Key Concepts and Vocabulary

This chapter defines the terms used throughout Fusor Studio's manual. Most are short. A few (fusor, deck role) are worth reading carefully because every other chapter relies on them.

If you have Fusor Studio Plus, the Plus manual has a companion New Concepts chapter for the additional vocabulary Plus introduces (track, transition, crate, set list, venue, performance history).

What you work with

Fusor Studio

The name of the application.

Demo

Fusor Studio running without a licence. What that state can and can't do is on the Licensing page.

fusor

A single piece of authored automation. A fusor describes how a set of DJ-app controls (EQ, stems, channel fader, FX, filters) should 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 small piece of automation that can be fired on demand, independent of a transition. 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. Tags you create yourself are a Fusor Studio Plus feature.

Deck roles

Fusor Studio doesn't care which physical deck on your DJ controller is "Deck A" and which is "Deck B." It cares about which deck is playing the track being mixed out and which is playing the track being mixed in. These are roles, not deck identities.

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. Fusor Studio 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. See Manual Role Swap for the manual version of this when telemetry isn't available.

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 stepped curve: the labels and levels that an authored stepped binding picks from. 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

Online

Fusor Studio sends MIDI to your DJ app and receives telemetry back: deck play/pause state, volumes, tempo, crossfader position. With full telemetry, Fusor Studio applies guards and warnings before it moves a parameter. Without telemetry Fusor Studio does not know when the crossfader moves, when decks start, etc.

Blind Mode

You tell Fusor Studio to keep sending MIDI and stop listening. It exists because some DJ apps (djay most notably) don't broadcast state over MIDI, and because some sessions run without a DJ app connected at all, for example demoing fusor output through a synth or a recorder. Blind Mode forces Auto Run Mode, since Manual Run Mode requires telemetry to detect actuator motion. You turn it on; Fusor Studio never does it for you, and it's off again at every launch. See Blind Mode for the details.

Progress Actuator

The DJ-app control that drives the transition's progress in Manual Run Mode, and that Fusor Studio drives back 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. The crossfader can also run in bypass mode, where it stops controlling deck levels in your DJ app but still drives progress here. Crossfader and Deck Levels covers the setups, and Bypass the Crossfader and Put It Back builds the bypass toggle.

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. Manual Run Mode requires full telemetry, so it is only available while Online.

Auto Run Mode

The transition's progress is driven by a timer based on the transition's bars and BPM. Fusor Studio starts the timer when the user presses the play button or, if start with Incoming deck is enabled it starts when it detects the incoming deck begin to play. The transition advances on its own from there.

Pad Mode

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

Session View

An inline inspector panel below the 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 drive, and any actions it runs before or after. Opened with the info icon next to the fusor picker. Session View is also where you make session edits: per-run adjustments that apply only to the currently loaded fusor. 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; any virtual bus that presents itself as both an input and an output will work, including loopMIDI and Windows MIDI Services. In the Windows MIDI Services tooling a bus is called an endpoint; the terms refer to the same thing. Installation owns the setup steps for both, and Troubleshooting covers the known interoperability issue between them (I-018).

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, XML for Mixxx and Virtual DJ, .djayMidiMapping for djay. Mapping files for the supported apps are published on the Fusor downloads page. Settings includes Teach Mode for building or validating this mapping one binding at a time, without needing a hardware controller.

Fusor Hardware Controller

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

Authoring

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 automates the channel fader on both decks has one domain, Channel Fader, with two sides. See Domains for the full list.

Parameter Binding

A single automated 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 controls whose meaningful values are indexed (tempo ranges, FX type selectors). See Stepped Output.

File formats

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