Beat, tempo and sync

The app finds the tempo and predicts each beat a little ahead of time, so pulses land with the music rather than after it. It also tracks bars and phrases, and estimates the song's mood and sections. All of this is in the Audio tab.

The beat

The Beat section shows the tempo in BPM, the time signature, a dot for each beat of the bar (the outlined one is beat 1), and a bar showing how confident the tracker is. A chip says where the tempo comes from: detected, tap, held (beat detection is off), midi (a MIDI clock) or file grid (from the analysed file).

The tempo readout always shows four digits (098.5, 128.0) and only moves in visible steps, so it stays put while the tracker fine-tunes. A new tempo needs a couple of seconds of steady evidence before the tracker switches to it, and much more when the new tempo is double, half or 3:2 of the old one: in busy music like jazz those are usually the same music heard another way, not a real change.

Time signature and beat 1. The tracker tells 3/4 from 4/4 and finds beat 1 from where the kick drum and bass land, and moves either only when the evidence stays clear for a while. It's most reliable on music with a drummer playing a clear pattern. Swing and other music with few cues on beat 1 can leave it a beat or two out: press Beat 1 on the one, or choose the time signature yourself in Time signature (Detect, 2/4, 3/4, 4/4, 5/4, 6/8 or 7/8).

Beat detection on or off. Turn off Beat detection (here, in Settings → Beat & analysis, with the Live pane's Auto/Hold button, or Alt T) to hold the tempo, bar and beat where they are: only taps, nudges and Beat 1 change them. It's handy once the tracker has it right and you don't want it to wander, or for music it struggles with. Tap tempo and the Live pane keep working.

It usually locks within a few seconds of steady music. If it's wrong, you can steer it:

Button	Key	What it does
Tap	T	Tap along with the beat. Two taps set the tempo and every tap marks a beat; keep tapping to refine it (it takes the middle of your last eight). Pause for more than two seconds to start afresh.
Beat 1	⇧ T	Press on the first beat of a bar, so bars and phrases line up with the music.
−10ms / +10ms	Z / X	Nudge the beat earlier or later.
½× / 2×	⇧ Z / ⇧ X	Halve or double the tempo when it has locked to half- or double-time.

The Tap button is also in the Live pane, so you can tap during a show without opening the panel.

Tempo range. If the music is very slow or very fast, set Settings → Beat & analysis → Slowest tempo / Fastest tempo so the tracker looks in the right place.

Phrase length (same section, default 16 bars) sets how long a phrase is — used by phrase-quantized changes and auto-pilot.

MIDI clock. With MIDI on, the app can follow a clock from DJ software or a drum machine instead of detecting the beat: Settings → Beat & analysis → Follow MIDI clock. See MIDI.

The song

The Song section shows the current section — intro, groove, build-up, drop or breakdown — and four meters: Energy, Intensity, Brightness (how happy or dark the sound is) and Build-up. They are estimates from the sound, and they drive the Mood modulation sources and auto-pilot's "change on drops & breakdowns".

Sync: picture and sound together

Your screen shows each picture a little after it's drawn, and TVs and projectors can add tens of milliseconds more. If flashes seem to land early or late compared with the sound:

1. Press Calibrate… in the Sync section.
2. Tap along to the clicks you hear, then tap along to the flashes you see. The difference between the two is your display's delay (your own reaction time cancels out).
3. Press Use this.

Do this once for each screen and speakers you use. You can also adjust by hand:

• Display latency — how long your screen takes to show a picture (0–150 ms).
• Fine offset — a final nudge (positive = visuals later).
• Delay playback to match visuals — for sound the app itself plays (files, the demo, a captured tab), delays the sound slightly so picture and sound land exactly together. With a live microphone the sound is already in the room, so the visuals are timed to it instead.

Big rooms

In a large venue, sound takes about 3 ms per metre to reach the audience. If the screen is far from the speakers, a little fine offset helps.