problems for various
kinds of external USB devices, including some models of audio
interfaces. It is very difficult to discover whether this is true or
not, without simplying trying it out.
</dd>
<dt>CPU speed control
</dt>
<dd>Handling audio with low latency requires that your processor keeps running at its best performance (speed) at all times. Many portable systems try to regulate processor speed in order to save power - for low latency audio, you want this totally disabled, either in the BIOS or at the OS level</dd>
@ -29,9 +44,16 @@ menu_title: The Right Computer System
<dt>System Management Interrupts (SMIs)
</dt>
<dd>SMIs are interrupts sent by the motherboard to tell the computer about the state of various hardware. They cannot be (safely) disabled, but they can also take a (relatively) long time to process. It is better to have a motherboard which never sends SMIs at all - this is also a requirement for realtime stock trading systems, which have similar issues with latency.</dd>
<dt>Hyperthread</dt>
<dd>This technology is becoming less common as actual multi-core CPUs
become the norm, but it still exists and is generally not good for
realtime performance. Sometimes you can disable this in the BIOS,
sometimes you cannot. A processor that uses hyperthreading will be
less stable in very low latency situations than one without.
</dd>
<dt>Excessive (bass) vibration
</dt>
<dd>This doesn't affect the flow of data to/from the audio interface, but it can cause the flow of data to/from your disk storage to become <em>much</em> slower. If you are going to use a computer in an environment with live sound, make sure to place it so that the disk is not subject to noticeable bass vibration. What actually happens is that the vibrations cause the mechanism inside the disk to detect read errors, and this forces a retry of the reading from the disk itself. Retrying over and over massively reduces the rate at which data can be read from the disk. Avoid this.</dd>
</dl>
<p>  </p>
<!-- remove if more text is added below --><!-- remove if more text is added below -->
<!-- remove if more text is added below --><!-- remove if more text is added below -->

30
_manual/03_setting-up-your-system/07_using_more_than_one_audio_device.html
View File

@ -43,17 +43,31 @@ that some people might not care about them.</p>
</p>
<h3>OS X</h3>
<p>You will need to set up what Apple refers to as an "aggregate
device" if any of the following conditions are true:
<ul>
<li>You want to use two entirely separate
devices <strong>AND</strong> want to start JACK using Ardour.
<li>You want to use your builtin audio device <strong>AND</strong>
want to start JACK using Ardour.</li>
</ul>
If instead you are using a <strong>single</strong> typical 3rd party
audio interface (such as those from Apogee, RME, Presonus, and many
others), you do not need to worry about this
</p>
<p>The precise instructions for creating an "aggregate device" on OS X have varied from one released to another.</p>
<dl class="wide-label">
<dt>OS X 10.5</dt>
<dd>Please read <a href="http://support.apple.com/kb/HT1215">http://support.apple.com/kb/HT1215</a>
</dd>
<dt>OS X 10.6 or later<dt>
</dt>
</dt>
<dd>Please read <a href="http://support.apple.com/kb/HT3956">http://support.apple.com/kb/HT3956</a>
</dd>
<dt>OS X 10.5</dt>
<dd>
Please read <a href="http://support.apple.com/kb/HT1215">http://support.apple.com/kb/HT1215</a>
</dd>
<dt>OS X 10.6 or later</dt>
<dd>
Please read <a href="http://support.apple.com/kb/HT3956">http://support.apple.com/kb/HT3956</a>
</dd>
</dl>
<p>
Aggregate devices also provide a method to use multiple soundcards as