MIDI Analyzer
How to Analyse a MIDI File: Key, Tempo, Tracks and Notes
7 min read·
Downloaded MIDI files are often a black box. Which track is the melody? Is that a real tempo change or a badly quantised import? What key is it in, and does it modulate? Analysing the file before you open it in a DAW saves a lot of guessing.
What lives inside a MIDI file
A Standard MIDI File is a container of timed events grouped into tracks. Each track carries note events with pitch, velocity and duration, plus meta events such as track name, instrument program change, tempo, time signature and key signature.
- Tracks: the separate parts, usually one instrument each
- Channels: 1–16, with channel 10 reserved for percussion
- Notes: pitch, velocity, start time and duration
- Tempo map: one or many BPM markers across the timeline
- Control changes: sustain pedal, modulation, expression
How automatic key detection works
The standard approach is the Krumhansl-Schmuckler algorithm. It builds a twelve-element histogram of how much total time each pitch class sounds for, then correlates that profile against reference profiles for all 24 major and minor keys. The best-correlating key wins.
It is reliable on tonal music and less certain on chromatic, modal or heavily percussive material — which is why a good analyser reports confidence rather than presenting one answer as fact.
Reading a tempo analysis
A single tempo marker means a fixed grid, which is ideal for programming. Dozens of markers usually mean the file was captured from a live performance and keeps its rubato, which sounds human but is harder to edit against a click.
If you plan to add quantised drums or loops, a file with a dense tempo map should be flattened to one BPM first.
The KeyVerse MIDI Analyzer
Drag any .mid file in and KeyVerse reports the track breakdown, per-track note counts and pitch ranges, the full tempo map, time signature, detected key with confidence, and a visual timeline showing where each track plays. You can export the whole report as a PDF for your notes or students. Each analysis costs 20 coins.
Frequently asked questions
- How accurate is MIDI key detection?
- Very accurate for clearly tonal music. Modal, chromatic or atonal files may return a lower-confidence result, which the report shows explicitly.
- Can I see how many notes are in a MIDI file?
- Yes — the analyser reports total notes and a per-track breakdown, along with pitch ranges and durations.
- Can I export the analysis?
- Yes. The analyser generates a downloadable PDF report containing every section of the analysis.