commit e8bfb981cca4d3feb3046eb92502179a51a54854
Author: Mattéo Delabre <spam@delab.re>
Date:   Thu Dec 17 23:08:07 2020 +0100

    Initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..114e85e
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+out.wav
diff --git a/analyze-shorttime.py b/analyze-shorttime.py
new file mode 100644
index 0000000..88493fd
--- /dev/null
+++ b/analyze-shorttime.py
@@ -0,0 +1,34 @@
+import soundbox
+import numpy as np
+import scipy.signal as sig
+import matplotlib
+import matplotlib.pyplot as plt
+
+signal = soundbox.load_signal('out.wav')
+
+freq, time, fts = sig.stft(signal, soundbox.samp_rate, nperseg=soundbox.samp_rate * 0.5)
+
+fig, ax = plt.subplots()
+ax.pcolormesh(
+    time, freq,
+    np.abs(fts),
+    cmap='plasma',
+    shading='gouraud')
+
+
+def freq_format(value, pos):
+    return f'{value:.0f} Hz'
+
+
+def time_format(value, pos):
+    return f'{value:.0f} s'
+
+
+ax.set_xlabel('Temps')
+ax.xaxis.set_major_formatter(matplotlib.ticker.FuncFormatter(time_format))
+
+ax.set_ylabel('Fréquence')
+ax.set_ylim(0, 800)
+ax.yaxis.set_major_formatter(matplotlib.ticker.FuncFormatter(freq_format))
+
+plt.show()
diff --git a/analyze-single.py b/analyze-single.py
new file mode 100644
index 0000000..9635bb2
--- /dev/null
+++ b/analyze-single.py
@@ -0,0 +1,23 @@
+import soundbox
+import numpy as np
+import matplotlib
+import matplotlib.pyplot as plt
+
+signal = soundbox.load_signal('out.wav')
+freqs = np.fft.fft(signal)
+scale = soundbox.samp_rate / len(signal)
+
+fig, ax = plt.subplots()
+ax.plot(np.absolute(freqs))
+
+
+def freq_format(value, pos):
+    return f'{value * scale:.0f} Hz'
+
+
+ax.set_xlabel('Fréquence')
+ax.set_xlim(0 / scale, 800 / scale)
+ax.xaxis.set_major_formatter(matplotlib.ticker.FuncFormatter(freq_format))
+ax.xaxis.set_major_locator(plt.MultipleLocator(100 / scale))
+
+plt.show()
diff --git a/generate.py b/generate.py
new file mode 100644
index 0000000..cdc79b2
--- /dev/null
+++ b/generate.py
@@ -0,0 +1,53 @@
+import soundbox
+
+
+def sine(dur, freq, value=1):
+    return soundbox.envelope(
+        attack=.01, decay=.2, release=.2,
+        signal=soundbox.sine(dur, freq, value))
+
+
+def square(dur, freq, value=1):
+    return soundbox.envelope(
+        attack=.01, decay=.2, release=.2,
+        signal=soundbox.square(dur, freq, value))
+
+
+signal = soundbox.silence(9)
+
+chords_l = (
+    (('do', 2),),
+    (('sol', 2),),
+    (('la', 2),),
+    (('sol', 2),),
+    (('do', 2),),
+    (('sol', 2),),
+    (('la', 2),),
+    (('sol', 2),),
+)
+
+chords_r = (
+    (('do', 3), ('mi', 3), ('sol', 3)),
+    (('sol', 3), ('si', 3), ('re', 4)),
+    (('la', 3), ('do', 4), ('mi', 4)),
+    (('fa', 3), ('la', 3), ('do', 4)),
+)
+
+for shift in (.5, 4.5):
+    for i in range(len(chords_l)):
+        soundbox.add_signal(signal, start=i / 2 + shift,
+            source=soundbox.chord(
+                instr=square, dur=.6,
+                freqs=soundbox.note_freqs(chords_l[i]),
+                value=.05
+            ))
+
+    for i in range(len(chords_r)):
+        soundbox.add_signal(signal, start=i + shift,
+            source=soundbox.chord(
+                instr=sine, dur=1.1,
+                freqs=soundbox.note_freqs(chords_r[i]),
+                value=.6
+            ))
+
+soundbox.save_signal('out.wav', signal)
diff --git a/soundbox.py b/soundbox.py
new file mode 100644
index 0000000..a55f624
--- /dev/null
+++ b/soundbox.py
@@ -0,0 +1,97 @@
+import wave
+import numpy as np
+import scipy.signal as sig
+import math
+
+# Nombre d’octets par échantillon
+samp_width = 2
+
+# Valeur maximale d’un échantillon
+max_val = 2 ** (8 * samp_width - 1) - 1
+
+# Fréquence d’échantillonnage (Hertz)
+samp_rate = 44100
+
+
+def add_signal(dest, start, source):
+    dest[int(samp_rate * start):int(samp_rate * start) + len(source)] += source
+
+
+def silence(dur):
+    return np.zeros((int(samp_rate * dur),))
+
+
+def sine(dur, freq, value=1):
+    x = np.arange(int(samp_rate * dur))
+    return value * max_val * np.sin(2 * np.pi * freq * x / samp_rate)
+
+
+def square(dur, freq, value=1):
+    x = np.arange(int(samp_rate * dur))
+    return value * max_val * sig.square(2 * np.pi * freq * x / samp_rate)
+
+
+def envelope(attack, decay, release, signal):
+    total = len(signal)
+    attack = int(attack * total)
+    decay = int(decay * total)
+    release = int(release * total)
+    sustain = total - attack - decay - release
+
+    return signal * np.concatenate((
+        np.linspace(start=0, stop=1, num=attack, endpoint=False),
+        np.linspace(start=1, stop=2/3, num=decay, endpoint=False),
+        np.linspace(start=2/3, stop=2/3, num=sustain, endpoint=False),
+        np.linspace(start=2/3, stop=0, num=release, endpoint=True),
+    ))
+
+notes = {
+    'do': 0, 'si#': 0,
+    'do#': 1, 'reb': 1,
+    're': 2,
+    're#': 3, 'mib': 3,
+    'mi': 4, 'fab': 4,
+    'fa': 5, 'mi#': 5,
+    'fa#': 6, 'solb': 6,
+    'sol': 7,
+    'sol#': 8, 'lab': 8,
+    'la': 9,
+    'la#': 10, 'sib': 10,
+    'si': 11, 'dob': 11,
+}
+
+
+def note_freq(note, octave):
+    return (440
+        * (2 ** (octave - 3))
+        * math.pow(2, (notes[note] - 9) / 12))
+
+
+def note_freqs(notes):
+    return list(map(lambda info: note_freq(*info), notes))
+
+
+def chord(instr, dur, freqs, value=1):
+    signal = np.zeros((int(samp_rate * dur),))
+
+    for freq in freqs:
+        signal += instr(dur, freq, value / len(freqs))
+
+    return signal
+
+
+def save_signal(out_name, signal):
+    with wave.open(out_name, 'w') as file:
+        file.setnchannels(1)
+        file.setsampwidth(samp_width)
+        file.setframerate(samp_rate)
+        file.writeframesraw(signal.astype('<h').tostring())
+
+
+def load_signal(in_name):
+    with wave.open(in_name, 'r') as file:
+        assert file.getnchannels() == 1
+        assert file.getsampwidth() == samp_width
+        assert file.getframerate() == samp_rate
+        size = file.getnframes()
+        return np.ndarray((size,), '<h', file.readframes(size))