Schema

This page gives a top-down view of how a memon file is structured

Root

{
    "version": "x.y.z",
    "metadata": {},
    "data": {}
}

This is the root / top level structure of a memon file.

It’s a json object with the following keys :

  • version

    • string, required

    • Indicates the schema version this memon file uses, follows semver. If a memon file does not have this key it’s probably following the pre-semver format

  • metadata

  • data

Metadata

{
    "song title": "",
    "artist": "",
    "music path": "",
    "album cover path": "",
    "BPM": 120.0,
    "offset": 0.0,
    "preview": {},
    "preview path": "",
}

Contains information that applies to the whole set of charts

  • song title

    • string, required

  • artist

    • string, required

  • music path

    • string, optional

    • Path to the music file, relative to the memon file.

  • album cover path

    • string, optional

    • Relative path to the jacket / album cover / album art to be shown in music select for example. usually a square image

  • BPM

    • number, required

    • Song tempo in Beats per Minute.

  • offset

    • number, required

    • In seconds, opposite of the time position of the first beat in the music file. For instance, if the first beat occurs at 0.15 seconds in the audio file, offset̀ should be -0.15

  • preview

  • preview path

    • string, optional

    • Path to a preview file to be played on loop at the music select screen. Alternative to the music sample described by preview.

Preview

{
    "position": 0.0,
    "length": 0.0,
}

Describes the part of the music file that’s meant to be played on loop when previewing this song at the music select screen

  • position

    • number, required

    • In seconds, start of the loop

  • length

    • number, required

    • In seconds, duration of the loop

Data

{
    "BSC": {},
    "ADV": {},
    "...": {},
    "My cool chart": {}
}

The data object maps difficulty names to chart objects.

Keys in this object are not fixed, they can be any string.

By convention, "BSC", "ADV" and "EXT" are to be understood as the usual 3 levels found in jubeat. Other values are “edits” or bonus charts.

When sorting, difficulties may be presented in that order :

BSC ➔ ADV ➔ EXT ➔ (everything else in alphabetical order)

Chart

{
    "level": 10.3,
    "resolution": 240,
    "notes" : []
}

  • level

    • number, required

    • Chart level, can be an integer or a decimal value

  • resolution

    • number, required

    • Greater than 0, always an integer

    • Number of ticks in a beat, denominator of all beat fractions. Usually 240

  • notes

Tap Note

{
    "n": 0,
    "t": 3600,
}

A classic note

  • n

    • number, required

    • Integer between 0 and 15 inclusive

    • The note position, given this way :

      0  1  2  3
4  5  6  7
8  9 10 11
12 13 14 15

  • t

    • number, required

    • Integer greater or equal to 0

    • Note timing in ticks.

    It can be seen as the numerator of the beat fraction.

    A tick is a fraction of the beat, its duration is defined as 1/ the chart’s resolution. For example if the resolution is 240, a tick lasts for 1/240th of a beat.

    For more info about measuring time in ticks ticks, see bmson’s docs (their docs refers to ticks as pulses).

Long Note

{
    "n": 0,
    "t": 3600,
    "l": 10000,
    "p": 5
}

A classic long note, with a tail

n and t are the same as in a tap note

  • l

    • number, required

    • Integer greater than 0

    • Long note duration (“l” as in length ?!), in ticks

  • p

    • number, required

    • Integer between 0 and 11 inclusive

    • Tail starting position, relative to note position, counting from 0 to 11, spiraling out, clockwise, starting one square above the note

      Here the possible values have been laid out visually, "■" marks the note :

             8
       4
       0
11 7 3 ■ 1 5 9
       2
       6
      10

      For example, "p": 7 produces the following long note :

      ▷—■

      and "p": 10 gives :

      ■
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