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

<p>
  This section will help you get acquainted with the basic terminology and
  concepts associated with Ardour. More detailed information on each aspect
  of the program is provided in later chapters.
</p>

<h2>Sessions</h2>
<p>
  An <dfn>Ardour 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, or
  perhaps an entire album or a complete live recording.
</p>
<p>
  Ardour sessions are held 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 kept in 
  <abbr title="eXtensible Markup Language">XML</abbr> format, which is
  advantageous as it is somewhat 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>
  More details can be found at 
  <a href="/working-with-sessions/">Working With Sessions</a>.
</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 might use a track each 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 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>
  More details can be found at
  <a href="/working-with-tracks/">Working With Tracks</a>.
</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>
  One might typically use a bus to collect together the outputs of related
  tracks. Consider, for example, a 3-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 equalisation or compression) can be
  applied to the mix of all tracks. Such buses 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>
  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>
  More details can be found at
  <a href="/working-with-playlists/">Working With Playlists</a>.
</p>

<h2>Plugins</h2>
<p>
  Ardour allows you to process 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 class="wide-table">
  <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 to run a
  large amount of Windows code in an emulated environment.<br>
  If it is at all possible, you are strongly advised to use native
  LADSPA, LV2 or Linux VST plugins on Linux, or AU on Mac OS X.
</p>
<p>
  More details can be found at
  <a href="/working-with-plugins/">Working With Plugins</a>.
</p>