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

botched new section introduction

Browse Source
This commit is contained in:
Paul Davis 2013-04-01 11:09:32 -04:00
parent 385c4554cc
commit 28f75f8ad5
1 changed files with 0 additions and 144 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

144
_manual/03_setting-up-your-system/08_platform-details/01_ubuntu-linux.html
View File

@ -1,144 +0,0 @@
---
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>