Scope and non-goals

This page is the explicit list of things the Disklavier MIDI Visualizer does not do, and why. If you are evaluating whether the tool fits your workflow, this is the page that will tell you fastest.

What's in scope

• Opening a single .mid file and displaying its first track as a falling-keys piano roll.
• Scrubbing the playhead via canvas drag, slider drag, slider trough click, arrow-key tick stepping, and double-click on a note.
• Wheel-zooming the time axis (0.5 s – 60 s viewport), reset to 5 s on each new file load.
• Marking timestamps as named anchors and saving the list as a JSON sidecar bound to the loaded MIDI by absolute path.
• Re-loading a session by opening the saved .json — the visualizer locates the referenced MIDI (or prompts you to relocate it), restores the anchors, and warns if the MIDI's duration has drifted since save.

What's deliberately not in scope

No audio playback

There is no MIDI synthesis, no audio file output, no master clock, no transport (play/pause/stop) buttons. Scrubbing is visual-only. If you need audio, route the .mid through a DAW or a synth (FluidSynth, etc.) — the visualizer is purely an inspection tool.

No MIDI editing

You cannot move, resize, delete, or insert notes. You cannot transpose, change velocities, or edit tempo. The .mid file is opened read-only and never written back. Anchors are the only persistent output, and they go in a separate *.anchors.json file.

No multi-track or multi-instrument view

The visualizer reads pretty_midi.instruments[0] and ignores the rest. Disklavier exports are single-track piano so this is correct for the intended use case, but it does mean a MIDI file with multiple instruments will only show the first one.

No camera, no video, no alignment

The sibling midi_camera_alignment_tool project pairs MIDI with overhead camera video and provides a two-phase alignment workflow (global shift + per-clip anchors). None of that is here. This visualizer's anchors are MIDI-only timestamps with optional labels — they do not encode any external time reference.

No persistence between sessions (besides anchor files)

The app does not remember:

• The last folder you opened from.
• A recent-files list.
• Window geometry or dock position.
• Zoom level or playhead position from a previous run.

Every launch starts at a blank canvas. The only state that survives is the explicit .anchors.json you save.

No multi-anchor selection or bulk operations

The anchor table supports single-row selection only. There is no multi-select, no "delete all", no copy/paste between tables, no import/export beyond the dedicated save/load. Each operation is one row at a time.

No automation, no command-line interface

The app is launched as python -m disklavier_visualizer and that's it. There are no flags, no headless mode, no scripting hooks. If you need to batch-process anchor files, the disklavier_visualizer.io.anchor_io module's load_anchors / save_anchors functions are pure-Python and importable, but the UI itself is not driveable from the command line.

No annotation types beyond timestamped labels

An anchor is (timestamp_seconds: float, label: str). There are no:

• Region anchors (start + end).
• Per-note tags.
• Categories or colours.
• Linked anchors across files.

If a richer annotation model is needed, that is a feature request — open an issue with the use case.

Why this scope

Two reasons:

1. Single-purpose tools are easier to maintain. Every feature listed in "in scope" has a corresponding test in tests/ and a path on the §3 Reference pages. Features outside that perimeter would expand the surface area without clear benefit for the intended workflow.
2. The sibling project already exists. If you need camera-paired alignment, intensity probes, or per-clip workflows, use midi_camera_alignment_tool. This visualizer is the trimmed, MIDI-only subset of that tool.