Arming and Running a Transition

Once you've loaded a fusor, the next step is to start the transition. In Manual Run Mode, or with Start-with-Incoming on, you first arm the Fusor player, and it starts the transition when its start trigger fires. In Auto and Mixed Run Mode, pressing PLAY starts it.

This chapter walks through the full lifecycle of a transition: arming, starting, running, and completing.

Before you start

A few things need to be in place before a transition can start:

• A fusor must be loaded. Without one, the Arm/Play/Pause button is inactive. See Loading a fusor.
• For Auto and Mixed Run Mode, the bars and BPM values need to be sensible, because they define the timing window. In Manual Run Mode the bars/BPM readout is hidden, because the crossfader drives the timing. It disappears the same way when you take over a run by hand mid-run, and when a Mixed run reaches its stop.
• Tempo Ramp can be on or off. If it's on, a tempo-sync setup runs as soon as the outgoing deck is playing, before the transition starts. See Tempo Ramp below.
• In Auto Run Mode, Start-with-Incoming can be on or off. See "What arming does" below for what changes when it's on.

What arming does

Arming tells the Fusor player you're ready for the transition to start. While armed, the player waits for the start trigger. What that trigger is depends on the mode, and in Auto Run Mode, on whether Start-with-Incoming is on.

Fusor Studio never runs a control-state capture while you're armed or while a transition is running: capturing can reset deck roles and rewrite control positions, either of which would disrupt an armed player or a run already under way. If a capture comes due during either (telemetry recovering while you're armed and waiting, for example), it's held until you return to Idle, and the status line marks the wait with a RECAPTURE PENDING — prefix in gray. See The Player Window for the full prefix rules. The wait doesn't block arming or starting.

Manual Run Mode

Click the Arm button (the large left-hand button on the progress strip). The button lights up to indicate you're armed.

While armed, the Fusor player is waiting for crossfader movement. As soon as you move the crossfader in the direction of the incoming deck, the transition starts and progress follows the crossfader.

The status line reads "Armed: move crossfader to start."

Auto Run Mode (default: press Play)

The Arm/Play/Pause button shows the PLAY label. There is no arm step for you to take: pressing PLAY starts the transition.

This is the default Auto Run Mode flow. The Fusor player doesn't wait on the incoming deck's state. The transition starts the moment you press Play. The button stays gray, and the status line reads "Armed", until the outgoing deck is playing. Then the button turns yellow and the status line reads "Armed: Press Play to start".

Auto Run Mode with Start-with-Incoming on

Turning the Start-with-Incoming toggle on arms the Fusor player in a different waiting state: instead of a Play button, the arm control becomes a solid dot, and the trigger is now the incoming deck starting to play. The player watches for telemetry saying the deck holding the incoming role has begun playback, then starts the transition timer.

The status line reads "Armed: starts with incoming deck" while it waits.

Where the toggle is and when it can't be clicked are in Transport Controls; which path to choose, and what else changes, is the deep dive.

Mixed Run Mode

A Mixed run starts exactly as an Auto run does. Pressing Play starts it, or, with Start-with-Incoming on, the incoming deck starting does. The arming rows above for Auto Run Mode apply unchanged.

In Blind Mode

Blind Mode leaves only the press-Play path. The other two triggers, crossfader movement and a deck starting, depend on telemetry, and Blind Mode ignores telemetry. The button shows PLAY, and it does not wait for the outgoing deck to be playing, because that is telemetry too. See Blind Mode.

Disarming

You can disarm at any time before the transition starts. The gesture depends on which armed state you're in:

• Armed (Manual Run Mode). Click the Arm button.
• Auto Run Mode, default press-Play. There is no arm step, so there is nothing to disarm: you simply don't press PLAY.
• Armed (Auto Run Mode, Start-with-Incoming on). Click the Arm dot or toggle Start-with-Incoming off.

Disarming returns the Fusor player to Idle with the same fusor still loaded.

Starting and the setup pause

The transition begins the moment your mode's trigger fires, whichever of the ones above applies to you.

In Manual Run Mode, and with Start-with-Incoming on, the trigger only fires once the Fusor player is armed. Until then, crossfader motion and incoming-deck playback are things happening in your DJ app, and neither starts anything.

