Beat Time
The timeline runs on beats, so a show stays locked to the music when the tempo changes.
Spectralite measures everything on the timeline in beats. At 174 BPM a show plays fast, and at 90 BPM the same show plays slow, but every effect still lands on the same beat. When the tempo changes, the whole show stretches or compresses with it and stays in time with the music.
Beats and bars
A beat is one pulse of the music, the count you tap your foot to. Tempo is measured in beats per minute (BPM). At 120 BPM, a beat comes every half second. At 60 BPM, a beat comes every second.
Beats group into bars. In Spectralite a bar is four beats, the steady one-two-three-four count that repeats under most music. You arrange a show in bars, so a timeline eight bars long is a 32-beat loop.
The timeline holds a length in bars and a global beat clock counting through them. It holds no length in seconds, which is why a tempo change never breaks timing.
Scheduling on the beat grid
Each layer has a grid of on/off slots, in one row per layer. The effect of the layer plays wherever a slot is on.
Each bar has sixteen slots, four per beat, so a slot is a sixteenth of a bar. A layer switched on for the whole first beat fills the first four slots. A layer that flickers on every other slot pulses twice per beat. You paint the pattern you want across the timeline's bars, and it repeats every time the loop comes around. The grid is the whole schedule, at a fixed resolution of sixteen slots per bar. There are no clips to trim, durations to set, or snapping to arrange.
Because the grid is measured in slots, it follows the tempo like everything else. A pattern that hits on beats one and three keeps hitting on beats one and three in a slow song and in a fast one.
A timeline can be from 1 to 128 bars long. When you change the length, Spectralite keeps the existing pattern. If you make the timeline longer, Spectralite repeats the pattern into the new bars. If you make it shorter, Spectralite trims bars from the end.
Effects and layers explains how layers stack and combine while they play, and what opacity and blending do. The beat grid controls only when a layer plays.
Shaping time per layer
The beat grid decides when a layer is on. Three per-layer controls change how its effect moves through time while it plays.
Speed multiplier scales the layer's playback rate against the beat. At 1.0 the effect runs at the master tempo. A value of 2.0 runs it twice as fast, and 0.5 runs it half as fast. If one layer must run faster or slower than the rest of the show, use Speed multiplier. The master BPM stays the same.
Beat offset shifts a layer's phase by a number of beats. Its motion then runs earlier or later than the beat, and every other layer stays unchanged. A small offset between two otherwise identical layers makes them chase each other.
Hold controls what happens when a layer's slots switch off. With hold at zero, the layer cuts to dark the instant its slot ends. With a hold time set, the layer fades out from its current level, so a pattern with gaps fades between hits. Hold shapes only the release. The window in which the layer counts as playing stays the same.
These are the only per-layer timing controls. Layers have no start, end, or duration. The grid sets when a layer plays, and these three controls set how its effect moves.
Setting the tempo
The beat clock runs on a BPM. You set it in one of three ways, all in the Beat Matcher panel.
Set it manually by typing a BPM. If the reading settles on twice or half the real tempo, nudge it with the double and halve controls. When you know the BPM in advance, or the music has none to detect, use manual tempo. An ambient set is one example.
Set it by tap tempo: tap along with the music four or more times. Spectralite averages your taps into a BPM. When you do not know the BPM of a track, tap tempo lets you match it by ear.
Set it automatically: turn on beat detection. Beat detection listens to the incoming audio and finds the tempo. It stays locked to the beat as the tempo drifts, and it adjusts the clock many times a second. As a result, the show tracks a live band that speeds up, or a DJ set that eases between tracks.
While beat detection runs, it drives the tempo, and the manual field and tap tempo have no effect. The double and halve controls stay active, so you can correct an octave without losing the lock. The Beat Matcher panel reference covers full setup, the lock indicator, and latency calibration.
Beat detection reads the incoming audio, which is the same signal the Audio Spectrum panel shows. Audio input covers how to choose and test that input.
Where to go next
Arrange layers in the Timeline panel and drive the tempo from the Beat Matcher. For the rest of the model, see the Core concepts overview.