manual/_manual/03_setting-up-your-system/08_platform-specifics/01_ubuntu-linux.html

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layout: default
title: Ubuntu Linux
---                        

<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>

<h2>Problems with Ardour Packages</h2>

<dl>
<dt>What is the problem?</dt>
<dd>
<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>
<dt>Symptoms</dt>
<dd>
<p>
  Ardour starts up and basically runs, but you encounter subtle
  problems (for example, with plugin GUIs or with export, or with the
  use of certain specific plugins), or are missing functionality, or
  run into crashes.
</p>
</dd>
<dt>How to Fix</dt>
<dd>
<p>
  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. The ardour.org
  packages install along side your distribution versions, and do not
  interfere or interact in anyway other than sharing your own personal
  Ardour settings and configuration choices.
</p>
</dd>
</dl>

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

<dl>
<dt>Background Info</dt>
<dd>
<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>
</dd>
<dt>What is the problem?</dt>
<dd>
<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>
</dd>
<dt>Symptoms</dt>
<dd>
<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>
</dd>
<dt>How to fix</dt>
<dd>
</dd>
</dl>

<h2>Problems with JACK configuration</h2>

<dl>
  <dt>What is the problem?</dt>
  <dd>
    <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>
  </dd>
  <dt>Symptoms</dt>
  <dd>
    <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>
  </dd>
  <dt>How to fix</dt>
  <dd>
    <p>
      Run the command <code>sudo usermod -a -G
        audio <em>YOUR-LOGIN-NAME</em></code>. Then logout and login again.
    </p>
  </dd>
</dl>