If the fusor has any setup work to do before progress starts, that runs first as a brief setup pause at the very start of the transition.

During the setup pause, progress sits at 0% while the Fusor player runs any setup actions. For example, automatically assigning FX units to the incoming and outgoing decks, or running an authored pre-run action. Most fusors have no setup work, so the pause is invisible.

The status line names each setup action as it runs. On a quick setup they change too fast to read. During a longer setup the line reads Preparing, in both Run Modes, and where the app can predict how long the whole setup will take it says so: Preparing — starting in ~8000ms. In Manual Run Mode, and whenever the wait cannot be predicted, it reads Preparing with no figure. Either way, progress sitting at 0% during this stage is expected.

Setup has a hard ceiling of 5 seconds. If it runs longer than that, an error appears in the status line, and what happens next depends on the Run Mode:

• In Auto Run Mode and Mixed Run Mode, the transition aborts back to the armed state.
• In Manual Run Mode, the Fusor player skips whatever setup is left and runs the transition anyway. You keep the run; you lose the unfinished setup.

The same split applies to a single setup action that merely errors rather than overrunning the ceiling: Manual warns you and continues, while Auto and Mixed treat it as a failure. See Pre-run actions.

Once setup completes, the transition runs normally from that point.

Running

Once the transition is running, what you see and do depends on the mode.

In Manual Run Mode

The crossfader is the master clock. As you move it from the outgoing side to the incoming side, the progress meter advances; stop moving and progress stops. Move it back and progress reverses. You can go slow, fast, in fits and starts, even reverse course; the fusor follows.

In Fusor Studio Lite: Manual Run Mode is unavailable, so this section does not apply. Lite runs every transition in Auto Run Mode. See Licensing.

While the run is going, the Play/Pause button on the progress strip shows a yellow dot, and pressing it does nothing. A Manual run has no pause: progress stops when the crossfader stops. To leave a Manual run before it completes, press and hold Abort.

In Auto Run Mode

The total transition duration is computed from the transition's bars and BPM and becomes a fixed timing window. Progress advances on its own from 0% to 100%.

There are two distinct ways the transition can be paused, and they behave differently.

Pausing the fusor. Pressing the Play/Pause button on the progress strip. The fusor stops producing new values; parameter values freeze at their current position. The timing window keeps ticking the whole time. When you resume, the Fusor player recalculates the pace from remaining-progress over remaining-time. The rest of the transition runs faster than originally planned so it still finishes at the moment it was originally due.

The catch-up is capped at twice the authored pace. If finishing on time would need more, for example because you paused for longer than the time that was left, the rest runs at twice the pace and finishes late, rather than moving every control to its end value at once.

If your DJ app stops the incoming deck while the fusor is paused, the deadline moves back by however long the deck was stopped, and only the time with the music playing counts toward catch-up. The deck coming back does not restart the fusor; only pressing Play ends a pause you started. (Stopping the incoming deck is a different pause, and that one does resume when the deck returns; see below.)

Pausing the transition. Stopping the incoming deck in your DJ app. The transition's clock stops too. When you resume the incoming deck, the transition picks up exactly where it left off, at its original pace. The transition's finish time is pushed back by however long the pause lasted. Stopping both decks does the same thing and says so on the status line (Both decks stopped); the incoming deck is still the one that resumes it.

Pressing Play/Pause stops the fusor's output; stopping the incoming deck stops the whole transition.

The Fusor player does not control deck transport. The incoming deck plays or doesn't based on what your DJ app is doing, and the player reads that state to decide what the transition should do.

The status line shows the current mode label while running.

In Mixed Run Mode

Until the stop, a Mixed run is an Auto run, with the same pause behavior and the same takeover. Its clock runs to the fusor's mix point instead of the end: Middle is 50% of the transition, and End on a fusor with an effect tail is the End mark. The countdown timer counts down to that point and is captioned to mix point; the bars count still covers the whole transition. The orange mix mark on the progress strip marks the stop. When the pace calculation or the late-finish warning applies, it measures against reaching the mix point.

