Created
June 8, 2022 07:38
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Turning drawings from SOB into audio
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| from numpy import arange, linspace, where, maximum, sqrt, floor, clip, concatenate | |
| from matplotlib.pyplot import plot, legend, show | |
| import scipy.io.wavfile | |
| # --- Helpers --- | |
| def sqrt0(x): | |
| return sqrt(maximum(0, x)) | |
| def triangle(x): | |
| x = x - floor(x) | |
| return 1 - 4*abs(x - 0.5) | |
| def fold(x): | |
| return triangle(0.25*x + 0.25) | |
| # --- SOB drawings --- | |
| def cups(x, separation=1): | |
| x = x - floor(x) | |
| return where(x < 0.5, | |
| separation - sqrt0(1 - (4*x-1)**2), | |
| sqrt0(1 - (4*x-3)**2) - separation | |
| ) | |
| def clipped_triangle(x, overdrive=2): | |
| return clip(triangle(x + 0.25) * overdrive, -1, 1) | |
| def folded_triangle(x, overdrive=2): | |
| return fold(triangle(x + 0.25) * overdrive) | |
| # --- Plot waveforms --- | |
| phase = linspace(0, 2, 1000) | |
| plot(phase, cups(phase), label="cups") | |
| legend() | |
| show() | |
| plot(phase, clipped_triangle(phase), label="flat peak") | |
| legend() | |
| show() | |
| plot(phase, folded_triangle(phase), label="double peak") | |
| legend() | |
| show() | |
| # --- Render audio --- | |
| SAMPLE_RATE = 44100 | |
| t = arange(SAMPLE_RATE) / SAMPLE_RATE | |
| def chord(waveform): | |
| return 0.4 * (waveform(220 * t) + waveform(275 * t) + waveform(330 * t) + waveform(385 * t)) | |
| data = 0.49 * concatenate([ | |
| cups(220 * t), | |
| clipped_triangle(220 * t), | |
| folded_triangle(220 * t), | |
| 0*t, | |
| chord(cups), | |
| chord(clipped_triangle), | |
| chord(folded_triangle) | |
| ]) | |
| scipy.io.wavfile.write("/tmp/sob.wav", SAMPLE_RATE, (data * 2**15).astype("int16")) |
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