manual/include/understanding-playlists.html

  
<p>
  A <dfn>playlist</dfn> is a list of regions ordered in time. It defines 
  which parts of which source files should be played and when.  Playlists 
  are a fairly advanced topic, and can be safely ignored for many types 
  of audio production. However, the use of playlists allows the audio 
  engineer more flexibility for tasks like multiple takes of a single 
  instrument, alternate edits of a given recording, parallel effects such 
  as reverb or compression, and other tasks.
</p>
<p>
  Each audio <dfn>track</dfn> in Ardour is really just a mechanism for
  taking a playlist and generating the audio stream that it represents. 
  As a result, editing a track really means modifying its playlist in 
  some way. Since a playlist is a list of regions, most of the 
  modifications involve manipulating regions: their position, length 
  and so forth. This is covered in the chapter
  <a href="@@working-with-regions">Working With Regions</a>.<br>
  Here, we cover some of the things you can do with playlists as objects
  in their own right.
</p>

<h2>Tracks are not Playlists</h2>
<p>
  It is important to understand that a track <em>is not</em> a playlist. 
  A track <em>has</em> a playlist. A track is a mechanism for generating 
  the audio stream represented by the playlist and passing it through a 
  signal processing pathway. At any point in time, a track has a single 
  playlist associated with it. When the track is used to record, that 
  playlist will have one or more new regions added to it. When the track 
  is used for playback, the contents of the playlist will be heard. 
  You can change the playlist associated with a track at (almost) any 
  time, and even share playlists between tracks.
</p>
<p>
  If you have some experience of other 
  <abbr title="Digital Audio Workstation">DAW</abbr>s, then you might 
  have come across the term <dfn>"virtual track"</dfn>, normally defined as a track 
  that isn't actually playing or doing anything, but can be 
  mapped/assigned to a real track. This concept is functionally 
  identical to Ardour's playlists. We just like to be little more 
  clear about what is actually happening rather than mixing old and 
  new terminology ("virtual" and "track"), which might be confusing.</p>

<h2>Playlists are Cheap</h2>
<p>
  One thing you should be clear about is that playlists are cheap. They 
  don't cost anything in terms of CPU consumption, and they have very 
  minimal efforts on memory use. Don't be afraid of generating new 
  playlists whenever you want to. They are not equivalent to tracks, 
  which require extra CPU time and significant memory space, or audio 
  files, which use disk space, or plugins that require extra CPU time. 
  If a playlist is not in use, it occupies a small amount of memory, and 
  nothing more.
</p>