92 lines
2.3 KiB
Python
92 lines
2.3 KiB
Python
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import wave
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import numpy as np
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import math
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# Nombre d’octets par échantillon
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samp_width = 2
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# Valeur maximale d’un échantillon
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max_val = 2 ** (8 * samp_width - 1) - 1
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# Fréquence d’échantillonnage (Hertz)
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samp_rate = 44100
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def add_signal(dest, start, source):
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dest[int(samp_rate * start):int(samp_rate * start) + len(source)] += source
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def silence(dur):
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return np.zeros((int(samp_rate * dur),))
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def sine(dur, freq, value=1):
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x = np.arange(int(samp_rate * dur))
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return value * max_val * np.sin(2 * np.pi * freq * x / samp_rate)
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def envelope(attack, decay, release, signal):
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total = len(signal)
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attack = int(attack * total)
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decay = int(decay * total)
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release = int(release * total)
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sustain = total - attack - decay - release
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return signal * np.concatenate((
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np.linspace(start=0, stop=1, num=attack, endpoint=False),
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np.linspace(start=1, stop=2/3, num=decay, endpoint=False),
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np.linspace(start=2/3, stop=2/3, num=sustain, endpoint=False),
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np.linspace(start=2/3, stop=0, num=release, endpoint=True),
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))
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notes = {
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'do': 0, 'si#': 0,
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'do#': 1, 'reb': 1,
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're': 2,
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're#': 3, 'mib': 3,
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'mi': 4, 'fab': 4,
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'fa': 5, 'mi#': 5,
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'fa#': 6, 'solb': 6,
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'sol': 7,
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'sol#': 8, 'lab': 8,
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'la': 9,
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'la#': 10, 'sib': 10,
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'si': 11, 'dob': 11,
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}
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def note_freq(note, octave):
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return (440
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* (2 ** (octave - 3))
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* math.pow(2, (notes[note] - 9) / 12))
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def note_freqs(notes):
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return list(map(lambda info: note_freq(*info), notes))
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def chord(instr, dur, freqs, value=1):
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signal = np.zeros((int(samp_rate * dur),))
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for freq in freqs:
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signal += instr(dur, freq, value / len(freqs))
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return signal
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def save_signal(out_name, signal):
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with wave.open(out_name, 'w') as file:
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file.setnchannels(1)
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file.setsampwidth(samp_width)
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file.setframerate(samp_rate)
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file.writeframesraw(signal.astype('<h').tostring())
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def load_signal(in_name):
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with wave.open(in_name, 'r') as file:
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assert file.getnchannels() == 1
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assert file.getsampwidth() == samp_width
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assert file.getframerate() == samp_rate
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size = file.getnframes()
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return np.ndarray((size,), '<h', file.readframes(size))
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