3.6 Playlists

A playlist 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.

Each audio track 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 about regions. Here, we cover some of the things you can do with playlists as objects in their own right.

In a traditional recording studio, the playlist is the choice of tape which is played through the tape machine.  You can change the tape (and therefore the sequence of sound events) without changing the later stages of processing (such as fader level, equalization, etc).  There is one difference though:  Ardour allows you to choose a playlist per track, instead of switching out all the tracks at once, as you would do with an analog tape machine.

3.6.1 Tracks are not Playlists

It is important to understand that a track is not a playlist. A track has 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. Old tape operators will feel comfortable thinking of the playlist as one of the tracks on the tape, and the track as a tape machine head.

However, you can change the playlist associated with a track at (almost) any time, and even share playlists between tracks.

3.6.2 Playlists are Cheap

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 to plugins that require extra CPU time. If a playlist is not in use, it occupies a small amount of memory, and nothing more.

3.6.3 Playlists as "Takes" or "Virtual Tracks"

If you have a background in audio engineering, then it might be easiest for you to think of playlists as "takes". This isn't a particularly useful analogy by itself, and it can be misleading. But if you are working with music where most tracks feature single-pass recordings of a single instrument, then the idea of using one playlist per "take" can make life very convenient. Each time you need to record another take, create a new playlist list first. You will then end up with a simple way of switching back and forth between each version, or even listening to several at the same time.

If you have some experience of other DAWs, then you might have come across the term "virtual track", 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") into confusing terminology.

3.6.4 Playlist Operations

All operations on playlists start by clicking on the playlist button (labelled p) in the control area of a track in the editor. Clicking the button will popup a menu with the following choices:

(Local Playlists)	Shows all of the playlists associated with this track, and indicates the currently selected playlist
Rename	Pops up a dialog that allows the current playlist to be renamed
New	Creates a new empty playlist, and switches this track to use it
New Copy	Creates a new playlist that is a copy of the current playlist, and switches this track to use it
Clear Current	Removes all regions from the current playlist
Select from All	pops up a playlist browser to manually choose which playlist this track should use ( you can even select playlists from other tracks here)

3.6.5 Renaming Playlists

Playlists are created with the name of the track of which they are associated, plus a version number. So, the first playlist for a track called "Cowbell" will be called "Cowbell.1". This name will be used to define the names of any regions added to the playlist by recording. You can change the name at any time, to anything you want. Ardour does not require that your playlist names are all unique, but it will make your life easier if they are. Suggested examples of user-assigned names for a playlist might include "Lead Guitar, 2nd take", "vocals (quiet)", and "downbeat cuica". Notice how these might be different from the associated track names, which for these examples might be "Lead Guitar", "Vocals" and "Cuica". The playlist name provides more information because it is about a specific version of the material that may (or may not) end up in the final version of the track.

If you are going to rename your playlists, do so before recording new material to them.

3.6.6 Selecting Playlists

If you click on the "Select" choice of the playlist button menu, a dialog will appear that displays all playlists in a tree-structure (many will be hidden). Playlists will be grouped by the track for which they were created, with all those created for the current track displayed. Other tracks are hidden in a collapsed tree that can be expanded as you wish to find other playlists.

3.6.7 Sharing Playlists

It is entirely possible to share playlists between tracks. The only slightly unusual thing you may notice when sharing is that edits to the playlist made in one track will magically appear in the other. If you think about this for a moment, its an obvious consequence of sharing.  One application of this attribute is parrallel processing, described below.

You might not want this kind of behaviour, even though you still want two tracks to use the same (or substantially the same) playlist. To accomplish this, select the chosen playlist in the second track, and then use New Copy to generate an independent copy of it for that track. You can then edit this playlist without affecting the original.

3.6.8 Using Playlists for "Parallel Processing"

One of the uses of Playlists is to apply multiple effects to the same audio stream.  For example, let's say you have a track and you'd like to apply a second set of effects, at the same time to the original track.  In this case you could make a new track, select the original track's Playlist, and then apply different effects to the second track than the first (including panning, inserts, and bussing changes).  Now, if you edit either of the track's playlists, the changes will appear in both tracks.

3.6.9 Using Playlists for "Takes"

Using Playlists for takes is a good solution if you are going to need the ability to edit individual takes, and select between them, but you won't be "compositing" multiple takes together.  This might be the case if you were recording multiple languages of a given track, and you want to use the same "track" for each language so that they get the same processing.  Then you select each language before exporting the mix for each separate language.

You use the Clear Current operation each time you want to start a new take. This is a non-destructive operation that removes all existing regions from the current playlist. Although you won't lose any information doing this, its probably not appropriate unless the last take was so awful that you want to discard it (although without the finality of Remove Last Capture ). Finally, and probably most useful, you can use the New operation in the playlist button menu to create a new empty playlist, ready for the next take. Later, you can Select your way back to previous or later takes as desired, either in this or some other track.

If you want to record multiple takes and then "comp" between them, it is probably better to simply record each successive take on top of the others in "layers" and then edit them using the layer tools, explained later.