chorder 0.1.2

December 4, 2020 ยท View on GitHub

Installation

chorder is a chord detection and reharmonize tool for .mid files. You can download chorder using pip:

pip install chorder

To check if chorder is successfully installed, type python in the terminal, and do the following:

>>> from chorder import Chord
>>> Chord()
Chord(root_pc=None, quality=None, bass_pc=None)

Documentation

Chord

The Chord class is the basic building block for the whole chorder package. A Chord instance has four attributes, including:

  • root_pc
    • the pitch class of a chord's root note
    • is an integer ranging from 0 to 11
  • quality, the quality of a chord (the complete list of quality)
    • the quality of a chord
    • is a string
    • the complete list of qualities covered in chorder can be found at Chord.standard_qualities
  • bass_pc
    • the pitch class of a chord's bass note
    • is an integer ranging from 0 to 11
  • scale
    • the scale of the chord
    • is a list of strings representing the note names of each pitch class from 0 to 11
    • if a scale is not specified, a default scale is used, which is in Chord.default_scale

Chord.__init__(self, args=None, scale=None)

Parameters
  • args: None or str or tuple, optional
    • None: implies constructing an empty chord
    • str: a chord symbol, such as 'Bbmaj7'
    • tuple: a tuple consisting of `(root_pc, quality, bass_pc)
  • scale: list, optional
    • specify the scale the chord uses
    • will use Chord.default_scale if left as None

Chord.root(self)

Returns the root note name of a chord based on the chord's scale.

Chord.bass(self)

Returns the bass note name of a chord based on the chord's scale.

Chord.bass(self)

Returns if any attributes of a chord is None. This can help filtering empty chords.

Chord.transpose(self, key)

Transposes a chord to C-based relative chord. For example, Chord('Bb7').transpose(3) should return Chord('G7').

Parameters
  • key: int
    • the pitch class of the key
    • ranges from 0 to 11

DeChorder

DeChorder is a class that consists of static methods related to chord recognition. To utilize this class, the midi information has to be in the form of miditoolkit objects.

Dechorder.get_bass_pc(notes, start=0, end=1e7)

Returns the pitch class of bass note among the notes between the time range of start and end.

Parameters
  • notes: list
    • the group of notes
    • notes are in the form of miditoolkit.midi.containers.Note
  • start: int
    • the start tick of the notes to be considered
    • set it to notes[0].start for now, as this feature will later be updated
  • end: int
    • the end tick of the notes to be considered
    • set it to notes[-1].end for now, as this feature will later be updated

Dechorder.get_chord_quality(notes, start=0, end=1e7, consider_bass=False)

Returns the chord among the notes between the time range of start and end.

Parameters
  • notes: list
    • the group of notes
    • notes are in the form of miditoolkit.midi.containers.Note
  • start: int
    • the start tick of the notes to be considered
    • set it to notes[0].start for now, as this feature will later be updated
  • end: int
    • the end tick of the notes to be considered
    • set it to notes[-1].end for now, as this feature will later be updated
  • consider_bass: `bool
    • decreases the likelihood of chords with non-chord tones as bass to be chosen as the answer

Dechorder.dechord(midi_obj, scale=None)

Returns a list of chords by beat.

Parameters
  • midi_obj: miditoolkit.midi.parser.MidiFile
    • the midi object to extract chord symbols from
  • scale: list
    • the list of note names for each pitch class
    • must be a list of strings