Ardour runs on Linux and Mac OS X, and uses the Jack Audio Connection Kit (JACK) to interface with the computer's sound card, as well as with other audio applications running on the same system.
Understanding Basic Concepts and Terminology.
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.
An Ardour session is a container for an entire project. A session may contain an arbitrary number of tracks and busses consisting of audio and MIDI 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.
Ardour sessions are held in directories; these directories contain one or more session files, 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.
Ardour's session file is kept in XML 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 SMF (standard MIDI format).
Ardour has a single current session at all times; if Ardour is started without specifying one, it will offer to load or create one.
A track is a concept common to most DAWs, and used also 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.
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.
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.
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.
A track may contain many segments of audio or MIDI. Ardour contains these segments in things called regions, 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.
The details of what exactly each track should play back is described by a playlist. 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.
Busses 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.
One might typically use a buss 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.
Ardour allows you to process audio and MIDI using any number of plugins. These are external pieces of code, commonly seen as VST plugins on Windows or AU plugins on Mac OS X. Generally speaking, a plugin is written using one (and maybe more) standards. Ardour's plugin support is for the following standards:
- the first major plugin standard for Linux. Many LADSPA plugins are availble, mostly free and open-source.
- the successor to LADSPA. Lots of plugins have been ‘ported’ from LADSPA to LV2, and also many new plugins written.
- Ardour supports VST plugins that have been compiled for Linux.
- AudioUnit (AU)
- Mac OS X versions of Ardour support AudioUnit (AU) plugins.
- 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. 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.