Table of Contents > Basic Concepts
QLab Documentation
This page last modified: 01 Feb 2011 08:40:05 PM.

Basic Concepts

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QLab offers powerful, flexible and intuitive live show control. With QLab you can play back audio and video with precision and reliability day after day, night after night. More than simple playback, QLab is an automation system which allows you to construct complex sequences of volume changes, animations, and MIDI messages in an event-based framework. Extremely subtle media sequences can be built quickly and then triggered with the simple press of a button.

Cues

Cues are the fundamental building block of QLab. Each kind of cue performs a different kind of action. For example, an Audio Cue will play an audio file, a Pause Cue will pause other cues, and a MIDI Cue will send a MIDI message.
A detailed description of how cues operate may be found in the Cue documentation.

Cue lists

Cue lists are ordered collections of cues. All cues are in one and only one cue list. You may organize the order in which cues will play by reordering their position in the cue list. Each cue list has a single playback position. The playback position is the next cue that will run when the cue list is triggered. Triggering, or "firing", a cue list advances this playback position. When the playback position reaches the end of the cue list, firing the cue list will cause no more actions until the playback position is reset.

Cue sequences

Understanding the behavior of cue sequences is fundamentally important to the effective use of QLab.
When a cue list is fired the cue at the current playback position is played. If the auto-continue () or auto-follow () parameter of this cue is enabled the subsequent cue will also be fired (after any specified waiting period has elapsed). This process is repeated until a cue is reached that does not auto-continue or auto-follow. A consecutive series of these connected cues is called a cue sequence.
Cue sequences are an important concept because they allow you to create a number of actions which will all occur after firing a cue list a single time. Conceptually, a cue sequence is like a series of dominoes: knocking over the first domino will cause all the dominoes to fall until a gap between dominoes is reached.

Playback position

Each cue list has only one playback position. The current playback position is indicated by the teardrop icon (). You may select any cue in the list to make it the current playback position (including cues in the middle of a cue sequence). When a cue list is fired the playback position is automatically advanced to the beginning of the next sequence.
New in Version 2: QLab now allows you to select and edit cues without changing the playback position of the cue list. This can be handy for a designer who wishes to edit a previous or upcoming cue without disturbing the playback position for an operator. This option may be turned on and off in the workspace preferences.
While a cue list has only one playback position, it may have many active cue sequences. In other words, many different series of dominoes may be falling within a cue list at any given time. Do not confuse the "currently falling domino" in a cue sequence with the playback position of the cue list.
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