Basic Concepts & Glossary

Q Light Controller (QLC for short) is meant to control lighting equipment used in various performances, like live concerts and theatres etc. The main purpose is that QLC could outperform commercial lighting desks with an intuitive and flexible user interface, without the need for a 500+ page manual.

This page has been arranged in alphabetical order to ease searching for a specific topic.

Blackout

Blackout is used to set all channels in all universes to zero and keep them that way, regardless of what functions are currently being run or what values have been set to them manually. When blackout is turned off, current values of all channels are set to each universe.

Buses

Buses provide different speed settings to the various functions that the user creates. One bus may control the fading speed for a group of scenes, another the time it takes for an EFX function to complete a full circle, etc..

Functions have speed buses that are set by users. A maximum of 32 different speed settings called buses, are possible. One function can have exactly one bus and many functions can share one bus. The speed setting of each bus can be changed at any time with a resolution of 1/64th of second. Any of the buses can be assigned in design mode to any function. The only exception to this is made by collection functions, which don't have a speed setting at all.

Each bus can have a name set by the user can for convenience and to help in identification. The name of the first bus is, "Fade" (unless you have already changed it) and it is assigned to all newly-created Scenes and EFXs. The second bus, named "Hold" by default, is assigned to all newly-created Chasers.

Buses can also send special "tap" signals, that can be used, for example, to manually synchronize chaser stepping to match tempo.

Capabilities

Some channels in intelligent fixtures provide many kinds of functions, or capabilities like switching the lamp on when the channel value is [240-255], setting a red color on a color wheel when the value is exactly [15], or simply controlling the fixture's dimmer intensity with values [0-255]. Each of these individual function is called a capability and each of them has these three properties:

Chaser

A chaser function encapsulates multiple scenes that are run in serial, one after the other, when the chaser function is started. The next function is run only after the previous has finished. Any number of scenes can be inserted to a chaser.

Chaser functions' direction can be reversed. The function can also be set to do an infinite loop, an infinite ping-pong-loop (direction is reversed after each pass) or it can run thru just once, in a single-shot mode, after which it terminates by itself. If the function is set to do an infinite loop, it must be stopped manually.

Bus number 2 (Default Hold) is assigned to all newly-created chasers by default. The bus value specifies step duration for chasers. If the speed setting of a chaser's members scene is higher (slower) than the chaser's speed setting, the scene won't have enough time to fade to its target value before the chaser triggers the next step. Respectively, if a member scene's speed setting is lower (faster) than the chaser's speed setting, the chaser will wait after the scene has finished before it triggers the next step.

Copies of chaser functions can be created with the Function Manager. The scenes inside a chaser are not duplicated when a chaser is copied. Only run order, direction, bus and the order of scenes are copied to the new chaser.

Collection

A collection function encapsulates multiple functions that are run simultaneously when the collection function is executed. Any number of functions can be inserted to a collection, but each function can be inserted only once and a collection cannot be a direct member of itself.

Speed setting has no effect on collections. Each member function's speed is set individually thru their own buses.

Copies of collection functions can be created with the Function Manager. The functions inside a collection are not duplicated; only the list of functions is copied.

DMX

DMX is short for Digital MultipleX. It basically defines a whole bunch of properties, protocol, wiring etc. but in the case of a lighting software, it defines the maximum number of channels (512) per universe and the channels' value range (0-255).

QLC supports 4 individual universes, that need not be necessarily connected to DMX hardware; rather, DMX has just been selected as the de facto lighting standard. Actual hardware abstraction (whether it's analog 0-10V, DMX or some other method) is achieved thru output plugins.

EFX

An EFX function is mainly used to automate moving lights (e.g. scanners & moving heads). The EFX can create complex mathematical paths on an X-Y plane that are converted to DMX values for the fixture's pan and tilt channels. Only fixtures that contain valid pan & tilt channels can take part in an EFX function.

Bus number 1 (Default Fade) is assigned to all newly created EFX's by default. The bus value is used as the overall time for the EFX algorithm to complete one cycle. In other words, with a circle algorithm, the bus value is understood as the time available to complete a full 360 degree circle.

EFX functions can have special start and stop scenes, that are run just before the EFX is started and immediately after the EFX stops. These scenes are not, however, faded as would happen with a normal scene. Instead, their values are set immediately, as if their speed setting was zero.

