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# -*- coding: utf-8 -*-
""" utilities to convert midi note number to and from note names """
__all__ = ['note2midi', 'midi2note', 'freq2note']
import sys
py3 = sys.version_info[0] == 3
if py3:
str_instances = str
int_instances = int
else:
str_instances = (str, unicode)
int_instances = (int, long)
def note2midi(note):
" convert note name to midi note number, e.g. [C-1, G9] -> [0, 127] "
_valid_notenames = {'C': 0, 'D': 2, 'E': 4, 'F': 5, 'G': 7, 'A': 9, 'B': 11}
_valid_modifiers = {None: 0, u'♮': 0, '#': +1, u'♯': +1, u'\udd2a': +2,
'b': -1, u'♭': -1, u'\ufffd': -2}
_valid_octaves = range(-1, 10)
if not isinstance(note, str_instances):
raise TypeError("a string is required, got %s (%s)" % (note, str(type(note))))
if len(note) not in range(2, 5):
raise ValueError("string of 2 to 4 characters expected, got %d (%s)" \
% (len(note), note))
notename, modifier, octave = [None]*3
if len(note) == 4:
notename, modifier, octave_sign, octave = note
octave = octave_sign + octave
elif len(note) == 3:
notename, modifier, octave = note
if modifier == '-':
octave = modifier + octave
modifier = None
else:
notename, octave = note
notename = notename.upper()
octave = int(octave)
if notename not in _valid_notenames:
raise ValueError("%s is not a valid note name" % notename)
if modifier not in _valid_modifiers:
raise ValueError("%s is not a valid modifier" % modifier)
if octave not in _valid_octaves:
raise ValueError("%s is not a valid octave" % octave)
midi = 12 + octave * 12 + _valid_notenames[notename] + _valid_modifiers[modifier]
if midi > 127:
raise ValueError("%s is outside of the range C-2 to G8" % note)
return midi
def midi2note(midi):
" convert midi note number to note name, e.g. [0, 127] -> [C-1, G9] "
if not isinstance(midi, int_instances):
raise TypeError("an integer is required, got %s" % midi)
if midi not in range(0, 128):
raise ValueError("an integer between 0 and 127 is excepted, got %d" % midi)
_valid_notenames = ['C', 'C#', 'D', 'D#', 'E', 'F', 'F#', 'G', 'G#', 'A', 'A#', 'B']
return _valid_notenames[midi % 12] + str(int(midi / 12) - 1)
def freq2note(freq):
" convert frequency in Hz to nearest note name, e.g. [0, 22050.] -> [C-1, G9] "
from aubio import freqtomidi
return midi2note(int(freqtomidi(freq)))
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