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1 //
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2 // Spectrogram.cpp
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3 // Tempogram
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4 //
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5 // Created by Carl Bussey on 07/08/2014.
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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 "Spectrogram.h"
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10 using namespace std;
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11 using Vamp::FFT;
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12
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13 SpectrogramProcessor::SpectrogramProcessor(unsigned int inputLength, unsigned int windowLength, unsigned int fftLength, unsigned int hopSize) :
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14 m_inputLength(inputLength),
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15 m_windowLength(windowLength),
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16 m_fftLength(fftLength),
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17 m_hopSize(hopSize),
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18 m_numberOfOutputBins(ceil(fftLength/2) + 1),
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19 fftInput(0),
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20 fftOutputReal(0),
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21 fftOutputImag(0)
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22 {
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23 initialise();
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24 }
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25
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26 SpectrogramProcessor::~SpectrogramProcessor(){
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27 cleanup();
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28 }
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29
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30 void SpectrogramProcessor::initialise(){
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31 fftInput = new double [m_fftLength];
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32 fftOutputReal = new double [m_fftLength];
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33 fftOutputImag = new double [m_fftLength];
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34
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35 int numberOfBlocks = ceil(m_inputLength/m_hopSize) + 2*(ceil(m_windowLength/m_hopSize)-1); //The last term corresponds to overlaps at the beginning and end with padded zeros. I.e., if m_hopSize = m_windowLength/2, there'll be 1 overlap at each end. If m_hopSize = m_windowLength/4, there'll be 3 overlaps at each end, etc...
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36 spectrogramOutput = vector< vector<float> >(m_numberOfOutputBins, vector<float>(numberOfBlocks));
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37 }
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38
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39 void SpectrogramProcessor::cleanup(){
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40 delete []fftInput;
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41 delete []fftOutputReal;
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42 delete []fftOutputImag;
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43
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44 fftInput = fftOutputReal = fftOutputImag = 0;
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45 }
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46
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47 //process method
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48 vector< vector<float> > SpectrogramProcessor::process(const float * const input, const float * window){
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49
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50 int readPointerBeginIndex = m_hopSize-m_windowLength;
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51 int writeBlockPointer = 0;
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52
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53 while(readPointerBeginIndex < m_inputLength){
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54
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55 int readPointer = readPointerBeginIndex;
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56 for (int n = 0; n < m_windowLength; n++){
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57 if(readPointer < 0 || readPointer >= m_inputLength){
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58 fftInput[n] = 0.0; //pad with zeros
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59 }
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60 else{
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61 fftInput[n] = input[readPointer] * window[n];
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62 }
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63 readPointer++;
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64 }
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65 for (int n = m_windowLength; n < m_fftLength; n++){
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66 fftInput[n] = 0.0;
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67 }
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68
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69 FFT::forward(m_fftLength, fftInput, 0, fftOutputReal, fftOutputImag);
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70
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71 //@todo: sample at logarithmic spacing? Leave for host?
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72 for(int k = 0; k < m_numberOfOutputBins; k++){
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73 spectrogramOutput[k][writeBlockPointer] = (fftOutputReal[k]*fftOutputReal[k] + fftOutputImag[k]*fftOutputImag[k]); //Magnitude or power?
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74 }
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75
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76 readPointerBeginIndex += m_hopSize;
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77 writeBlockPointer++;
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78 }
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79
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80 return spectrogramOutput;
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81 }
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