--- /dev/null
+---
+layout: default
+title: Ubuntu Linux
+---
+
+<h2>Ubuntu Linux</h2>
+
+<p>
+ Ubuntu Linux is the most popular variety of Linux in use on desktop
+ and laptop systems. It has the backing of a for-profit corporation
+ (Canonical Inc.) behind it, a defined philosophy and a huge and
+ worldwide user base.As a result, it is a common platform for people
+ who want to use Ardour and other tools for music creation and
+ pro-audio work.
+</p>
+<p>
+ Unfortunately, Ubuntu has repeatedly caused major headaches for
+ people who want to use Ardour. These problems have arisen from a
+ combination of two basic issues:
+
+ <ul>
+ <li>Badly built packages of Ardour</li>
+ <li>Poor system configuration related to JACK, which Ardour (and
+ most other pro-audio tools on Linux) uses for audio and MIDI I/O.
+ </li>
+ </ul>
+</p>
+
+<h3>Problems with Ardour Packages</h3>
+
+<p>
+ It is not possible to know whether the current package of Ardour
+ released by Ubuntu has been correctly built or not. Ubuntu has a
+ history of making packaging errors that lead to crashes, missing
+ functionality and odd behaviour that is not present in the
+ ready-to-run version of the program that you can get from ardour.org
+ (or in the packages released by other distributions)
+<p>
+ If you plan to use Ardour on Ubuntu, you are <strong>strongly
+ recommended</strong> to download the ready-to-run version from
+ ardour.org. Ardour's lead developer (and many of the most active
+ members of our user community) will not provide support for, and
+ will not investigate bugs reported for, Ubuntu's own packages of
+ Ardour.
+</p>
+<p>
+ If have already installed the Ubuntu package of Ardour and find that
+ although the program starts up and basically runs, but you are
+ running into more subtle problems (for example, with plugin GUIs or
+ with export, or with the use of certain specific plugins), then you
+ are <strong>strongly recommended</strong> to download the
+ ready-to-run version from ardour.org.
+</p>
+
+<h3>Problems with PulseAudio and JACK Configuration</h3>
+
+<h4>Problems with the interaction between PulseAudio and JACK</h4>
+
+<p>
+ Like many distributions, Ubuntu has decide to use PulseAudio as the
+ default audio system. PulseAudio is a rich and capable system that
+ provides excellent services for typical users of Linux on the
+ desktop. However, it is not capable of the type of performance that
+ tools like Ardour require and in particular does not offer the
+ possibility of sending audio between applications that can makes the
+ Linux audio environment a very interesting one.
+</p>
+<p>
+ This would not a problem if it were not for the fact that JACK will
+ not run correctly (if at all) if it needs to use the same
+ soundcard/audio interface that PulseAudio is using. And since on
+ Ubuntu, PulseAudio is configured by default to always use the
+ (typically single) audio interface on your computer, this is a bit
+ of a problem.
+</p>
+<p>
+ The developers of JACK and PulseAudio got together in 2009 and
+ agreed upon a mechanism by which PulseAudio and JACK could cooperate
+ in their use of a single soundcard. Whether or not PulseAudio is running by
+ default, when JACK starts up it sends out a request to use the
+ soundcard. If PulseAudio is running, it will give up its use of the
+ soundcard to allow JACK to take over (and can optionally be told to
+ route its own audio through JACK). When JACK finishes, it sends out
+ another message, and PulseAudio can once again use the soundcard
+ directly.
+</p>
+<p>
+ This relatively simple system ought to be the basis for excellent
+ cooperation between PulseAudio and JACK. Unfortunately, it relies on
+ everything being correctly configured for it to work, and Ubuntu
+ have repeatedly failed to get this configuration correct.
+</p>
+
+<p>
+ The specific issues known at this time (spring 2013) are:
+ <ul>
+ <li>a bug in PulseAudio that causes it not to give up the
+ soundcard when JACK asks</li>
+ <li>bad package dependency information that causes a critical
+ package to be missing even when JACK and PulseAudio are
+ installed</li>
+ <li>a bug that causes JACK to freeze up when told to stop,
+ causing issues with restarting</li>
+ </ul>
+
+<h5>Symptoms</h5>
+
+<p>
+ <ul>
+ <li>Cannot start JACK (though see the next section for other
+ causes of this)</li>
+ <li>JACK starts but there is no sound coming from Ardour or other
+ applications that use JACK.</li>
+ </ul>
+</p>
+
+<h5>How to fix</h5>
+
+<h2>Problems with JACK configuration<h2>
+
+<p>
+ To function as intended, JACK needs to run with access to two
+ operating system facilities called "realtime scheduling" and "memory
+ locking". This means that you, the user who starts JACK, must be
+ allowed access to these facilities. By default, Ubuntu does create a
+ user group that has this permission but ... it does not put new
+ users into this group by default. Consequently, you will not have
+ permission to run JACK in the way you should.
+</p>
+
+<h5>Symptoms</h5>
+
+<p>
+ A message like "Cannot lock down memory" in the output from JACK as
+ it starts up. This output may be "hidden" in the Messages window of
+ QJackctrl (aka JACK Control), so you should check there.
+</p>
+
+<h5>How to fix</h5>
+
+<p>
+ Run the command <code>sudo usermod -a -G
+ audio <em>YOUR-LOGIN-NAME</em></code>. Then logout and login again.
+</p>