Switching between Auto and Mixed during the run. Before the stop, the run's mode can change on the Run Mode switch with the same 0.4-second hold as a takeover. Holding Mixed during an Auto run makes it a Mixed run: it continues on the clock, stops at the mix point, and the crossfader drives the rest. Holding Auto during a Mixed run cancels the stop, and the run finishes on the clock. Arm/Play stays usable in both cases. The countdown and the late-finish warning are recalculated for the new target when the switch happens. Mixed is refused when progress is already at or past the mix point, and the status line reads Mixed: already past the mix point. After the stop the mode cannot change.

When progress reaches the mix point, the run stops. The parameters take their values for that point, then every parameter holds and the decks play on. The bars, BPM and timer readouts go away, Arm/Play shows the yellow dot, as in Manual Run Mode, and the status line reads At mix point: crossfader to the line. The Run Mode switch still reads Mixed.

From the stop the run is a Manual Run Mode run at the mix point. It resumes when your crossfader reaches the stop position, then follows the crossfader to the end. The DJ app's soft takeover holds your hardware crossfader until your hand reaches that position, so soft takeover must be on in the DJ app. If it is off, or you move the DJ app's on-screen fader, progress goes to wherever the fader is.

The stop is not a takeover. The outgoing deck's end-of-run settings still apply at completion. Completion works as it does in Manual Run Mode, including moving the crossfader back from 100%.

A run with an effect tail

A fusor has an effect tail when at least one of its enabled domains has the Effect tail switch on. It is set when the fusor is authored; see FX Routing → Effect tail. The switch applies to the outgoing side of FX Unit, FX Banks and Mixer FX domains on a fusor whose mix point is End.

A tail leaves room after End for the effect to taper off. The bars you set are the length of the run to End, tail or no tail, so line the decks up as for any End fusor. The tail is added after End: in Auto, the clock plays it out over a further 25% of the transition's length (2 bars on an 8-bar transition), so the whole run lasts 1.25 times the bars. If you run an End fusor with a tail in Auto, consider switching to Mixed Run Mode to control when the tail tapers off. The player rescales its progress strip to make room for the tail, which is why the orange End mark is drawn short of the strip's right edge. The run has two parts:

• The mix, up to End. The fusor's curves play across this part. End is the point where they finish, marked by the orange End mark. The countdown counts down to End.
• The tail, after End. On each tailed effect, the Dry/Wet tapers off from its value at End to dry. On a Mixer FX the knob controls the whole effect amount, so the Amount fades back to the knob's center, where the effect is off. The effect rings out while it fades. Every other parameter holds its value from End, so a channel fader cut at End stays cut. An effect whose Effect tail switch is off holds its End values through the tail with nothing fading it. If you take over a tailed control by hand during the tail, you keep it.

When the meter reaches 100%, the run completes as any run does: each domain's End of run setting acts on the outgoing deck, so an outgoing FX Unit set to Home has the controls the fusor binds sent to their neutral positions (effect off, Dry/Wet at zero) and a Mixer FX or FX Bank set to Restore goes back to where you had it, while a domain set to Leave is not touched. Completion waits for the outgoing deck to stop as usual.

Who moves the meter depends on the Run Mode:

A Mixed run on a tail fusor stops at End as it does at any mix point, with the status line reading At mix point: crossfader to the line, and the tail is played on the crossfader, for as long as the track needs. The crossfader is linear in progress across the whole strip, so at End it sits at the End mark. Moving it back inside the tail brings the effect back up.

Abort during the tail. Holding Abort once the meter is at or past End, while the run is going or at its completion wait, ends the tail and finishes the transition: the end-of-run settings and post-run actions run and the deck roles swap. No control is moved and no Restore is offered. In a paused run, and before End, Abort is the ordinary abort.

Manual takeover

You can take over one parameter the fusor is modulating, or the whole transition. Two forms:

• Per-control takeover. In any Run Mode, with full telemetry (Online), moving one modulated control in your DJ app (an EQ knob, a channel fader, a filter, and so on) stops the fusor modulating that one parameter for the rest of the transition. The control stays manual even if you let go. In a Manual run, or once you have taken a run over, moving the crossfader afterwards leaves that control where you put it.
• Whole-transition takeover. Press and hold Manual on the Run Mode switch while the run is on the clock (in Auto Run Mode, or in the clock part of a Mixed run), the same 0.4-second hold Abort uses. A quick press does nothing, and letting go before the hold completes cancels it. Moving the crossfader by hand does not take a run over, unless the player receives MIDI from your controller's crossfader and Allow crossfader takeover during a run is on: then bringing the crossfader to where the player has it completes the same takeover. Completing the hold converts the entire transition to manual operation from that point on, and the crossfader becomes the master clock.

