c@7: //
c@7: //  Spectrogram.cpp
c@7: //  Tempogram
c@7: //
c@7: //  Created by Carl Bussey on 07/08/2014.
c@7: //  Copyright (c) 2014 Carl Bussey. All rights reserved.
c@7: //
c@7: 
c@7: #include "Spectrogram.h"
c@7: using namespace std;
c@7: using Vamp::FFT;
c@7: 
c@9: Spectrogram::Spectrogram(unsigned int inputLength, unsigned int windowLength, unsigned int fftLength, unsigned int hopSize) :
c@7:     m_inputLength(inputLength),
c@9:     m_windowLength(windowLength),
c@7:     m_fftLength(fftLength),
c@7:     m_hopSize(hopSize),
c@8:     m_numberOfOutputBins(ceil(fftLength/2) + 1),
c@7:     fftInput(NULL),
c@7:     fftOutputReal(NULL),
c@7:     fftOutputImag(NULL)
c@7: {
c@7:     initialise();
c@7: }
c@7: 
c@7: Spectrogram::~Spectrogram(){
c@7:     cleanup();
c@7: }
c@7: 
c@7: void Spectrogram::initialise(){
c@7:     fftInput = new double [m_fftLength];
c@7:     fftOutputReal = new double [m_fftLength];
c@7:     fftOutputImag = new double [m_fftLength];
c@7:     
c@9:     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...
c@7:     spectrogramOutput = vector< vector<float> >(m_numberOfOutputBins, vector<float>(numberOfBlocks));
c@7: }
c@7: 
c@7: void Spectrogram::cleanup(){
c@7:     delete []fftInput;
c@7:     delete []fftOutputReal;
c@7:     delete []fftOutputImag;
c@7:     
c@7:     fftInput = fftOutputReal = fftOutputImag = NULL;
c@7: }
c@7: 
c@9: //process method
c@7: vector< vector<float> > Spectrogram::audioToMagnitudeSpectrogram(const float * const input, const float * window){
c@7:     
c@9:     int readPointerBeginIndex = m_hopSize-m_windowLength;
c@7:     int writeBlockPointer = 0;
c@7:     
c@7:     while(readPointerBeginIndex < m_inputLength){
c@7:         
c@7:         int readPointer = readPointerBeginIndex;
c@9:         for (int n = 0; n < m_windowLength; n++){
c@7:             if(readPointer < 0 || readPointer >= m_inputLength){
c@7:                 fftInput[n] = 0.0; //pad with zeros
c@7:             }
c@7:             else{
c@7:                 fftInput[n] = input[readPointer] * window[n];
c@7:             }
c@7:             readPointer++;
c@7:         }
c@9:         for (int n = m_windowLength; n < m_fftLength; n++){
c@9:             fftInput[n] = 0.0;
c@9:         }
c@7:         
c@7:         FFT::forward(m_fftLength, fftInput, NULL, fftOutputReal, fftOutputImag);
c@7:         
c@7:         //@todo: sample at logarithmic spacing? Leave for host?
c@7:         for(int k = 0; k < m_numberOfOutputBins; k++){
c@7:             spectrogramOutput[k][writeBlockPointer] = (fftOutputReal[k]*fftOutputReal[k] + fftOutputImag[k]*fftOutputImag[k]); //Magnitude or power?
c@7:         }
c@7:         
c@7:         readPointerBeginIndex += m_hopSize;
c@7:         writeBlockPointer++;
c@7:     }
c@7:     
c@7:     return spectrogramOutput;
c@7: }