Help & Reference

Track order

In AUTO the order is chosen from the transitions that will actually play: as few cuts and echoes as possible first, then the best smooth transitions, keeping every track close to its own tempo. Pairs that only mix with a tempo walk are put side by side only when nothing else works. Two tracks by the same artist never follow each other (the artist comes from the file's tags and its name, co-artists and remixers included). An order you set by hand is left alone.

Where the junction goes

• Leaving — late in the first track, where its beat still plays — not in a dip in the middle of it.
• Coming in — early in the second, where it has a beat and its bass holds, and so that it keeps playing without a dip afterwards.
• Level — the overall level across a transition should not sag well below how the set sounded before it — as when a quiet outro meets a quiet intro.
• Length — usually 22–40 seconds, longer the better the pair sounds together. At fast tempos (DnB) up to 24 bars.

Tempo

• Matching — the incoming track is matched to the tempo the previous one actually plays at. By default by speed (the pitch moves with the tempo); with Time Stretch, without a pitch change.
• The 5 % limit — no track is pulled more than 5 % off its own tempo for a smooth transition.
• Tempo walk — for a 5–7.6 % gap the tracks meet halfway: the first one changes tempo smoothly beforehand, the second is pulled to meet it. The bigger the change, the longer it takes.
• Easing home — when the chain would keep drifting, a track eases back to its own tempo after coming in (Ramp).
• Over 7.6 % — an atmospheric blend, an echo or a cut — the tempos are not matched.

Tempo ramp: when, how long, where to

A ramp is a smooth tempo change while a track plays on its own, between its two transitions — the way a DJ brings the pitch fader back to zero or walks the tempo towards the next record. The tempo never changes during a transition itself: two decks only play together at one tempo.

• Why — without ramps every next track is matched to the one before, and over a few tracks the whole set drifts to the first track's tempo: tracks play 5–7 % faster or slower than their own. A ramp brings a track back to its own tempo or walks it to the tempo where it meets the next one.
• Where to — to its own tempo — when the track has Ramp ticked, or when otherwise the next track would have to be pulled more than 5 % off its own (the engine does this by itself). To the halfway tempo — in a tempo walk, when a pair is 5–7.6 % apart: the first track moves towards the second beforehand, and neither moves more than 5 %.
• When it starts — right after the transition into the track has finished, i.e. once the previous track is gone.
• How long — 16 bars by default: about 31 s at 124 BPM, about 22 s at 174 BPM; never fewer than 4 bars. The tempo changes by at most 0.2 % per bar, so a big change takes longer: 7.5 % takes about 38 bars, over a minute at 124 BPM.
• Where it ends — at least 4 bars before the point where the track starts to leave, so the next track meets a steady tempo. If there is not that much room between coming in and leaving, there is no ramp; the tooltip on the Ramp tick says there was no room.
• Shape — even: the tempo changes by the same amount every bar. The beat grid follows it, so the next transition is matched to the real tempo after the ramp.
• How the tempo is changed — without Time Stretch, by playback speed, like a pitch fader without Master Tempo: the pitch moves with the tempo. 1 % of tempo is about 0.17 semitones, 3 % about half a semitone, 6 % about a semitone. Up to 2–3 % it is barely audible; from 5 % you hear it on vocals and melodies. With Time Stretch the ramp is time-stretched along the same curve and the pitch stays put (see below).
• When there is no ramp — BPM Ramping (the master switch) is off; the track's Ramp is unticked; Sync is off; the track is pulled more than 6 %; there was no room. The track then plays at one speed throughout, and pairs that cannot be matched without a tempo walk get an atmospheric blend, an echo or a cut.
• Where you see it — on the track card: a filled Ramp circle and a tempo line with two values — what the track comes in at and what it leaves at, with percent and semitones.

Time Stretch and pitch

There are two ways to change a track's tempo, and they differ in pitch. By speed (vinyl, or a CDJ without Master Tempo) the tempo and the pitch change together. By time-stretch (Master Tempo) the tempo changes and the pitch stays. The Time Stretch tick picks the second way for every tempo match.

• The price — time-stretch (the WSOLA algorithm, SoundTouch) cuts the audio into short pieces and glues them back together: drums get slightly phasey. The bigger the tempo change, the more noticeable.
• Ramps with stretch — ramps work with Time Stretch too: the track is stretched along the same tempo curve a speed ramp follows, with a changing ratio, and the pitch stays. Easing home and tempo walks work as without it. When the ramp takes a track home, the original plays untouched after it ends — the stretch stays only on the way in and in the ramp itself.
• AUTO decides — with AUTO on the engine picks the method per track: a track moved less than 2 % from its own tempo at any point (up to a third of a semitone, inaudible) changes tempo by speed, which is cleaner; more than that, by time-stretch. Without AUTO it is stretch wherever the tempo moves. The track card shows the choice: semitones or "key kept".
• Accuracy — the algorithm itself puts the audio 10–20 ms early, earlier the more it slows down. The engine compensates: the beats of a stretched track sit within about ±5 ms of where they belong.
• Which to use — for sets with close tempos (within 2–3 %) Time Stretch is not needed — the pitch shift is inaudible and the sound is cleaner. It helps when tracks are pulled 4 % or more and the key of vocals and melodies must not move.

EQ during a transition

The bands are handed over according to what the tracks play, not one curve for all:

• Bass — switches over two bars at the point from which the second track's bass holds to the end of the transition; earlier if the first track's bass drops out by itself. Never two basslines at once.
• Highs — are handed over in a window around where they appear in the second track. If the second has hardly any, the first track's hats stay to the end.
• Mids — smoothly across the whole transition.

Beat and loudness

• Beat alignment — the beats of both tracks are lined up on the kick, and on the snare for breakbeats and DnB.
• Loudness — every track is brought to −14 LUFS, and a master limiter keeps peaks under −1 dBFS.

Tempo on the card

• "128 BPM ✎" — the track's own tempo as the engine read it. Click to type your own if it is wrong (happens on psychill and chillout: read 1.5× too high); "reset" undoes it.
• Tempo in the mix — "▼ 126.0 (−3.1 %, −0.54 st) → ▲ 135.4 (+4.2 %, +0.71 st)": the tempo the track comes in at and, if it changes along the way, leaves at; the change from its own tempo and the pitch shift in semitones (with Time Stretch: "key kept"). ▲ sped up, ▼ slowed down. Colour: green under 2 %, amber 2–4 %, red from 4 %. "Plays at its own tempo" — not matched.
• Sync — on — the track is matched to the previous one. Off — it plays at its own tempo, and the transition into it is atmospheric, an echo or a cut.
• Ramp — the circle is filled when the track's tempo changes along the way — set by you or by the engine. Tick it to bring the track back to its own tempo after it comes in; untick it to forbid any tempo change on this track. Disabled when the global BPM Ramping or Sync is off. The tooltip says why a ramp was not made when there was no room.

Warnings

• "Cut / echo here" — this pair has no smooth transition. The Alternatives button shows what the engine can build instead: another transition, a track moved, a different tempo when it may have been misread, a tempo walk or Sync. Each can be heard first (the pair is rendered through the engine, about 8 seconds) and applied; if the mix is already made, "Mix again" appears.
• "The next track would be more than 5 % off" — the chain drifted and there is no room to bring it back. Turn BPM Ramping on or change the order.
• "Sync is off" — the next track plays at its own tempo, so this cannot be a blend.
• "The chosen transition does not fit" — your choice will play, but it does not suit this pair.