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72 lines
2.0 KiB
Python
72 lines
2.0 KiB
Python
import numpy as np
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class Interpolator(object):
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def __init__(self, resolution=10000, width=128):
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self.width = width
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self.resolution = resolution
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self.N = resolution * width
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u = np.arange(-self.N, self.N, dtype=float)
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window = (1 + np.cos(0.5 * np.pi * u / self.N)) / 2.0
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h = np.sinc(u / resolution) * window
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self.filt = []
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for index in range(resolution): # split into multiphase filters
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filt = h[index::resolution]
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filt = filt[::-1]
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self.filt.append(filt)
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lengths = map(len, self.filt)
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assert set(lengths) == set([2*width])
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assert len(self.filt) == resolution
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def get(self, offset):
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# offset = k + (j / self.resolution)
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k = int(offset)
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j = int((offset - k) * self.resolution)
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coeffs = self.filt[j]
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return coeffs, k - self.width
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class Sampler(object):
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def __init__(self, src, interp):
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self.src = iter(src)
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self.freq = 1.0
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self.interp = interp
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coeffs, begin = self.interp.get(0)
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self.offset = -begin # should fill samples buffer
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self.buff = np.zeros(len(coeffs))
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self.index = 0
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def __iter__(self):
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return self
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def correct(self, offset=0):
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assert self.freq + offset > 0
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self.offset += offset
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def next(self):
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res = self._sample()
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self.offset += self.freq
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return res
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def _sample(self):
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coeffs, begin = self.interp.get(self.offset)
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end = begin + len(coeffs)
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while True:
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if self.index == end:
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return np.dot(coeffs, self.buff)
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self.buff[:-1] = self.buff[1:]
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self.buff[-1] = self.src.next() # throws StopIteration
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self.index += 1
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if __name__ == '__main__':
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import common
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import sys
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df, = sys.argv[1:]
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df = float(df)
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_, x = common.load(sys.stdin)
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sampler = Sampler(x, Interpolator())
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sampler.freq += df
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y = np.array(list(sampler), )
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sys.stdout.write( common.dumps(y*1j) )
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