QLab is a multimedia playback cue-based software designed for theatre and live entertainment.

History

QLab is a multimedia playback software created by a company based in Baltimore, Maryland, known as Figure 53. Version 1.3.5 of the software was released on May 25, 2007, for use on Macintosh OSX. The current version as of February 10, 2011 is version 2.3.3.

Cues

In QLab, a cue is a marker for an action to take place in the program. When triggered, a cue executes an operation. The list of available cues is as follows:

Group

Audio

Fade

Video

Animation

Camera

MIDI

MSC

MIDI File

MIDI SysEx

MTC

Start

Stop

Pause

Reset

Devamp

Load

Script

Goto

Target

Wait

Memo

Arm

Disarm

Audio playback

QLab allows an end-user or designer to align audio files in a sequential order. Once the audio files are inserted into the cue list, the end-user can then manipulate it by looping it, changing the amplitude or volume, and adding fades in or out. Audio cues can also be placed into groups, so that multiple files can be triggered at one moment.

Video playback

The video capability of the software in its most recent version allows a designer to add video files to their cue lists, allowing them to be time aligned with other cues, including audio files. Video files can be altered in real time in QLab, by integrating a Quartz Composer

Quartz Composer

Quartz Composer is a node-based visual programming language provided as part of the Xcode development environment in Mac OS X for processing and rendering graphical data....

 file. The designer can also select on which video card

Video card

A video card, Graphics Card, or Graphics adapter is an expansion card which generates output images to a display. Most video cards offer various functions such as accelerated rendering of 3D scenes and 2D graphics, MPEG-2/MPEG-4 decoding, TV output, or the ability to connect multiple monitors...

 or cards the video will play. It is useful to note that the speed of the computer processor and video card can affect the quality of video playback.

MIDI integration

MIDI is integrated into QLab and is set up to be bi-directional. QLab allows MIDI signals to be sent as a cue to trigger other devices, such as digital audio consoles

Digital mixing console

In professional audio, a Digital Mixing Console , is an electronic device for combining, routing, and changing the dynamics of digital audio samples. The digital audio samples are summed to produce a combined output. A professional digital mixing console is a dedicated desk or control surface...

. The software also accepts MIDI signals as triggers for its own cues. MIDI signals can be sent to QLab from other computers running QLab software, or any other MIDI capable device, using a MIDI Interface.

Live playback

A key software feature with QLab is its ease of use in live playback situations. The designer of a cue sheet can save their show file, and lock it, preventing any changes to the cues. After doing so, an untrained user can run the software in a playback situation. By default, a cue is triggered by clicking a large GO button on the screen, or by pressing the space bar.