While the Fusor player is receiving MIDI from your controller, moving a controller control that the player is modulating shows a bar over the picker row: a cyan line for the player's value and a white dot for your controller's position. The player keeps modulating the control until the dot reaches the line, then releases it; the lane turns green and reads Yours, or The transition is yours · Manual for the crossfader. With two hands on two controls, the row holds two lanes. The bar clears a moment after you stop moving.

The two forms behave differently at the end of the run. Per-control takeover changes nothing at completion: every domain still follows its end-of-run choice on the outgoing deck, so an outgoing knob you took over on a domain set to Restore still goes back where it was. On a whole-transition takeover, the moment you take the run over the Fusor player discards what it had recorded of your mixer, so nothing is put back at completion and every control stays where you and the fusor left it. The same applies to aborting afterwards: with nothing recorded, there is no RESTORE to offer, unless the fusor has post-run actions of its own.

Aborting

Aborting terminates a transition immediately and permanently. There's no resume; you'd load the fusor fresh and start over. It's available while a transition is under way, running or paused or in its setup pause, and deliberately hard to fire by accident. Transport Controls has the gesture and the availability rules.

Abort does not run the completion sequence. Roles don't swap, nothing is put back, and no post-run actions fire. The fusor stays loaded and the Fusor player returns to Idle. Your mixer is left exactly as the transition left it: EQs part-swept, faders mid-travel, FX still engaged, so no control moves while you correct the mix.

What abort does do is re-derive which deck is outgoing and which is incoming from where the crossfader ended up. Abort a transition late, with the crossfader over on the incoming side, and the roles can come out swapped. Check the direction indicator before re-arming, and use Manual Role Swap if it's wrong.

For where Abort sits against the resumable options, see Pause vs Abort.

Putting things back: the RESTORE button

An abort leaves the mixer for you to reset by hand, and a fusor's setup actions can change things you didn't touch and might not notice, like which crossfader side a deck is assigned to.

So after an abort, the Abort button becomes RESTORE. Hold it the same way you held Abort, and everything goes back to where it was before the run started: the controls the Fusor player was modulating, any FX routing it set up, and anything the fusor's own post-run actions put back. It's the same button and, on a hardware controller, the same command: you press the one button twice.

It waits a second first. For one full second after an abort the button still reads Abort and still behaves as Abort, so a double press does not restore. Only after that does it offer RESTORE. Nothing is lost if you do press twice fast; the second press is simply refused.

On a started run, RESTORE is audible. "Before the run" means the outgoing deck full and the incoming deck not yet in. Press it half-way through a mix with both decks playing and every control it drove returns at once to where it was before the mix started. If you only want part of it back, move those controls by hand instead. RESTORE is all or nothing.

Before a run has started it's silent, and the Fusor player does it for you. If the transition never got past its setup pause, whether you aborted during setup, both decks stopped, or a setup action failed, nothing was mixed and nothing is audible, so there's nothing to decide. The player undoes the setup by itself and says Pre-run setup unwound on the status line. There's no button to press.

The offer doesn't expire on a clock. It stands until you arm the next transition (in Auto, press PLAY for it), load a different fusor, or press it. Once you press it, it's used up and the button goes back to reading Abort. And if there's nothing to put back, no RESTORE appears at all.

RESTORE puts controls back. It does not resume the mix, and it does not move the deck roles.

In Blind Mode there's no RESTORE button. The Fusor player never saw where your controls were, so it has nothing to put them back to.

Completion and role swap

When the progress meter reaches 100%, the transition enters its Completing phase. In every mode with telemetry, Manual as much as Auto, completion is gated on the outgoing deck stopping, and the arm control becomes an End button you can press to commit instead of waiting.

End ends the transition, and leaves the track playing. Pressing it tells the Fusor player to stop treating that deck as the outgoing side of an active transition. The track keeps playing in your DJ app until you stop it or it reaches its end.

