Guitar difficulties

Generate guitar Hard, Medium, and Easy from Expert

This tool automatically adds Hard, Medium, and Easy guitar parts from the Expert track.

  • Runs in your browser. Your chart and audio are never uploaded.
  • No graphics-card requirement: the model uses your graphics card when the browser offers one, and runs on the CPU when it does not.

Above: each tier reduces from the higher difficulty, based on a set of rules.

Start a chart

Drop a .sng, .zip, or chart folder that has an Expert guitar track and its audio files. The generated tiers are a first pass: you review them in the chart editor and decide what ships.

Drop a .sng or .zip file, or select a chart folder.

Drop a chart folder, .zip or .sng here, or click to browse

or

The rules each tier is built on

A trained model predicts what each tier keeps at every moment of your Expert track, from up to 96 measurements of the chart around that moment. A fixed sequence of steps, the same on every run, turns the model’s predictions into notes, sustains, and markings.
Chord shape
Which of the five frets are held at this instant.
Neighbor shapes
The frets held at the note before and the note after.
Note spacing
How long since the previous note and until the next, in beats.
Bar position
Where the moment sits in its bar, and the beat it lands on.
Sustain length
How long each fret’s note is held.
Technique
Whether each note is a strum, a HOPO, or a tap.
Nearby notes
How crowded the chart is within half a beat, a beat, two, and four, on either side.
Section membership
Whether the moment sits inside a Star Power or solo section.

and the rest

  1. Predict each moment’s notesThe model gives probabilities over a fixed menu of shapes the tier can play at that moment: single notes, some two-note chords on Hard and Medium, or nothing. A chord is decided as one whole shape.
  2. Judge repeats togetherShort phrases that repeat with the same notes and rhythm are pooled: each repeat’s prediction is blended a quarter of the way toward the group’s average, which pushes repeats toward the same reduction without guaranteeing it. Medium also blends in a fixed table of common phrases.
  3. Pick the cheapest shapeEach moment then takes the shape with the lowest expected number of edits against the prediction, using a fixed cost table that prices added notes, dropped notes, and fret moves.
  4. Write sustains and markingsFixed rules place the predicted sustains, strum and HOPO markings, and Star Power and solo ranges, then all four difficulties open in the chart editor.

Sustains follow the same split: the model proposes whether a note sustains and for how long, and fixed rules cap the sustain at the next note on that fret. Medium and Easy also keep at least a beat of space before the next note. Hammer-ons and pull-offs survive only on Hard; Medium and Easy are written as all strums, and a Hard hammer-on or pull-off that repeats the previous note’s highest fret is forced to a strum. Taps survive on no tier: a tapped Expert note comes back as a strum or a hammer-on.

Star Power and solo ranges are predicted moment by moment and rebuilt on each tier, so a range can start or end at any note.