Fixtures taking part in an EFX function can be set to follow the algorithm either in parallel or serial:

EFX functions' direction can be reversed for all fixtures at once or on a per-fixture basis. The function can also be set to do an infinte loop, an infinite ping-pong-loop (direction is reversed after each pass) or it can run thru just once, in a single-shot mode, after which it terminates by itself. If the function is set to do an infinite loop, it must be stopped manually.

Copies of EFX functions can be created with the Function Manager. All of the EFX's contents are copied to the duplicate.

Fixtures

A fixture is essentially one lighting device. It can be, for example, one moving head, one scanner, one laser etc.. However, for simplicity, individual PAR cans (and the like) that are usually controlled thru one dimmer channel per can, can be grouped together to form one single fixture.

With the Fixture Definition Editor, users can edit shared fixture information stored in a fixture library that contains the following properties for each fixture:

These fixture definitions can then be used to create actual fixtures, that will in the Q Light Controller application, have additional properties defined by users:

Several instances of a fixture can be created (i.e. users must be able to have several instances of a MAC250 in use). Each fixture can be named, but the name is not used internally to identify individual fixture instances. The same goes for the DMX address. Nevertheless users are encouraged to name their fixtures in some systematic way to help identify each of them -- if necessary.

Generic dimmer devices don't need their own fixture definitions, because usually multiple dimmers are patched into a common address space, employing one or more dimmer racks. Users can create instances of these generic dimmer entities just by defining the number of channels each one of them should have.

Fixture Mode

Many manufacturers design their intelligent lights in such a way that they can be configured to understand different sets of channels. For example, a scanner might have two configuration options: one for only 8bit movement channels (1x pan, 1x tilt) and another one for 16bit movement channels (2x pan, 2x tilt). Instead of creating a completely new fixture definition for each variation, they have been bundled together in QLC's fixture definitions into fixture modes.

Functions

The number of functions is practically unlimited. Functions are used to automate the setting of values to DMX channels. Each function type has its own way of automating lights.

The function types are:

Each function can be named and although the name is not used to uniquely identify individual functions, users are encouraged to name their functions in some systematic and concise way to help identify each of them. For your own comfort.

Grand Master

The Grand Master is used as the final master slider before values are written to the actual physical DMX hardware. Usually, the Grand Master affects only Intensity channels, but can be also changed to have effect on the values of all channels.

The Grand Master has also two Value Modes that control the way how the Grand Master affects channel values passing through:

Input plugins

Primary input methods for QLC are naturally the keyboard and mouse. Users can attach keyboard keys to virtual console buttons and drag sliders and do pretty much everything with a mouse. It is possible to attach additional input devices to one's computer to alleviate the rather clumsy and slow user experience that is achieved with a regular mouse and a keyboard. Special input plugins provide capabilities for getting external devices (mainly slider boards) to produce input data to various QLC elements.

Input (line)

An input is a physical input line provided by some hardware which is accessed thru an input plugin. It can be, for example, a MIDI IN connector in the user's computer (or peripheral) to which users can connect MIDI-capable input devices like slider boards etc.

Input profiles

Input profiles can be thought of as fixtures' cousins; they contain information on specific devices that produce input data. An input device can be, for example, a slider board like the Behringer BCF-2000, Korg nanoKONTROL, an Enttec Playback Wing...

Modes

Q Light Controller is based on the common concept of having two distinct operational modes to prevent accidental or otherwise harmful changes during operation:

Output plugins

DMX output is achieved thru output plugins that can support one or more output lines. It is also possible to run QLC without actual DMX hardware.

Output (line)

An output is a physical output line provided by a hardware device which is accessed thru an output plugin. In other words, it is a real DMX universe, but has been dubbed output to separate it from QLC's internal universes. You could think of them as individual XLR output connectors in your DMX hardware.

Scene

A scene function encapsulates the values of selected channels owned by one or more fixture instances. When a scene is started, the duration it takes for its channels to reach their target values depends on the function's speed setting. Bus number 1 (Default Fade) is assigned to all newly created scenes by default. If the bus' value is 0 seconds, the scene values are set immediately and no fading occurs. Otherwise the values are always faded from what they currently are, to the target values defined in the scene. Channels that are not enabled in the scene will not be touched at all by the function.

Copies of scene functions can be created with the Function Manager. All of the scene's contents are copied to the duplicate.