Chapter 05c

MIDI visualizer

The MIDI visualizer is an underlay effect — an 8×8 field of colored pads that light with incoming notes while your base app (idle clock, launch countdown, or tide) continues above. It visualizes MIDI notes, not recorded audio, loudness, or tempo.

Schematic of MIDI pad grid on a B0rd panel
Fig. — MIDI pad field under base chrome (schematic).

Turn it on

Set the underlay preference to MIDI:

  • SoftAP Display → Underlay effect → MIDI (wording may vary by build).
  • USB:settings set display.underlay_effect midi thensettings save.
  • Pads only — SoftAP preset Music visualizer(or USB presets apply music_visualizer) clears base scene rotation and shows the pad field full-screen. Most desks keep clock or countdown on top instead.

Other underlay choices include ring, plasma, and lissajous. Only one underlay runs at a time. Switch back withsettings set display.underlay_effect ring (or your preferred effect).

How notes reach the sign

The sign does not accept a USB MIDI cable directly. A Mac MIDI bridge on your LAN reads a CoreMIDI source (for example Ableton Live through the macOS IAC Driver) and publishes standard B0rd Events to your MQTT broker. Every sign subscribed to those events updates its pad table in real time.

  1. Enable MQTT on the sign and point it at a broker on home Wi‑Fi — see MQTT Events.
  2. Run the Mac bridge against the same broker and virtual MIDI port your DAW uses.
  3. Play or sequence notes — pads attack and release with velocity-colored brightness.

Pad layout

Sixty-four semitones map bottom-left to top-right in an 8×8 chromatic grid. The lowest note in the window is scene.midi.note_lo (default 36, C2). USB:settings set scene.midi.note_lo 48 shifts the window upward if your controller range differs.

Velocity picks a color from scene.midi.palette (defaultphosphor_paper). Attack and release times (scene.midi.attack_ms, scene.midi.release_ms) control how quickly pads brighten and dim.

What MIDI does not do

  • It does not take its own playlist visit — there is no separate “MIDI scene” slot in rotation.
  • scene.midi.enabled and scene.midi.dwell_ms persist for compatibility but do not schedule base chrome.
  • It does not analyze audio from speakers or microphones.

Multi-sign desks

Every B0rd subscribed to the same broker topic receives the same note events, so a room of signs can light together without pairing or a leader election. Match firmware, underlay selection, and MIDI window settings if you want identical colors and layout.

Related: App catalog page ·MQTT Events ·Display & idle clock ·Playlist and scene timing ·Settings reference