manual/include/understanding-basic-concepts-and-terminology.html

<p>
  In order to fully grasp the terms used in Ardour (and this manual), it is
  necessary to understand what things like sessions, tracks, busses, regions
  and so on&mdash;as used in Ardour&mdash;are.
</p>

<h2>Sessions</h2>

<p>
  An Ardour <dfn>session</dfn> is a container for an entire project. A session
  may contain an arbitrary number of <dfn>tracks</dfn> and <dfn>busses</dfn>
  consisting of audio and <abbr title="Musical Instrument Digital
  Interface">MIDI</abbr> data, along with information on processing those
  tracks, a mix of levels, and everything else related to the project. A
  session might typically contain a song, an entire album, or a complete live
  recording.
</p>

<p>
  Ardour sessions are kept in directories; these directories contain one or
  more <dfn>session files</dfn>, some or all of the audio and MIDI data, and a
  number of other state files that Ardour requires. The session file describes
  the structure of the session, and holds automation data and other details.
</p>

<p>
  Ardour's session file is written in <abbr title="eXtensible Markup
  Language">XML</abbr> format, which is advantageous as it is <em>somewhat</em>
  human-readable and human-editable in a crisis. Sound files are stored in one
  of a number of optional formats, and MIDI files as <abbr title="Standard MIDI
  File">SMF</abbr>.
</p>

<p>
  It is also possible for Ardour sessions to reference sound and MIDI files
  outside the session directory, to conserve disk space and avoid unnecessary
  copying if the data is available elsewhere on the disk.
</p>

<p>
  Ardour has a single current session at all times; if Ardour is started
  without specifying one, it will offer to load or create one.
</p>

<p class="note">
  More details can be found in the <a href="@@sessions">Sessions</a> chapter.
</p>

<h2>Tracks</h2>

<p>
  A <dfn>track</dfn> is a concept common to most <abbr title="Digital Audio
  Workstation">DAWs</abbr>, and also used in Ardour. Tracks can record audio or
  MIDI data to disk, and then replay it with processing. They also allow the
  audio or MIDI data to be edited in a variety of different ways.
</p>

<p>
  In a typical pop production, one track might be used for the kick drum, another for the snare, more perhaps for the drum overheads and others for bass, guitars and vocals.
</p>

<p>
  Ardour can record to any number of tracks at one time, and then play those
  tracks back. On playback, a track's recordings may be processed by any number
  of plugins, panned, and/or its level altered to achieve a suitable mix.
</p>

<p>
  A track's type is really only related to the type of data that it stores on
  disk. It is possible, for example, to have a MIDI track with a synthesizer
  plugin which converts MIDI to audio. Even though the track remains MIDI (in
  the sense that its on-disk recordings are MIDI), its output may be
  audio-only.
</p>

<p class="note">
  More details can be found in the <a href="@@tracks">Tracks</a> chapter.
</p>

<h2 id="busses">Busses</h2>

<p>
  <dfn>Busses</dfn> are another common concept in both DAWs and hardware
  mixers. They are similar in many ways to tracks; they process audio or MIDI,
  and can run processing plugins. The only difference is that their input is
  obtained from other tracks or busses, rather than from disk.
</p>

<p>
  A bus might typically be used to collect together the outputs of related
  tracks. Consider, for example, a three track recording of a drum kit; given
  kick, snare and overhead tracks, it may be helpful to connect the output of
  each to a bus called "drums", so that the drum kit's level can be set as a
  unit, and processing (such as equalization or compression) can be applied to
  the mix of all the tracks. Such busses are also called <dfn>groups</dfn>.
</p>

<h2>Regions</h2>

<p>
  A track may contain many segments of audio or MIDI. Ardour contains these
  segments in things called <dfn>regions</dfn>, which are self-contained
  snippets of audio or MIDI data. Any recording pass, for example, generates a
  region on each track that is enabled for recording. Regions can be subjected
  to many editing operations; they may be moved around, split, trimmed, copied,
  and so on.
</p>

<p class="note">
  More details can be found at <a href="@@working-with-regions">Working With
  Regions</a>.
</p>

<h2>Playlists</h2>

<p>
  The details of what exactly each track should play back is described by a
  <dfn>playlist</dfn>. A playlist is simply a list of regions; each track
  always has an active playlist, and can have other playlists which can be
  switched in and out as required.
</p>

<p class="note">
  More details can be found in the <a href="@@playlists">Playlists</a> chapter.
</p>

<h2>Plugins</h2>

<p>
  Ardour allows processing audio and MIDI using any number of
  <dfn>plugins</dfn>. These are external pieces of code, commonly seen as VST
  plugins on Windows or AU plugins on Mac OS X. Ardour supports the following
  plugin standards:
</p>

<dl>
  <dt><abbr title="Linux Audio Developers' Simple Plugin API">LADSPA</abbr></dt>
  <dd>the first major plugin standard for Linux. Many LADSPA plugins are
  available, mostly free and open-source.</dd>
  <dt><abbr title="LADSPA Version 2">LV2</abbr></dt>
  <dd>the successor to LADSPA. Lots of plugins have been ported from LADSPA to
  LV2, and also many new plugins written.</dd>
  <dt><abbr title="Virtual Studio Technology">VST</abbr></dt>
  <dd>Ardour supports VST plugins that have been compiled for Linux.</dd>
  <dt><abbr title="Audio Units">AU</abbr></dt>
  <dd>Mac OS X versions of Ardour support AudioUnit plugins.</dd>
</dl>

<p>
  Ardour has some support for running Windows VST plugins on Linux, but this is
  rather complicated, extremely difficult for the Ardour developers to debug,
  and generally unreliable, as it requires running a large amount of Windows
  code in an emulated environment. If it is at all possible, it is strongly
  advisable to use native LADSPA, LV2 or Linux VST plugins on Linux, or AU on
  Mac OS X.
</p>

<p class="note">
  More details can be found at <a href="@@working-with-plugins">Working With
  Plugins</a>.
</p>