Drum Patterns

Step Sequencer

A step sequencer triggers sounds on a rhythmic grid. Each step is either ON (1) or OFF (0). At a given BPM, you convert the step grid into onset times.

Formula

Each step is a sixteenth note (1/4 of a beat):

stepDuration = 60 / (bpm × 4)
onsets = steps where pattern[i] === 1, at time i × stepDuration

Classic Drum Patterns

// 4-on-the-floor kick (16 steps):
kick:  [1,0,0,0, 1,0,0,0, 1,0,0,0, 1,0,0,0]

// Snare on beats 2 and 4:
snare: [0,0,0,0, 1,0,0,0, 0,0,0,0, 1,0,0,0]

// Closed hi-hat every eighth note:
hihat: [1,0,1,0, 1,0,1,0, 1,0,1,0, 1,0,1,0]

Your Task

Implement patternOnsets(pattern, bpm) that returns an array of onset times (in seconds) for each active step.

Run your code to hear a basic beat: kick on 1 and 3, hi-hat on every eighth.