#!/usr/bin/python
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# Copyright (C) 2012 The Android Open Source Project
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from consts import *
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import numpy as np
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import scipy as sp
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import scipy.fftpack as fft
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import matplotlib.pyplot as plt
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# generate random signal with max freq
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# Input: peak amplitude,
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# duration in msec,
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# sampling rate HZ
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# high frequency,
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# Output: generated sound (stereo)
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def do_gen_random(peakAmpl, durationInMSec, samplingRate, fHigh, stereo=True):
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samples = durationInMSec * samplingRate / 1000
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result = np.zeros(samples * 2 if stereo else samples, dtype=np.int16)
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randomSignal = np.random.normal(scale = peakAmpl * 2 / 3, size=samples)
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fftData = fft.rfft(randomSignal)
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freqSamples = samples/2
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iHigh = freqSamples * fHigh * 2 / samplingRate + 1
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#print len(randomSignal), len(fftData), fLow, fHigh, iHigh
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if iHigh > freqSamples - 1:
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iHigh = freqSamples - 1
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fftData[0] = 0 # DC
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for i in range(iHigh, freqSamples - 1):
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fftData[ 2 * i + 1 ] = 0
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fftData[ 2 * i + 2 ] = 0
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if (samples - 2 *freqSamples) != 0:
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fftData[samples - 1] = 0
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filteredData = fft.irfft(fftData)
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#freq = np.linspace(0.0, samplingRate, num=len(fftData), endpoint=False)
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#plt.plot(freq, abs(fft.fft(filteredData)))
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#plt.plot(filteredData)
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#plt.show()
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if stereo:
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for i in range(len(filteredData)):
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result[2 * i] = filteredData[i]
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result[2 * i + 1] = filteredData[i]
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else:
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for i in range(len(filteredData)):
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result[i] = filteredData[i]
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return result
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def gen_random(inputData, inputTypes):
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output = []
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outputData = []
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outputTypes = []
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# basic sanity check
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inputError = False
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if (inputTypes[0] != TYPE_I64):
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inputError = True
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if (inputTypes[1] != TYPE_I64):
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inputError = True
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if (inputTypes[2] != TYPE_I64):
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inputError = True
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if (inputTypes[3] != TYPE_I64):
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inputError = True
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if inputError:
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output.append(RESULT_ERROR)
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output.append(outputData)
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output.append(outputTypes)
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return output
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result = do_gen_random(inputData[0], inputData[1], inputData[2], inputData[3])
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output.append(RESULT_OK)
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outputData.append(result)
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outputTypes.append(TYPE_STEREO)
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output.append(outputData)
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output.append(outputTypes)
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return output
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# test code
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if __name__=="__main__":
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peakAmplitude = 10000
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samplingRate = 44100
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durationInMSec = 10000
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#fLow = 500
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fHigh = 15000
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result = do_gen_random(peakAmplitude, durationInMSec, samplingRate, fHigh)
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plt.plot(result)
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plt.show()
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