void MedianSeparator::convertToSpectrogram()
{
// create STFT object to perform FFT
ScopedPointer<STFT> stft = new STFT(WINDOW_SIZE);
stft->initWindow(1); // initialise hann window
// 2d array to hold pointer to sample data
float* bufferData[2];
// 2d array of complex floats to hold complex spectrogram data after fft
std::complex<float>* spectrogramData[2];
for (int i = 0; i < 2; i++)
{
// initialise structures to hold audio data in different forms
bufferData[i] = new float[WINDOW_SIZE];
spectrogram[i] = MatrixXcf::Zero((WINDOW_SIZE / 2) + 1, numCols); // holds entire spectrogram
spectrogramData[i] = new std::complex<float>[(WINDOW_SIZE/2) + 1];
}
// loop through each column of spectrogram
for (int column = 0; column < numCols; column++)
{
// for each channel
for (int i = 0; i < numChannels; i++)
{
// get pointer to sample data
bufferData[i] = (float*)samples.getReadPointer(i, startSample);
// perform FFT
float* fftData = stft->performForwardTransform(bufferData[i]);
// convert from real to complex spectum data
spectrogramData[i] = stft->realToComplex(fftData, WINDOW_SIZE);
// fill column in spectrogram with complex data from FFT
for (int sample = 0; sample < 2049; sample++)
{
spectrogram[i](sample, column) = spectrogramData[i][sample];
}
}
// increment beginning sample by HOP_SIZE (1024)
startSample += HOP_SIZE;
}
}
