Beat Matcher
Set your show's tempo with the BPM display, tap tempo, and automatic beat sync from the audio input.
The Beat Matcher sets and adjusts the tempo for your lighting show.
Related concept: Beat time.
BPM display
The large BPM readout shows the current tempo. Type a specific BPM into the number input, or use the ×2 and ÷2 buttons to double or halve it.
When Auto Beat-Sync is on, the readout shows the detected tempo that the loop tracks. Because the loop drives the rate, the number becomes read-only and Tap grays out. ×2 and ÷2 stay active so you can fix an octave while synced.
Phase
The Phase readout sets where the beat lands. Type a millisecond value into it, or use the + and − buttons to step it by 10 ms. A positive value shifts the beat earlier so lights fire ahead of the music.
When Auto Beat-Sync is on, the same readout shifts the sync latency instead of the raw offset. Spectralite clamps it to the ±150 ms range. The lock loop cancels a raw offset while it tracks, so the readout adjusts latency, because latency is what moves the beat. A positive value still fires the lights earlier, with or without the loop. MIDI-mapped offset and nudge controls follow the same routing, so while synced they adjust the sync latency too.
Beat visualization
The beat display shows 4 blocks, one per beat in the bar. The active beat flashes in the accent color and fades as the beat progresses.
Multipliers
| Button | Effect |
|---|---|
| ×2 | Double tempo |
| ÷2 | Half tempo |
Use them when the BPM is a multiple or fraction of the true tempo. The global keyboard shortcuts ] and [ double and halve the BPM.
Tap tempo
The Tap button sets BPM from your taps. Tap along with the music four or more times to set the tempo. The longer you tap, the more precise the reading gets. Spectralite ignores a tap that lands well off the beat, so a steady hand matters more than hitting the first downbeat. To start a fresh take, pause for a few beats.
Tap Tempo is also a MIDI input assignment type, so you can map a controller pad to it. See MIDI Input Dialog.
Cue align
The Cue button realigns the current moment to beat 1 of the bar. When the BPM is correct but the phase drifts, use it to snap the beat grid to a downbeat in the music. When your target is the start of the next bar, it is faster than small phase adjustments.
While Auto Beat-Sync is on, one press sets the bar downbeat and also calibrates the sync Latency from the press. A press on a downbeat you hear thus absorbs the room's delay at the same time. The press counts from the moment the button goes down. Press it on a downbeat in the music, where a drop hides the snap.
Cue Align is also a MIDI input assignment type under "Cue / Align Beat".
Auto Beat-Sync
Auto Beat-Sync listens to live music on an audio input and locks the show's tempo to it. Beat-driven effects then stay on the beat without tapping. It corrects only the rate of the clock and eases tempo and phase toward the music. As a result, musical time never jumps or runs backward while it tracks. To snap to a downbeat, press Cue by hand (see Cue align).
The Auto button turns it on and off, and lights orange while sync is on. While it runs, the line under the BPM readout shows its status and confidence. The panel's toolbar holds a microphone button that opens the Audio Input dialog, and a button for the settings popover.
The status under the BPM readout moves through these states:
- No signal until the detector hears beats in the incoming audio.
- Listening while the loop finds the tempo or holds through an unclear passage.
- Locked, in orange, once it holds tempo and phase to the music. The lock reading is sticky, so a short dip in confidence does not make it flicker.
A status stuck on No signal means that no beats reach the detector. Check that you selected the right input device and channel, and that the music is on. The level meter in Edit > Inputs > Audio confirms that audio arrives. If the status shows Unavailable, beat detection failed to start and auto beat-sync cannot analyze audio. To restore it, reinstall the app.
When you turn Auto off, Spectralite keeps the tempo that the loop held. You can thus drop out of sync mid-show without a jump in the clock.
Live readout
While synced, the tracker's tempo appears in the panel's main BPM readout (see BPM display). The beat display's blocks flash on the show's own beat, so you can check them against the music. Matching BPM numbers do not prove the phase is right, but a flash that lands with the kick does.
Next to the status, a percentage shows how confident the tracker is of the current lock. It appears once the detector hears beats and hides while the status reads No signal. The level meter for the incoming audio sits with the device controls in Edit > Inputs > Audio. You can check the signal there whenever capture runs.
Setup
The detector needs about two seconds of music before its first reading. After that it updates its tempo and beat reading ten times a second. The first tempo the panel shows is an early read. For a few seconds after it appears, it can still jump to another octave when the detector hears more of the track.
The input device and channel come from the Audio Input dialog, which the Audio Spectrum visualizer shares. Open it from Edit > Inputs > Audio or with the microphone button on the Auto Beat-Sync row. When you turn Auto Beat-Sync on, it starts that capture. Capture continues as long as either feature needs it. Prefer a direct feed from the mixer over a booth microphone.
Spectralite compensates for the time it takes to render a frame and send it to your outputs. The lights thus change on the beat instead of a frame or two behind it. Spectralite cannot measure the delay in the room, which is the sync Latency. That delay comes from the distance between the speakers and the microphone, the audio interface, and your network and fixtures. While synced, the Phase readout shifts it (see Phase above). A press of Cue on a downbeat you hear sets it for you (see Cue align).
The sliders button in the panel's toolbar opens the settings popover, which holds Correction strength. Higher values hold the lock tighter to the music. Lower values hold through dropouts and blend more smoothly. The setting starts in the middle of its range, where the lock is tuned. A project saved with another value keeps that value.
Fixing a wrong lock
A confident lock can still be wrong. The tracker can settle an octave off or land on the off-beat, and the panel's buttons fix both by hand.
- ÷2 and ×2 halve or double the locked tempo, which fixes a wrong octave in one tap. While synced, they move the sync tempo an octave up or down.
- Cue snaps the beat grid to the current moment as beat 1 of the bar. While synced, it also sets the sync Latency from the press (see Cue align).
- Auto turns sync off and keeps the tempo that the loop held, so you can drop a bad lock before a live moment.
Integration
With Timeline
The Timeline uses this BPM. The beat grid aligns to the tempo, effect timing scales with BPM, and tempo changes apply immediately.
With effects
Beat-synced nodes use this tempo. The Time node cycles per beat, the Beat node provides the beat position, and all timing is relative to BPM.
Troubleshooting
BPM is double or half what it should be. Try the ×2 or ÷2 multipliers.
Beats feel off. Use the Phase controls to move where the beat lands. Step it with + and −, 10 ms at a time, until beats align.
Related
- Timeline: beat-based sequencing.
- Beat-Synchronized Effects: a tutorial.