Merge pull request #5 from yuma-m/feature/scale

Support scale expression to generate chord

Author: yuma-m

.travis.yml

@@ -5,6 +5,8 @@ python:
   - "3.4"
   - "3.5"
   - "3.6"
+  - "3.7"
+  - "3.8"
 
 before_install:
   - sudo apt-get -qq update
@@ -15,6 +17,7 @@ install:
   - pip install .
 
 script:
+  - pip install parameterized
   - python setup.py test
 
 deploy:

CHANGELOG.md

@@ -1,3 +1,7 @@
+## TBD
+
+- Support scale expression to generate chord
+
 ## 0.1.5
 
 - Support triangle wave.

README.md

@@ -44,7 +44,11 @@ $ pip install pyaudio
 
 ```python
 # Play C major
->>> chord = [261.626,  329.628, 391.996]
+>>> chord = ["C3", "E3", "G3"]
+>>> player.play_wave(synthesizer.generate_chord(chord, 3.0))
+
+# You can also specify frequencies to play just intonation
+>>> chord = [440.0, 550.0, 660.0]
 >>> player.play_wave(synthesizer.generate_chord(chord, 3.0))
 ```
 
@@ -64,7 +68,7 @@ $ pip install pyaudio
 >>> from synthesizer import Writer
 >>> writer = Writer()
 
