Piano Roll

A pattern-event visualizer that draws notes as rectangles on a pitch-time grid. It sits in the signal chain as a pass-through.

pianoroll

Piano Roll - Pattern event visualization on a pitch-time grid.

Param	Type	Description
in	signal	Pattern signal
name	string	Display label (optional)
opts	record	Options (optional)

Options:

Option	Type	Default	Description
width	number / string	200	Width in pixels, or "100%" for full width
height	number / string	50	Height in pixels, or "100%" for full height
beats	number	auto	Number of beats visible in the window
showGrid	boolean	true	Show beat grid lines
scale	string	"chromatic"	Scale filter: "chromatic", "pentatonic", or "octave"

Displays pattern events as rectangles on a piano-roll grid. The playhead scrolls through the pattern in real time.

// Basic piano roll
pat("c4 e4 g4 b4") |> pianoroll(%)

beats

Number of beats visible in the scrolling window. By default, the pianoroll auto-fits the pattern’s cycle length. Set explicitly to show more or less of the timeline at once.

// Wide view with 8 beats visible
pat("c4 e4 g4 c5 ~ e4 g4 b4") |> pianoroll(%, "melody", {beats: 8, width: 400, height: 80})

showGrid

Toggle the beat-grid overlay. Off can be useful for screenshots or when overlaying multiple pianorolls.

scale

Highlight notes that fall inside a named scale; notes outside are dimmed. Helps eye-check whether a melody stays in key.

chromatic

"chromatic" (default): every note is highlighted; no filtering applied.

pentatonic

"pentatonic": highlights C major pentatonic (C, D, E, G, A). Notes outside this set are dimmed.

// Pentatonic scale filter, no grid
pat("c4 d4 e4 f4 g4 a4 b4 c5") |> pianoroll(%, "scale check", {scale: "pentatonic", showGrid: false})

octave

"octave": highlights only root notes (C across octaves). Useful for verifying tonal centers in a long progression.

Related: oscilloscope, spectrum