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1 //
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2 // FIRFilter.cpp
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3 // Tempogram
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4 //
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5 // Created by Carl Bussey on 25/06/2014.
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6 // Copyright (c) 2014 Carl Bussey. All rights reserved.
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7 //
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8
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9 #include "FIRFilter.h"
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10
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11 using namespace std;
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12 using Vamp::FFT;
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13
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14 FIRFilter::FIRFilter(const unsigned int lengthInput, const unsigned int numberOfCoefficients) :
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15 m_lengthInput(lengthInput),
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16 m_numberOfCoefficients(numberOfCoefficients),
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17 fftInput(0),
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18 fftCoefficients(0),
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19 fftReal1(0),
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20 fftImag1(0),
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21 fftReal2(0),
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22 fftImag2(0),
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23 fftFilteredReal(0),
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24 fftFilteredImag(0),
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25 fftOutputReal(0),
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26 fftOutputImag(0)
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27 {
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28 initialise();
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29 }
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30
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31 FIRFilter::~FIRFilter()
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32 {
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33 cleanup();
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34 }
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35
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36 //allocate memory
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37 void
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38 FIRFilter::initialise()
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39 {
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40 //next power of 2
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41 m_lengthFIRFFT = pow(2,(ceil(log2(m_lengthInput+m_numberOfCoefficients-1))));
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42
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43 fftInput = new double[m_lengthFIRFFT];
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44 fftCoefficients = new double[m_lengthFIRFFT];
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45 fftReal1 = new double[m_lengthFIRFFT];
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46 fftImag1 = new double[m_lengthFIRFFT];
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47 fftReal2 = new double[m_lengthFIRFFT];
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48 fftImag2 = new double[m_lengthFIRFFT];
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49 fftFilteredReal = new double[m_lengthFIRFFT];
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50 fftFilteredImag = new double[m_lengthFIRFFT];
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51 fftOutputReal = new double[m_lengthFIRFFT];
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52 fftOutputImag = new double[m_lengthFIRFFT];
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53
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54 for(int i = 0; i < m_lengthFIRFFT; i++){
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55 fftInput[i] = fftCoefficients[i] = fftReal1[i] = fftImag1[i] = fftReal2[i] = fftImag2[i] = fftFilteredReal[i] = fftFilteredImag[i] = fftOutputReal[i] = fftOutputImag[i] = 0.0;
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56 }
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57 }
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58
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59 void
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60 FIRFilter::process(const float* input, const float* coefficients, float* output)
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61 {
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62 //Copy to same length FFT buffers
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63 for(int i = 0; i < m_lengthFIRFFT; i++){
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64 fftInput[i] = i < m_lengthInput ? input[i] : 0.0;
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65 fftCoefficients[i] = i < m_numberOfCoefficients ? coefficients[i] : 0.0;
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66 }
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67
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68 FFT::forward(m_lengthFIRFFT, fftInput, 0, fftReal1, fftImag1);
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69 FFT::forward(m_lengthFIRFFT, fftCoefficients, 0, fftReal2, fftImag2);
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70
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71 //Multiply FFT coefficients. Multiplication in freq domain is convolution in time domain.
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72 for (int i = 0; i < m_lengthFIRFFT; i++){
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73 fftFilteredReal[i] = (fftReal1[i] * fftReal2[i]) - (fftImag1[i] * fftImag2[i]);
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74 fftFilteredImag[i] = (fftReal1[i] * fftImag2[i]) + (fftReal2[i] * fftImag1[i]);
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75 }
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76 FFT::inverse(m_lengthFIRFFT, fftFilteredReal, fftFilteredImag, fftOutputReal, fftOutputImag);
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77
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78 //copy to output
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79 for (int i = 0; i < m_lengthInput; i++){
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80 output[i] = fftOutputReal[i];
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81 }
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82 }
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83
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84 //remove memory allocations
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85 void
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86 FIRFilter::cleanup()
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87 {
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88 delete []fftInput;
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89 delete []fftCoefficients;
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90 delete []fftReal1;
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91 delete []fftImag1;
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92 delete []fftReal2;
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93 delete []fftImag2;
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94 delete []fftFilteredReal;
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95 delete []fftFilteredImag;
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96 delete []fftOutputReal;
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97 delete []fftOutputImag;
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98 fftInput = fftCoefficients = fftReal1 = fftImag1 = fftReal2 = fftImag2 = fftFilteredReal = fftFilteredImag = fftOutputReal = fftOutputImag = 0;
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99 }
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