80 lines
2.0 KiB
Python
80 lines
2.0 KiB
Python
import math
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import librosa
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import numpy
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import soundfile as sf
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def params(freq, damping, dt):
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w = freq * 2 * math.pi * dt
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d = damping * dt
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e = math.exp(d)
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c1 = 2 * e * math.cos(w)
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c2 = e * e
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t0 = (1 - 2 * e * math.cos(w) + e * e) / (d * d + w * w)
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t = d * d + w * w - math.pi * math.pi
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t1 = (1 + 2 * e * math.cos(w) + e * e) / math.sqrt(t * t + 4 * d * d *
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math.pi * math.pi)
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b2 = (t1 - t0) / (t1 + t0)
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b1 = b2 * dt * dt * (t0 + t1) / 2
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return c1, c2, b1, b2
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def wave(count: int, sample_rate):
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freq = 3875
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dt = 1 / sample_rate
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damping = -1210 # -0.015167
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c1, c2, b1, b2 = params(freq, damping, dt)
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# freq2 = 525
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# damping2 = -130
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#
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# cc1, cc2, bb1, bb2 = params(freq2, damping2, dt)
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# mult2 = 1# 0.11
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y1 = y2 = 0
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x1 = 0
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x2 = 0
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# tm = math.atan(w/d)/w
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# scale = 500 * math.sqrt(d * d+ w * w) * math.exp(-d * tm) / (dt * 2000)
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x1 = 1.0
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th = 23 # sample_rate // 10
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switch = th
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scale = 650 # TODO: analytic expression
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maxy = 0
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for i in range(count):
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# y = (c1 * y1 - c2 * y2 + b1 * x1 + b2 * x2) + mult2 * (
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# 1 - cc1 * y1 + cc2 * y2 - bb1 * x1 - bb2 * x2)
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y = (c1 * y1 - c2 * y2 + b1 * x1 + b2 * x2)
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# print(i, y / scale, x1)
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x2 = x1
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if i >= switch:
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x1 = -x1
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switch += th
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y2 = y1
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y1 = y
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if math.fabs(y) > maxy:
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maxy = math.fabs(y)
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yield y / scale
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print(maxy)
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def main():
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# print(list(wave(1020400)))
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sample_rate = 1015657
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output = numpy.array(list(wave(1015657, sample_rate)), dtype=numpy.float32)
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output_rate = 96000 # int(sample_rate / 4)
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output = librosa.resample(output, orig_sr=sample_rate,
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target_sr=output_rate)
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with sf.SoundFile("out.wav", "w", samplerate=96000, channels=1) as f:
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f.write(output)
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if __name__ == "__main__":
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main()
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