Key Concepts and Vocabulary

This chapter defines the terms used throughout Fusor Studio's manual.

What you work with

Fusor Studio

The name of the application.

Fusor Player

The player window: the part of Fusor Studio that runs a fusor and sends its MIDI to your DJ app. This manual calls it the Fusor player, or simply the player.

Fusor Studio Lite

Fusor Studio running without a license, called Lite for short. A license adds three things: Manual and Mixed Run Mode, transition lengths other than 16 bars, and making or changing fusors. Lite runs any fusor as often as you like, and keeps session edits, actions and Your Notes. Refer to Licensing for details.

fusor

An authored transition effect. A fusor describes how a set of parameters in your DJ app (EQ, stems, levels and effects) modulate as a transition progresses from 0% to 100%. fusors are saved as .fusor files. Lowercase "fusor" always refers to the file, never to the app.

Action

A short sequence of control settings that you fire on demand, independent of a transition (a macro). Where a fusor is progress-driven (its output is a function of the transition's 0–100% progress), an action is event-driven: it runs once when triggered. Actions are saved as .faction files and written in a small text-based language called the Action DSL.

Tag

A short label attached to a library record, used to organize and filter. Fusor Studio ships with a set of app tags, one per supported DJ app, so authors can mark fusors built for a specific app.

Deck roles

A fusor is authored against which deck is playing the track being mixed out and which is playing the track being mixed in. Physical deck position, "Deck A" or "Deck B" on your DJ controller, plays no part in it. These are called roles.

Deck Role

What a deck is doing in the current transition, Outgoing or Incoming, as distinct from its position (Deck A, B, C, D) in your DJ app.

Outgoing Deck

The deck we're mixing out of.

Incoming Deck

The deck we're mixing into.

Authoring uses roles. A fusor that says "incoming EQ low goes from 0 to 1" works whether the incoming deck is your DJ app's Deck A, Deck B, Deck C, or Deck D. The Fusor player resolves the role to the right deck at runtime.

When a transition completes, the roles swap: the deck that was outgoing is now playing the just-mixed-in track and is positioned to become the next transition's outgoing deck.

Mix points

Mix Point

Where the listener's attention shifts from the outgoing track to the incoming track. Each fusor records one of three: Start, Middle or End. The Fusor player draws it as the orange mark on the progress strip. See Mix Points.

Mix-out Point

The point in the outgoing track where the listener's attention shifts to the incoming track. It is not the start of the transition, but it can be the end.

Mix-in Point

The point in the incoming track where the listener's attention shifts to it from the outgoing track. It is not the end of the transition, but it can be the start.

A transition is aligned when the mix-out point and the mix-in point meet on the fusor's mix point. See Starting a Transition.

How things are grouped

These are Fusor Studio's library grouping types. They sit alongside one another and don't overlap.

Collection

A named group of fusors. Collections organize authored fusors for easy access, for example "EQ Swaps," "Filter Build-ups," or "Stems Tricks." The fusor picker is filtered by the currently active collection.

Pack

A group of actions, with exactly eight positional slots (1–8). Packs are the source of pads in Pad Mode. When a pack is active, its slot 1 becomes pad 1, slot 2 becomes pad 2, and so on. Each slot holds one action or is empty.

Step set

A reusable preset for a set of stepped values: the labels and levels that an authored stepped binding picks from. For example, a step set for a beat-synced effect's rate: 1/8, 1/4, 1/2, 1 beat, 2 beats or 4 beats. Step sets ship as a built-in catalog; any step set you save while authoring joins your user step set library.

How Fusor Studio runs

Telemetry

MIDI between Fusor Studio and your DJ application runs both ways. Fusor Studio sends control values, and receives telemetry: the MIDI messages your DJ app sends back reporting its controls and deck states. Without telemetry the Fusor player receives no MIDI when you move a control or start a deck, and at startup it cannot sync with your DJ app. If your DJ app can receive MIDI but not send it, or no DJ app is running, you can run Fusor Studio in blind mode, with reduced capabilities.

Crossfader as Progress Actuator

The DJ-app control that drives the transition's progress in Manual Run Mode, and that the Fusor player moves in Auto Run Mode to keep the same control aligned with progress. It is the crossfader: the crossfader's outgoing-to-incoming travel maps naturally onto a transition's 0%→100% progress. This manual says "crossfader" when describing what you touch and "progress actuator" when the role it plays is the point. It keeps driving progress whether or not it is in the audio path. See Crossfader Bypass below.

Crossfader Bypass

A state of your mixer, not a setting inside a fusor: the crossfader is taken out of the audio path, so deck level comes from the two channel faders alone and the crossfader's own curve contributes nothing wherever it happens to sit. Some DJ apps call it thru, through mode or pass-through; in Traktor it is the per-channel crossfader assignment, and a deck assigned to neither side is out of the path. Bypass does not stop the crossfader driving progress: it still travels the full width of every transition, silently.

