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 preconfigured, 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 you to install the official
  ready-to-run version of the program that you can get from <a
  href="https://community.ardour.org/download">ardour.org</a>, as Ubuntu native
  packages are not supported in official Ardour forums or other
  support channels.
</p>
<p>
  Follow these steps to install the latest version of Ardour.
  <ol>
  <li>Download the latest release from <a href="https://community.ardour.org/download">
    ardour.org</a>.</li>
  <li><kbd class="mouse">Right+Click</kbd> 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>
</p>

<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 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>
<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>
    <samp>Cannot start JACK</samp> (though see the next section for other
      causes of this)
</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 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&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, you will not have permission to run JACK in the way you 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
      QJackctrl (aka JACK Control), so you 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/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
  derivitives 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>