manual/include/ubuntu-linux.html

<p>
  <dfn>Ubuntu Linux</dfn> 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.), 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>

<h2>High Level Recommendations for Ubuntu Users</h2>

<p>
  Currently, installing pro audio applications on vanilla Ubuntu requires some
  configuration, in order for the user to gain realtime privilege (read below).
  Ubuntu Studio, which is an official flavor of Ubuntu, and thus shares the
  repositories with Ubuntu, has this already configured. Other distributions,
  such as KXStudio, and Dreamstudio are largely based on Ubuntu, and like
  Ubuntu Studio, has these settings pre-configured, while also containing
  customized versions of Ubuntu packages, which often are more up to date.
</p>

<h2>Installing Ardour</h2>

<p>
  There may be unintended differences, and even bugs in Ubuntu native packages,
  as a result of a different building method. For this reason, Ardour
  developers highly recommend installing the official ready-to-run version of
  the program that can be downloaded from <a
  href="https://community.ardour.org/download">ardour.org</a>, as Ubuntu native
  packages are not supported in the official Ardour forums or other support
  channels.
</p>

<p>
  Follow these steps to install the latest version of Ardour:
</p>

<ol>
  <li>Download the latest release from <a
  href="https://community.ardour.org/download">ardour.org</a>.</li>
  <li><kbd class="mouse">Right</kbd>-click the downloaded file and choose
  properties.</li>
  <li>Click the Permissions tab and check the option "Allow this file to run as
  a program".</li>
  <li>Close the dialog and double-click the file.</li>
  <li>Follow the prompts.</li>
</ol>

<h2>Problems with the interaction between PulseAudio and JACK</h2>

<h3>Background Info</h3>

<p>
  Like many distributions, Ubuntu has decided to use <dfn>PulseAudio</dfn> 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 make the Linux audio environment a very
  interesting one.
</p>

<p>
  This would not be 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, PulseAudio on Ubuntu is
  configured by default to always use the (typically single) audio interface on
  the 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>

<h3>What is the problem?</h3>

<p>
  The specific issues known at this time for all flavors of Ubuntu 12.04 and
  12.10 are:
</p>

<ul>
  <li>a bug in PulseAudio that causes it not to give up the soundcard when JACK
  asks (<a
  href="https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/1163638">LP:
  #1163638</a>, fixed in Ubuntu 13.04).</li>
</ul>

<h3>Symptoms</h3>

<p>
  A message like <samp>Cannot start JACK</samp> in the output from JACK as it
  starts up (though see the next section for other causes of this). This output
  may be hidden in the Messages window of QJackCtl (aka JACK Control), so one
  should check there.
</p>

<h3>How to fix</h3>

<p>
  These bugs do not affect releases from 13.04, and earlier releases (12.04 and
  12.10) are in the process of being fixed.
</p>

<h2>Problems with JACK configuration</h2>

<h3>What is the problem?</h3>

<p>
  To function as intended, JACK needs to run with access to two operating
  system facilities called <dfn>realtime scheduling</dfn> and <dfn>memory locking</dfn>. This means that the user who starts JACK <em>must</em> be
  allowed access to these facilities. By default, Ubuntu does create a user
  group that has this permission but&mdash;it does not put new users into this
  group by default. Read more about why <a
  href="https://wiki.ubuntu.com/Audio/TheAudioGroup">here</a>. Consequently,
  the user will not have permission to run JACK in the way they should.
</p>

<h3>Symptoms</h3>

<p>
  A message like <samp>Cannot lock down memory</samp> in the output from JACK
  as it starts up. This output may be hidden in the Messages window of QJackCtl
  (aka JACK Control), so one should check there.
</p>

<h3>How to fix</h3>

<p>
  Make sure the file /etc/security/limits.d/audio.conf exists. If it is named
  /etc/security/limits.d/audio.conf.disabled, rename it to the former. Run the
  command:
</p>

<kbd class="cmd lin">sudo usermod -a -G audio <em>YOUR-LOGIN-NAME</em></kbd>

<p>
  Then log out and log in again. On Ubuntu Studio the user is a member of audio
  group by default, but not on other official flavors.
</p>

<h2>Reporting Issues</h2>

<p>
  Given the difficulties in supporting Ubuntu and the limited time and
  resources of the Ardour team, the <dfn>Ubuntu Studio Project</dfn> has
  requested that issues and bug reports related to Ubuntu, Ubuntu Studio and
  other derivatives be directed to them.
</p>

<h3>Contact Information for Ubuntu Studio</h3>

<p>
  <a href="http://ubuntustudio.org">The Ubuntu Studio Homepage</a>
</p>

<p>
  <a href="http://ubuntuforums.org/forumdisplay.php?f=335">The Ubuntu Studio
  Forums.</a>
</p>

<p>
  <a href="https://help.ubuntu.com/community/UbuntuStudio/MailLists">Information
  on the Ubuntu Studio Mailing Lists.</a>
</p>

<p>
  <a href="https://help.ubuntu.com/community/UbuntuStudio/IRC">Information on
  the Ubuntu Studio IRC channel.</a> #ubuntustudio on irc.freenode.net
</p>