[piano-roll-midi] MIDI Piano Roll Visualization

[MarkusNeusinger]

Description

A grid-based visualization of musical notes over time, as seen in DAWs and music production software. Each note is a horizontal bar positioned by pitch (y-axis) and time (x-axis), with length indicating duration and color indicating velocity.

Key Visual Elements

• Time on x-axis (beats/measures)
• Pitch on y-axis (MIDI note numbers or note names)
• Piano keyboard graphic along y-axis
• Note rectangles colored by velocity (soft=blue, loud=red)
• Beat/measure grid lines
• Black/white key shading on background

Applications

• Music production: MIDI editing in DAWs (Ableton, FL Studio, Logic)
• Music analysis: visualizing melodic and rhythmic patterns
• Algorithmic composition: visualizing generated music
• Music education: teaching notation and arrangement

Domain

Audio / Music

[claude]

✅ Spec ID: piano-roll-midi

Rationale: Piano roll is the standard term for this grid-based MIDI note visualization used in DAWs; the midi modifier clarifies the data source and distinguishes it from other grid/bar-over-time plots.

This is a valid and unique plot type with no existing duplicates. It fills a gap in music/audio domain visualizations.

[github-actions]

✅ Specification Ready: piano-roll-midi

PR: #4596

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specification.md

piano-roll-midi: MIDI Piano Roll Visualization

Description

A grid-based visualization of musical notes over time, as seen in digital audio workstations (DAWs). Each note is represented as a horizontal rectangle positioned by pitch (y-axis) and time (x-axis), with bar length indicating note duration and color indicating velocity (dynamics). The background alternates between white and dark rows to mirror piano keyboard layout, with vertical grid lines marking beats and measures.

Applications

• Music production: visualizing and editing MIDI data in DAWs (Ableton Live, FL Studio, Logic Pro)
• Music analysis: examining melodic contour, rhythmic patterns, and harmonic structure of compositions
• Algorithmic composition: displaying output from generative music algorithms or AI-composed pieces
• Music education: teaching note relationships, intervals, and arrangement concepts visually

Data

• start (float) - Note onset time in beats (e.g., 0.0, 1.5, 3.0)
• duration (float) - Note length in beats (e.g., 0.5 for eighth note, 1.0 for quarter note)
• pitch (int) - MIDI note number from 0-127 (e.g., 60 = Middle C / C4)
• velocity (int) - Note intensity from 0-127, mapped to color (low=soft/blue, high=loud/red)
• Size: 20-200 notes covering 4-16 measures
• Example: A short musical phrase or chord progression with varying dynamics

Notes

• Y-axis should display note names (C4, D4, etc.) alongside or instead of raw MIDI numbers
• Background rows should alternate shading to distinguish black keys from white keys on a piano
• Vertical grid lines should mark beat divisions (quarter notes) with stronger lines at measure boundaries
• Color scale for velocity should use a sequential or diverging colormap (e.g., blue for piano/soft to red for forte/loud)
• The pitch range displayed should auto-fit to the data with a small margin, not show all 128 MIDI notes

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Next: Add approved label to merge this specification to main.

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🤖 spec-create workflow

[github-actions]

🚀 Specification Merged!

Specification: piano-roll-midi
PR: #4596 (merged)

The specification is now in main and synced to PostgreSQL.

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Next: Add generate:{library} labels to start generating implementations.

Available libraries: matplotlib, seaborn, plotly, bokeh, altair, plotnine, pygal, highcharts, letsplot

Or use workflow dispatch for bulk operations.

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🤖 spec-create workflow