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67 lines
1.5 KiB
Python
67 lines
1.5 KiB
Python
15 years ago
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############################################################
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#
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# karplus.py
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#
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# Author: MV (http://electro-nut.blogspot.com/)
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#
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# Generates a plucked string sound WAV file using the
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# Karplus-Strong algorithm.
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#
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############################################################
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from math import sin, pi
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from array import array
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from random import random
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import wave
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# KS params
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SR = 44100
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f = 220
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# WAV params
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NCHANNELS = 1
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SWIDTH = 2
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FRAME_RATE = 44100
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NFRAMES = 44100
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NSAMPLES = 44100*2
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# max - 128 for 8-bit, 32767 for 16-bit
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MAX_VAL= 32767
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class String:
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def __init__(self, freq, SR):
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self.freq = freq
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self.N = SR/freq
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# 'pluck' string
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def pluck(self):
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self.buf = [random() - 0.5 for i in range(self.N)]
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# return current sample, increment step
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def sample(self):
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val = self.buf[0]
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avg = 0.996*0.5*(self.buf[0] + self.buf[1])
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self.buf.append(avg)
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self.buf.pop(0)
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return val
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str1, str2 = String(196, SR), String(440, SR)
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str1.pluck()
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str2.pluck()
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samples = []
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for i in range(NSAMPLES):
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sample = str1.sample()
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if(i > NSAMPLES/8):
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sample += str2.sample()
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samples.append(sample)
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# samples to 16-bit to string
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tmpBuf = [int(x*MAX_VAL) for x in samples]
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data = array('h', tmpBuf).tostring()
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# write out WAV file
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file = wave.open('karplus.wav', 'wb')
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file.setparams((NCHANNELS, SWIDTH, FRAME_RATE, NFRAMES,
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'NONE', 'noncompressed'))
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file.writeframes(data)
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file.close()
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