A crossfader is either live or in bypass. Which you use depends on the fusor. A fusor that modulates deck levels needs the crossfader in bypass, because a live crossfader's curve multiplies against the fusor's. To run one with the crossfader live instead, disable its Channel Fader domain in Session View. A fusor that modulates no deck levels can run with the crossfader live, or in bypass while you manipulate the channel faders.

Crossfader and Deck Levels covers the three setups, Channel Fader is where you first run in bypass, and Bypass the Crossfader and Put It Back steps through a pair of actions that sets and restores it around a run.

Manual Run Mode

The transition's progress is driven by the crossfader: it advances as you physically move it, and stops when you stop moving it.

Mixed Run Mode

The transition runs on the clock up to the fusor's mix point (Middle, or End on a fusor with an effect tail), then stops with every parameter holding. It resumes when your crossfader reaches the stop position and follows the crossfader to the end. Mixed is available only for a fusor whose mix point is Middle, or End with an effect tail. See Manual Run Mode vs Auto Run Mode.

Auto Run Mode

The transition's progress is driven by a timer set from the transition's bars and BPM. The timer starts when you press Play or, with Start-with-Incoming on, when the incoming deck starts playing.

Pad Mode

A view of the Fusor player that replaces the transition controls with an 8-pad grid for firing actions. See Pad Mode.

Session View

An inline inspector panel above the Fusor player that shows the loaded fusor's details as a single chronological stack, read top to bottom in performance order: its name, the author's intent, the domains it will modulate, and any actions it runs before or after. Opened with the expand arrow in the toolbar. Session View is also where you make session edits: the adjustments you make to fit a fusor to your rig while setting up (which domains fire, which FX unit and slot they use, which actions run), saved into the fusor as you make them. See Loading a fusor.

MIDI and communication

MIDI Bus

A virtual MIDI port that carries messages between Fusor Studio and your DJ app. You pick a port by name in Settings → Connection. On Windows the recommended bus is a loopMIDI port named Fusor Studio, the name the Fusor mapping file expects. On the Mac, Fusor Studio provides its own connection, listed as Fusor Studio in your DJ app, and no bus is needed; any other bus you choose in Settings → Connection, such as the IAC Driver, replaces it. On Windows, any virtual bus that presents itself as both an input and an output will work, including Windows MIDI Services, but at the time of release Windows MIDI Services still had unresolved issues. In the Windows MIDI Services tooling a bus is called an endpoint; the terms refer to the same thing. Connect Your DJ App owns the setup steps.

Mapping

The translation between Fusor Studio's internal control vocabulary (for example, "incoming deck EQ low") and the specific MIDI messages your DJ app expects. Each DJ app has its own mapping file, .tsi for Traktor. Mapping files are published on the Fusor downloads page. Settings' Mapping entry includes Teach Mode, the DJ app tab, for building or validating this mapping deck by deck, without needing a hardware controller.

Fusor Hardware Controller

A physical MIDI controller assigned to control the Fusor player itself: arming transitions, firing pads, switching modes. It can be the same controller you use to control your DJ app; the player listens on its own bindings independently. See Hardware Controller for the setup walkthrough.

Authoring

Parameter

A value in your DJ app that a fusor modulates, such as an EQ band, a stem's level, a channel fader or an effect's amount. Every parameter belongs to a domain. The knob or fader you move by hand is a control.

Domain

A grouping of related parameters in an authored fusor, spanning both deck roles at once. For example, 3-Band EQ exposes Low, Mid, and High as its parameters, on the outgoing deck and the incoming deck alike. A domain's per-role halves are its sides (the outgoing side and the incoming side), not separate domains. Its enable switch turns the whole domain on or off, both sides together. A fusor that modulates the channel fader on both decks has one domain, Channel Fader, with two sides. See Domains for the full list.

Parameter Binding

A single authored parameter inside a domain, for example "incoming EQ low" or "outgoing FX 1 wet/dry." A binding has a curve (or a stepped value list) describing how the parameter modulates from 0% to 100% transition progress.

Curve

A function describing a parameter's value at each point in the transition, authored visually in the domain editor by placing anchors. Each anchor sets the interpolation mode (Bezier, Linear, or Hold) for the curve between it and the next anchor. See Curve Editor.

Stepped Output

A binding mode where the curve is constrained to a small set of discrete values rather than continuous interpolation. Used for parameters whose meaningful values are indexed (a delay's rate in beat fractions, a beat slicer's pattern). See Stepped Output.

Effect Tail

A per-domain switch on the outgoing side of an FX Unit, FX Banks or Mixer FX domain of a fusor whose mix point is End. It leaves room after End for the effect to taper off: the curves finish at End, and the tailed effect rings out after it. The bars you set are the length of the run to End. In Auto Run Mode the clock plays the tail out over a further 25% of the transition's length. In Mixed Run Mode your crossfader sets how long the tail takes. To control when the tail tapers off, run a tail fusor in Mixed. See A run with an effect tail and FX Routing.

File formats

Step sets are stored as their own files inside the library's step_sets/ folder.