->>> chord = [261.626,  329.628, 391.996]
+>>> chord = ["C4", "E4", "G4"]
 >>> wave = synthesizer.generate_chord(chord, 3.0)
 >>> writer.write_wave("path/to/your.wav", wave)
 ```

example/play_chord.py

@@ -6,45 +6,42 @@
 from synthesizer import Player, Synthesizer, Waveform
 
 
-BASE = 261.626  # C4
-
-
 def main():
     player = Player()
     player.open_stream()
 
     print("play major chord")
     synthesizer = Synthesizer(osc1_waveform=Waveform.sine, osc1_volume=1.0, use_osc2=False)
-    chord = [BASE,  BASE * 2.0 ** (4 / 12.0), BASE * 2.0 ** (7 / 12.0)]
+    chord = ["C4", "E4", "G4"]
     player.play_wave(synthesizer.generate_chord(chord, 3.0))
     time.sleep(0.5)
 
     print("play minor chord")
-    chord = [BASE,  BASE * 2.0 ** (3 / 12.0), BASE * 2.0 ** (7 / 12.0)]
+    chord = ["C4", "Eb4", "G4"]
     player.play_wave(synthesizer.generate_chord(chord, 3.0))
     time.sleep(0.5)
 
     print("play sus4 chord")
-    chord = [BASE,  BASE * 2.0 ** (5 / 12.0), BASE * 2.0 ** (7 / 12.0)]
+    chord = ["C4", "F4", "G4"]
     player.play_wave(synthesizer.generate_chord(chord, 3.0))
     time.sleep(0.5)
 
     print("play 7th chord")
-    chord = [BASE,  BASE * 2.0 ** (4 / 12.0), BASE * 2.0 ** (7 / 12.0), BASE * 2.0 ** (10 / 12.0)]
+    chord = ["C4", "E4", "G4", "Bb4"]
     player.play_wave(synthesizer.generate_chord(chord, 3.0))
     time.sleep(0.5)
 
     print("play add9 chord")
-    chord = [BASE,  BASE * 2.0 ** (4 / 12.0), BASE * 2.0 ** (7 / 12.0), BASE * 2.0 ** (14 / 12.0)]
+    chord = ["C4", "E4", "G4", "D5"]
     player.play_wave(synthesizer.generate_chord(chord, 3.0))
     time.sleep(0.5)
 
     print("play chord sequence")
-    chord = [BASE * 2.0 ** (2 / 12.0),  BASE * 2.0 ** (5 / 12.0), BASE * 2.0 ** (9 / 12.0), BASE * 2.0 ** (12 / 12.0)]
+    chord = ["D4", "F4", "A4", "C5"]
     player.play_wave(synthesizer.generate_chord(chord, 1.0))
-    chord = [BASE * 2.0 ** (2 / 12.0),  BASE * 2.0 ** (7 / 12.0), BASE * 2.0 ** (11 / 12.0)]
+    chord = ["D4", "G4", "B4"]
     player.play_wave(synthesizer.generate_chord(chord, 1.0))
-    chord = [BASE,  BASE * 2.0 ** (4 / 12.0), BASE * 2.0 ** (7 / 12.0), BASE * 2.0 ** (12 / 12.0)]
+    chord = ["E4", "G4", "C5"]
     player.play_wave(synthesizer.generate_chord(chord, 1.0))
 
 

requirements.txt

@@ -1,4 +1,4 @@
-enum34==1.1.6
-numpy==1.13.3
-PyAudio==0.2.11
-scipy==0.19.1
+enum34>=1.1.6
+numpy>=1.13.3
+PyAudio>=0.2.11
+scipy>=0.19.1

synthesizer/frequency.py

@@ -0,0 +1,35 @@
+A1_FREQ = 55.0
+
+BASE_FREQUENCY = {
+    "C": A1_FREQ * 2 ** (-9 / 12.0),
+    "C#": A1_FREQ * 2 ** (-8 / 12.0),
+    "Db": A1_FREQ * 2 ** (-8 / 12.0),
+    "D": A1_FREQ * 2 ** (-7 / 12.0),
+    "D#": A1_FREQ * 2 ** (-6 / 12.0),
+    "Eb": A1_FREQ * 2 ** (-6 / 12.0),
+    "E": A1_FREQ * 2 ** (-5 / 12.0),
+    "F": A1_FREQ * 2 ** (-4 / 12.0),
+    "F#": A1_FREQ * 2 ** (-3 / 12.0),
+    "Gb": A1_FREQ * 2 ** (-3 / 12.0),
+    "G": A1_FREQ * 2 ** (-2 / 12.0),
+    "G#": A1_FREQ * 2 ** (-1 / 12.0),
+    "Ab": A1_FREQ * 2 ** (-1 / 12.0),
+    "A": A1_FREQ,
+    "A#": A1_FREQ * 2 ** (1 / 12.0),
+    "Bb": A1_FREQ * 2 ** (1 / 12.0),
+    "B": A1_FREQ * 2 ** (2 / 12.0),
+}
+
+
+def frequency_from_scale(scale):
+    """ Calculate frequency from pitch
+
+    :param str scale: e.g. C4, Ab3, D#5
+    :rtype: float
+    :return: Frequency of pitch
+    """
+    base, octave = scale[:-1], scale[-1]
+    octave = int(octave)
+    if base not in BASE_FREQUENCY:
+        return ValueError("Unknown note: {}".format(base))
+    return BASE_FREQUENCY[base] * 2 ** (octave - 1)

synthesizer/synthesizer.py

@@ -4,6 +4,8 @@
 import scipy.signal
 from enum import Enum
 
+from .frequency import frequency_from_scale
+
 
 class Waveform(Enum):
     sine = "sine"
@@ -89,18 +91,20 @@ def _generate_wave(self, phases):
     def generate_constant_wave(self, frequency, length):
         u""" generate wave with constant frequency
 
-        :param float frequency: frequency of wave
+        :param (float|str) frequency: frequency or scale of wave
         :param float length: length of wave (seconds)
         :rtype: numpy.array
         :return: normalized wave
         """
+        if isinstance(frequency, str):
+            frequency = frequency_from_scale(frequency)
         phases = np.cumsum(2.0 * np.pi * frequency / self._rate * np.ones(int(self._rate * float(length))))
         return self._generate_wave(phases)
 
     def generate_chord(self, freqs, length):
         u""" generate wave consists of multiple frequencies
 
-        :param list[float] freqs: list of frequencies
+        :param list[float] freqs: list of frequencies or scales
         :param length: legnth of wave (seconds)
         :rtype: numpy.array
         :return: normalized wave

test/test_frequency.py

@@ -0,0 +1,33 @@
+# -*- coding: utf-8 -*-
+
+from nose.tools import assert_almost_equal
+from parameterized import parameterized
+
+from synthesizer.frequency import frequency_from_scale
+
+
+@parameterized([
+    ("A0", 27.5),
+    ("A#0", 29.135),
+    ("Bb0", 29.135),
+    ("B0", 30.868),
+    ("C1", 32.703),
+    ("C#1", 34.648),
+    ("Db1", 34.648),
+    ("D1", 36.708),
+    ("D#1", 38.891),
+    ("Eb1", 38.891),
+    ("E1", 41.203),
+    ("F1", 43.654),
+    ("F#1", 46.249),
+    ("Gb1", 46.249),
+    ("G1", 48.999),
+    ("G#1", 51.913),
+    ("Ab1", 51.913),
+    ("A1", 55),
+    ("C3", 130.813),
+    ("A4", 440),
+    ("E5", 659.255),
+])
+def test_frequency_from_scale(scale, frequency):
+    assert_almost_equal(frequency_from_scale(scale), frequency, places=3)