Source code for quasimoto.sampler.notes

"""
A module implementing an interface to musical notes.
"""

# third-party
from runtimepy.enum.registry import RuntimeIntEnum

DIVISIONS = 12
TWELVE_TONE_EQUAL: float = 2 ** (1 / DIVISIONS)

ROOT_FREQUENCY = 8.175799




def note_by_index(index: int) -> float:
    """
    Get the frequency of a note based on its index from the root (lowest)
    frequency.
    """
    assert index >= 0
    return TWELVE_TONE_EQUAL**index * ROOT_FREQUENCY



# Start 5 octaves above the root note by default (middle C).
OCTAVE_BASE = 5




class Note(RuntimeIntEnum):
    """An enumeration interface for notes."""

    C = 0

    CS = 1
    DB = 1

    D = 2

    DS = 3
    EB = 3

    E = 4
    F = 5

    FS = 6
    GB = 6

    G = 7

    GS = 8
    AB = 8

    A = 9

    AS = 10
    BB = 10

    B = 11



    def frequency(self, octave_offset: int = 0) -> float:
        """Get the frequency of a note."""
        return note_by_index(DIVISIONS * (octave_offset + OCTAVE_BASE) + self)




    @staticmethod
    def from_index(index: int) -> tuple["Note", int]:
        """Get a note from a specified index."""
        return Note(index % DIVISIONS), (index // 12) - OCTAVE_BASE




DEFAULT_FREQUENCY: float = Note.C.frequency()