In Auto Run Mode

1. Progress reaches 100%. The Arm/Play/Pause button changes to an End button (rendered as END on the button face).
2. The Fusor player waits for telemetry confirming the outgoing deck has stopped playing. If it does, completion proceeds automatically. If it doesn't, the player waits. The status line shows Completed — stop outgoing deck or press End. The user can press End at any time to commit.
3. The deck roles swap. The deck that was incoming becomes the new outgoing deck; the deck that was outgoing is now positioned to be the next incoming deck.
4. Each domain does what its End of run setting says for the deck that was outgoing: leave its controls where they are, put them back where you had them, or send them to their neutral positions. Putting them back is the part the Snapshot / Restore setting governs (Settings → Guards, on by default); going home happens either way. Set per domain on the domain card: Domains → End of run.
5. Any post-run actions the fusor has are run, with the same 5-second ceiling the setup queue has. See Pre-run actions.
6. The Tempo Ramp toggle resets to off, whether the run completed or was aborted. Press it again to ramp the next run.
7. The player returns to its loaded-but-idle state, ready for the next transition.

In Manual Run Mode

The flow is similar, with one important difference: while the transition is at 100% waiting for the outgoing deck to stop, you can still move the crossfader back, which returns the transition to the Running state and lets you continue adjusting from there.

If the user doesn't back out, the same End path applies: outgoing deck stops naturally → completion proceeds, or user presses End to commit manually.

In Blind Mode

There's no telemetry to wait for, so completion is simpler: when progress reaches 100%, the Fusor player treats the outgoing deck as stopped and the transition completes. Deck roles swap exactly as they do while Online. Snapshot restore is the one step that has nothing to do: with no telemetry there were no pre-transition values to capture, so domains set to Restore stay where the transition left them. Domains set to Home still go to their home positions, which needs no baseline, and out of the box that includes the FX Unit domain. See Blind Mode.

Tempo Ramp

If Tempo Ramp is switched on, the tempo-sync setup sequence runs as soon as the outgoing deck is playing. It does not wait for you to arm, and arming does not trigger it. The status line reports what it finds. If the outgoing deck isn't playing yet, the sequence waits for it and the Tempo Ramp button shows yellow until it runs.

During the run, the outgoing deck stays tempo master and the Fusor player moves its tempo fader toward a target that brings both decks to the incoming track's original tempo. The incoming deck follows via sync. See Traktor Pro Setup for the app-specific detail.

By default the tempo ramp turns key lock on for each deck where it is off before it starts, and turns it back off on those decks when the transition completes. See Settings → General.

Tempo Ramp is for cases where the incoming and outgoing tracks have different tempos and you want them brought together without an audible jolt.

How transitions end

A transition can end in four ways. Three of them are covered above; the fourth is started by the Fusor player.

Auto-abort is the one case the Fusor player initiates, and it only applies before the run starts. If both decks stop while the transition is still in its setup pause, the player aborts it, disarms, and shows Both decks stopped: aborted on the status line. Nothing had been mixed, so it also undoes the setup for you rather than offering you the choice.

Once the run has started, both decks stopping is not an ending at all. In Auto Run Mode it pauses the transition and waits, exactly as stopping the incoming deck alone does: the status line reads Both decks stopped: paused, the Fusor player stays armed, and starting the incoming deck again resumes the transition from where it stopped. The pause has no time limit. If you don't want to finish the transition, hold Abort; that ends it and offers RESTORE on the usual terms.

In Manual Run Mode a started run ignores it entirely. The crossfader drives the transition and your hand is still on it, so the decks stopping changes nothing: no pause, no status message, and the fader still moves the transition. This is the one place the two Run Modes read differently: in Auto the deck telemetry paces the run, and in Manual you do.

Aborted and Disarmed leave the Fusor player looking the same afterwards (Idle, fusor still loaded), and they are different events: Abort interrupts a transition that was already running, Disarm cancels a start that hadn't fired.

States at a glance

A quick summary of what the Fusor player can be doing at any moment:

The pickers are locked while you're in any state other than Idle or Loaded. Loading a different fusor requires aborting or completing the current one.