1#!/usr/bin/python 2 3# Copyright (C) 2012 The Android Open Source Project 4# 5# Licensed under the Apache License, Version 2.0 (the "License"); 6# you may not use this file except in compliance with the License. 7# You may obtain a copy of the License at 8# 9# http://www.apache.org/licenses/LICENSE-2.0 10# 11# Unless required by applicable law or agreed to in writing, software 12# distributed under the License is distributed on an "AS IS" BASIS, 13# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14# See the License for the specific language governing permissions and 15# limitations under the License. 16 17from consts import * 18import numpy as np 19import scipy as sp 20import scipy.fftpack as fft 21import matplotlib.pyplot as plt 22 23# generate random signal with max freq 24# Input: peak amplitude, 25# duration in msec, 26# sampling rate HZ 27# high frequency, 28# Output: generated sound (stereo) 29 30def do_gen_random(peakAmpl, durationInMSec, samplingRate, fHigh, stereo=True): 31 samples = durationInMSec * samplingRate / 1000 32 result = np.zeros(samples * 2 if stereo else samples, dtype=np.int16) 33 randomSignal = np.random.normal(scale = peakAmpl * 2 / 3, size=samples) 34 fftData = fft.rfft(randomSignal) 35 freqSamples = samples/2 36 iHigh = freqSamples * fHigh * 2 / samplingRate + 1 37 #print len(randomSignal), len(fftData), fLow, fHigh, iHigh 38 if iHigh > freqSamples - 1: 39 iHigh = freqSamples - 1 40 fftData[0] = 0 # DC 41 for i in range(iHigh, freqSamples - 1): 42 fftData[ 2 * i + 1 ] = 0 43 fftData[ 2 * i + 2 ] = 0 44 if (samples - 2 *freqSamples) != 0: 45 fftData[samples - 1] = 0 46 47 filteredData = fft.irfft(fftData) 48 #freq = np.linspace(0.0, samplingRate, num=len(fftData), endpoint=False) 49 #plt.plot(freq, abs(fft.fft(filteredData))) 50 #plt.plot(filteredData) 51 #plt.show() 52 if stereo: 53 for i in range(len(filteredData)): 54 result[2 * i] = filteredData[i] 55 result[2 * i + 1] = filteredData[i] 56 else: 57 for i in range(len(filteredData)): 58 result[i] = filteredData[i] 59 return result 60 61 62def gen_random(inputData, inputTypes): 63 output = [] 64 outputData = [] 65 outputTypes = [] 66 # basic sanity check 67 inputError = False 68 if (inputTypes[0] != TYPE_I64): 69 inputError = True 70 if (inputTypes[1] != TYPE_I64): 71 inputError = True 72 if (inputTypes[2] != TYPE_I64): 73 inputError = True 74 if (inputTypes[3] != TYPE_I64): 75 inputError = True 76 if inputError: 77 output.append(RESULT_ERROR) 78 output.append(outputData) 79 output.append(outputTypes) 80 return output 81 82 result = do_gen_random(inputData[0], inputData[1], inputData[2], inputData[3]) 83 84 output.append(RESULT_OK) 85 outputData.append(result) 86 outputTypes.append(TYPE_STEREO) 87 output.append(outputData) 88 output.append(outputTypes) 89 return output 90 91# test code 92if __name__=="__main__": 93 peakAmplitude = 10000 94 samplingRate = 44100 95 durationInMSec = 10000 96 #fLow = 500 97 fHigh = 15000 98 result = do_gen_random(peakAmplitude, durationInMSec, samplingRate, fHigh) 99 plt.plot(result) 100 plt.show() 101