# -*- coding: utf-8 -*- """ utilities to convert midi note number to and from note names """ __all__ = ['note2midi', 'midi2note', 'freq2note', 'note2freq'] import sys from ._aubio import freqtomidi, miditofreq 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 = { u'𝄫': -2, # double flat u'♭': -1, 'b': -1, '\u266d': -1, # simple flat u'♮': 0, '\u266e': 0, None: 0, # natural '#': +1, u'♯': +1, '\u266f': +1, # sharp u'𝄪': +2, # double sharp } _valid_octaves = range(-1, 10) if not isinstance(note, str_instances): msg = "a string is required, got {:s} ({:s})" raise TypeError(msg.format(str(type(note)), repr(note))) if len(note) not in range(2, 5): msg = "string of 2 to 4 characters expected, got {:d} ({:s})" raise ValueError(msg.format(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): msg = "an integer between 0 and 127 is excepted, got {:d}" raise ValueError(msg.format(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] " nearest_note = int(freqtomidi(freq) + .5) return midi2note(nearest_note) def note2freq(note): """Convert note name to corresponding frequency, in Hz. Parameters ---------- note : str input note name Returns ------- freq : float [0, 23000[ frequency, in Hz Example ------- >>> aubio.note2freq('A4') 440 >>> aubio.note2freq('A3') 220.1 """ midi = note2midi(note) return miditofreq(midi)