"""
ReSpeaker Python Library
Copyright (c) 2016 Seeed Technology Limited.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
"""
import array
import math
from respeaker.fft import FFT
class SpectrumAnalyzer:
def __init__(self, size, sample_rate=16000, band_number=12, window=[50, 8000]):
self.size = 1 << math.frexp(size - 1)[1]
self.sample_rate = float(sample_rate)
self.resolution = self.sample_rate / self.size # (sample_rate/2) / (band/2)
self.set_band(band_number, window)
self.fft = FFT(self.size)
def set_band(self, n, window=[50, 8000]):
self.band = n
self.breakpoints = [0] * (n + 1)
self.frequencies = [0.0] * (n + 1)
self.strength = [0.0] * n
delta = math.pow(float(window[1]) / window[0], 1.0 / n)
for i in range(n + 1):
self.frequencies[i] = math.pow(delta, i) * window[0]
breakpoint = 0
for i in range(1, self.size / 2):
if self.resolution * i >= self.frequencies[breakpoint]:
self.breakpoints[breakpoint] = i
breakpoint += 1
if breakpoint > n:
break
self.breakpoints[n] = self.size / 2 + 1
self.band_size = [self.breakpoints[i + 1] - self.breakpoints[i] for i in range(n)]
# print self.frequencies
# print self.breakpoints
def analyze(self, data):
amplitude = self.fft.dft(data)
for i in range(self.band):
self.strength[i] = sum(amplitude[self.breakpoints[i]:self.breakpoints[i + 1]]) # / self.band_size[i]
return self.strength
if __name__ == '__main__':
N = 2048
rate = 16000
data = array.array('h', [0] * N)
w = 2 * math.pi * 50 / rate
for t in range(N):
data[t] = int(100 * math.sin(w * t))
analyzer = SpectrumAnalyzer(N, rate)
strength = analyzer.analyze(data.tostring())
print([int(f) for f in analyzer.frequencies])
print([int(s) for s in strength])
